How much plumbing is to much for IC

[pk2]

I have a Porsche Boxster with an Eaton sc, quite a bit of plumbing. I’d like to add an a-a intercooler. The closest place would require about 4 more feet of tubing. Would this much pluming degrade the performance.

Does the intercooler do anything in itself or only allow you increase the boost?

Thanks, PK

[FormerDatsun510Man]

If it is a total of a 4 ft of plumbing I wouldn't think that is excessive, but just keep in mind that as long as you have the throttle body at the pre-blower position it adds to the throttled volume. Now, I am not sure about the Boxster's ECU, as it is probably a bit more sophisticated than the Miata's, but at least on the Miata, increasing the throttled volume degrades idle and low speed driveability. On my Miata Hotside setup I had to put a special low volume intake manifold to get the throttled volume back down after I added the air/air IC so that the car would drive as well as it did without the intercooler.

The intercooler in itself adds no hp, however it allows you to run more pulley (boost) and that is how you make more hp and torque. As far as intercoolers go, the lessons I have learned from the many I have tried is that, first of all, for the track, an air/water IC is pretty much as bad as having no intercooler. Secondly, when using an air/air IC the size is crucial. Go just a little bit too small in the core cross section area and it becomes a hp bottleneck. For Miatas, a core size of 8(height perpendicular to flow path)x16(width along flow path)x3(thickness) is about ideal. This causes air temps to get back down within about 20 deg F over ambient at the outlet of the intercooler, and can support up to around 300rwhp worth of airflow. With this setup I have found ping is no longer a problem at the track at high boost levels and the nice thing is it stays steady in power output as you push the car since the air temps are kept in check. Drawbacks? Besides driveability issues that you may need to overcome, it blocks the radiator. I have found that this hasn't given me problems at the track (I am running a PWR radiator), but it does give me overheating problems in the summertime when in stop and go traffic with the A/C on. I am going to try upgrading to more powerful fans for next summer.

I guess my point is there is a tradeoff. To get more power and torque that the air/air IC allows you to achieve you have driveability and overheating problems to address. Of course, it can be addressed, but in the end I found it cost me roughly double the cost of the original non-intercooled setup.

One note about the throttle location. Apparently there are some Miata Hotside owners that have moved the throttle body post-blower... like a turbo setup... and they are reporting favorable results. The advantage is that way plumbing and intercooler volume no longer adds to throttled volume. Requires a blowoff valve though. I could see this sort of thing working better on a car that uses a MAP based ECU rather than a MAF one.

Bill

[pk2]

If it is a total of a 4 ft of plumbing I wouldn't think that is excessive, but just keep in mind that as long as you have the throttle body at the pre-...first of all, for the track, an air/water IC is pretty much as bad as having no intercooler. Secondly, when using an air/air IC the size is crucial. Go just a little bit too small in the core cross section area and it becomes a hp bottleneck. ...With this setup I have found ping is no longer a problem at the track at high boost levels and the nice thing is it stays steady in power output as you push the car since the air temps are kept in check. Drawbacks? Besides driveability issues that you may need to overcome, it blocks the radiator. ...but it does give me overheating problems in the summertime when in stop and go traffic with the A/C on. I am going to try upgrading to more powerful fans for next summer.

I guess my point is there is a tradeoff. To get more power and torque that the air/air IC allows you to achieve you have driveability and overheating problems to address. Of course, it can be addressed, but in the end I found it cost me roughly double the cost of the original non-intercooled setup.


Bill

Hey Bill,

Thanks for the very insightful feedback. To thicken the gravey (appriate today) a few more variables to throw in to the equation.

1) The current setup is pretty primitive in that it uses a simple“ piggy back” AIC box that controls a 7th injector, using only a tach signal and manifold vac/pres for control. There Are more sophisticate AIC that can control timing, more prcice mapping, valve timing etc. Not sure how far I want to go in that direction.

2) The car has an 11:1 compresion ratio so the boost is limited to 5 psi. Detonation is DEATH to this motor.

3) It’s also mid engine and has precious few places to mount an IC… (ambient air flow) Thus the thought of w/a setup See pics

4) The throttle body is indeed on the cold side and probably has about 3.5 ft. to the sc. & the same back to the manifold. The 7th injector is right next to the intake manifold. Does the 7th injector negate drivability issues?

5) This is a daily driver , no track time as of yet. Drivability is an issue. As is passing So Cal. emissions (does now…sniff test anyway & the rt. tech. doesn’t even try to find the motor for a visual…)

With that said, do you stand by your O.K. with the added tube length (7th injector help)?
Will I need more boost just to accommodate the added plumbing?

For the intercooler I was just going by inlet/outlet tub diameter as a guide, match it with the hot side tube. Good nough’ or should I look for a unit from an engine of the same displacement?

As far as over heating, is that only due to blocking off the rad? The only places I’ve seen an intercooler mounted on these things are quite bizarre, trunk and under the trans.

http://img132.imageshack.us/img132/5485/ic1ar5.jpg
By kroak (http://profile.imageshack.us/user/kroak) at 2007-11-22
Under trans. (mid engine)Must have a scoop or somthing...thoughts?

http://img132.imageshack.us/img132/7360/ic2lz4.jpg
By kroak (http://profile.imageshack.us/user/kroak) at 2007-11-22
Trunk mount...don't get it, 1 tube, told it was a/w...or not...clues?

I gues w/a was intriquing because theres plent of room up front for a radiator (I gues)I guess my goal here would be to add a modest 30 odd hp bump, still pass smog,and absolutely eliminate possibility of detonation…wadaya think?

Thanks again for all your well informed insight.

Regards, P.K

[Tom @ Fast Forward]

PK,

If there is anybody at all that can answer your questions, Bill is the man. I am a great believer in AIC for both needed extra fuel and cooling of the charge air. We run one on all of our kits and they work extremely well.

I also agree with his assessment of the W/A IC. I had one when I had my hotside and tossed it. Chuck had one on his MP62 hotside and sold it off as well. The worst thing you will find with added throttled volume is a possible lag in throttle response with the onset of boost. Kind of like what turbo guys get.

Anyhow, I'll let you two get back to it. I'm sure Bill can help you immensly.

Happy Thanksgiving.

Almost forgot. With 11:1 compression do you have a way to pull a couple degrees of timing? If you can, you should. Especially in the higher RPM ranges.

[pk2]

PK,

If there is anybody at all that can answer your questions, Bill is the man. I am a great believer in AIC for both needed extra fuel and cooling of the charge air. We run one on all of our kits and they work extremely well.

I also agree with his assessment of the W/A IC. I had one when I had my hotside and tossed it. Chuck had one on his MP62 hotside and sold it off as well. The worst thing you will find with added throttled volume is a possible lag in throttle response with the onset of boost. Kind of like what turbo guys get.

Anyhow, I'll let you two get back to it. I'm sure Bill can help you immensly.

Happy Thanksgiving.

Almost forgot. With 11:1 compression do you have a way to pull a couple degrees of timing? If you can, you should. Especially in the higher RPM ranges.


Hello Tom,

Yes, bill does seems quite go-to-man, just the sort wealth of information I was looking for. Didn’t’ realize this was a Miata centric forum but I guess SC advice is fairly universal. Strange about W/A IC would be such a dud, Wonder why? Is it car specific? Water is a such a great conductor of heat. And it would fit my app. so beautifully. But I’ll take your word for it.

Throttle lag, hmm. Makes sense, bit disturbing though. Low end torque is where you really feel the boost, hate to loose that. But It suppose that could be offset by extra hp,

There’s a generic piggy back device from Perfect Power called an SMT6 which will hijack spark timing and run my 7th injector plus lamba tuning(??) and some other stuff I don’t need. It allows for mapping both spark and extra injector timing etc from a laptop. Not terribly pricy but I assume it would take a dyno to tune. No clue what that would cost and who could do it.

Thanks for the welcome,

Regards,

PK

[Tom @ Fast Forward]

I think the main problem with W/A IC is heat soak. The IC is typically sufficient but these little cars don't have a lot of space for the heat exchanger so it typically ends up too small. You can get the heat into the water but only get 90% out, for example. Then you have 81% (90% of 90%), Then 73% and so on. Pretty soon the water is as hot as the boosted air. If you had a 72 Buick, you would have room for a big enough one to work. :)

Are you familiar with Split Second? I have a couple of used ones of those you could have. They are AIC controllers. I think I still have one that is AIC and timing in one box. Yours for the asking. Our new PC-Pro Timing Card will probably do a better job if you have two coils (wasted spark) for the six cylinders.

[chuckerants]

My experience with WA IC is that it is heat soaked after ONE WOT run on the street. Since Tom and I both live on the surface of the sun, that was just not acceptable.

I installed the AW IC one Saturday at Tom's house and removed it at my house the next weekend. :(

[pk2]

I think the main problem with W/A IC is heat soak. The IC is typically sufficient but these little cars don't have a lot of space ... If you had a 72 Buick, you would have room for a big enough one to work. :)

Are you familiar with Split Second? I have a couple of used ones of those you could have. ...Our new PC-Pro Timing Card will probably do a better job if you have two coils (wasted spark) for the six cylinders.

Hi Tom.

