87 octane? [Archive] - Chevy Cobalt SS Forum : Chevrolet Cobalt SS Forums

: 87 octane?


Nocturn
01-26-2005, 03:23 PM
Was looking at the cobalt website and realized that it runs on regular. I find this odd for a FI car. Whats the SRT4 run on? I imagine that you could turn the boost up higher and run premium and get better performance all day long with no problems.

Pablo
01-26-2005, 05:25 PM
SRT-4 is premium, and still runs shitty on our cheap 91 octane gas.

87camaroPA
01-26-2005, 07:45 PM
Wow i thought it would run on premium.

Nocturn
01-26-2005, 07:55 PM
Wow i thought it would run on premium.
As did I, makes me wonder how far one could turn up the PSI running it on premium, and if it would push it past the SRT4 in power terms, whats the stock PSI ratios on both cars?

Pablo
01-26-2005, 10:45 PM
SRT-4 stock is usually 11-13 psi, the computer controls boost according to the outside temperature. The cobalt SS is at 12 psi, but you can't compare them in that way, because an SRT-4 with a 50 trim turbo running 10 psi pulled on a stock SRT-4.

Pablo
01-26-2005, 10:45 PM
Plus with the high compression of the Cobalt SS, I don't know if you can turn it up to much without having to replace the pistons at least.

Nocturn
01-27-2005, 12:14 AM
Plus with the high compression of the Cobalt SS, I don't know if you can turn it up to much without having to replace the pistons at least.
Nevermind, chevy has contradicting information, some say 87, others say 91.

nuked
01-27-2005, 04:36 PM
Plus with the high compression of the Cobalt SS, I don't know if you can turn it up to much without having to replace the pistons at least.

What is the compression ratio on the SS?

Jay

Pablo
01-27-2005, 05:34 PM
What is the compression ratio on the SS?

Jay

It's 9.5:1 on the SS.

nuked
01-27-2005, 05:49 PM
It's 9.5:1 on the SS.


Hmm, that is pretty high for FI. Hell, that is run of the mill for a N/A 4 cyl. Are the pistons forged?

Jay

Nocturn
01-27-2005, 06:02 PM
Hmm, that is pretty high for FI. Hell, that is run of the mill for a N/A 4 cyl. Are the pistons forged?

Jay

They are "heavy duty" It does have a forged crank.

NIVO88T
01-27-2005, 11:42 PM
SRT-4 is also a boost happy motor as some guys have done 21psi on stock turbo. A local did 305whp on stock turbo with supporting exhaust mods and stage 2.

I would love to see what the cobalt/redlines put out with more boost. Even an added turbocharger with about 18psi(9.5:1 compression here) they would do great!

turbododgesrt4
01-28-2005, 05:17 PM
I think the cobalts need lower compression, so they can run more boost, or they gonna have problems with head gaskets and stuff.

NIVO88T
01-29-2005, 08:47 AM
I'm wondering if thew guys raising their boost over at redlineforums.com are using 87 octane or premium?

makes me wonder since sometimes people juat get into the boosted scene without knowing the ill effects of raising boost vs fast burning fuels :)

cbbwrx
02-02-2005, 04:25 PM
My WRX runs on premium, gay :(

Fineline
02-02-2005, 06:18 PM
I own an ION Red Line and use nothing but premium, it is what is recomended for the engine but the manual says you can get away with a mid grade octane. I also live in an area that has reformulated gas with 10% ethenol, but the boarder of the county west of where I live is not far away and they do not have reformulated gas so I try to fill up with non-reformulated gas as much as possible. I have read some bad things about injector problems from the reformulated gas. Enjoy those Cobalts when you get them, I am having a great time with my Red Line. :D