Hi, im new to the page as far as posting forums. I have read numerous posts in the past while building and working on my cavalier and i appreciate all the knowlege you guys post.
To start off i have a 98 2.2 ohv. It spun a rod bearing on me so i pulled it out and rebuilt it. I put new oem 9:1 pistons, crank, oil pump, etc. You know all the usual sh#t you replace when rebuilding. After buying all that i realised my cam bearing were shot after 195,xxx miles which ruined my stock cam. So i replaced it with a stage 2 camshaft bought from chevycavalierworld.com. and 6500 rpm behive springs. When i get it all back together it wasnt putting out as notible gains as i had thought. So i done some researching and it says it really doesnt produce much more hp gains unless you use 10:1 - 10.5:1 pistons. i drove the car 3000 miles and my rear main seal started leaking so i have to pull the engine reguardless. So i was wondering. Being a daily would itrun alright on pump gas without pre det. Or pinging if i change it to 10.5:1?
Stock ecotecs are 10.0:1 so I don't see why not and I believe gm runs up to 12.5:1 in production ecotecs. If you didn't get your car tuned for the cams you are only hurting performance.
On the inside my car looks like a fighter jet.
thanks for the quick response. I plan to tune once i swap my pistons back out. Ive not got the ecotec. I have the 2200 i4 ohv. These engines only have 2 valves per cylinder unlike the ecotec which has 4. I have read that engines with 4 valves per cylinder can take more compression because the 2 valves for exhaust can deposit exhaust gases easier and quicker than the 1 valve for exhaust and 1 for intake. Just what i have read. I thought 10.5:1 sounds a little high to me. I could probably get away with 10:1 but for the same price of the pistons i would rather get the best bang for my buck and still be reliable. As long as it can run on pump gas. I know alot of people with high compression also run octane booster which im kind of trying to avoid. Also another ? I have is would my stock rods and pins hold up to the added compression. I know a stock engine can hold up to i think it was 10 psi when turboed so idk what it can hold. Looking for reliability along with a little play at the stoplight.
Sucks that no one replied earlier, but I hope you went for the 10.5s. Hopefully it wakes that motor up a little. Keep in mind that the 60s Z28's had a 302 with an 11:1 compression ratio. If they could do it then on pump gas, so can you. Granted, 100 octane was available most places but I think 93 will get the job done for you.
"In Oldskool we trust"
Y3llowCav wrote:Keep in mind that the 60s Z28's had a 302 with an 11:1 compression ratio. If they could do it then on pump gas, so can you. Granted, 100 octane was available most places...
That same engine also used iron heads, which are less forgiving to a high-compression/low-octane combination--Hence need for 100+ octane fuels. Not to mention that most of that octane's detonation resistance came from copious amounts of Tetra-Ethyl lead, which I haven't seen
commonly available since 1987... Even in "Regular" form.(89-octane)
Go beyond the "bolt-on".
