Bill's '00 Miata 130mm Pulley

[FormerDatsun510Man]

I made it out to the dyno yesterday to do some initial tuning with my Coldside running a 130mm pulley. This was on 91 octane fuel + Torco. The purpose of this test was to see how the Coldside does flowwise with this pulley. I wasn't too concerned with tuning the middle range as you can see. I was focused on tuning the top end power. I found I needed about 2 deg of timing retard at the top rpm to keep ping at bay. My engine is a stock '00 with stock pistons from a '96 so the CR is 9:1. The injectors are 310cc Mains + E-Cool. I was running the mains near max and E-Cool at 70%.

We have a lot more testing with this setup, as we are going to see what we can do to get to 240rwhp and also perhaps lower the octane requirements for it. Currently, I wouldn't recommend anything less than 93 with this big of a pulley. However, who knows what the future may have in store? :biggrin:

Bill

[socal pat]

Ha! that torque is nuts. 150 at tip in... too bad it falls off so badly up top. ;)

[pat conlon]

Now, can you repeat these numbers in the middle of July, in stop and go Phoenix driving?

IIRC, didn't Tom get to 225 a couple of years ago...?

Keep up the good work laddie.

[FormerDatsun510Man]

Thanks! Yes, Tom achieved very similar numbers with a nearly identical setup running a 125mm pulley. Thus, I think with the current Coldside setup, the 125mm is likely the optimum pulley size for max power on a stock engine.... provided larger than stock injectors, 93 octane and of course, timing control.

Actually, this is just the beginning. I'm looking at what we have to do to make maximum power with the Coldside, one step at a time. This will evolve into what I intend to call our High Output kit. Anything goes, provided that it:

1) stays reliable under all conditions encountered on the road or racetrack
2) runs on pump gas (perhaps 93 octane minimum)
3) doesn't sacrifice any of the well known Coldside driveability nor practicality

I am going to find out exactly what we need to do with our fueling and ignition to get there. Ultimately, a built engine with better flow and a higher rev limiter would really unleash a lot of power potential with the Coldside.

Bill

[tann3r]

Very nice!

Do you think you are running into efficiency problems? Maybe at those blower speeds, the air is getting too hot and the resulting timing you have to pull is causing the torque to drop off. How much boost were you seeing?

I hope you hit your 240 rwhp goal...so i can copy it :D

[FormerDatsun510Man]

Makes 10psi at 3000rpm, 15psi at 5000rpm and 17psi at 7000rpm. While the boost is high, I know from past experience that this is where the MP62 will still make power. We are going to look in much more depth into both the fueling and ignition system to see what might be limiting us. I definitely believe one can only go so far with a certain amount of boost and heat in the air charge, but at the same time according to my data logs we have a lot to gain with improvements to the fueling and I also think the ignition system may be at it's limit. I intend to tackle those two items first and then move on to looking at what is needed next to make a reliable 240rwhp on pump fuel. Also note that on the graph I have the smoothing option turned all the way down to 0, so that there is no smoothing. I like to do this, even if it makes the graph look more jagged, because I can really see what is happening better.

Bill

[FormerDatsun510Man]

Attached is a comparison of my best run with 310cc main injectors vs. stock (250cc) main injectors. As you can see, I had to run leaner at the top end with stock injectors. At the same time, there was a very minor improvement in torque output with the larger injectors up to 5000rpm when the AFR was the same between both setups. With the leaner high rpm power, the stock injector setup predictably made slightly better output. I think this illustrates how we do not have a fuel distribution problem running stock injectors, even with the 130mm pulley. What I have found is that we need more E-Cool capacity to run a richer AFR at top end with the 130mm pulley and stock injectors. I did these back to back tests... one day 130mm pulley + 310cc main injectors and another day 130mm pulley + stock main injectors.... to determine which path made the most sense to pursue for our max power setup. I have determined that it makes the most sense to stick with stock main injectors and further improve the E-Cool system for the fueling requirements in going to 225rwhp and beyond. Stay tuned.

run_177 - 310cc main injectors
run_195 - stock main injectors

[Steve in VC]

