Quote:
Originally Posted by KingLT1
I am speaking in terms of longevity not what the car can do for a couple track days. Setting a car up for street use is a different ball game. You are not always in the optimal gear. There might be times where you leave it in a lower gear and floor it which puts a heavier load on the engine. Or running it out past the 1/4 mi will be a massive difference in heat. Run 6th gear out to redline in a A8 car and let me know how long the SBE lasts on 93. All that makes a difference.
I retuned a P1x car on E60 and we picked up over 5mph in 1/4mi changing nothing else in the setup. Probably would have gained more but I believe #7 was already hurt as it was smoking a bit on the dyno before switching it over. It made 600whp on 93 octane @ 9psi peak. It was on 93 octane, LT4 fuel system and 12-13 degrees of timing for 2-3 seasons. The tune was done by a big name around here. After my friend got the car, I went over the tune. It was showing KR commanding 13 degrees. I actually took more timing out to get rid of the knock. It's currently getting forged drop-ins.
Moral of the story. Can you run 93 on low boost and squeak by....Yes. Will it live a long life, depends on how you use it. An occasional WOT rip not running it out past 140 probably fine. Track use with cool down time, probably ok. 1/2 mile rips or roadcourse...not gonna live long. Too much heat in the cylinder. As I previously mentioned when you pull excessive amounts of timing that starts to work against you and EGT's will actually increase as the engine is now laboring to make power. That is when you know you don't have enough octane.
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King, I know you said you don't currently run longtube headers, but from what you have gathered, would you say that 2" longtube headers with offroad midpipe connections helps alleviate some of those high EGT conditions for those of us forced to keep the timing low on a mild boost LT1 with LT4 fuel system and flex fuel?