Octane question..

[Savier]

so i have my 347, last summer i was running Chevron 94 octane. Cleaner, better, higher octane blah blah blah. Its not tuned or anything for it, but i was running it.

havent driven the car yet, but i just put 87 in it for now till i get er going again, and everything runs good.

Over the winter i think i read somewhere on here that stock car wouldnt benefit anything from more octane, and its a waste.

What would you guys suggest i run?

EDIT: oh yeah, motor is low comp. like 8.7:1 i think i was told.
Probe Forged Aluminum Dished Pistons (-20.1cc)

....i dunno im not a motor head yet

[Tomak]

Depends on the engine,compression,cam timing etc....

Depends if you reach peak torque before you reach the knock limit with your current fuel.

Only way to know is to try,,,,,

[GT4MT]

I'm no tuner type guy, but for what it's worth, I believe if your owners manual says to run 89 octane, and you're running something higher, you're wasting your cash. (Pretty sure that would be the true for newer vehicles and those that haven't been modded.) Anything after that I defer to the experts!!!!

Which doesn't really answer your question....but it is kinda on topic right?

[darcyb62]

2008 Bullitt has a tune that senses and compensates for octane. Higher octane results in higher torque.

[Savier]

Originally Posted by Tomak

Depends on the engine,compression,cam timing etc....

Depends if you reach peak torque before you reach the knock limit with your current fuel.

Only way to know is to try,,,,,

try what?

maybe i'll just run somthing in the middle for now...till i get it to one of you tuners...its about the same drive either way i go to alberta or down to Van

[Tomak]

Say you have 87 octane in the tank.... you put it on the dyno, dial in the AF, and tweek the spark timing.... IF the car is gaining power (torque really) all the way up to where it starts to ping, it could benefit from premium.

If on the other hand, it hits peak torque, but does not ping, and advancing timing further starts to hurt power (no detonation still), then higher octane fuel will be of no benefit...

[4 CRUZEN]

Originally Posted by Savier

so i have my 347, last summer i was running Chevron 94 octane. Cleaner, better, higher octane blah blah blah. Its not tuned or anything for it, but i was running it.

havent driven the car yet, but i just put 87 in it for now till i get er going again, and everything runs good.

Over the winter i think i read somewhere on here that stock car wouldnt benefit anything from more octane, and its a waste.

What would you guys suggest i run?

EDIT: oh yeah, motor is low comp. like 8.7:1 i think i was told.
Probe Forged Aluminum Dished Pistons (-20.1cc)

....i dunno im not a motor head yet

If you have low compression you do not need high octane fuel. Poster was right also about your tune and your timing. Try the low octane and if you get a pinging noise switch back to higher octane or have your timing checked. Don't continue to pound on it if it is pinging ok to drive but not hard it could blow a piston. Try it and see if you don't get pinging your ok and a few dollars richer. High Octane is high $$$$$$$.

[Savier]

the car was never tuned for higher octane, they said just to run somthing higher for "performance"

[smoothy]

Originally Posted by Savier

the car was never tuned for higher octane, they said just to run somthing higher for "performance"

Sure, the higher the octane, the quicker the $60-$0 stopping distance of your bank account The oil companies are great at using (cheap) words to encourage folks to buy higher octane (and higher margin) gas even though most cars don't need it.

[collinjay71]

higher octane fuel doesn't necessarily mean the fuel has more energy, all it means is it is more resistant to detonation

[Carnage]

Higher octane = larger combustion = more HP

This is what I was told. Kinda makes sense. I'm running a custom 94 octane tune for my car and if I were to run that tune on, say, 87 octane, the car would run like a toilet. With higher octane, my tune's global spark is able to advance an extra 5 degrees which gives my car more HP without the engine pinging. I also think that 94 octane burns alot faster than lower octane levels. I maybe wrong though.

[lone sailor]

The higher the octane rating, the better the ability to prevent and resist detonation. It is known that higher octanes also allow for better tuning and can relate to increased power by being able to still prevent pre-ignition with added ignition timing.

/story

[kaisoboy]

I was running 94 octane in my coby and this is what I learnt. Higher the octain the better the performance plus higher HP. Now with that said this is how you gain HP. You want to run 94 octain...OK. You start by dailing in the MAF once the rims are in line you want to advance the timing to gain the greatest HP and TQ you can...BUT, you can only advance the timing so much before KR happens and you back it down a degree to get rid of the KR. In my coby the ceiling degree of advance was somewhere arond 25* for 94 octain anything above that while tuning for 94 would get KR and Detonation. I would then back it down a degree in the cell that got KR. Now sometimes if you add to much you can also loose HP and TQ. So unless your car is tuned for it you will see no gains from running 94 octane.