Flat Tops vs Dished Pistons
Flat Tops vs Dished Pistons
(OP)
Just to give you all a load more to type, i'll ask a broad question:
Which is better, Flat tops or Dished pistons?
-=Whittey=-
Which is better, Flat tops or Dished pistons?
-=Whittey=-





RE: Flat Tops vs Dished Pistons
RE: Flat Tops vs Dished Pistons
RE: Flat Tops vs Dished Pistons
-=Whittey=-
RE: Flat Tops vs Dished Pistons
RE: Flat Tops vs Dished Pistons
Direct injection diesels use a 'chamber' built into the top of the piston that looks like the letter W . Known as a Mexican hat design, when the piston starts toward TDC, the air starts to swirl in the hat and helps to create better turbulance when the fuel is injected.
phasers
RE: Flat Tops vs Dished Pistons
RE: Flat Tops vs Dished Pistons
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Some have expressed a view that the small chamber heads are a better design, the fact that they have to be used with a dished piston appears ignored in this assumption. My personal opinion is that a small chamber with a dished piston is no better and possible not as good as a large chamber with flat top piston.
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300cid Inline Six (gasoline).
-=Whittey=-
RE: Flat Tops vs Dished Pistons
Whittey, My two cents worth---In my experience, chamber in piston designs like the Ford Kent 1600 make power on a par with earlier 116E designs with a combustion chamber in the head. This brings up the question of valve shrouding and final combustion chamber shape (and ,of course, the bottom line).
In my work with hemi, semi-hemi, pentroof chambers, the closer to a flatop piston, the better the results. Valve shrouding here would not seem to be a problem, but turbulance (swirl?) and squish area would.
Just for the heck of it, I'd like to see what an analysis of the Chevy 235 Blue Flame 6's combustion chamber and valve placement design, based on modern theory.
Rod
RE: Flat Tops vs Dished Pistons
RE: Flat Tops vs Dished Pistons
The piston serves more than just a slug to move up and down! It is an integral part of the combustion chamber. Its surface shape should represent a desired control of the combustion sequence, directing the flow of combustion gasses inside the chamber to enhance the process. It is easy to place a flat piston top in a dished chamber, and it would work relatively well. It is also easy to place a dished piston in the same head to reduce compression without changing head castings, the same for a domed piston. In the old days, I remember (sorry Rod!) the concept of “make a big combustion chamber, then stuff it full of piston dome”!
Feuling (http://www.feuling.com/) has done a lot of research on small combustion chambers and valve sizes and shaken up some of the engineering world (myself included) with non conventional designs that seem to work exceedingly well. The same for “The Old One”.
Some of the diesel piston shapes have to do with the combustion control processes, and to eliminate noise. A simple reshaping of the dish can reduce particulates and improve power, without changing the compression ratio.
Ideas?
Franz