Piston dish vs head cc debate
05-19-2015, 10:27 AM
#1
Piston dish vs head cc debate So i am starting my 403 ls2 build with an f1-a. Im shooting for 10.1 compression. Car is on 93 plus meth. Going for 12ish pounds on the street and eventually pulley it for around 18lbs max.
Which would you guys rather have a deeper dish piston around -20cc with around a smaller cc head approx 62-64cc or more of a flat top with reliefs with a 72cc head?? Any benefits or pros and cons for one another?
Which would you guys rather have a deeper dish piston around -20cc with around a smaller cc head approx 62-64cc or more of a flat top with reliefs with a 72cc head?? Any benefits or pros and cons for one another?
05-19-2015, 11:39 AM
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General idea is to keep the combustion volume in the head for better heat management as the water in the head will extract more heat than if it was in the bore. This would be beneficial to help prevent detonation or preignition type stuff.
Other concern is first ring location with respect to piston crown. Its beneficial to keep first ring down away from the top of piston where all the heat is. But can always gap more if its closer. This is mainly a rod length vs piston height type concern. Depending where dish is and wrist pin could also have oil ring inside the wrist pin. Not a problem but some dont like it that way
Lastly for best combustion its said a piston that mirrors the chamber shape is preferred for best performance. This would be a type of inverted dome.
But for what you are doing i dont think its gonna matter as much either way.
Other concern is first ring location with respect to piston crown. Its beneficial to keep first ring down away from the top of piston where all the heat is. But can always gap more if its closer. This is mainly a rod length vs piston height type concern. Depending where dish is and wrist pin could also have oil ring inside the wrist pin. Not a problem but some dont like it that way
Lastly for best combustion its said a piston that mirrors the chamber shape is preferred for best performance. This would be a type of inverted dome.
But for what you are doing i dont think its gonna matter as much either way.
05-19-2015, 01:02 PM
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Flat top, bigger head cc. Makes for better flame travel and a more efficient burn, less heat in the motor, hopefully thicker piston tops ect...... just my .02 always worked well with all the boosted hondas I built. I know this isn't a honda motor but i,have yet to fire off my turbo lq4 so I'm only speaking on experience that I have with hondas.
05-19-2015, 01:40 PM
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Lastly for best combustion its said a piston that mirrors the chamber shape is preferred for best performance.
this>>>
but that being said, a very efficient combustion chamber with a flat top piston will likely result in a stronger and potentially lighter piston
a true flat top is easily available, cheap, and will do pretty well!
I believe the smaller combustion chamber and dished piston would potentially require a custom vs off the shelf piston
one think I know for sure. the pent roof combustion chamber and dished pistons on my old ZR-1 LT5 engine are efficient and very detonation resistant.
good question!!!
this>>>
but that being said, a very efficient combustion chamber with a flat top piston will likely result in a stronger and potentially lighter piston
a true flat top is easily available, cheap, and will do pretty well!
I believe the smaller combustion chamber and dished piston would potentially require a custom vs off the shelf piston
one think I know for sure. the pent roof combustion chamber and dished pistons on my old ZR-1 LT5 engine are efficient and very detonation resistant.
good question!!!