Boost guage ?s Vacuum especially

[socal pat]

So, no more guessing. Yes I'm at 10lbs full boost as I scream up the onramp. So what vacuum #s should I be seeing at different stages?
Eg. idle?
Cruise @3200 rpm
Cruise @4000 rpm
Deceleration (no gas) from oh 6k rpm?
Thanks.

[Tom @ Fast Forward]

idle 18-20"
cruise on flat road ~10-12"
Deceleration 26" or better.

Cruise is the interesting one. It really depends on gear AND RPM. For example 65 MPH in 4th is probably 15-16" and 65 MPH in 5th is probably 10-11". On RPM, 4000 RPM in 3rd could be more than 20" as vs. 4000 in 5th being 10".

All numbers are somewhat rough as it depends a lot on the condition of the engine. Static compression, rings, valves, etc.

On this subject, let me say that there is NO SUCH THING as a small vacuum leak. Make sure those hoses are tight. As a test, let it idle all warmed up and pull the vacuum hose off of the small barb on the side of the IM that feeds the JRPC and SS and see what happens to the idle. That hole is only about 1/16" diameter.

[socal pat]

Thanks Tom, I knew you'd have the numbers. Interesting thing happened. After a nice cruise I suddenly lost boost on the guage. HMMMM it was the compression fitting on the vacuum line at the guage. I came to a stop and the thing idled perfectly. I stuck my tongue on it and it was pulling nicely. I couldn't make the idle change thumb on the line or off. Whadda ya make of that? Oh, BTW it is Teed in the hard black line from the SST to the JRPC.

[Tom @ Fast Forward]

That tube is about 1/16 diameter and several feet long. Not bad enough to hurt idle but probably had a serious effect on the JRPC and SS.

[socal pat]

Ah, makes sense. Thanks Tom!

[ThomS]

Can I ask are you glad you got a boost gauge and do you think it is important to have one. How tough is it to put in 1 to 10 SCALE???????
Thom

[chuckerants]

Can I ask are you glad you got a boost gauge and do you think it is important to have one. How tough is it to put in 1 to 10 SCALE???????
Thom

2 - I'd say easier than an oil change on a Miata.

Most mechanical vacuum/boost gauges come with a length of tubing and a T fitting to tap off an existing vacuum line like a split second or a JRPC.

[chuckerants]

http://www.autometer.com/img/products/2601_d.jpg

This is the Autometer boost gauge I just got.

http://www.sw-performance.com/productpics/194pic1.gif

This is a Stewart Warner gauge I was also considering.

[99mx5]

I also have the Autometer gauge. I also bought a A-pillar gauge pod. I teed it to the boost tube under the dash and connected the lighting wires to the dimmer switch. It was easier to install than expected. Id rate it a 1 for the gauge connections and a 2 for the pod because I had to modify the gauge pod to mount without drilling the plastic because I wanted to make the mounting removable and completely reversible without damaging my piller panel. I have pictures that I should post in the mods forum. If theres any Interest Ill post them.

I think the vac/boost gauge is worth it to have even only for diagnostic purposes. I do have to admit that I also like seeing that needle jump on command. 8)

[ThomS]

I would like to see the pic's for sure if you have time.

[Banshee]

I have an electric boost gauge. If money is not tight, I highly recomend that you go that route as they have a memory feature. Its nice because you do don't have to stare at the boost gauge while screaming down the inner state. Hook up is just as easy as a mechanical one. I use the autometer ultralight pro-comp one myself. Bought it from egauges.com

[socal pat]

Am I glad I got it? Emphatic Y-E-S! I think the vacuum feature is as important if not more thn the boost. I'm still waiting to find the right guge mount panel, so mine is just sitting on top of the steering column.

[Tom @ Fast Forward]

I also have the electronic version and appreciate the memory feature. In the '05 I have the mechanical version. In either case, if you are only going to have one gauge, vac/boost is it. Vacuum leaks are easily noticed as you should idle around 17-20" Hg. When my copper EGR tube cracked and it wouldn't idle right, a quick glance showed ~12" Hg at idle. All I had to do was find the leak. When we dyno't Chuck's car last week, seeing 9.5PSI, 9PSI and 8.5PSI on consecutive runs, explained real quick why WHP was falling each run. Belt slippage. We first thought heat soak but that wouldn't drop boost. We confirmed that by watching timing and seeing that it wasn't dropping off. Heat soak causes ping and that drops timing. So the instant clue was loss of boost.

[Banshee]

I have 2 gauges in my car. This one mounted on the a-pillar:
http://www.egauges.com/images/autometer/Large_d/4376_d.jpg

and this one mounted on the steering column:
http://cgi.ebay.com/AIR-FUEL-MIXTURE-DISPLAY-GAUGE-WITH-SHIFT-LIGHT_W0QQitemZ220002830259QQihZ012QQcategoryZ7220 5QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I use them both everyday. That air/fuel display has the benefit of also being a rpm meter with shift light. 2 shift lights as a matter of fact. One to tell me to get ready to shift, then one to shift.

