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Old 05-24-2002, 10:29 AM   #1
Rich L
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Question Exhaust temps vs C/R

Assuming your getting very low exhaust temps from running rich...

How important is it to consider the C/R when messing with the boost levels on stock pistons?

If your E-temps are low enough...
can you just raise the boost with some disregard of potential piston failure??
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Old 05-26-2002, 05:03 AM   #2
Rich L
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Default ???

any ideas?
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Old 05-26-2002, 11:28 AM   #3
skywalker
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Well since you have a 99 that will help a little bit compared to a 00 or 01, your theory I would say is partially correct. Though C/R won't be your only concern, you will probably need to adjust your timing as well, or at least watch it. You may or may not have to retard timing. Some cars you can just add fuel to the top end and things are fine, other cars though, you may need to retard the timing and not add as much fuel. This is just because the timing is really on the edge of pinging in some cars, so no matter how much fuel you add your spark could still go off to early. Also when adding mroe boost, not sure how much you are adding but you may want to drop a step colder in spark plugs too. Which will help with your timing.

You will have to make sure you have big enough injectors to support more boost. Once you start raising the boost you just can't add more fuel, since there will be a point that the injectors, lines, whatever can't flow anymore fuel.

So right now, if your car under full boost feels like it si bogging a little and you have no pinging, you could possibly add another pound of boost, it is just the timing you should watch more closely.
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Old 05-28-2002, 09:31 PM   #4
Rich L
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Thanks skywalker for your imput.

Anyone have an idea of what max safe limits of boost might be at a certain temp at full throttle???

for example is it safer to run WOT: 6 psi max at 1400F vs. 10psi at 1200F???(lower temp due to richer mixture)

What level of boost and temps do you guys run?
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Old 05-29-2002, 10:06 AM   #5
Fitz
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Keep in mind here what your ultimate goal is. Your goal isn't to run more boost, but to produce more horsepower. A finely tuned motor running 8 psi will produce more hp/tq than an untuned 10psi motor. When you run overly rich, you are are costing yourself hp.

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Old 05-29-2002, 03:32 PM   #6
Rich L
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Quote:
Keep in mind here what your ultimate goal is. Your goal isn't to run more boost, but to produce more horsepower. A finely tuned motor running 8 psi will produce more hp/tq than an untuned 10psi motor.
I realize this. My question remains basically... what can the EJ25 handle? If an 8psi tuned motor make more hp than a 10psi untuned motor.... doesnt that mean the 8psi motor is undergoing more stress? And thus less safe??

Since there are many of us that do NOT have the tunability of a great aftermarket ecu...
Im trying to find some guidelines that some guys have had success with.

Or maybe I should be asking everyone who blew a motor what was their situation at the time?!?!
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Old 05-29-2002, 04:10 PM   #7
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From all I've read here I wouldn't suggest going beyond 8psi on stock internals and injectors. In fact I would suggest a slight upgrade in injectors right now. Have you been monitoring fuel pressure?

And of course the best way to tune an engine is to get aftermarket engine management rather than ITC/AFC combos. Haltech E6K is only $1300...

~Garrett
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Old 05-29-2002, 06:00 PM   #8
Rich L
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Question

FWIW:

I did upgrade to 370cc injectors and am running pretty pig rich, with piggy back fuel management and stock ecu.

Temps look a bit too low at WOT... even at 10psi.
The car feels stronger than it did at 6psi and stock injectors, but it feels only about 20hp better, like a 8psi RS-T.

No idea about fuel pressure. Rallispec did removed the RRFPR because it was not needed. (The car has a SupraTT pump)
So I am caught in a dilemma...

So if temps are low enough... how much boost is too much?!!!!
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