wicked383lt1

Some of my buddies where discussing octane. One was saying AV GAS will messup the car and that the highest octane any car with a computer can handle is 97. The others were saying that AV GAS won't hurt anything and if anything it would help by cleaning the injectors.

zacht

iTrader: (18)

i dont think octane has anything to do with what a computer can handle or wont. i think what they're getting at is unleaded/leaded. usually (usually) the higher octane (av) is leaded, and tends to burn through O2's pretty quick, possibly other sensors, but mainly O2's. also, dont know how well leaded fuel does in injectors, but i dont think its a huge problem. i also think ive seen quite a few cars (computer) run 100+ octane. think of meth/alky injection (devil's own, snow, etc.) octane rating of that stuff takes 91 (or what have you) to 110+.

wicked383lt1

Well they sell here 97 is that equivielant to 100 octane or do you also need to mix it with 93?

SOMbitch

iTrader: (8)

The thing is if your timing tables aren't tuned to to take advantage of the higher octane fuels you will gain nothing anyway... These motors in general make the best power in the 28* +/- 2* range anyway so you need to run around there with no detonation...anything more is wasted. Usually 91-93 octane fuels do this just fine. Other factors like high compression, F/I or no2 change this some but for a N/A street motor this is a good general rule.... A power adder will need better fuel AND less timing in most all cases.....

EDIT: and yes LEADED race fuel will fubar o2's.

RPM WS6

iTrader: (3)

Any engine will always make the most power when the LOWEST possibile octane is used that still 100% prevents detonation. For a stock LS1, 93 octane should do the trick. Running a higher octane than necessary can only hurt power and gas mileage.

This is a long time rule that applies to more than just LS1s.....

WizardofDetailing

iTrader: (7)

I agree. My GSXR 1000 runs it's best times on 89 octane. My buddy put some 110 octane (leaded) in my bike before I raced him and my bike ran it's slowest time ever. Didn't hurt my bike or anything, just didn't have it's normal top end power.

Fb0dy0nly

iTrader: (10)

Thats because it was not tuned to take advantage of the extra octane in the gasoline, unless it was tuned, then someone did a bad job...

RPM WS6

iTrader: (3)

The higher the octane, the harder it is for gasoline to combust. This is great for prevention of detonation, but any octane past the amount needed to prevent said detonation will always hurt power.

Higher compression and forced induction setups will always be more prone to detonation, thus higher octane is recommended and often required. Setups with aggressive timing curves may also benefit, but it can be a losing battle as you're adding more timing for more power, yet more octane to compensate for detonation, and thus harder combustion leading to power reduction.

Thing about timing is, every engine will like a different curve and total advance. LS1s generally do their best under 30* total. On the other hand, my old SBC likes 36-37* total. Jacking up timing just because more octane *could* be used isn't always going to help the bottom line (power). It's a balance.

pewter2002

iTrader: (4)

More octane = slower burn = more cylinder pressure = more torque?

71novaguy

iTrader: (2)

=no

but more octane= controlled burn = no detonation= no timing retard = more power

RPM WS6

iTrader: (3)

More octane does nothing at all to help you once you've hit the point of no detonation. After that point, it's doing nothing but hurting power and MPG.