Engine: Piston ring end gap in supercharged engines

[oilnsteel]

I spoke with a Mr. Landon at Silv-O-Lite pistons about the ring end gap in supercharged engines with their hypereutectic pistons. He stated that the gap must be further increased
because of the boost. For a 1957 GH engine with a .030 overbore, the top ring should be at .025 to .027, and the second ring at .020 to .024. He was very helpful, and I wanted to share this information. JT

[PackardV8]

Thanks for sharing. However, from here, we cannot know how much data Mr. Landon was given to formulate his recommendations.

There are modern supercharged engines with high compression which make double digit boost all across their RPM range and there are old school low compression '57 Golden Hawks which make low single digit boost only at higher RPM. The ring end gap would differ.

jack vines

[altair]

Engine assembly can be all things to all people, some people can eyeball and by feel assemble an engine while others require vernier calipers and micrometers. I have always eyeballed I have used a ring compressor and inserted the piston in from the top to check for clearance, if it goes in easy well that is good enough. After each piston is inserted and connected to the crankshaft I will rotate the engine 360 and check for any binding. After all 8 are in another couple of 360s then the rest is general assembly. I can't do much about the ring gap I assume the manufacture has it right. I have assembled many engines this way with no catastrophic failures, some engines I managed 100,000 miles.

[PackardV8]

Engine assembly can be all things to all people, some people can eyeball and by feel assemble an engine while others require vernier calipers and micrometers. I have always eyeballed I have used a ring compressor and inserted the piston in from the top to check for clearance, if it goes in easy well that is good enough. After each piston is inserted and connected to the crankshaft I will rotate the engine 360 and check for any binding. After all 8 are in another couple of 360s then the rest is general assembly. I can't do much about the ring gap I assume the manufacture has it right. I have assembled many engines this way with no catastrophic failures, some engines I managed 100,000 miles.

No one can argue with what works for you. Most times, rings are correct for the bore.

We measure everything, because the manufacturer occasionally doesn't have it right and there are such things as file-to-fit rings.

No, ring end gap can't be made smaller, if it's too large, get another set.

Yes, it can be made larger, to spec. We use a $1000 machine from Total Seal to set the end gap as needed, because it's faster and more accurate, but a feeler gauge is plenty good enough.



jack vines

[altair]

In business doing work for paying customers versus doing work for yourself are two different scenarios. Your education, training, skill and understanding of the functions of an engine are all factors. Some people can recognize a problem in its incipient stage while others will continue to a point of total destruction.

[bezhawk]

Unless you get gapless rings on new forged pistons. New technology is better, whether anyone likes it or not.

[PackardV8]

Unless you get gapless rings on new forged pistons. New technology is better, whether anyone likes it or not.

For true, Brad.

SI decided to have new Champion pistons made in Taiwan. They're excellent quality pistons, but the grooves are still cut for the steam-era 1/8" wide second ring. I asked, since this is new production and the Champion would definitely benefit from the reduced friction of modern thin rings, why not take advantage of them? The reason, "There are not enough hours in the day to answer the phone and explain to CASOs how anything new or different is better . We don't need the grief."

jack vines

[Mike Van Veghten]

Unless you get gapless rings on new forged pistons. New technology is better, whether anyone likes it or not.

Mmmm, even Total Seal (gapless) need to have their gap checked, verified for the application.
Even my lowly ol 299 Stude engine has a set of gapless rings in it.

Mike

[bezhawk]

Mmmm, even Total Seal (gapless) need to have their gap checked, verified for the application.
Even my lowly ol 299 Stude engine has a set of gapless rings in it.

Mike

Of course, all measurements in any part of any engine should be a matter of course to check when rebuilding. I'm just reiterating , modern engines use better materials less friction, better oils than engines of the fifties and sixties. Why not embrace those improvements?