Hey guys im really close to getting a new cobalt ss but i have a quick question. I hear that the manual reccomends 93 octane but the highest we have here is 91. Would it be bad for the motor, or is their anything i could do to help it? Thanks.

 

just run premium u will be fine

 

thats fine, it should have a map for 91 and 93...

 

yup I only have 91 here and its been fine for a couple weeks so far...I hear if you use 93 you shoot the same color as your car, flame out the tail pipe.

 

i've been using 87 and frankly I think it makes the car more responsive, I already got 20k miles on it. no probs here

 

i hope you are joking ....

 

Manual (and a sticker on the inside of the fuel door) recommends 91 not 93.

 

Nope, there are 4 timing tables but all are done by cam position not high octane and low octane tables like the LSJ and LS series GM cars have.

Are you serious. The stock tune is silly lean and your running 87 octane in it. I hope your pistons like all that knock they are seeing. Mine had 3* or KR at 3-4K RPMS on 93 octane. I would hate to see a log of your car at WOT on 87 octane we are talking 8-10* or KR so you might have 2* of advance max at WOT.

 

Yeah, my car is way more responsive on 87 octane, I ran a 1/4 mile in 13.8@ 108mph whereas using 92 octane got me a time of 14.1@ 104mph

And I made multiple passes using each gas. 87 is the bestest.

 

running 87 in a car that is tuned for 91 or higher will result in the car pulling timing. there is no way in hell 87 makes your car run better than 91 or 93.

 

Your car trapped 108 mph stock? I call BS unless you have a video of it. There are guys that are tuned that are running only 107-108 mph and they have 50 whp 80 wtrq more than your car.

 

you are right, there is no way he trapped 108 stock. let alone running 87 octane

 

lol seriously? you believe any of that about 87 octane? lol

 

im raising the BS flag on this also. Plus why in the F**K would you buy a turbo car and run 87 in it.

 

When I bought my car the stupid dealer put 87 in it and let me tell you it probably would have run a 15 sec QM at 90 mph with that crap in there you could feel the car pulling a ton of timing. I was very slow I almost did not buy it.

 

He hasn't. Trust me. I know this for a fact.

I trapped 104.5 and I had to hit 4th for that.

 

again you guys he is kidding... the only 80 something would be running E85 which I dont think 99% of SS owners even use :P

 

BS on trap speed..

He probably got a better launch or some **** when he changed fuels...

If your running a high performance car, with LOW GRADE (your not even using mid for chris sake) you are a moron...

There are about 10 factual reasons why higher octane will run better than lower octane..

 

no need to worry.... he hasn't even been to the track yet and he has a boost leak

 

He should let us know he is kidding then WTF. I would love to get a hold of E-85 I can forsee pretty big power running it.

 

Oh come on if you cant see 87oct in a FI car being f'd up thats ridiculous. I mean I know FI noobs ask the question etc but its common sense 87 will not optimize the car.

Yeah E85 would be sweet but I dont know how much needs to get upgraded to push it through the DI engine. I dont think Ive ever seen a ms3 running it either... Lots of Hondas up near me are running it though.

 

It's not even strictly due to the engine being FI, it's due to the compression ratio of the engine. Far too many people don't explicitly understand the differences between 87 and 91 once it's in the combustion chamber and the spark ignites...if people want to run 87 go nutts but at the very least I wish they'd understand WHAT is occurring at the ECM, timing and combustion level.

 

Well yes but we are talking on a forum where its a NA 87 oct car or a 91+oct FI car.. I didnt feel the need to clarify my generic answer much...

 

Oh agreed was just further backing your point more than anything else . Point being if people understood what is happening they would be far less likely to question the octane levels. At least in this case the OP is making sure 91 is ok...typically these threads are "Can I run 87 in an SC/TC".

 

manual states nothing lower than 91