Attached is a comparison of my best run with 310cc main injectors vs. stock (250cc) main injectors. As you can see, I had to run leaner at the top end with stock injectors. At the same time, there was a very minor improvement in torque output with the larger injectors up to 5000rpm when the AFR was the same between both setups. With the leaner high rpm power, the stock injector setup predictably made slightly better output. I think this illustrates how we do not have a fuel distribution problem running stock injectors, even with the 130mm pulley. What I have found is that we need more E-Cool capacity to run a richer AFR at top end with the 130mm pulley and stock injectors. I did these back to back tests... one day 130mm pulley + 310cc main injectors and another day 130mm pulley + stock main injectors.... to determine which path made the most sense to pursue for our max power setup. I have determined that it makes the most sense to stick with stock main injectors and further improve the E-Cool system for the fueling requirements in going to 225rwhp and beyond. Stay tuned.

run_177 - 310cc main injectors (from the first post - The injectors are 310cc Mains + E-Cool. I was running the mains near max and E-Cool at 70%).
run_195 - stock main injectorsWhat was E-Cool running with the stock injectors, 100% (and running out of steam)?

Bill knows I am a big advocate of adding as much E-Cool as possible. Cooling the air in the intake manifold, increases density (reduces boost), reduces air velocity past the valves (or whatever the major restriction is), reducing drag and improving volumetric efficiency of the engine. The combination increases power from the engine and reduces power required to drive the supercharger - more power to the wheels.

As I understand it, the limit to E-Cool is even fuel distribution and fuel condensation in the intake manifold.

Fuel distribution with E-Cool running 100% should be very even and allow maximum surface area and time for the gasoline to evaporate in the intake manifold.

I believe the E-Cool injector is a 550cc.

Running stock injectors and increasing E-Cool to:


625cc (@ 100%) would give you the same fuel as 4 ea. 310cc and a 550cc at 70%.

750cc (@83%) would give you the same fuel as 4 ea. 310cc and a 550cc at 70%.

1600cc (@ 39%) would give you the same fuel as 4 ea. 310cc and a 550cc at 70%.


Based on the above, I would inclined to use the 750, as it close but gives some margin.

[FormerDatsun510Man]

I know you might not want me to say this :biggrin: but it isn't that simple. Tom and I have different ideas as to what we need to do as the next step to allow E-Cool to function better and uncork the top end... and perhaps allow the use of even higher pulleys and lower than 93 octane. The answer? We will try both of our ideas :biggrin:. The problem is we have a 1.6 project that I need to finish when I get back so that will take precedence for the next couple weeks until I can get back on this.

I don't want to give away exactly what our ideas are until they are tested and then we figure out what actually works. What I will say is that they all involve simple bolt on mods that may require a hood scoop and also may require a significant price increase for what I would term the "High Output Option". But for the next power level I think it is worth it? Afterall, an intercooled turbo kit with standalone would run you well over $5500 to start.

The details I can give you so far is we are running out of available E-Cool and going to a larger injector doesn't solve the problem. Something is going on at the last 1000rpm with this pulley size... I saw this even with the 310cc injectors in there. I will give you a more technical answer with the actual data when I get some more results with further testing to figure things out. I don't want to give our competition too much information ya know :biggrin:.

Bill

[kevin]

Subscribing. I'm definitely interested :)

[Tom @ Fast Forward]

I wouldn't say "different" ideas. They just aren't the same. :) (That's political speak, ya know.) :boxing_smiley:

[Steve in VC]

I wouldn't say "different" ideas. They just aren't the same. :) (That's political speak, ya know.) :boxing_smiley:I trust the two of you will come up with a better, and more reliable, solution than either of you would by yourself.

[tann3r]

I wonder what these changes will be. I'll be driving in the Texas miata challenge in march. I need all the power i can get, those turbo guys have power to spare.

[Tom @ Fast Forward]

I wonder too? ;)

At the moment, the ideas are not past what can be done to existing systems. I also think that getting the head flowed by a reputable place like Rebello's along with the 130mm pulley and the other mods will be a step towards 250WHP.

We will know more along those lines in a couple weeks.