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Originally Posted by sp00ln
No, there are several arguments for the after turbo installation... if you would read the posts. Also, there is an argument there that "why does *cylinder 3* (#1 in the DSM case) run the hottest?" Do you really think it's struggeling for fuel? I doubt it. Every car is different, and I bet that every car's runner can vary in temps from what's the leanest, to whats the coolest. As far as external factors are conserned, you could make the same argument about the manifold too, however, I tend to think once the engine is warm, external factors wont cause a change in temp readings. Besides, the EGT is reading GAS tempretures, not o2 (up-pipe) housing temps. Plus, you should never TUNE with your EGT, a dattalogger is the choice here. And EGT is just a device for you to monitor while unleashing your car on the freeway, and make sure everything is reading NORMAL. If temps DO rise, in any of the runners, you'll be able to tell in your overall egt readings.
However, it seems that steve got the autometer, so *if* he does choose to install it in one of the runners and he's at WOT on the freeway with the EGT pegged at 1600*, how's he supposed to know what his ACTUAL temps are. He could be running 1800*? :?
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Actually in the case of the WRX (I don't know squat about DSMs), yes #3 is struggling for fuel. It doesn't matter if the pump is flowing enough for fuel to be returning to the tank, because this isn't a flow issues, it's a pressure issue. The stock fuel rails leave #3 way out on the end, so it cannot generate the same pressure at the injector as the other 3... therefore it *can* run lean on cars that approach 100% duty cycle on the injectors. It's not really an issue on stock cars, but once you start boosting more and adding fuel to compensate, it can be an issue.
As far as the temp readings... having a probe *and* a gauge that can read 2000F is the right way to go (and one of the reasons I sold my Autometers), however, you can get by with only a 1600F gauge if your probe is fairly decent. 1600F in the header is pretty much the redline... so if you get there, back off... even if it's trying to go to 1800F, once it hit 1600F you're too hot. And, as I mentioned before, I never saw above 1550F and that's with a full turbo-back and mediocre tuning (via my old UniChip), driving like a maniac.
As far as uses for the EGT. I consider it simply a cheaper alternative to a Wide Band O2. Since I don't "unleash on the freeway" (
), and since I don't tune the car off of a dyno, an EGT is just a piece of mind tool to let me know if something's b0rked and the car isn't supplying enough fuel.