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Polishing Piston Top and Combustion Chamber
Posted: Sat Jul 05, 2008 12:44 pm
by mactheknife
I have seen some engine builders polish the top of the piston and the combustion chamber to a high finish. But have never been able to get a good answer from them. Is this to keep the heat in the chamber? I always thought if you polished something that it would hold the heat verses push the heat away.
There was also a SAE paper that I think Mitsubishi did that cam to the conclusions that it was good for mileage and about 1% increase in power but not practical for production.
Just like to get some better informed opinions.
polish heads
Posted: Sat Jul 05, 2008 5:56 pm
by bigjoe1
I have had some people come to test on my dyno and they did the polish chambers and piton tops. We ddidf NOT do a before and after, but none of those engines ran any better than the ones without the polishing. It is very hard to do any back to back testing because it cost so much for the dyno time.I like to see a textured surface on the chambers, and a glassbeaded surface works real good on the piston tops.
JOE SHERMAN RACING ENGINES
Re: polish heads
Posted: Sat Jul 05, 2008 6:00 pm
by trmnatr
bigjoe1 wrote:I have had some people come to test on my dyno and they did the polish chambers and piton tops. We ddidf NOT do a before and after, but none of those engines ran any better than the ones without the polishing. It is very hard to do any back to back testing because it cost so much for the dyno time.I like to see a textured surface on the chambers, and a glassbeaded surface works real good on the piston tops.
JOE SHERMAN RACING ENGINES
Joe,
How about Dart or Polydyn or Calico ceramic piston top coating?
I know Mikronite i think it is, offers a polishing to piston tops. I dont know if its gonna make any more power though
Posted: Sat Jul 05, 2008 6:45 pm
by muggs
We used to polish top of piston and comb. chamber on dragbikes to slow carbon buildup. Primarily two strokes, though we did do it on high end 4 strokes too.
I have thought about doing it on our bracket race motors as well. Son is running flat top pistons in his 421, builds carbon pretty fast.
piston tops
Posted: Sat Jul 05, 2008 6:53 pm
by bigjoe1
After the Engine Master contest I did the piston tops and skirts oon several serious buildups, I do NOT even consider this stuff unlees the engine cost more than 15 K. I knoe it does not hurt anything, but it does cost alot and I never really felt it was worth any(or much ) horsepower. The coated bearing are the best deal for trhe money, the piston cost too much.
JOE SHERMAN RACING ENGINES
Re: piston tops
Posted: Sun Jul 06, 2008 12:55 am
by RW TECH
bigjoe1 wrote:After the Engine Master contest I did the piston tops and skirts oon several serious buildups, I do NOT even consider this stuff unlees the engine cost more than 15 K. I knoe it does not hurt anything, but it does cost alot and I never really felt it was worth any(or much ) horsepower. The coated bearing are the best deal for trhe money, the piston cost too much.
JOE SHERMAN RACING ENGINES
I second that with the bearings. A couple weeks ago a customer had an oil pump failure with his foot buried in it at over 7000 RPM. He hit the switch as fast as he could, but realize this is an agressive, hard contact off-road course on dirt.
At the end of the day, the coated rod & main bearings allowed the crank to not be destroyed, and the only damage is a set of very ugly rod bearins. Rods only got hot enough to discolor the oil, which is well below a temperature that can "change" 300M material. They will get reconditioned with new bolts, along with crank polishing and new bearings. No other damages.