Heat soak, that makes sense, so it is the application (or it’s breadth of it) that matters. My car is designed for a third optional radiator up front. Motors in the middle of the car so I’ve plenty of room to mess around up front. It’s in the vicinity of the SC that it gets really tight (thus my original post) and no good cool air flow


Would need to figure out how big a heat exchanger (radiator??) it would require… then figure out if it would fit…


“Heard of split Second”, as a matter of fact I have. Aside from them being in the next city over, they are the supplier (or were) of the AIC’s for the manufacturer of my set-up; (TPC). My current AIC is actually a crude precursor to the Split Second versions of the kit, it’s an analog ditty, tuned by twiddling 4 little pots on the front.

So would I be interested in your split second units YOU BET! Be nice little stepping stones, especially if one included timing. Let me at least handle the shipping & if I can reciprocate let me know! (I do this: krokodesign.com ...not much crossover but you never know )

My car actually has six coils, little boxes right on top of the plugs. You P.C pro card looks interesting. I think that’s the direction I ultimately want go.

Any, thanks a ton and I am certainly interested in your split second stuff and down the road a bit I’d sure like to learn more about the P.C. Pro timing card and the like.

Regards, Peter

[pk2]

My experience with WA IC is that it is heat soaked after ONE WOT run on the street. Since Tom and I both live on the surface of the sun, that was just not acceptable.

I installed the AW IC one Saturday at Tom's house and removed it at my house the next weekend. :(

I’m not sure if there could be a more damning affirmation. :) I live in So Cal. so ambient temp. is an issue here to. In fact my original reason to consider an intercooler was just preventive medicine for the summer… But, if I can cool it down enough, maybe I can raise the boost.

If you could fit it in, do you think a larger heat exchanger would be effective? My engines in the middle with very few places I can see that would get much air flow at all. Where as the front has scads of space and actually has mounts for a 3rd radiator.

Curious, why is the W/A component of that system so expensive? Is it that much different from an A/A unit in complexity?

Regards, PK

[Tom @ Fast Forward]

Email me your address. I'll get it off to you.

[FormerDatsun510Man]

Hey PK,

A/W IC systems are usually best for drag racing or short sprints of speed. It worked ok on the street for me, but not when I would push it hard for any length of time over about 30 sec :). I then had to wait a few minutes of easy driving for the water temps to come down and then it could work well again for another sprint of speed. I suppose theoretically if you can get a large enough heat exchanger for ambient air for the system, then I could see it working better... but it still won't match an A/A IC system in terms of cooling efficiency in the long term. Technically, the drawback to the A/W system comes from what is initially its benefit (water has a high specific heat capacity). You would have to have a much larger radiator, for the A/W system, compared to the size of the A/W IC core, in order to match the heat exchange rate at the IC core. This is because the heat capacity of water is much greater than that of air. Otherwise the water temps will just continue to rise higher and higher until it is heatsoaked. Even if the heat exhange rate of the radiator matches the IC core, the best post IC air temps you will see is about midway between ambient and the SC outlet. Intially, the post IC air temps can be much lower. This is why A/W systems are great for dragracing. In fact, for dragracing, it is common to ice them down so that below ambient air temps are possible (for 10 sec or so :D)... just long enough for the 1/4 mile. One other point, for the same reason that the water can absorb a LOT of heat from the air, it takes a much longer time for the water to cool back down again once it is heat soaked.

With an Air/Air IC system, the heat capacity problem is eliminated. Basically, the core is in direct contact with ambient (hopefully) air. Here, if the core is too small and thus heatsoaks, you will know in very short order :). Likewise, if it does heatsoak, it will very quickly become unheatsoaked if the sytem is allowed to cool down. Basically, the only mass that is absorbing the heat that is part of the system, is the metal of the IC core itself. This is the heat exchange medium to the outside air. The solution to the Air/Air IC system is to make sure the core is of the correct size (not just simply "large" enough, but specifically having the correct dimensions, length, height, depth). Once made of the correct size, the Air/Air IC system won't heatsoak and will not hinder power. Basically, the frontal area of the IC core determines the heat removal ability whereas the cross section (to internal airflow) area determines the CFM it can handle. It is important to get both of these dimensions as close to optimum as possible.

To answer some of your questions:

1) Should you simply get a Air/Air IC with the right size piping and not worry about the core size? Well, I wouldn't go about it this way. The piping size would perhaps get you close to right for the CFM requirements, but it won't tell you much if anything about the cooling requirements. Specifically, hp is analogous to CFM whereas hp x psi is closer to the heat requirements. You could have Car A that makes 400hp with only 5psi of boost that would have 2.5" pipes and a small core. Conversely, you could have Car B that makes 200hp but with 20psi of boost. The pipes on it may only be 2", but the core size would probably be about double that of Car A. The best answer to this is to determine the boost and hp level you are targeting your system at and find the closest size Air/Air IC that meets this target or better.

2) Will the 7th injector help with driveability issues posed by the increase in throttled volume with an Air/Air IC system? No. It will of course help make sure you have good a/f ratios (which are about the most important thing in a boosted setup). But as far as driveability is concerned, your most crucial thing is to try to keep that throttled volume down. However, along with this, good engine management works wonders. With the PC Pro, my Air/Air IC driveability has greatly improved. I think the best method here is to try to locate the Air/Air IC as close to the supercharger as possible, using ducting if necessary, and then use the best engine management solution you can. The engine management will be a discussion all its own :).

3) The pic you have of the Air/Air IC under the engine looks a little worrisome to me. It seems that the IC is exposed to road hazards this way. All it takes is a nice hole in that IC core and you will be in big trouble. Since the TB is located pre blower, this means you will have a huge vacuum leak at the road level... wouldn't be pretty. I would rather look at mounting the IC above the engine and use a scoop... like a Subaru. The nice thing with this is that since it doesn't block the radiator you won't have any cooling issues to worry about.

4) The Split Sec has a version that handles just fuel and one that handles both fuel and timing. They both allow you to program the maps (rpm vs psi).

5) I would use that extra radiator mount for something like an oil cooler :). That is, if you need to use it at all. Probably only something to consider for the track.

Hope everyone had a Happy Thanksgiving!!

Bill

[pk2]

Email me your address. I'll get it off to you.

Thanks again Tom,

Emailed info.

What do you think of that “under the transmission installation of an IC in my earlier post? Its part of a twin turbo install. I can’t see how it gets any airflow without a scoop or something. At best in it’s illustrated config, its just a heat sink?

Regards, Peter

[Tom @ Fast Forward]

Got the address. Too late today for UPS. it will go out Monday.

The "under transmission" question is best for Bill. My impression is that if it doesn't have a high flow of air through it, it is just added weight to the car.

The other question about the PC-Pro AIC card, it will work with a 6 cylinder engine. The main fuel card won't yet, unless they are batch fired 3 and 3. The timing card is in the same catagory. If there is just two coils, it will work. If three or more coils, no go.

Thanks again Tom,

Emailed info.

What do you think of that “under the transmission installation of an IC in my earlier post? Its part of a twin turbo install. I can’t see how it gets any airflow without a scoop or something. At best in it’s illustrated config, its just a heat sink?

Regards, Peter

[FormerDatsun510Man]

Peter,

As far as the under the engine placement of the A/A IC, I have no experience putting them there, but to me it seems like a hazardous spot to put it. All it takes it one road hazard, large rock or some other object going under the car, and you could punch a nice hole in the intercooler. Then you would have a big vacuum leak (since the throttle on a supercharged setup is pre-blower) and could suck up whatever happens to be on the road at the point. Wouldn't be pretty :). Besides that, it is perpendicular to airflow so you would need fans above it and preferably a scoop below it to get the air through it. However, a scoop below it would probably be scraping on the ground. I think a better solution would be to mount the A/A IC above the engine and use a top mounted hood scoop, like a Subaru WRX. Top mount A/A IC are not as efficient as a front mount, however, I think in the mid-engine setup on your Boxster you really don't have much choice. The good news is with over 11:1 CR you probably wouldn't want to go much over 10psi boost anyway, so the A/A IC doesn't have to cool as much as say a 15psi setup :). The other solution would be to mount the throttle body post supercharger at the intake manifold (like a turbo setup) and run a front mount A/A IC at the nose of the car where that extra mount is located. This would be a bit more expensive and there would probably be bugs to work out in the system. You would need a lot of piping and a blowoff valve, along with possible changes to the engine management.

Bill

[pk2]

Peter,

As far as the under the engine placement of the A/A IC, I have no experience putting them there...The other solution would be to mount the throttle body post supercharger at the intake manifold (like a turbo setup) and run a front mount A/A IC at the nose of the car where that extra mount is located. This would be a bit more expensive and there would probably be bugs to work out in the system. You would need a lot of piping and a blowoff valve, along with possible changes to the engine management.

Bill

Bill your awesome!

I’ve got to go over your replies with a highlighter. before I pepper you more and further mine your brain.

One general thought I had, I wonder if there were some approximate equations or tables that I could plug in all the variables into (PSI, Displacement, compression ratio, tube diameters, etc) to get a fair approximation of what I need IC wise. THen maybe up it a notch...play it safe.

Anyway, I’ll have a well researched reply shortly.

I hope you had a good thanksgiving too, had two in as many days myself and the wives got a birthday tomorrow…

Thanks again & again, Peter

[FormerDatsun510Man]

I feel a little ignorant about the Boxster at the moment :). At closer inspection I notice it has ducts in front of the rear wheels on each side. Is one of these for the radiator and the other for the optional additional radiator, oil cooler, etc? If so, that would be the perfect place to put an air/air IC. With that sort of setup the plumbing would be short enough that I think you could run the MP62 the conventional way, with the throttle blower pre-blower, and have good driveability. Besides, the snorkel above the engine idea doesn't seem like it would have good airflow unless you had a crazy looking one that went higher than the roofline LOL.

