Piston Rings
04-18-2017, 06:36 PM
#31
Registered
99% of Blowby and Oil consumption issues are due to Incorrect Honing Procedures . Piston Ring design has less to due with sealing than most think, just with oil control and friction. If you find a ring pack that fits your particular cylinder wall finish specs , it will stand out amongst the other designs. I know about all the napcar builders use Mahle pistons ,
and about half of them use either Rikken or Total Seal rings and not the gapless ones over the Mahle rings. Ive participated in dozens of piston - ring - cyl wall finish tests.
The biggest common denominator is Cyl Wall Finish , AKA honing procedures. Every ring wants a uniform cross hatch , nice flat plateau , and very little burr in the crosshatch. We tried the smooth as hell finish on some of the production race engines , to cut down on friction , all they did was eat oil and smoke! Ring faces were burnished and so were the bores. The rings just slid across the bore and never sealed up.
The only honing stones capable of this are diamond , and believe it or not you need an automated hone . The old crown wheel hones do an excellent job also , but
your finish will not be quite as accurate and your ring seating cycles will take longer . Also your honing oil needs to be clean,clean, clean! Ive seen microscopic shots
of cylinder walls with broken down abrasive and cast iron stuck in the plateaus! The engine would not seal up , it just destroyed the ring faces. What it boils down to is , an old cast ring will seal up on about anything , for alittle while . But the newer metric , and tool steel rings need a very specific honing procedure to make them work.
and about half of them use either Rikken or Total Seal rings and not the gapless ones over the Mahle rings. Ive participated in dozens of piston - ring - cyl wall finish tests.
The biggest common denominator is Cyl Wall Finish , AKA honing procedures. Every ring wants a uniform cross hatch , nice flat plateau , and very little burr in the crosshatch. We tried the smooth as hell finish on some of the production race engines , to cut down on friction , all they did was eat oil and smoke! Ring faces were burnished and so were the bores. The rings just slid across the bore and never sealed up.
The only honing stones capable of this are diamond , and believe it or not you need an automated hone . The old crown wheel hones do an excellent job also , but
your finish will not be quite as accurate and your ring seating cycles will take longer . Also your honing oil needs to be clean,clean, clean! Ive seen microscopic shots
of cylinder walls with broken down abrasive and cast iron stuck in the plateaus! The engine would not seal up , it just destroyed the ring faces. What it boils down to is , an old cast ring will seal up on about anything , for alittle while . But the newer metric , and tool steel rings need a very specific honing procedure to make them work.
04-18-2017, 10:59 PM
#32
Registered
I sold a '04 Ford Mustang Cobra prior to buying my boat. They are blown (supercharged) 4.6's from the factory and the engines are hand assembled using Mahle pistons and file fit rings. The OE engines were are good into the 750 hp realm without issue. When built most of the big wig's were using Total Seal file fit rings over gapless to well over 1300 hp, ring material varied by builder.............for reference.
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