I have a 2004 cavalier LS sport automatic. I am in college now and money is nowhere to be seen. I am school for automotive so i have a shop at my desposle and was wondering if you could give me ideas on cheap performance as in almost free. I already have a 2-1/2 in catback exhaust and a short intake. Thanks for your help.

What kind of mods? Visual, performance, etc?

preferably performance but visual is cool too.

Sorry to break this to you but there are no cheap or free mods really

i was wondering of stuff like port and polishing the throttle body or maybe little things that i could do like that.

save your money, get a 4-2-1 header

like the one from Rksport and weapon R.

Yep I would recommend either, personally I like rksport better. even though i dont have either. I have a pacesetter 4-1 header which is alright but has to be welded on and not a bolt on.

that sounds like a pain in the a$$.

its not really just takes a little bit of time, all depends if you want to spend $450 on a nice header or $175 for the pacesetter.

you could always paint your brakes. i did that when i had a girlfried who sucked up all of my money lol.

already done. I was mainly looking for something i could do with my hands to the motor quys.

run 89+ octane. There are 2 timing maps on our PCM, low and high octaine. You will notice and increase of power at higher RPM levels and a smother idle after about 50-75 miles.

Running a higher octane doesnt give you more power. It gives you a better/cleaner burn and help prevent detonation.

Unless I've been told completely the wrong thing. I would however like to see a dyno difference.

there is a thread on this on ecotecforum.com, but they are down at the moment. There is some interesting data on this. The Ecotec 2.2 like higher octane and backs the timing way off with lower octane fuel because of knock. You would be shocked at the difference. it's seat of the pants noticable.

i ran 93 octane when i could afford it a never really felt like i saw a difference other than runing smoother at idle.

Same here. No difference in performance, but that was from a butt dyno. Better mileage though

Well, someone hooked up a scanner and tested different octane fuels and proved there was a major difference in timing between them, and posted the results. Not everyone's butt dyno is set to the same level of sensitivity. With lower octaine the PCM backs off the timing to prevent knock. With higher octane, there is no knock and the timing can be advanced. Pretty simple.

Just by putting in higher ocane? How high can i go before i hurt something with stock internals?

I should explain. Higher octane does nothing UNLESS you are running too low octane to begin with.

The computer in your car has the ability to retard the timing if it senses knock. If you are running 87 octane (or 85 octane in high altitude areas), your PCM has to back down the timing to avoid detonation. This reduces performance but does no harm. If you put in 89 or higher octaine (87 or higher @ high altitude), your PCM can advance the timing since there will be no knock, giving you better performance and usually better gas mileage if you don't suddenly change your driving habits. Running anything higher than 93 octane won't do anything (91 in high altitude areas), it just will cost you more $$.

ok thats cool so on the days were i feel like being crazy could i go to the gas station down the road that sell 110 and put that in there. I know my buddy has a stock 2000 mustang and runs it all the time and it runs great, smells cool and never has any problems.

I did talk to Trifecta tuning and they did support that statement that there are two programs.
One is for low octane 87, and the other is for high 91+.

One reason is, these Ecotecs are barely getting away with running without going lean.
The compression is 10.1:1 and that is pushing it for 87 octane.

The program for low octane will not let the engine go balls out or else there will be predetonation.
It sounds about right, 50 or so miles for the computer to identify the higher octane gas and swap into the second program.

The difference is small, so more response and better idling sounds more accurate in describing the difference.

For most cars with 9.5:1 or lower, it really is a waste of money to use higher octane.


2003 Sunfire with 2 1/4 inch turbo muffler, 2 1/4 piping, 2 1/2 inch resonator, a 2 1/4 inch catalytic converter, 2 1/2 inch down-pipe, a 4:2:1 RK Sports 'clone' header, E-bay strut brace, ground wire kit and an AEM true cold air intake NOPI edition.

I forgot to mention, on lower compression motors, high octane being harder to burn all the excess will burn up in the catalytic converter. The end result is, you will toast your cat a lot quicker than normal.


2003 Sunfire with 2 1/4 inch turbo muffler, 2 1/4 piping, 2 1/2 inch resonator, a 2 1/4 inch catalytic converter, 2 1/2 inch down-pipe, a 4:2:1 RK Sports 'clone' header, E-bay strut brace, ground wire kit and an AEM true cold air intake NOPI edition.

Mike85220 wrote:I forgot to mention, on lower compression motors, high octane being harder to burn all the excess will burn up in the catalytic converter. The end result is, you will toast your cat a lot quicker than normal.

Looks like I need to go get some race fuel!! burn up that cat and reduce some back pressure!!

ok then how high of an octane can i run without harming anything.