Anyway, if you have any pics of your current supercharger setup and also of the engine bay it would be very helpful in me giving recommendations, ideas, etc.

Bill

[pk2]

I feel a little ignorant about the Boxster at the moment :). At closer inspection I notice it has ducts in front of the rear wheels on each side. Is one of these for the radiator and the other for the optional additional radiator, oil cooler, etc? If so, that would be the perfect place to put an air/air IC. With that sort of setup the plumbing would be short enough that I think you could run the MP62 the conventional way, with the throttle blower pre-blower, and have good driveability. Besides, the snorkel above the engine idea doesn't seem like it would have good airflow unless you had a crazy looking one that went higher than the roofline LOL.

Anyway, if you have any pics of your current supercharger setup and also of the engine bay it would be very helpful in me giving recommendations, ideas, etc.

Bill

Hi Bill,

I’ll try to post some pic’s here today, thought that would be a good Idea my self .

Perfectly reasonable thought. The drivers side is the air intake for the induction system. The right side though has some potential, its just a fan that blows across the motor. It’s nicely situated near SC plumbing to.

However, The engine bay is pretty well optimized. It would only fit a small 9x9x3 IC (at most) IC and would require the air pump to be repositioned and a much thinner profile fan to be cobbled in there. Plus, I don’t know how hot the IC gets but, if significant, it might not be great blowing hot air across the motor. I keep revisiting it though.

The really beautiful place would be the trunk but this would require hacking into the firewall for tubes and the wheel well or floor for air. Pretty anxious about that butchering the thing up.

I’m trying to figure some equation that I could determine the optimal tube length and IC size. So far it’s voodoo to me.

Thanks for your thoughts,

Regards PK

[fourwhls]

Peter,
Have you ever concidered water/meth injection for intercooling? Just seems to be a much simpler solution for your application.

[Steve]

Hi Peter,

Having seen the insides of a Boxter, I'm impressed someone could fit anything else in there!

http://img132.imageshack.us/img132/5485/ic1ar5.jpg

The box with the braided lines is a scavenge pump for the (twin)turbos on this car: they are mounted quite low so they won't drain by gravity. Where that intercooler is mounted is the lowest point under the car so it would get destroyed by the first bit of road debris (track curb, rock, small animal, etc.) that you drove over.

Here's an alternate opinion: for the relatively low boost you will be running, combined with the rather large water capacity you can carry (a front-mounted I/C water radiator and piping will hold a lot of coolant) I think an A/W cooler may be an option for you.

I see you're in The O.C.... my shop is in the City of Orange. I'd love to see the installation on your car: if you can drop by sometime I'd be happy to put your car on my lift and we can see what can fit where.

[pk2]

Peter,
Have you ever concidered water/meth injection for intercooling? Just seems to be a much simpler solution for your application.

Hi,

I’ve thought a bit about the meth/H20 option but I don’t know much about it. At this point I’m focused on an intercooler route just because it can be set it up once, presumably, and forgotten about it.

As it is , I have to make a home brew out the best of our pumps & race fuel just to get 93-95 oct. Having another brew to concoct and monitor isn’t to appealing at face value. Saw one get-up that was pretty pricey, though I once heard you could use straight water)

If you have time, please enlighten me.

Thanks, Peter

[pk2]

I feel a little ignorant about the Boxster ...

Anyway, if you have any pics of your current supercharger setup and also of the engine bay it would be very helpful in me giving recommendations, ideas, etc.

Bill

Hi,

These are pics are of a system the same as mine. It’s probably not clear whats going on, but its worse when the things installed & the plumbing is pretty well hidden. I’m on a deadline right now, but I’ll get a few more up as soon as I can (weekend).

Just remember it’s a flat six with a giant spider of an intake manifold on too. The SC is tucked down with the head and exhaust manifold, I’ve also attached a pic of the motor/sc installed…tight fit

Regards, Peter

P.S. The tubes in the 2 exposed pics are just sort of hanging in place


http://img401.imageshack.us/img401/4774/dscf08x6fz9.jpg
By kroak (http://profile.imageshack.us/user/kroak), shot with FinePix2800ZOOM (http://profile.imageshack.us/camerabuy.php?model=FinePix2800ZOOM&make=FUJIFILM) at 2007-11-27
Actually the back of the motor...confused?


http://img508.imageshack.us/img508/9757/dscf98x6gk7.jpg
By kroak (http://profile.imageshack.us/user/kroak), shot with FinePix2800ZOOM (http://profile.imageshack.us/camerabuy.php?model=FinePix2800ZOOM&make=FUJIFILM) at 2007-11-27
SIde veiw of the beast


http://img401.imageshack.us/img401/4612/installzg1.jpg
By kroak (http://profile.imageshack.us/user/kroak) at 2007-11-27
Not much to see installed

[FormerDatsun510Man]

One thing I notice is the custom outlet manifold on the M62 supercharger is not very efficient. It is a flat plate with a pipe welded in the middle of it. That has got to be costing you hp. For example of a more efficient outlet manifold, check out the Hotside kits here.

Another thing I notice is the repositioned throttle body is costing you a lot of unneeded throttled volume. I'm not sure if it was put there because of space requirements, available throttle cable length, etc., but moving it closer to the blower would lower the throttled volume. Your kit is using the M62, the later MP62, which is what the Miata kits use, has an internal bypass, and the throttle body is mounted right on the blower. Of course, there are other kits using the MP62 that mount the throttle body further away from the blower, but I haven't seen any with as much piping as the kit there for the Boxster.

One Boxster noob question, what is the black hose connecting from the intake pipe to the blower (between the TB and blower)? It looks like it connects to some sort of valve and chamber near the intake manifold to the engine?

Looks very cramped in there, though the outlet pipe from the supercharger would be perfect for a PWR barrel style A/W intercooler. I suppose if you use the largest barrel you could fit in there and perhaps dual radiators mounted up front somewhere, you could have a decent A/W intercooling system... as long as you keep the boost somewhat low (8-10psi max). However, water injection is looking pretty attractive for your setup, though I am not a fan of it. Water injection would allow you to run a similar increase in boost as the A/W intercooling system, but the advantage would be it would weight less, since you wouldn't need to plumb in so much water lines. It also wouldn't heatsoak :). The disadvantages are that it requires that you stay on top of keeping the water tank for the water injection system filled, if the nozzle gets clogged you are in trouble (solution is to clean the nozzle at regular intervals) and it requires a bit of tuning to get it right. An A/A IC would be ideal, but I don't see any room in there for one and I definitely WOULD NOT mount one like in the pic you attached, under the car. There is a book I have seen for modifying the 911 that showed an Eaton M62 setup on a 911 using an A/A IC. They mounted the intercooler in the wheel well area and put a cover over it to protect it. Not sure if you have any room there on your Boxster though. The only other place that seems reasonable to me to put an A/A IC is on top of the engine. This would probably require a new hood for the engine and perhaps a big snorkel for ducting. I would definitely put powerful fans behind (below) the intercooler. Doing that you might be able to get away without the snorkel and simply have the engine hood vented sufficiently. However, I think it most likely will still require a different hood than the factory one for clearance.

Bill

[FormerDatsun510Man]

One other thing, regarding the sizing of the piping, intercooler etc. A data point with same size blower for the Miata is the following:

IC pipe size: 2.25"
Air/Air IC core size: 3"x8" cross section, 16" across
TB size: 70mm

With this size it supports running the MP62 blower up to 16K rpm and 20psi without causing a loss of power from being undersized. This max setup results in around 280-300rwhp on a Miata. The difference with the Porsche is that you have more flow on the engine side, so boost will be lower and rwhp will be higher at the same blower rpm. I wouldn't recommend running the blower past 16K (and in fact with the older M62 it might be better to run 14K max). So, in short, the max rpm on the blower for your setup will be the same as for the Miata kits, just with lower boost. This would mean that the same number of air molecules coming in on the inlet side of the supercharger will take up more space on the outlet and intercooler side. Thus you would probably want slightly larger pipes and IC core cross section for your application. How much larger would depend on the difference in boost your setup would see at the same blower speed as on the Miata setup. I could give you that answer if you tell me the following pieces of info on your setup:

1) what is the pulley ratio (engine pulley driving blower divided by the blower pulley size)
2) what is the max rpm of your engine
3) what boost does your setup see at engine redline

Bill

[FormerDatsun510Man]

Intuitively I think 2.5" pipes and going with a core cross section of 4"(thick)x8"(height) would be the about right. Since the boost would be lower on your setup the width of the IC could be less than 16"... less heat to remove. This is the IC dimension I reduce since your setup is limited in space. A core width in the 8" to 12" range would still have decent efficiency.

Bill

[pk2]

Hi Peter,

Having seen the insides of a Boxter, I'm impressed someone could fit anything else in there!

http://img132.imageshack.us/img132/5485/ic1ar5.jpg

The box with the braided lines is a scavenge pump for the (twin)turbos on this car: they are mounted quite low so they won't drain by gravity. Where that intercooler is mounted is the lowest point under the car so it would get destroyed by the first bit of road debris (track curb, rock, small animal, etc.) that you drove over.

Here's an alternate opinion: for the relatively low boost you will be running, combined with the rather large water capacity you can carry (a front-mounted I/C water radiator and piping will hold a lot of coolant) I think an A/W cooler may be an option for you.

