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When im on the high way im always in vac almost never in positive pressure when crusing.

Are high egts an issue when you in vac or does it only happen when you flooring it with positive boost?
 

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It won't be a problem when you are cruising, and it shouldn't be a big problem if your car in not modified.

The EGT will raise when you are in WOT, and it has a lot to do with your boost level and exhaust efficiency. Try running high boost with a small turbo and OEM exhaust setup will cause more back pressure build-up, and that in turn will increase the EGT. Also, if your car is running lean your EGT will also increase.
 

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I have always experienced and been told by engine builders (of turbo imports) that EGT is highest at high speed cruising (low throttle at 65+ mph). When you go WOT, your EGT's had better DROP as you should be transitioning from cruise throttle A/F ratios close to 14.7:1 to power friendly rich of 11:1, etc. I have seen cruise EGT's (on a fairly heavily modded 2L turbo) up to 850~860 degrees C that drop to about 820 when I go WOT.
 

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WizardBlackWRX said:
I have always experienced and been told by engine builders (of turbo imports) that EGT is highest at high speed cruising (low throttle at 65+ mph). When you go WOT, your EGT's had better DROP as you should be transitioning from cruise throttle A/F ratios close to 14.7:1 to power friendly rich of 11:1, etc. I have seen cruise EGT's (on a fairly heavily modded 2L turbo) up to 850~860 degrees C that drop to about 820 when I go WOT.
You are right, and I didn't make myself very clear. I did mention that if the car was not modified, and I was implying that in factory trim or properly tuned state the EGT would not really be a problem since the factory a/f map and ignition map will keep the cylinder temperature in check.

Ususally in modified car, the EGT becomes a problem when the a/f mixture is not tuned properly and causes the car to run lean and drive up the cylinder temperature as well as the EGT. You can use EGT and cylinder temperature to detect detonation as well, but mostly we the lay people use it to determine a/f mixture.

I don't know that anyone now days that suffers from a high EGT in cruising, maybe in older carbuerated car where the adjustment can't be made by the ECU(or lack of ECU). I would say with intercooling the intake charge would be cool enough to perform cylinder cooling when in cruising mode.
 
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