So where I live, I have easy access to 91, 92, and 94 octane gas at the pumps, and I've been experimenting with them a bit. I also have a 91-octane Superchips tune. I've read that people have datalogged mild knock in the mid-range on stock cars with 91 octane gas, so I thought I'd give 94 a try.

Low-end and part-throttle response does feel better with 94 octane vs 91, but when I floor it, I swear the 91 octane feels faster and the engine actually sounds better. I get a strange fluttering sort of sound and sensation with 94 octane. Granted, the 91 octane is Shell and the 94 octane is Chevron, so maybe that's the difference.

It's funny though, I think the 91 octane might feel faster just because the part-throttle response isn't quite as good, so when full boost hits it feels like it's coming on harder, where the 94-octane power curve might be a little smoother and not feel as fast, even if it's making slightly more power.

Maybe I'll just keep alternating between them with each fill-up

 

I found my car would get knock on anythin lower then 94 octane when tuned with anything over 5degrees of timing increase. So all i run is 94 and with meth very soon here.

Any others see this? could just be the different conditions where i live.

 

im stock and my car is faster with 94, i tried top end on both 91 and 94 with 91 just got to 130mph and it took a while, with 94 i got to 150mph and it was decently fast, i had to slow down though when i got to 150 cause a car was in front of me, so im sure i could have gotten it higher. plus it pulls a little harder.

 

Unless you're tuned for it, I would suspect any perceived power increase would be chalked up as placebo effect. I've tried 94 but didn't see a noticable difference, though I regularly use 93 octane. Going from 91 to 94 may be worth the jump but again you'd want to be tuned for it to get the best benefit.

 

When my car was stock and running 93 octane it would still pull 4 degrees of timing at WOT. I'd say running the highest (93-94) octane is your best bet.

 

hey man! what area do you live in? im in davison, you anywhere near there?

 

a car will not gain power by using a higher octane unless it is either A: tuned to use the higher octane or B: you're seeing knock on any lower octanes which will pull timing

If anything, you will lose power

 

I've read that the Bosch ECU used in the LNF has fairly aggressive timing at lower revs and is designed to run with a tiny bit of knock, which is detected and the timing is dialed back. Higher-octane gas would make more torque in that case.

I'd love to see a 91 vs 94 octane dyno (stock and with a tune).

I've been running 94 octane with my Superchips tune for a few days now, and it's been pretty cool and dry in the evening. I'm getting a good amount of tire squeal from a 2nd gear roll, so I'm happy. Keep in mind I've got an HHR SS which is a bit of a piggy compared to the Cobalt, so squealing the tires is a bigger deal

 

this is something you should all learn, realize and remember! run the lowest octane gas you can run with your setup/tune that does not cause pre detonation/knocking and you will make the most power.

 

Yo! I'm in Waterford, a little bit south of you.

 

WIERD i have access to 87 89 and 93. occassionally 91 which is what my manual says i believe. i use 93 and have never heard a knock or anything

 

If your not seeing any knock on 93 then you won't see any benefit in running 94. The cost difference between 91 and 93 is so small that there is no reason not to run 93 IMHO.

 

Lucky bastards in the US

We get screwed in Canada on premium. When I filled up in the states it was like 4 cents to go from 87 to 91 I believe (maybe 3!). For a gallon. We pay 11 cents in Canada for a liter - that's basically about 44 cents per gallon premium! Yikes.

So for us 91-94 is actually a big deal.

 

where i live in canada we have 1 station that has 94 and its about cents more than 91

 

Try Sunoco GT (98 Octane) it was $8.95/gal last time I put it in, I'm not tuned, but DAMN did it make a difference!!!

 

Honest to god, I run 87/89.. whatever is cheaper where I'm at in my car (really dont care about this car, sorry) and I see ZERO knock on the RPD and it feels the same no matter what. This really shocks the hell out of me since the car is in the mid/upper 14's on AFR during WOT according to the RPD. My fuel economy is pretty damn good too, I keep track of it with an iPhone app.

If I had a stage or aftermarket tune, it would be a no brainer for me to run higher octane. As it is, ... my car doesn't seem to care.

 

I ran 100 octane Cam2 in my SS/SC one time to try and figure out if the knock i was seeing was true or not ..... turned out to be false knock . The only thing i felt was 40 bucks poorer.

Another thing you have to watch for in higher octane fuels is if they are leaded or not . There is alot of leaded high octane gas on the market that would put a hurt on your o2's

 

i agree higher octane totally makes a diff even when ur not tuned. i know what my car did with and without it and ur not gonna tell me thats in my head.

 

These are correct. Higher octane would not give any more power or fuel economy. By definition, octane rating tells you how fast it burns. Higher octane=slower burn, hence less knock. http://en.wikipedia.org/wiki/Octane_rating Or, if you don't believe Wikipedia, take an internal combustion engines class

 

I run 87 or 93 during the winter and never had any knock show on the RPD either way. 87's great for long trips on the highway where you don't expect to have to get on it or anything. I noticed the turbo spooled more/made more noise too on the lower octane.

During the 90*-100*+ summers though, I've been running 93 only.

 

You're lucky to find 91 in my town lately, and when you do its .30-40c higher. I'd say 80% of the time I have 89 in though since 89 is cheaper then 87 here in Iowa. Its if I need to fuel up down in Missouri or Nebraska where 87 is cheaper.

If I saw a lot of KR, I'd be worried ... but I'm not. Don't get any audible knock either and yes, I WOT the car semi regularly.

Especially knowing how the stock ECU operates, I think all of you guys running 6966969 octane are having a severe case of placebo. If its not seeing KR, the cars going to shoot for whatever it can in the tables. I also believe it depends quite a bit on the operating environment too. Its been an UNUSUALLY cool winter in Iowa this year. 100F ambient and I might be singing a different tune too.

On the flip side of that, my MR2 and the Syclone knock like a bitch on anything < 91 so I don't play there. They have really crappy cylinder heads compared to the LNF though.

 

Like Cam2. That's leaded fuel. At least what I saw on the pump it was.

 

Cam2 can be many different octanes and is a generic term for sunoco racing gas....... or atleast thats what delta sonic states . Delta soncic carries it at the pump as a 100oc unleaded .

I ran 100 oc unleaded and was positive about what i put in the car........others might not .