I see you're in The O.C.... my shop is in the City of Orange. I'd love to see the installation on your car: if you can drop by sometime I'd be happy to put your car on my lift and we can see what can fit where.
Hello, sorry for the delay. Just finished project with a bruising deadline. I may well take you up on that lift offer. I have to run over to orange to my high(er) octane fuel brew “clinic” in a few days.

Regards, Peter

[pk2]

One thing I notice is the custom outlet manifold on the M62 supercharger is not very efficient. It is a flat plate with a pipe welded in the middle of it. That has got to be costing you hp. For example of a more efficient outlet manifold, check out the Hotside kits here.

Another thing I notice is the repositioned throttle body is costing you a lot of unneeded throttled volume. I'm not sure if it was put there because of space requirements, available throttle cable length, etc., but moving it closer to the blower would lower the throttled volume. Your kit is using the M62, the later MP62, which is what the Miata kits use, has an internal bypass, and the throttle body is mounted right on the blower. Of course, there are other kits using the MP62 that mount the throttle body further away from the blower, but I haven't seen any with as much piping as the kit there for the Boxster.

One Boxster noob question, what is the black hose connecting from the intake pipe to the blower (between the TB and blower)? It looks like it connects to some sort of valve and chamber near the intake manifold to the engine?

Looks very cramped in there, though the outlet pipe from the supercharger would be perfect for a PWR barrel style A/W intercooler. ... However, water injection is looking pretty attractive for your setup, though I am not a fan of it. Water injection would allow you to run a similar increase in boost as the A/W intercooling system, but the advantage would be it would weight less, since you wouldn't need to plumb in so much water lines. It also wouldn't heatsoak :). The disadvantages are that it requires that you stay on top of keeping the water tank for the water injection system filled, if the nozzle gets clogged you are in trouble (solution is to clean the nozzle at regular intervals) and it requires a bit of tuning to get it right. An A/A IC would be ideal, but I don't see any room in there for one and I definitely WOULD NOT mount one like in the pic you attached, under the car. There is a book I have seen for modifying the 911 that showed an Eaton M62 setup on a 911 using an A/A IC. They mounted the intercooler in the wheel well area and put a cover over it to protect it. Not sure if you have any room there on your Boxster though. The only other place that seems reasonable to me to put an A/A IC is on top of the engine. This would probably require a new hood for the engine and perhaps a big snorkel for ducting. I would definitely put powerful fans behind (below) the intercooler. Doing that you might be able to get away without the snorkel and simply have the engine hood vented sufficiently. However, I think it most likely will still require a different hood than the factory one for clearance.

Bill


Hi, Bill

Sorry for the delay in getting back to you, self employed, deadlines you know.

That bent, flattened pipe is also a royal pain get in and probably restrictive. (You’ll also notice the pipes been beaten to fit, mine an I know many other are to) It would be a cinch to install and not have to be flattened out if it were more “S” shaped. This would require a slightly longer tub…Think it would be a good trade off?.

I like the idea of h2o injection. Is this something that would actually allow for a boost increase (current 5 psi with11:1 compression) or would it be a a safe guard against detonation.

What’s the mpg of h20? I assume distilled water? Also, how involved would retuning be? Could it be done with a good AIC and with passenger laptop/software interface and a wideband f/o gauge while I romp around highways abd byways or does it need a dyno? Also, what’s the mpg of h20?

As to the over the engine solution, just no room, even with mods. The convertible top tucks in right on to of the engine hatch. The wheel well is something that I’ve pondered and been intrigued by. Lots of other solutions seem to be borrowing heat off the engine. This (wheel well) would seem to ensure ambient air probably n fan. Might require some butchering that I’m not to keen about though/

Thanks for your continued interest,

PK

BTW, I believe that is an M45 with 2 inch tubes.

O Ya, Noob question, (I'm the noob here) I think your talkng about a sort of cut of valve that cuts of the blower when you don't need it...dosn't sound right... you probably need to elaborate..

[FormerDatsun510Man]

You have to be running an M62 not M45, because the M45 runs out of steam on Miatas at about 170rwhp (almost 200 crank hp). This means on the Boxster 2.5L engine, you probably wouldn't even be able to make boost with the little M45. More specifically, with a 1.8L engine, if the M45 is spinning 1.9X the engine speed it makes about 5psi boost. To make that same 5psi boost on a 2.5L engine would require it to spin at 2.6X the engine speed. On your Boxster, which redlines around 7000rpm, this would put the blower at over 18000rpm!

Mpg of water injection? Actually, the better way to look at it is the ratio of water to fuel. Generally, you set them up to have around 15:1 fuel:water ratio. This means when you go through 15 gallons of fuel, you would use up 1 gallon of water. However, that is at WOT (wide open throttle). Water injection generally doesn't come on until about 5psi and above, so how much water you use becomes more a function of how often you are in boost. Water injection does give you a safe guard against detonation, but this same safe guard is what allows you to run more boost with it. Generally, you can boost about 2-4psi higher when running it. IMHO, it is not as good as using an Air/Air intercooler... which you can basically run the blower to its limits with. However, it will give you a nice power boost and in your application it might be your only choice. Though it sounds like taking it to the shop in your area to have a look at it would be a great idea. Maybe they will find an efficient place to put an intercooler. Anyway, when I was running water injection, I used the windshield washer bottle as the water source and found that I needed to fill it up, with distilled water, every other gas stop. I would check it more often than this though because you don't want to run out of water! If you do, the water pump needs to be reprimed and also, more importantly, during boost you won't have the safeguard of the water injection. If you are running more boost, because you have water injection, this can be a very, very bad thing! Like no more engine, bad thing! :) With water injection, the tuning of the engine is the same except you generally run a leaner a/f ratio. Without WI, you would run an A/F ratio of about 12:1 on a supercharged setup. With WI, you would want to lean it out to closer to 13:1. Exactly the right A/F ratio would require some experimentation. To further compound the tuning, anytime you change the amount of water injected (by changing jet sizes or, if you have it equipped with programmable WI, changing the WI maps) you have to readjust the fuel. I definitely recommend a dyno for this.

As far as the blower outlet, yes anything you can do to change the design from that flat plate with a pipe at 90 deg coming out of it would be an improvement IMO. Going with an S shape would be fine as long as you use mandrel bends.

Bill

[pk2]

Hey Bill,

I’ve poured over all your post and those of others and H20 injection seems pretty appealing. I’ve thought myself through all the scenarios in what turned out to be a three page post (I spared you this time… but I’ll post it if you want though!).

You wrote I could probably set a safe extra boost of about 2-4 psi with just WI. Assuming I’ve gone from 200hp to 275hp (approx) with a 4.5 psi boost (approx), do you have any idea approximately what that would 2 PSI increase would correspond to in added hp? (Straight linear math says I’m getting about 16 hp per 1 psi…thus 33hp increase).

Next question would be, how do I calculate the new sized SC pulley to get 2 more PSI.

The next obvious question would be how to calculate the H2O needs to tune its injector? Would this be done in conjunction with tuning the 7th injector AIC with a wideband 02/fuel
Meter?

Can the O2 injector be set to start firing at any PSI ( you said 5 PSI, I’d be more comfortable at 4.5)?

And last but not least, It sounded like you sort of cobbed a WI system together, if so, with what components?

Thanks, Peter

[FormerDatsun510Man]

Your power increase estimate is reasonable. Of course, there will be adjustments because as the blower spins faster and at a higher boost psi it consumes more hp to drive the pulley. A really basic power increase estimate for boost is to use the pressure ratio X stock hp = boosted hp. In other words:

for 4.5psi boost and a 200 stock hp engine:

200 hp * (4.5+14.7)/14.7 = 261 hp (boosted)

if you were to increase this to 6.5psi:

200 hp * (6.5+14.7)/14.7 = 288 hp (boosted)

So by this method we get approximately an extra 27hp for a boost increase of 2psi.

The pulley size to run depends on what your current pulley sizes are :). I can tell you the percent change in size for the pulley though. It is simply the ratio of the absolute pressures. In other words it would be (6.5+14.7)/(4.5+14.7) = 1.1. So that would mean you would either need to add 10% to the diameter of the crank pulley on the engine side or reduce 10% from the supercharger nose drive. I recommend not going smaller than 65mm on the supercharger nose drive pulley because you might start to have issues with belt slip with smaller nose pulley. In that case you would be better off adding to the size of the crank pulley driving the blower.

Aquamist has a lot of information about sizing for the water nozzle. It basically calculates to 15% of your total fuel. The nozzles are rated by cc. Likewise your fuel injectors are rated by cc for flow. So if you take your fuel injector size x number injectors x 15% you will get a ballpark water injector nozzle size to get. For example, if your fuel injectors are 300cc, this would calculate to:

300cc x 6 x 15% = 270cc

The actual size nozzle to get can be gathered from this chart:

http://www.flyinmiata.com/index.php?deptid=4534&parentid=0&stocknumber=05-36030%20%20.4X4MM

270cc = .7mm nozzle ... for this example. Of course, I would also recommend you get one size larger and one size smaller so you can experiment. The experiment is basically that you want to run the smallest nozzle size without getting any knock during boost. Of course, you want to be VERY, VERY careful with knock. To sense knock it is best to use an electronic means rather than your ears. For example, I use a scan tool in the OBDII port. By watching the ignition timing degrees I can tell when the factory knock sensor is detecting knock. Better yet, you can run it on the dyno and see which nozzle works the best.

