Finding power in pistons

G

guru

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Mar 25, 2008
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OK so a flat top piston is a flat top piston and there shouldnt be a lot more to it than that. But like everything else, I seriously doubt that this is true.

Where can I find power in pistons, and if I am only going to buy 1 set and lets say that within reason money is no object where should I look?

Jegs has a graph from Mahle saying that their pistons are the best.

What makes for a good piston?

Since I have more time than money, I am not afraid to over analyze the issue.
 
So the issues I have to think about are:

2618 or 4032 aluminum (I am leaning towards 4032)
Gas ports
weight
ring package
Valve relief depth
Where the top ring is in relation to the top
"Anti-detonation grooves" whatever they are
Ring tension as it relates to gas ports
Coatings (not afraid to throw swaintech some money)
 
In nascar JE sponsors them but they put mahle's in

And if they use JE it's essentially the same piston as mahle by the time there done with prepping them. Coatings, machining, lightening...etc.
 
smaller combustion chambers make more power, so a smaller chamber with a dished piston should make more power than a flat top with a larger chamber.

Gas ports help force the ring into the wall for a better sealing piston.
 
WOW, real hard to follow that last post! But I agree with TT. A smaller combustion chamber makes more power. Howerver, this usually is accompanied by more cylinder compression. More compression usually promotes detonation which can be lessened by setting cylinder quench, (Basically, piston to head measurement). My understanding is that .030 to .040 quench is best for a SBC. This is done with head gasket thickness, (depending on piston deck height). Most Gen I blocks have the pistons .025 down in the cyl., so a .005 to .015 thick HG would help control detonation. I know alot of people use a felpro .018 with good results. This all depends on critical measurements: valve to piston; valve to valve. There is power here.
 
Yeah, zero decking (or close to zero) is preferred since it doesn't limit your choice of gaskets and you can go narrower or wider depending on the gaskets. Most GenI and II blocks have a deck height of right around 9.025 and @ TDC the piston doesn't even sit @ 9.000. Usually you're already right @ .030 or so down the hole.
 
Yeah, prefered by ya'all with deep pockets! How much is decking. align boring, at a competent machine shop?

guru, you said ya had more time than money, Fel-pro fpp 1094 .015 compressed thickness $19.88 at Summit Racing
 
I definately agree with you TT, decking is the way to go, but I also think .030 is .030 no matter how ya get there. I've done both, and can't tell any difference.
 
I have no problem saving my pennies for a good machine job. That will only benefit me as we go on.
 
While in my parts searching for my engine build I came across something on the KB site about their pistons. According to them the limiting factor in quench distance was found to be piston rock in the cylinders. They had a hypereutectic piston with very low expansion that could be installed with a tighter piston to cylinder wall clearances, thus less piston rock. They claimed a considerably tighter quench was possible without the risk of contact. I was going to post the link, but couldn’t quite find it.

A tighter quench leads to a faster and more efficient burn. Something I’m looking for in my mostly street driven Vette. That compromise between power and streetbility.

What’s the opinion amongst the experts here? At what power level (or should that be max rpm) should forged pistons be chosen over hypereutectic?
 
82Vettester said:
While in my parts searching for my engine build I came across something on the KB site about their pistons. According to them the limiting factor in quench distance was found to be piston rock in the cylinders. They had a hypereutectic piston with very low expansion that could be installed with a tighter piston to cylinder wall clearances, thus less piston rock. They claimed a considerably tighter quench was possible without the risk of contact. I was going to post the link, but couldn’t quite find it.

A tighter quench leads to a faster and more efficient burn. Something I’m looking for in my mostly street driven Vette. That compromise between power and streetbility.

What’s the opinion amongst the experts here? At what power level (or should that be max rpm) should forged pistons be chosen over hypereutectic?
Click to expand...


I've read that too. But, do you want to test that statment with your engine? On the "mule" motor I just built I used hypereutectic piston in it. But, only because I didn't care if the motor stayed together for a long peroid of time. I gave the pistons ( race engine specs ) a clearence of .003 ( twice recommended clearance). There is noticeable piston slap in the motor when cold. But it does run really strong this way. Quench is .054 on my motor. I have Alumumin Heads and a true static compression ration of 11 to 1. I use 91 octane gas with NO problems.
When I build the REAL motor the next time, it WILL have forged pistons not hypereutectic. Having tested these combos with a 6 inch rod I know this is the way to go with forged pistons.

Just some info in the "real" world to dell over. Well, the world of a Caveman anyways.:D
 
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