Pistons / Ring clearances . Talking about piston stuff

[@gearhead719]

Good info! In the process of putting a 5.9 CR together and noticed the PTW was only .004. I'm taking it back to the machine shop on Monday to loosen it up to .006 and .0065 on 1 & 6. Tow with it mostly up mountain grades. When I tore it down, compression ring on 1 & 6 were broken in half.

[@WhyNot6243]

On our blown alcohol engines we have typically run 0.0015”-0.002”/inch of bore diameter. This is a steel block, aluminum piston. And we have data logging with light indicators that help keep us below 1,400 degrees EGTS. I would think this would also work in a diesel as well if you were planning to run a setup with good air and kept your temps down. And then like you mentioned once you start to make more heat then you would be running as much as 0.003”0.004”/inch of bore. Then for ring gap we are in that .008”/inch bore range, making 30psi boost. Again we try to stay below 1,400 degrees, but we have had a couple times where we have hit 1,700+ and tulipped valves and melted pistons, but the rings and ring lands were fine.

[@CUTTERUPROB]

I am not familiar with the blown alcohol stuff but i know if you run cummins that tight you will have some issues. might has to do with the alcohol

[@WhyNot6243]

@@CUTTERUPROB it should be fine. 6.7 std bore is 4.210 so at .0015”/inch you would be 0.0063” ptw and at .002”/inch you would be 0.0084” ptw. The biggest benefit we have is we only run around 10.1:1-10.3:1 compression instead of the 16.9:1 or even 19:1 that diesels do. I would love to do an in cylinder pressure comparison from a 2,000hp alcohol engine to a 2,000hp diesel.

[@davidbosch3779]

Awesome video A lot of good info 👌

[@CUTTERUPROB]

Thanks buddy

[@kenblanchard4458]

What ring gap would you run with a 600hp compound turbo set up?

[@CUTTERUPROB]

high end of stock specs

[@joemaser9122]

How come you don't use a steel piston or a steel dome and aluminum skirt

[@CUTTERUPROB]

You can do a steel piston in the 305/325hp 5.9 Cummins. But no one offers a steel pistons for a 12v or a 6.7 ( that I know of )

[@tylerhowe3619]

If you have 40 over can i go with stock ring gaps size?

[@CUTTERUPROB]

If your staying in stock power range yep. You you want to turn it up just go to big end of factory specs