There are basically four different Aquamist WI kits which you can read a little bit about here:

http://www.flyinmiata.com/index.php?dept=66

The 1S is the simplest version in that it simply switches the water on or off at a given manifold psi. The psi is adjustable on the pressure switch it uses. The drawback with this method is that at mid rpm you will have to inject basically too much water to ensure you have enough water at redline. Thus mid range torque will suffer a little. Also, since you are having to inject too much water most of the time when in boost, you will find the rate of water consumption will be higher.

The 2D ties the fuel directly with the fuel injection signal. This is the one I would get. Since the correct amount of water to inject is in proportion to the amount of fuel injected, this takes all the trial and error work out of having to make your own maps if you use the 2S or 2C systems. Additionally, the fact that it can detect a clogged nozzle is VERY USEFUL in my opinion.

I would buy one of these brand new systems rather than trying to cobble something together like I did. Water Injection is pretty sophisticated and requires a special high pressure pump, stainless fittings, etc. Going with something less sophisticated can invite trouble down the road. WI is something that you don't want to fail.

A few other notes based on what I have found on WI and also with our MP62 setups. First of all, for placement of the WI nozzle it is most efficient to put it in the intake manifold, post-blower. I tried both pre and post blower locations and even tried with two nozzles (one pre and one post). I found simply putting the nozzle at the post blower location worked out the best. Secondly, make sure you get the WI kit with a checkvalve. Supercharged setups need this, otherwise the vacuum when not boosting will suck more water in when you don't need it and the engine will stumble like crazy. Thirdly, limit max blower rpm to 14000 for max safety, though you can go to 16000 if you really want to go all out. Your Boxster is has a redline of 6700rpm, so this works out to a 14000/6700 = 2.09 pulley ratio. I know with that same 14000rpm on a Miata it works out to 13psi of boost (27.7psi absolute pressure). For the Boxster I estimate that would yield 1839cc/2480cc * 27.7psi (absolute) = 20.5 psi (absolute) ~ 6psi. In other words, you will probably have to spin the blower past 14000rpm to get that 6.5psi. If you went all out, 16000/6700 = 2.39 pulley ratio. Estimated boost would be 1839cc/2480cc * 27.7 psi (absolute) * 16000/14000 = 23.5 psi (absolute) ~ 9psi. So, in short, spinning the blower at its 100% safe rated max rpm would yield about 6psi. If you ran it to the absolute max rpm that would be "somewhat safe", but will likely shorten its lifespan, you could squeeze about 9psi out of it.

I can understand why APC choose not to run an intercooler. With the M62 sized blower, the amount of boost you are looking at it somewhat limited... with the smallest of the Boxster engines (2.5L) you are looking at 9psi max (and overspinning the blower). With the larger engines engines, the M62 wouldn't even be able to make much more than 5psi even spinning to its limit. At these sort of boost pressures, intercooling isn't needed. In fact, on Miata we find we can run up to about 7psi before any form of intercooling is necessary (whether it be WI or an air/air IC). However, I suppose there is a reason APC chose 4.5psi for your kit in its standard form. Thus, since you want to run more boost than this, WI is probably a smart idea. Especially when one looks at the cost of a replacement Porsche engine :).

A nice side effect of WI is that it basically steam cleans your intake manifold, valves and combustion chambers. It also improves fuel economy because you can basically run a leaner a/f ratio since the water is being used for cooling instead of extra fuel.

Bill

[FormerDatsun510Man]

One thing I neglected in the calculation for the water nozzle size is the fact that you have a 7th injector. Be sure to add this fuel injector size to the other six to determine the water nozzle size to go with. I would still recommend that you use the signal for one of the six main injectors to run the water injection (if you go with the 2D).

Bill

[pk2]

One thing I neglected in the calculation for the water nozzle size is the fact that you have a 7th injector. Be sure to add this fuel injector size to the other six to determine the water nozzle size to go with. I would still recommend that you use the signal for one of the six main injectors to run the water injection (if you go with the 2D).

Bill

Hey Bill

Thanks as always for your insight, I’m on another deadline but I think I understand much of what you saying. In short, putting together a system is just simple math with right variables plugged in.

I looked at the Aquamist stuff and also looked on ebay. One thing stuck out on ebay was that most systems are alcohol/water. Can I get away with just water? I’ve lot more I’d like to clarify but I’ve got to get back to the drawing board right now.

Thanks again,

Peter

P.S. Thanks for reminding to put the 7th injector into the equation.

[pk2]

One thing I neglected in the calculation for the water nozzle size...(if you go with the 2D).

Bill

Ok Bill, I'm taking a break...

Does the water injector, fire every time the each injector fires (6 time per rev)? If so, how do you consolidate there signals (or do they spray all the time)

“First of all, for placement of the WI nozzle it is most
efficient to put it in the intake manifold, post-blower.”

I’ve got quit a long run from the SC to the manifold. The easiest place in fact to place the wi injector would be directly into the front intake of that “spider” intake manifold (see pixs). The sc install required the removal of a hose which is subsequently capped. Is that to close to the injectors and the like?

“However, I suppose there is a reason APC chose 4.5psi for your kit in its standard form. Thus, since you want to run more boost than this, WI is probably a smart idea.”

Ya, I’ve wondered why they set that limit (4.5), could it be the 11:1 compression ratio? (I’m going to guess the Miata is lower). So 4.5 is really where I’d like the water to kick in, hopefully mitigate whatever scared TPC off from going higher (M62 limitations not withstanding).

Regards, Peter

P.S. What do you think of this, theres one on ebay http://www.activeautowerke.com/cooling/main.php#wi

[fourwhls]

pk2,
Take a look at other kits also. 95% of the people using WI are using something other than Aquamist. Aquamist is top quality, but it also comes with the price tag.

I am running a progressive system made by AEM. I paid $350 for it and it came with everything I needed except for a check valve. There's not a lot of information about the AEM kit on the web, but one of my local shops swear by them and had one in stock for me to put my hands on.

Other companies such as cooling mist (http://www.coolingmist.com/), devils own (http://www.alcohol-injection.com), snow performance (http://www.snowperformance.net/), and I'm sure there are more that I have missed.

All of these companies offer a progressive rate systems that require soley on boost pressure. You set the controller to start spraying at 20-25% of your max boost and also tell it what 75% of your max boost is. It ramps up the amount of fluid injected accordingly. From 75% up you will be injecting maximum capacity.

Hope this opens a few more doors for you.

Shawn

[FormerDatsun510Man]

Progressive rate isn't bad, it is better than the on/off switch of the more basic WI setups. However, it still doesn't vary it with rpm. Well, to clarify, on a supercharged setup it does somewhat vary with rpm since boost climbs fairly linearly with rpm on a supercharged setup. However, it still isn't as good as the something like the Aquamist 2x series systems, which have the water injection pulse like a fuel injector. With a progressive rate, you get closer to the amount of water you need, but you still are are not going to be able to have it at the ideal air to water ratio throughout all rpm. To elaborate:

On my supercharged setup I see the 10psi at 4000rpm and 13psi at 7000rpm at WOT. First, lets look at what the ideal amount of water to inject would be. The best way to figure this out would be based on the amount of fuel being injected for these two cases. Let's suppose that at 13psi and 7000rpm, it is 1000cc/min. The actual number really doesn't matter, as you will see, I will be illustrating how the ratio changes. So the question is, how much fuel would be injected at 4000rpm? A reasonable estimate would be:

4000rpm/7000rpm * (10psi+14.7) / (13psi+14.7) * (amount of fuel at 7000rpm and 13psi) = .51 * 1000cc/min = 510cc/min

So, this means that we need 510cc/min or 51% the amount of fuel at 4000rpm and 10psi than what we would need at 7000rpm and 13psi. Now, let's look at the water to fuel ratio for these two cases with the various WI systems in place. With a simple on/off non-progressive setup, if we set it so that the water to fuel ratio is 15% at redline, this would mean we would be injecting:

1000cc/min * .15 = 150cc/min

This works at great at 7000rpm, however at 4000rpm we are injecting the same rate of water since we cannot control it. The water to fuel ratio at 4000rpm would be:

150cc/min / 510cc/min = 29%

So this means at 4000rpm, the water to fuel ratio jumps to a rather high 29%. Engine power would most definitely suffer. A solution would be to "lean" out the water to fuel ratio. Perhaps we would run it so we have 10% water to fuel at 7000rpm, which would give us 20% water to fuel at 4000rpm. The sacrifice here would be less cooling at high rpm, so that it runs better at mid rpm. Better, but far from ideal.

The next step up would be a progressive rate. This would vary the amount of water based on manifold pressure. Again, let's suppose we tune it so at 13psi and 7000rpm the system yields 15% water to fuel ratio. So we would have 150cc/min of water at 7000rpm. For the setup that Shawn describes, it would work the same as the non-progressive (since 10psi is greater than 75% of 13psi). It would give us better driveability at lower boost psi and rpm though since it would reduce the amount of water under those conditions.

The next step up is a programmable system or one tied to echo one of the main injector signals, using a fast-action valve to control the amount of water injected by pulsing it like a fuel injector. With this one could program it to inject a steady water to fuel ratio under all boosted conditions for optimum power and control. The one that echos one of the main injectors would be the simplest way to go.

I guess it comes down to what you wish to spend. For a $350 budget, the setup Shawn mentions (progressive) would be good. However, if you wish to go to a higher budget in the $1000 range, you can run a fully programmable WI system that would give you better water to fuel control.

