Whats up guys after a long arguement with my buddy that works down at the drag strip i can safely say that anything over 91 octane aint doing anything performance wise for the 2.4l ecotec

so anyway after some long begging i finally got him to let me fill my ride up with racing fuel ..... THE **** COST $5.00 A GALLON !!!!!!!!!!!!!!!! the stuff is rated at a minium of 105 octane, filled her up and drove at WOT on practically every turn ...........so to put to rest the long overdue arguement .....IT DOESNT DO **** BUT EMPTY YOUR WALLET



I am pretty disappointed because i figured with the 2.4l ecotec having such high compression the gains would be wonderful but that wasnt the case



anyway glad to be the ginea pig that saves some folks money

 

If you had hptuners, I bet you that you could get 20-30 whp with 105. You need to tune your car for that, you can't just go putting 105 in it....I hope you didnt' fill your gas tank full with 105...because that's expensive, and you can clog your cat....could, probably won't though

 

nah i put in 6 gallons at an empty tank ....how could this possibly clog my cat.???

 

as long as its 105 unleaded it won't clog the cat. And from talking with some tuners they say still tuned on 105 won't do anything.

 

just putting higher octane and expecing more hp without tuning is one of the biggest car myths ever... all octane is is a fuels resistance to detonation... nothing more... you're supposed to use the lowest octane that will not produce knock... anything more than that is a waste of money, and you're probably hurting performance more than helping it

 

well, actually octane is has the highest energy of the compounds in gasoline, so more octane in a fuel will have more BTU's than a low octane fuel. gasoline is made up of C5 thru C8 straight chain hydrocarbons plus some benzene and all the additives. octane is less volatile than the smaller chains, making it less combustible. This just means that a higher compression ratio should be used as well as more advanced timing. You can build an engine to make more power out of a high octane fuel, but its not some wonder juice that makes any old beater nto a dragster.

 

well heres the thing a buddy of mine she uses 87 octane religiously in her 2.4l ecotec ss and complains of nothing and i always use 91+ for mine because of what the manual says .....Iam just trying to understand if 91+ is the best for performance because it says in the manual if 87 is used you may feel less performance but it makes no scence because the engine only puts out a lil shy of 180 hp and isnt using FI ????????????

 

well I haven't seen the tune off of the 2.4, but if there is two octane maps for spark (high/low octane), then I would say the higher octane would give you more power and less change of knock.

 

(kind of off topic) If i wanted to run 100 octane in my ss/sc would the only diiference in my tune be adding more timing. I'm thinking about having one pcm for regular gas and one for high octane.

 

yup, the more octane, the more timing, the more compression without knock, the more power

instread of 2 PCM's, installing/removing, get HP Tuners and your set

 

I dont know about doing hptuners myself. Im scared ill brake something lol. And I already have 2 pcms.

 

I run 91 octain religuisly... a good friend of mine runs 87..... we raised a cuple times.. I'm a little quicker and if he manages to stick with me.. at about 160km/h its over and he hasent got a chance...

Anouther thing I've noticed is my tail pipe is a lot cleaner then his... is it because of the octain?? I don't know.. will I keep running premium @ 91 octain.... no question about it....

 

do u guys get any sort of knock when u run the lower octane, like 87? GM probably recommends it because of the 10.4:1 compression

 

i ran a tune just for 87, its was a good experience and i was able to get rid of all knock. in fact even with the dirty ass 87 we get here in california the stock tune needed very little changes.