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so lately i have been noticing that engines with head gaskets are making more power than those with "built" bottom ends. the 3mm gasket retains the stock piston and the CR is lowere to about 9:1 right? the aftermarket piston also reduced the CR to 9:1 depending on the brand.
engines running the HG seem to make more power per psi of boost running the same turbo as a motor running aftermarket pistons.
so my guess would be it has to do something with the dome of the original piston that causes better burn in the combustion chamber than a flat piston does.
judging by that would it be better if i were to have say CP pistons to make me a stock NA piston with lower ring lands for turbo and use a head gasket?
Most of the stock motor cars that have high numbers are running stock compression. I haven't seen any that are abnormally high which run a thicker headgasket. I ran a 2mm headgasket with stock pistons and then went to 9.5:1 Arias forged pistons. I don't miss the headgasket at all.
Another factor here is that built motors plus log manifolds will never make the same amount of power as a tubular equal length manifold on a stock engine. It's very helpful to normalize the turbo, manifold, engine management, and boost before comparing numbers. Unfortunately, that leaves few valid comparisons of turbo setups.
Tim
(edited for clarity in the first and second sentences)
The stock motor cars that seem to have high numbers are running stock compression. I haven't seen any that are really high on just the headgasket. I ran a 2mm headgasket with stock pistons and then went to 9.5:1 Arias forged pistons. I don't miss the headgasket at all. Another factor here is that built motors plus log manifolds will never make the same amount of power as a tubular equal length manifold on a stock engine. It's very helpful to normalize the turbo, manifold, engine management, and boost before comparing numbers. Unfortunately, that leaves few valid comparisons of turbo setups.
Tim
i have the head gasket and im shootnig for over 600whp.
are the forged pistons that are available on the market made to go with the stock sleeves? don't they have some special fiber reinforcing or something? i believe the prelude h22's had the same thing, hence the reason those pistons are good for using with the tsx crank for the 2.4L stroker setup.
Originally Posted by weiRtech,Jul 17 2008, 07:46 AM
are the forged pistons that are available on the market made to go with the stock sleeves? don't they have some special fiber reinforcing or something? i believe the prelude h22's had the same thing, hence the reason those pistons are good for using with the tsx crank for the 2.4L stroker setup.
Stock cylinder liners are FRM (Fiber Reinforced Matrix). The only aftermarket pistons I have ever heard of that are compatible are Mahle and Toda. I'm not sure if it's an anti-friction coating they put on the skirt to make it compatible or what.
When choosing a 2618 alloy piston ( which would be JE, Wiseco, Ect compression ratio is based off of stock combustion chamber size and stock head gasket. When dealing with a race engine, you have to take in to account lots of other things that will change the overall chamber size, bowl work, dished valves ect. Given,most that build for high amounts of hp will use a 9:0:1 piston. Increasing the size of the chamber, will reduce compression. The last thing to set compression is to choose the head gasket thickness you want. Choosing a thinner head gasket would mean you would have to drop below .030 . Using a .030 - 060 head gasket will usually do you fine. A 3mm headgasket is going to take you down to 9.0:1. Please correct me if I am wrong guys. Engine break in and overall compression after the break in will net you your end result. I cannot see a huge gap in power with the 3mm HG over forged pistons. Hard to say why his setup made more power on a 3mm HG. Could be many things.
i know high compression turbo makes good power at low boost. and i know its hard comparing people's setups because alot are very different. but alot run the inlinepro kit and a headgasket. they make sub 400hp at roughly a bar with something close to a gt30 or so. one of my friends has had a 3mm headgasket car make about 400hp at a bar, and then he built another engine with sleeves and cp pistons and to make 430hp he had to boost 23 psi. this is with everything the same between the 2 engines (turbo, intercooler etc...) besides the tune i guess.
how much power were you making on your HG setup and now at how much boost?
That sounds like a weird case. 430 whp on 23 lbs of boost suggests to me that something is wrong.
I never dyno tuned when I had the 2mm headgasket. I had purchased a 3mm headgasket, but scored a cylinder wall due to overheating before I had time to use either. That resulted in sleeving and rebuilding the motor.
I made over 400 whp on 10 psi on my first dyno run with only street tuning. By the last dyno runs, I was at 16 psi peak (10 psi at redline) and 443 whp and 353/363 torque (this is on 91 octane). All of the graphs are in my gallery including a comparison of the first and last run.
07-17-2008, 12:55 AM
piston design