Peter, that system you linked to looks good, but it is a non-progressive system from what I can tell and costs as much as the Aquamist 2D system that would give you a better water to fuel ratio. Also, the Aquamist water pump is probably the best one out there. Not trying to be an Aquamist weenie :), but it is known they are the highest quality WI systems out there.

One other thing, you can run alcohol/water or just water in these systems. Either way, always use distilled water.

Bill

[pk2]

pk2,
Take a look at other kits also. 95% of the people using WI are using something other than Aquamist. Aquamist is top quality, but it also comes with the price tag.

I am running a progressive system made by AEM. I paid $350...All of these companies offer a progressive rate systems that require soley on boost pressure. ...

Hope this opens a few more doors for you.

Shawn

Hello Shawn,

Thanks for the heads up on the Aquamist. They are a bit pricy. I did go to ebay and learned about some of those other brands you mentioned. They seem to go for about $200-250 for progressive setup. Most are sold as methanol/water. I assuming just water would be effective with different tunening. (I already have to mix my fuel to get 93+oct and don’t really feel like mixing the water to.)

The reasonable priced ones I saw run the injector based on vacuum/pressure. I suppose that’s good enough. But it would seem a signal off the injector would be nice…but the price.

Food for thought, Looks like bills served me up a hearty dose of wisdom below…much to think about I’m sure.

Thanks for the input

Regards, Peter

[pk2]

Hey Bill,

Still working to make my deadline so just a few quick points peculiar to my car. My car can give me full boost at 2500 RPM according to my $30 boost gauge. I’ve heard, and the seat of my pants confirms, that the Benefits of the sc disappear at 5-5.5k RPM’s. I think it’s just plain Boxster from there up to red-line.

I certainly like the price on the progressive setups but I’d have to re-read your critique in depth when I have a little more time. One point is that for 95 percent of my leadfoot driving, I don’t linger at any partial boost for very long.

I did do some research on that link I gave you after a bit of research, learned the meaning of “progressive” . I researched the components and functionality it a bit… you were polite, it’s a Rip off.

I’m always on to improvise and I wonder, Tom turned me on to a ”Split second” (SS) AIC for a Miata. Runs of vacuum/pressure and tach to run a 7th injector. Was hoping I could use it on my Boxster but SS says no. It is programmable with a PC & software. I wonder if it could drive a H20 injector.

Anyway, got to get back to work, hoping to be in bed by 2:am..

Regards, Peter

P.S. Really weird, on the right street, I can be rolling along at 10mph in first, stomp on it and the rear breaks loose. And that’s not all….

[fourwhls]

Peter,
Methanol/Water is the easy way out believe it or not. You use the cheapie -20* Windshield washer fluid. It's usually less than $1 at your local autoparts store.

The 20-30% Methanol in the mixture will add an octane boost to your air/fuel mixture. It can benifit you in one of two ways. You can run more boost due to the higher octane level or you can run lower/same boost and forgo on the trek to get 93+ octane and just use the local premium.

You also get the bonus of blue spark plug tips and a blue tint on the top of your pistons, that are carbon free because of water injection BTW.

[FormerDatsun510Man]

Peter,

Do you know what the pulley ratio (or the diameter of the pulleys on the engine crank and the supercharger nose drive) is on your setup? If the supercharger is not overspinning (past 16000rpm) power should not drop off at high rpm. Also, boost should climb all the way to redline. I guess what you are mentioning about the street performance is SOTP though :). If you haven't yet, I strongly suggest you bring your Porsche to a dyno to get a baseline set for it. This will accomplish a number of things:

1) make sure you have it currently tuned to a safe a/f ratio
2) make sure the power and torque curves are optimized and the car is running right.... before trying to make modifications
3) indicate if there are any current limitations that would make pushing the supercharger to higher boost levels counter-productive

All three of these are important, but I am thinking #3 might be particularly important for you right now. For example, if, even tuned to the optimum, it currently hits power peak at say 6000rpm and it drops pretty quickly off from there to the 6700rpm redline... then going to a higher boost pulley will likely be counter-productive. The reason being, once the power starts taking a nosedive this means the blower is past its efficiency. Running the blower at an even higher pulley ratio (more blower rpm per engine rpm) would likely gain you low and midrange torque.... but at the expense of high rpm power loss. But to determine if this is a "problem" or not, really requires one to go to the dyno with the baseline test. Then you can see if you think it is likely a faster pulley would be the direction you want to go. Additionally, if you do go to the faster pulley you can then run it again on the dyno and quantify the gains. It isn't cheap on the dyno, but my experience is it is the best money I have ever spent on my supercharged setup. Also, it saved my original engine early on when I had the kit and didn't realize until I got to the dyno that the a/f ratio was leaning out to the tune of 14:1 at 7000rpm. That wouldn't have been pretty at the track! :)

Bill

[pk2]

Peter,
Methanol/Water is the easy way out believe it or not. You use the cheapie -20* Windshield washer fluid. It's usually less than $1 at your local autoparts store.

The 20-30% Methanol in the mixture will add an octane boost to your air/fuel mixture. It can benifit you in one of two ways. You can run more boost due to the higher octane level or you can run lower/same boost and forgo on the trek to get 93+ octane and just use the local premium.

You also get the bonus of blue spark plug tips and a blue tint on the top of your pistons, that are carbon free because of water injection BTW.

Really!

Nothing in the windshield wiper fluid to gum up the works? Beats the heck out of the 2-3 gallons of race-fuel I currently use at $8 per gallon. Although I suppose if overboost I’ll probably want both.

Thanks, Peter

[pk2]

[QUOTE=FormerDatsun510Man;11572] Peter,

Do you know what the pulley ratio [/COLOR

Not yet but I can easilly enough...

[COLOR="Blue"] If the supercharger is not overspinning (past 16000rpm) power should not drop off at high rpm.

TPC only claims low and midrange “power” boost. The people I’ve heard from say the same. I recall seeing a dyno graph showing the boost leveling off at around 5500. Also, the 11:1 compression ratio probably make them deliberatly run only 4.5 psi

If you haven't yet, I strongly suggest you bring your Porsche to a dyno to get a baseline set for it. This will accomplish a number of things:

1) make sure you have it currently tuned to a safe a/f ratio
2) make sure the power and torque curves are optimized and the car is running right.... before trying to make modifications
3) indicate if there are any current limitations that would make pushing the supercharger to higher boost levels counter-productive

All three of these are important, but I am thinking #3 might be particularly important for you right now. For example, if, even tuned to the optimum, it currently hits power peak at say 6000rpm

2 problems, one real and one imagined. My local Porsche tuner with a Dyno won’t touch a Boxster with a TCP setup. Claims 4 out 5 they installed ultimately blew up. Never been to a dyno. I cringe at the sound of my car running full tilt for any prolonged length of time… unless they can shut it down quick at the fist sign of trouble.

...Also, it saved my original engine early on when I had the kit and didn't realize until I got to the dyno that the a/f ratio was leaning out to the tune of 14:1 at 7000rpm. That wouldn't have been pretty at the track! :)
Would you have been able to acomplish the same with a widband A/F guage and a steep hill?

I have an OBD II to laptop setup with tons of signal derived info and charts. Along with a wideban A/F guage, could I derive the information I need?

Thanks again Bill,

Peter

[FormerDatsun510Man]

I see about the dyno situation. Seems to me though, that if you are worried about the possibility of it blowing when on the dyno, I wouldn't even think of running hard to tune it on the street. Yes, you can tune it on the street with a wideband on level ground. In my Miata, I have done this many times and generally use 3rd gear to check the a/f ratio and also make sure there isn't ping (top up so you can hear for it and immediately let off the throttle if you hear any pinging whatsoever).... it is just that it is safer for the engine with an unknown setup to do it on the dyno. Yes, you heard me right :), it is safer check it on the dyno. The reasons being:
1) you can hear the engine a lot better for any problem sounds and immediately shut it down. When you are standing outside the car with the hood open... you hear a LOT of sounds you couldn't hope to hear while driving
2) you can concentrate on the things like the a/f ratio, ignition timing, engine sounds ,etc. much, much better and react more quickly to them. The reason being you aren't having to concentrate on driving :).
3) loads are generally less on the dyno (at least the Dynojet). You don't have to overcome air drag for example.
Basically, if you are afraid of running it for the 10-15 sec per run on a dyno I would be even less inclined to even think about running it hard on the street (especially for testing purposes) and wouldn't even consider a boost upgrade. To me, this makes it more imperative, not less, to bring it to a dyno (where they will touch it) and check things out until it is dialed in. Either that, or I would remove the supercharger kit and enjoy the Boxster normally aspirated. At least that way you can rev it all day and not worry. :)

Bill

[Satisaii]

Since you are in SoCal, you might try looking up Church Automotive for your tuning. I don't know if he has done anything with Porches, but he does work with S2000's, which have a high compression ratios, too.

Also, there is a guy out here with a very high hp 996TT. I know nothing about him, his car, or his tuner, but you might try searching S2KI for a user named "Sideways". He has posted about this 996 in the past.

[pk2]

I see about the dyno situation. Seems to me though, that if you are worried about the possibility of it blowing when on the dyno, I wouldn't even think of running hard to tune it on the street. ...

