has anyone out there changed out their pistons for a HIGHER compression ratio and what kind of gains have you seen. i am interested in swapping them out of my 02 sunfire but wondering how high i should go.
Awhile ago RKsport did up a cavalier and went with 11.2:1 compression, intake, exhaust, and cams and I think that was it. They were putting over 200whp. I think it was in sport compact.
Wouldn't mind figuring out where they got the pistons from. all i've found are stronger stock compression ones.
You can special order them from several places, probably any place that sells pistons can order them.
Before you decide to go with a higher compression piston, I would be weary about what Octane fuel you'll need. High Compression and not high enough octane could lead to problems like not even being able to drive the car at all. If you go too high you'll have to use octanes that aren't available at the pump (or considered race fuel).
Also be ready for your OEM computer to not like high compression, it could lead to knocking codes and more problems. To solve this, you might want to invest in a full standalone system. Expensive, yes but that might be the price you have to pay for high compression.
This is why people go boost by the way. I don't mean to scare you but this is the reality.
www.kronosperformance.com / 732-742-8837
NJHK (The JBO Negro) wrote:
This is why people go boost by the way. I don't mean to scare you but this is the reality.
i am trying to put an effort into making a n/a engine with as much horsepower as i can, what i am looking for is someone who can tell me (in numbers) what the maximum compression ration that the engine, as a whole, can handle. i understand that there are other issues involved but i am not concerned with those, i am concerned with how much i can raise the compression without incident, not the incident itself.
i apologize for my frustration, i am looking for a number, not an explanation as to what should be done. i have tried posting this here as well as on j-body.org with the same result. please, if there is someone who has the expertise to give me a solid number, could you?
James N wrote:NJHK (The JBO Negro) wrote:
This is why people go boost by the way. I don't mean to scare you but this is the reality.
i am trying to put an effort into making a n/a engine with as much horsepower as i can, what i am looking for is someone who can tell me (in numbers) what the maximum compression ration that the engine, as a whole, can handle. i understand that there are other issues involved but i am not concerned with those, i am concerned with how much i can raise the compression without incident, not the incident itself.
i apologize for my frustration, i am looking for a number, not an explanation as to what should be done. i have tried posting this here as well as on j-body.org with the same result. please, if there is someone who has the expertise to give me a solid number, could you?
James, seriously, you're missing the point. There is no maximum compression you can run. If you can make it run, than that's the max. What you're not realizing is what compression relates to other processes of your car. Say you say "ok, I'm gonna get 12:1 compression pistons", that 12:1 might need higher than 93 octane fuel...how are you going to get higher than that on a daily basis? Also, how will your computer like it? If you can't even find the right octane fuel, this is what will happen:
Crank
Start up Engine
Stall
If you don't have those things in order, you will NOT have a properly running vehicle. Also, too high could touch the valves and cause other issues.
www.kronosperformance.com / 732-742-8837
Ok...This needs to be stickied because I'm getting tired of it.
THERE IS NO SET LIMIT AS TO HOW HIGH OR HOW LOW YOU CAN GO ON COMPRESSION, BOOST, NITROUS "SHOT", OR ANYTHING ELSE YOU CAN THINK OF.
Before me and Jasmin went at over the last year the "limit" for boost on stock motors was said to be 10PSI. We both crushed that, with me running 15PSI and him running like 18PSI.
You can get anything you want made, after that it's a matter of making it all work. That's where NJHK's warning comes into play. If your not concerned with "the incident" then your not smart enough to modify. PERIOD. You always have to worry about the end result of what you do. When you do is when you get bit.
I used to race cars, now I race myself.
5K PB: 24:50
10K PB: 54:26
ok i see this is getting me nowhere, i was looking for a number for the stock engine, pretty easy reference to start. thanks for your input by the way.
Here's a number since your so damned eager for a number without doing ANY calculations, any thought, and any real thinking about the effects of what your doing.
The answer is 0.
The question is: "How many miles is this kid going to go before breaking something if he doesn't start thinking the right way?"
I know you just want a number so you can go get something made, but guess what, doesn't happen that way. Theyre gonna ask you a whole hell of a lot of questions that you ain't gonna have answers for. You know what they'll do then? One of two things...Make you something that won't work or fit OR Hang up on you an laugh. I'm sorry to be so rude, especially while flying my shops colors on this site, but you people need to learn to do some critical thinking and mathematics before you go out and think you can do anything.
There IS a reason no one has run a high HP N/A Ecotec...they do the math and see how hard it's going to be. I know the one person who is trying, and will ahve a 12 second Eco, is nearing at least $8k in parts, with guesstimates of $10k by the time the motor RUNS. Before it even makes a single pass he's going to be spending $10K. Here's a comparison. I'll be in the 11s this year with about $5k in parts. I ran 65 12 second passes this year on $4k investment. Tells you something.
I used to race cars, now I race myself.
5K PB: 24:50
10K PB: 54:26
haha ok so lets see if i got this right, you want to know how high of compression you can run, well the stock head/block is good for 600hp?? (please correct me)
to get that kind of horsepower, your limit isnt going to be how high compression you can go before the engine has problems, its the fuel and detonation, so maybe hypsy or njhk can post these formula and you can do this math.
or you can just give up and boost, save yourself the aggrivation
Blown Ecotec wrote:haha ok so lets see if i got this right, you want to know how high of compression you can run, well the stock head/block is good for 600hp?? (please correct me)
to get that kind of horsepower, your limit isnt going to be how high compression you can go before the engine has problems, its the fuel and detonation, so maybe hypsy or njhk can post these formula and you can do this math.
or you can just give up and boost, save yourself the aggrivation
The stock cylinder head won't flow upwards of 600 HP, you defenitley need to do some work to it. The block itself can handle that high of horsepower, yes.
There really isn't any type of formula we can show you. Each motor is different and each motor can handle a high compression piston different than another motor...especially being that this is more of a boost oriented motor, it hasn't really been done.
Hypsy is fully correct, you will spend WAY more money to get a properly running high compression N/A motor to reach an decent amount of horsepower than it would for a boosted application. The problem is that N/A cars need high compression and more RPMs to make power which can also lead to a higher chance of detonating if not done properly.
www.kronosperformance.com / 732-742-8837
There are formulas to determine how much HP is POSSIBLE from a set compresion ratio, piston stroke, cylinder bore, and numerous other variables. But any numbers you get are GUESSTIMATES at best. Until someone tries to build a HIGH HP N/A Ecotec we may never know what it can do.
Oh wait...someone is. So just wait and see.
I used to race cars, now I race myself.
5K PB: 24:50
10K PB: 54:26
i think you gotta give the formulas first
hes a mechanic, only gonna do what hes told will work
I wish I had all the formulas memorized. The @!#$s are crazy complicated though. I got too many other things to memorize for school right now. If you do some deep searching on the web I'm sure they can be found...ain't coming out of my exhausted brain though. Sorry.
I used to race cars, now I race myself.
5K PB: 24:50
10K PB: 54:26
Wesley Anderson wrote:you guys suck... just tell him the truth. you dont KNOW. He trust wants to build a strong reliable motor that runs on pump gas. Calculations and what ever will never replace actual experience. so if you don't know then shut your whole/
Wesley,
YOUR A BASTARD, I WAS GONNA SAY THAT.
^^^ that's what it comes down to. Real world experience.
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Car needs more work with tune. 13.9 with very rough tune.