[Invictus]

Originally Posted by Darrell What you feel is in your head. Your mind is telling you that the engine is making more horsepower and getting better gas mileage because you are using higher octane because that is the extent of the education you have on the subject. However, that is not how an internal combustion engine operates. If you put it on a dyno you will see that you may have actually lost a few horsepower versus the lower octane fuel. Same goes for fuel mileage.

theres no way you're going to LOOSE power by upping the octane. you may not get anything out of it but itll act as a buffer against detonation if worst comes to worst. you may not get anything out of it on a factory tune but it wont hurt you

[1slo5.0]

Originally Posted by Invictus theres no way you're going to LOOSE power by upping the octane. you may not get anything out of it but itll act as a buffer against detonation if worst comes to worst. you may not get anything out of it on a factory tune but it wont hurt you

Would you like to place a bet on that? We will run a stock 5 liter on a dyno. The first pull will be with 87-89 octane fuel. The second run will be with VP C16 race fuel. The engine will make less power with C16, I'll guarantee it. Internal combustion engines are most efficient when they are on the verge of detonation. Just enough octane so the engine does not detonate makes the most horsepower. That is a fact.

[FaStStAnG5-0]

darrells got ya on that one... it is definately true... i spoke to my engine builder all about different octanes & what not when we rebuilt my sbc350 for my truck... plus i just would argue with darrel cause he knows his shit!!!

[Invictus]

ah, with c16 i could understand but 87 vs 93 same concept i guess but I just don't see a motor loosing efficiency with such a small octane increase. he was talking about using supreme pump gas on a stock tune which imo is fine. but you're right i wouldn't run 117octane gas on my stock tune either lol

[StangAddiction]

I dont believe it's possible to make more horsepower on a higher octane fuel without doing some tuning and/or timing adjustments unless your vehicle is tuned and timed to run on that octane already. Otherwise, power benefits should be "VERY" slim to none..

[The eaglenator]

Mostly the extra power seems to be on take off only. So your not really getting more horsepower.

[Bossman351]

Darrell is 100% correct on this one. I was a tech at a GM stealership years ago and we had a guy from BG come in one time to do a demonstration on fuel systems and octane for us. Did you also know that the lower octane fuels burn cleaner than the higher octane fuels? The higher octane fuels have more carbon in them therefore leave more carbon deposits when burned which makes it more likely to start "labor knocking", fouling plugs and leave deposits on your valves which, over time, can keep them from performing properly.