Bill

Hey Tom,

You’re correct; I’m being a wuss I suppose. I guess I’ve been thinking I’d rather have it die doing what it (O.K. me) loves doing best than in a sterile room hooked to machines. But if it’s 15 or 20 seconds…I’ve kinda been doing that all over the place…

As to utilizing a wideband and an OBD to “do it myself”, I guess I inherited a need to know and DIY. But I think I’ll go visit my reluctant tuner and see what the dyno biz and what it takes to get a baseline

As far as pinging/detonation, I’ve run it with hatches off and haven’t heard anything resembling a ping as I know it (and the engine is quite… touchable!). But I’ve never run an engine modified like this either. Winding it up sounds like an F1 car (to me), the intake is right behind your left ear. There is though, when flat out, a slight, very fast tinny rattle…don’t know if it’s just that or some form of detonation I’ve never heard before.

Anyway, I’ll let you know what I come up with for a “baseline” and my pulley ratios.

Thanks again,

Peter

P.S. Fifth page and you guys are still with me, amazing!

[pk2]

Since you are in SoCal, you might try looking up Church Automotive for your tuning. I don't know if he has done anything with Porches, but he does work with S2000's, which have a high compression ratios, too.

Also, there is a guy out here with a very high hp 996TT. I know nothing about him, his car, or his tuner, but you might try searching S2KI for a user named "Sideways". He has posted about this 996 in the past.

Thanks,

I'll look in to church and see if their nearby. There arn't alot around here considering the historical So. Cal hot rod culture.

I'll look up "sideways", see what he's about.

Regards, Peter

[Tom @ Fast Forward]

Peter, that was Bill that called you a wuss, not me. However, I like the suggestion that you should look up a local church and attend. That might ease your mind about finding a dyno? :)

[BlownMX5]

There is though, when flat out, a slight, very fast tinny rattle…

Be careful then, that could be ping. To me, it sounds kind of like a few pennies in a coffee can and something is vibrating the bottom to make them jump around. With the intake right by your ear, you might not be able to hear it as well. I think it's dyno time for sure.

Pat.

[pk2]

Peter, that was Bill that called you a wuss, not me. However, I like the suggestion that you should look up a local church and attend. That might ease your mind about finding a dyno? :)

Hey Tom,

Sorry about the mix up, Tom Bill…,Bill Tom…been a little harried of late. Agreed, a little church time wouldn’t hurt. I’m still trying to figure if there is a way I could at least use that SplitSecond controller to run a WI injector. SS insists there’s no way to make it work on my car for it’s intended use.

Anyway, Happy holidays to you both!

Peter

[pk2]

Be careful then, that could be ping. To me, it sounds kind of like a few pennies in a coffee can and something is vibrating the bottom to make them jump around. With the intake right by your ear, you might not be able to hear it as well. I think it's dyno time for sure.

Pat.

Thanks Pat,

That’s sort of what sounds like, but it doesn’t seem to be coming from the intake as I recall. The odd thing is It doesn’t happen at low (3.5k) revs at full boost, happens at the upper end.

Dyno is probably the thing to do. At least find out where I’m at.

Thanks, Peter

[Tom @ Fast Forward]

Merry Christmas. There is no reason the SS couldn't use the injector output to run a WI solenoid. I did it that way.

Hey Tom,

Sorry about the mix up, Tom Bill…,Bill Tom…been a little harried of late. Agreed, a little church time wouldn’t hurt. I’m still trying to figure if there is a way I could at least use that SplitSecond controller to run a WI injector. SS insists there’s no way to make it work on my car for it’s intended use.

Anyway, Happy holidays to you both!

Peter

[chuckerants]

Merry Christmas. There is no reason the SS couldn't use the injector output to run a WI solenoid. I did it that way.

As am I - the Aquamist.

[BlownMX5]

Thanks Pat,

That’s sort of what sounds like, but it doesn’t seem to be coming from the intake as I recall. The odd thing is It doesn’t happen at low (3.5k) revs at full boost, happens at the upper end.

Dyno is probably the thing to do. At least find out where I’m at.

Thanks, Peter

What I meant by "With the intake right by your ear, you might not be able to hear it as well" was that with the loud sound of the intake, you might not be able to hear the ping as well, not that it would come from the intake.

[pk2]

Merry Christmas. There is no reason the SS couldn't use the injector output to run a WI solenoid. I did it that way.

And a merry Christmas to you and yours too Tom,

Bear with me, still climbing the WI, IC learning curves.

To use the Split Second would I need an amplifier of some sort to drive the solenoid ? Would remapping it be much of a trick?

I guess I could then pickup a simple (“stage I”?) WI system with a check valve, amplifier, and a high-speed solenoid & I’d be off to the races? A setup as good as they get (or better than a progressive anyway)?

Truly lame question, but does the WI injector squirt every revolution or every time an injector fires?

Regards, Peter

P.S. Apologies for my garbled thoughts and the like in my correspondence. I’ve dyslexia; it takes me forever to compose the simplest post. This one took about 35 minuets in a word processor to make it only mildly comical.

[pk2]

As am I - the Aquamist.

What model Aquamist are you using? And if you don’t mind, why Aquamist? Was mapping the SpitSecond a big deal?

Thanks, Peter

[Tom @ Fast Forward]

Peter,

Did we get you the R4 software to go with the SS?

[pk2]

Peter,

Did we get you the R4 software to go with the SS?

Ya you sure did, I appreciate it. Don't think I've installed it to take a peek yet. Probably need to have the AIC hooked up.

Sure do wish that I could figure away to make it work as an aic but SS was emphatic that it would not fly on my car. But If I can use for a WI setup all is not lost. Thanks again.

Regards, Peter

[pk2]

Hi All,

I’m way under the gun, another deadline, got time for an update.

I’m taking the plunge, I bought a Sureflow 150/100 psi pump on ebay for $45 on ebay, big deal right!, then the guy started throwing stuff in, getting real close to a full kit.

Something gnawing at me than I got to run, back to the drawing board; With progressive and whatever is better (AIC), how is the flow or pressure physically controlled? Is it a hi-frequency valve?, turning the pump on and off, turning some other sort of valve on and off, constricting the flow some how?

What is required to piggy back on an AIC to give the water circuit something to work with? How is the signal modified and what does it operate on, on the H20 circuit?.

Thanks for everything and happy New Year all,

Peter

P.S. One of the motors I posted, a twin turbo, has a 7 psi boost with IC…claimed 290 hp. So that’s my target.

[chuckerants]

Here's how I run my 5th injector and the WI nozzle:

The PC Pro handles the extra fueling for the main 4 injectors and for the newer setups, an additional PC Pro handle the 5th injector.

My set-up is a bit older, so the Split Second AIC controls the 5th injector on one "channel", and the Aquamist WI nozzle with the High Speed Valve with the other "channel".

The WI nozzle is pulsed just like the fuel injector so I have very precise control over how much water is being injected at any given RPM and boost levels.

[pk2]

Hello,

Thanks for the reply.

I’m using a sure flow 150/100 psi pump. If I read you correctly I’d do something like this:

1)Have split second on all the time.


2)set a solenoid on/off valve to turn the pump & solenoid on at a given psi?

3)Does the pump run full tilt full time till boost drops below said psi set point?



Does the signal from The SplitSecond injector signal provide the amps (and V.) necessary to pulse the high-speed solenoid valve? ( this Splitsecond AIC was from Tom, from one of his Miata projects)

How is this valve spec.’d and where would I find one?

Thanks a ton, It’s really tough to find information like I’ve gotten here

Regards, Peter

[pk2]

Hello all

Where’d everybody go. Must be someone discovered I had 2 more cylinders than everyone else.

Well any way, thanks everybody for the input and the help understanding all this stuff. I even made a PDF copy of this entire thread (gotta edit out my lamer questions though). I’m think I’m well on my way

Decision is W/I, progressive at a minimum. However I hate to let this old SplitSecond AIC Tom gave me gather dust and I picked up a deal on a EGT gauge/sensor setup. Means I could really dial in the WI. I just can’t get used to a $180-$280 HSV type valve. So I’m shopping for alternatives. Oughta be out there, there just can’t be only 2 HSV makers in the world. (Were it not for corrosion and rust, I’d think I could use a fuel injector.)

Still need to calculate the pulley size and source it, wait for my W/B sensor and gauge to show up, find a HSV or (sigh) a progressive controller and I should be good to go...maybe down to the upper 4 seconds.

Thanks again all, I’ll keep this this echo chamber thread posted on how things go.

Regards, Peter

[Tom @ Fast Forward]

The Split Second is progressive when properly programmed. It is RPM/Boost mapped. You get to fill in the map. Don't toss it out yet. :)

We're all still here. Just jealous that you have those extra two cylinders.

[pk2]

Hello Bill,

In measuring pulley sizes, do you measure the pulley on to of the ribs or in the crevices? Is it the diameter you use for calculating ratios to crank pulley (BTW, my super pulley seems to be about 2.5 to 5.5”crank pulley at.

Also, would running my older M63 at 15300rpms (max, my calculations) for brief intervals be that bad? Is dropping my pulley size to 2.3 going to be to tight a bend for the belt?

