Quote:
Originally Posted by TAQuest
That's obviously because you have it detuned for crappy fuel.
It doesn't take a rocket scientist to know that more octane has more power potential if tuned correctly for it.
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Not true. High octane fuel has "less" energy in it not more. If you have a engine that will not ping/detonate on 91 octane pump gas with timing set for max power you will always make less power with race gas.
Always.
The only reason race gas makes more power is if the engine/combo has enough cylinder pressure to light off 91 octane before the piston gets to TDC'
It has been proven in laboratory's. There is more energy in 87 octane pump gas then 110 race gas. If you use a gallon of gas to simply burn it and head up a big vat of water the 87 octane does a better job of it. More heat is transferred.
A gallon of race gas has additives in it inhibiting the flash point. Raising it so the air/fuel does not light off before the piston gets to TDC due simply to the heat generated from compressing the molecules together.
The high CR engine "will" make more power in the end even if there is less energy in the fuel. Its simply because there is more cylinder pressure from the higher compression and the fuel needs the higher flash point to let it all happen like it is supposed to.
Simply put, the additives is a gallon of race gas, to make it race gas just takes up space. That "space" taken up is the difference in the race gas having less energy in a given gallon of gas.
I am a iron head pump gas racer and have proven it in my car and others at the track. A guy at the track ran a sbc 350 with 10-1 CR and aluminum heads. He used to mix 50/50 with 91 and race gas. He got all worried when he ran out of race gas during a big race to mix with. I told him not to worry and just run straight 91. He ran his best time ever that day.
Tuning by ear is the reason Butler sends out their street 455s with aluminum heads out at 9.9 CR. Less come back from the guys tuning it that do not know what they are doing.