Thread: 91 octane benefits in N/A 3800?

I had the overkill 91 octane tune on my GT last year and it suppose to add some power but my car ran excellent with the tune plus I had full bolt ons.

I feel like my car is a little more spunky when it's running 93. Whether it's just a placebo effect or not, I've never been able to test.

i have the supercharger. i bought the car about 2 months ago from a girl who used 87. it ran like a champ. i put 93 in it (the two stations i can find anything higher than 91) and runs the same as far as I can tell. same mpg. i've put 4 or 5 tanks in it now and used seafoam in the first tank. i can't tell any difference.

maybe i'm just lucky, though.

i put 91 in my 89 regal 3.1L. made no difference at all.

It really depends on the car. The 04+ cars definately benefit from it because they had a lot of extra timing and would knock easily on 87. Using higher octane reduces some of the knock and gives you more power.

When I filled up last friday I put in a tank of 93. I just filled up this morning and got 18.6 MPG vs the basement 17's I normally get. My driving style didn't change at all from normal, in fact there were probably a couple of extra WOT pulls in there to see if the high octane made a difference. I wonder if it's a coincidence.

We had this thread last week: http://www.grandprixforums.net/91-oc...bad-75738.html

Originally Posted by Grimsin

And for the supercharged guy I hope you know you HAVE TO run atleast 91.

yeah. i know. i was saying previous owner ran it on 87. it seems to have little or no effect. she apparantly wasn't hot rodding it around.

I always run 93 octane in the Gtp. Always.

Depending on the amount of ethanol content in the fuel (its different everywhere), A higher octane rating can decrease your gas mileage.

I thought the car needed to be tuned for higher then 87 octane fuel if its n/a.

^^^ Nope. I run 90 in my NA all the time and have been totally fine. Seems to be better for it IMO

Originally Posted by Shiftingshaddow

i have the supercharger. i bought the car about 2 months ago from a girl who used 87. it ran like a champ. i put 93 in it (the two stations i can find anything higher than 91) and runs the same as far as I can tell. same mpg. i've put 4 or 5 tanks in it now and used seafoam in the first tank. i can't tell any difference.

maybe i'm just lucky, though.

i put 91 in my 89 regal 3.1L. made no difference at all.

i got my 04 from the dealer and immediatly noticed it has 87 in it when i test drove, i went to the gas station and filled up with 93 cus it was basicly empty and as i was driving(my dad was in the car and heard it too) you could hear and feel the 93 kicking in. The car started running so much smoother and had more of a roar to it.

Our pcms sense what octane gas we are burning and run accordingly unless obv tuned otherwise. So you would def see gains from 93, i would try a tune up, replace pvc clean maf wire plugs fuel filter air filter ect.

How do you hear higher octane?

I didn't say 04 made more power than 03, at least not on paper. My point was that GM put more timing in the cruising areas. This means that you can potentially have knock easier in those areas. Knock reduces power output by lowering timing to reduce knock and save the engine. A higher octane does not knock as easily, therefore the timing isn't reduced and the motor can using the additional timing and that equates to more power vs the lower octane fuel. This is subjective to the question... is the motor seeing KR?

Originally Posted by Grimsin

For all you n/a guy's without a tune running on 91 it wasting your money

Couldn't agree more.