[99mx5]

Added pics to mods subforum http://www.fastforwardsuperchargers.com/miata-forum/2-vt53.html?start=15

[chuckerants]

I went with the 3 gauge DIN panel that fits in the cubby hole where the radio is. I'm really paranoid about trying to keep my car as stealthy as possible. Otherwise, I would have gone with the boost gauge in the A pillar and WHITE Autometer gauges.

[99mx5]

I did think about that, but until I get more gauges it will have to do :)

[sinuous]

Boost gauge in the left airvent ..light power from fog switch directly below.
http://upload4.postimage.org/570957/boostafgauge.jpg (http://upload4.postimage.org/570957/photo_hosting.html)

[socal pat]

Hey Chuck, which guage mount did you choose? Our cars are almost twins so I hate to copy you, but the 3 on the DIN is exactly what I'm after as well. Did you get the angled one or the flat one? (assuming it's TDR)

[chuckerants]

I ordered the gauges from eGauges.com and got the 3 gauge DIN panel. My advise is to buy the one from Thomson Automotive. The panel from EGauges is C R A P!

I just removed the radio and the cubby hole and moved the radio to where the cubby hole was and the gauges will be going in the spot where the radio was.

This is as OEM looking as possible.

Again, if I didn't care about attracting attention, I would have put a boost gauge in the A Pillar.

As it is, I got the Autometer vac/boost (# 2601), an Autometer eletcric short sweep water temp and oil temp gauges (# 2635, #2639). also got the Autometer 1/8 NPT female x M14 x 1.5 male adapter to replace the oil drain bolt.

Also, in order to remove the radio, you will need a DIN removal tool. I just bought one from Checker Auto Parts for $5.99. But, now that I used it, you can use 2 pieces of a wire coat hanger to do the same thing.

[chuckerants]

http://www.thompson-automotive.com/catalog/item/2577811/2029659.htm

http://www.thompson-automotive.com/i//DIN_gauge_panelTN.jpg

http://www.thompson-automotive.com/i//ThompsonGaugePanelX1tn_.jpg

http://www.thompson-automotive.com/i//DIN_panel_matte_005TN.jpg

[raceskier]

I just got the angled 3 gauge panel from TDR: http://www.trackdogracing.com/website/gauges/panels.htm
Very well made. Steel with welded spring clips at the ends. I'll do the install this weekend and post some pics.

[Tom @ Fast Forward]

Post pictures when you get a chance. I have the flat three hole in my cubby slot and always thought the slanted ones would work better.

[chuckerants]

I just finished the gauge install.

As I said, I ordered the Thompson Automotive DIN panel. It really is much better than the POS eGauge.com's $16 DIN panel. The only thing I don't like about it is the fact that because the DIN panel is flat on the car, you can see the light peaking through the right side of the gauges at night.

This might be a great reason to get the angled DIN panel from TDR.

Also, I have the Autometer boost/vac, electric water temp, and the electirc oil temp gauges.

I have the boost gauge connected by T-ing off the ELF.

The water temp sender, I Teed off the small coolant hose going from underneath the thermostat housing to the base of the oil filter. One thing to remember - because this is an ELECTRIC gauge, the sender is grounded when it is mounted on the engine block. However, because most people T off a coolant line, you have to run a grounding strap from the body of the T or the sender to a chassis ground. This part had me puzzled for a couple of days.

The electric oil temp sender will be mounted inside a replacement oil pan bolt. As soon as I change the oil, I'll be connecting that too.

[raceskier]

Well, I got my instrument install STARTED this W/E. I swear, I have more hours in installing three lousy gauges than my SC. Having the wiring diagram from the factory manual was a big help to find things like the variable intensity instrument illumination circuit that goes to the radio. Anyway the boost gauge is up and running. I installed Westach gauges. (from TDR) The Westach temp sending units are two wire type, so they do not require grounding though their bodies. I am also installing the temp senders in-line. TDR reccomends the hose to the oil cooler/heater. Does anyone know if that is indeed the hottest point in the coolant loop? I am also considering the heater circuit. I got one of the in-line -8 AN adapters to go into my line to the oil cooler, but the temp sensor blocks off a considerable amount of the passage, so I'm adding a 90 deg pipe elbow there to move the sensor out of the direct path. I'm also installing an Innovate LC-1 to drive the A/F gauge. I've installed it upstream from the cat, so that hopefully I can monitor from there for dyno runs. The angled 3 gauge panel looks OK. You can see there is a gap at the RH side. I may get real motivated and fab some sort of filler for the gap.
Having trouble posting the pics now and I notice others had problems today. I'll try and add the pics later.

[chuckerants]

I'll see if I can take a pic of the "gap" tomorrow.

[raceskier]

Lets see if the pics load.

http://upload4.postimage.org/638317/IMAG0051.jpg (http://upload4.postimage.org/638317/photo_hosting.html)
http://upload4.postimage.org/638323/IMAG0052.jpg (http://upload4.postimage.org/638323/photo_hosting.html)
Success! Sorry for the glare on the second one, but you can see the gap.