piston/head design vs. HP question

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abdywgn

abdywgn

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Would there be a difference in HP (all else being the same from set-up to set-up) between a
piston with a dome/large CC head and a flat top piston with a small chamber head? Guess one thing right away might change and that would be ignition advance. If the heads flowed the same, compression and rocker arm ratios the same, camshaft the same,would there be a noticeable difference? Thanks! Bob
 
Are you talking about ending up with the same compression ratio? If so, I would only expect a difference if either set-up formed a quench area at TDC; that can improve detonation resistance and completeness of combustion (better efficiency).

(Not sure if the dome could change the intake flow near overlap.....)
 
Can't answer your question, but my preference would be the flat top piston combo since it would give better flame travel without any obstruction from a dome.
Answers from the piston gurus here will be interesting.
 
Personally - I believe there are benefits and power to be had by using a small chamber head and a piston with a corresponding small dish. Economy is better, oil contamination is less, burn is more complete, maximum pressure is developed on the crank without as much ignition lead, detonation tendency is reduced, cheaper fuels can be used.
All that being said, using available parts, you can't get higher compression without using domes. In terms of flow at overlap I can't see the dome being too much of an impediment. By the time (in crank degrees) that the exhaust blowdown has mostly finished and the intake charge is starting to be drawn in the piston would be out of the way.
 
Some size and shape play a roll in this matter as well as, just what compression ratio are we talking about?
I myself would use a flat top and small chambered head since that combo is readily available, easy to work with and modify to or for the need. Well, at least my needs.

But! A dome, can achieve very high ratios. Yes yes yes yes you can kill the flat top Pistons small chambered head to high heaven and get some where too.

The draw back of a dome is weight. Possible flame propergation issues could also come from a flat top small chambered head.
 
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