Regards, Peter

[FormerDatsun510Man]

Its been a while since I've measured pulleys, but I recall measuring them at the top of the ribs. I can check tonight with some known pulley sizes I have at home and see which way comes out correct. As far as a pulley size of 2.3" on the blower, that is about 58mm and that would be near the smallest size I have heard of used on supercharger nose pulleys on Miata applications. It will probably work, but you will need to tension the belt a little more and it will be harder on belts. I've run 60, 62.5 and 65 nose pulleys on mine with no ill effects, but I know it was basically settled with the 6-rib drive setups for the MP62 to use the 65mm pulley as being optimal. One way to check for a slipping belt is to note what your boost gauge is showing you. It should increase in boost all the way to engine redline. That applies for roots blowers. The reason is the engine V.E. is continually dropping after torque peak and up to engine redline, but the roots V.E. doesn't decrease nearly this quickly. The result is that you have more and more of a flow differential between the blower and the engine the higher the engine rpm. Thus this means the pressure ratio... or boost... will go up continually to engine redline. If it stops rising in boost at a certain rpm or worse, drops in boost, chances are your belt is slipping beginning at that rpm. It is easier to see if you can datalog the boost or even dyno the car.

Is 15300rpm overspinning the older M62? Well, according to Eaton it is, and with a redline of 14000rpm that would be overspinning it by 9%. For short bursts it would probably be ok, as we have had people overspin the newer MP62 by at least that much and not kill the blower. Also, I am not sure how the MP62 got its higher 16000rpm rating. Is it simply the effiency of the blower? Or is it the strength of the rotors/bearings or other strength related design issues? If it is the former reason, I would see no reason why the older M62 couldn't equally spin up to 16000rpm and not self-destruct.... it would simply be out of its efficiency range. On the other hand, if it is the later reason (strength) then there could be issues with overspinning it too much. But under 10% overspin is probably ok. I wouldn't run it at that kind of rpm on a high speed track with long straights, but for street and autox it should be ok.

Bill

[Tom @ Fast Forward]

That is real close to where Gates measures it. When you buy a Gates belt, it has two numbers. For example:

25-060441 which Gates says is the length in inches. 44.1 inches. then, on the back, it says 44-3/4 inch. That is the outside perimeter of the belt.

[pk2]

Hey Bill and Tom,

For some reason I no longer get notifications from this forum (my ISP doesn’t like some & blocks them). I just found this forum (again) in my car related “favorites” folder. (clocking in at about a150-200 sites & forums in 5 subfolders now) It’s 1am and I’m going to hit it. Just wanted to let you know I’m still interested and will be back.

Regards

Peter

[Tom @ Fast Forward]

I got my notice about this post of yours? There is a note at the bottom of the notification that says:

"There may be other replies also, but you will not receive any more notifications until you visit the forum again.
All the best,
Fast Forward Superchargers Forum"

I think that if you miss one notice, you wont get more unless you stop by the forum. Maybe you missed a notice?

[pk2]

... I recall measuring them at the top of the ribs. ... As far as a pulley size of 2.3" on the blower, ...you will need to tension the belt a little more and it will be harder on belts. ...One way to check for a slipping belt is to note what your boost gauge is showing you. It should increase in boost all the way to engine redline. That applies for roots blowers. ...If it stops rising in boost at a certain rpm or worse, drops in boost, chances are your belt is slipping beginning at that rpm. It is easier to see if you can datalog the boost or even dyno the car.

Is 15300rpm overspinning the older M62? Well, according to Eaton it is, and with a redline of 14000rpm that would be overspinning it by 9%. For short bursts it would probably be ok, ... I would see no reason why the older M62 couldn't equally spin up to 16000rpm and not self-destruct.... it would simply be out of its efficiency range. On the other hand, if it is the later reason (strength) then there could be issues with overspinning it too much. But under 10% overspin is probably ok. I wouldn't run it at that kind of rpm on a high speed track with long straights, but for street and autox it should be ok.

Bill

Hey Bill,

I’m not to concerned by the 2.4”pully, My car has some sort of self adjusting
tensioner, that is, it keeps the same tension on the belt regardless of its
length (within reason) and It’s pretty tight.

Measuring the tops of the ribs make the most sense to me. But, a couple of millimeters could make for several HP I suppose. I typed incorrectly; I’m thinking 2.4”. Right now I have 2.6” The pulleys I’ve found in that size range vary in .1” D. increments.

So I either settle for 2.5”d pulley with w/c just to get a modest 15 hp increase or go down another notch for 30 hp making everything else worth doing. The effort is the same, It’s only a question of hitting a wall of diminishing returns, In a sense dragging the SC like an anchor. I think your alluding to or blowing the super apart.

Tell me if these simulations tell you anything. Calculation, claims, and the seat of my pants say there correct. If I read you correctly, I don't have any belt chirp.

Theres more below the pix about the pix.

http://img170.imageshack.us/img170/4150/seudodinofd6.jpg


I have some dyno simulation software which I’ve assume(d) is/was a toy. But I plugged in my numbers & the ones I didn’t know I errored way on the conservative side.

I think your eluding to this but I have to study and digest a bit. Between 2.5 & 3.5K., flat footed is where you feel it, definitely tapers off around 5k to not much different from stock. So can anything meaningful be extrapolated from these? Or is any car going to look like this?

If you have any thoughts please pipe in.

Regards, PK

P.S. Got my hands on a more contemporary AIC, it want me to plug in a number for the “dwell”. I haven’t even heard the word for 25 years…what is it and how do I get it?

[pk2]

I got my notice about this post of yours? There is a note at the bottom of the notification that says:

"There may be other replies also, but you will not receive any more notifications until you visit the forum again.
All the best,
Fast Forward Superchargers Forum"

I think that if you miss one notice, you wont get more unless you stop by the forum. Maybe you missed a notice?

Hi Tom

Ya, Ive noticed that before on other forums, but it usually seems to forget the next day and all’s forgiven. I’ve checked the to see If I’m still subscribed and I am.

My ISP does weird things. It will not accept messages from some totally innocuous forums. I finally got it to except forwarded email from my bizz email and it comes in with the preface “THIS IS JUNK”

Oh well

PK

[FormerDatsun510Man]

I know that dyno simulation software :). I found it seemed to be a bit in error for positive displacement blower simulation in that it put the hp peak at too high of an rpm and also that it didn't show enough of a power boost. It seems very realistic for normally aspirated engines though. I think the pulley size change you are looking at seems reasonable though. Good you have an autotensioner. It probably won't have slip problems, but the dyno will tell you for sure.

[pk2]

Hey Bill,

The Dyno software; You to eh? I didn’t take it to seriously. Was also surprised at the peak hp being at 8+ grand…but what do I know.


Strange thing, I talked to TPC (the maker of my setup), they were trying to sell me a “Unichip” AIC with a new injector ($1700). Peculiar things came up though.

1) The new setups injector is 800cc instead of my 500cc. Wouldn’t think a change in an AIC regardless of the tune would justify such jump in injector size.

2) This injector apparently has 4 or 5 little jets on the tip as apposed to the standard (ever see one like that?)

3) I got an injector with weird fittings. The injection end is a thin walled compression type nut witch bolts around a manifold tube. The inlet end is threaded on the outside for a fuel line compression thin walled nut like fitting.


The reason I bring this up it that If I need to up my injector capacity (?), I haven’t seen anything that meets any of this criteria…Have you?

Regards,

PK

[FormerDatsun510Man]

LOL, $1700 sounds like a hell of a lot of money for just an AIC, even if it uses a funky multi-injector injector :biggrin:. For that kind of money you should be able to get a standalone and 6 bigger injectors (if necessary).

Bill

[Tom @ Fast Forward]

We did a recall awhile back on some injectors that we shipped that had three jets. Instead of a pintle, they use a flapper valve. They would fail to open from time to time. Probably has no meaning but thought I would toss it out. :)

[pk2]

Hi Tom,

...we shipped that had three jets. Instead of a pintle, they use a flapper valve. They would fail to open from time to time. Probably has no meaning but thought I would toss it out. :)

Well that doesn't sound so great. The guy trying to sell me the upgrade for my kit, (new AIC and & injector, up from 500cc to 800cc) was pretty darn proud of the things. The thing I don't get is how without introducing more air can you use that extra 300cc...regardless of the AIC. Who made your similar injector anyway?

I mean what can an AIC do that requires a larger injector, unless the injector atomizes the fuel in some way that it doesn't require as much O2 or something.

So, something kinda cool is happening, if the guy comes through. A tech/engineer from Aquamist who haunts the Evo, WRX, etc forums is going to build me a device to run a solenoid valve (for my WI setup in progress) from a mappable 1-5v channel on my latest AIC.

It should give me ridiculously precise WI control. Was going to try to use th Split Second you gave me but by my calculations it was going to be running a valve at 300 hz. Couldn't find a valve which will do that,

Hope alls well,

PK

[pk2]

LOL, $1700 sounds like a hell of a lot of money for just an AIC, even if it uses a funky multi-injector injector :biggrin:. For that kind of money you should be able to get a standalone and 6 bigger injectors (if necessary).

Bill
Hey Bill,

Ya, $1700, isn't that a hoot. The injector was presumably “thrown in” with th AIC. What I dont understand with any larger injector, without added boost, how you can still maintain a decent AFR? I don't see how a bigger injector with an optimally tuned AIC can get by the fact that theres no additional air.

Have you ever heard of these sorts of injectors? who makes them? Experience?

Regards,

Peter

[Tom @ Fast Forward]

The good ones we use are Bosch Nippon/Denso. We buy them and lathe cut threads on the body so they are screw in. 5/8"-18 thread. The bodies look so good with the threads that they look like they came that way from the factory. :)

This was the recall we put out. We got all of them back as far as I can tell.

http://www.fastforwardsuperchargers.com/forum/showthread.php?t=537