Ring End Gap

I have a friend building what would be a mild build here, but should be over the 500hp mark, and I was thinking about the fact that I've never seen much discussion about ring end gap on high power/high temp builds.

This app is a cummins cr, but the information could be useful for others.

What do you all have for guidelines? I understand if the info isn't something to be shared, but I though it was worth asking.

.025 to .028 untill you get well up there , then I've seen it butt at .028 .

Ive set one short block up at .030" but it showed in the leak down. Im thinking .020" to .025" is fine if temp's can be controlled to a somewhat sain level. Not sure exactly where Cummins puts them from the factory though.....

From Dodge service manuals...

From an 01 service manual:
Top Ring - .014 - .0177
Intermediate - .0334 - .0452
Oil Control - .010 - .0215

From an 05 service manual:
Top Ring - .010 - .014
Intermediate - .033 - .045
Oil Control - .010 - .021

IMO for a performance diesel application, I would not set the top ring gap that tight. I would set it to .025, a little looser if you are going to spray it. For the second (intermediate) ring because they are keystone rings, I would follow the factory recommendations. I pretty much set all oil control rings (no matter what engine), to .015.

Paul

"Biggy Biggy Biggy can't you see
Sometimes your words just hypnotize me
And I just love your flashy ways
Guess that's why they broke, and you're so paid (uh)"

Got some specs from a nice gentleman on this forum. They read as followed:

Intermediate: .0016 - .0043 thousandths
Oil control: .0016 - .0033 thousandths

Ring gap (installed in bore)

Top ring: .011 - .023 thousandths
Intermediate: .035 - .054 thousandths
Oil control ring .011 - .030 thousandths

He neglected to mention where the info was pulled, but he did seem like a knowledgeable fellow.

Dudge said:

"Biggy Biggy Biggy can't you see
Sometimes your words just hypnotize me
And I just love your flashy ways
Guess that's why they broke, and you're so paid (uh)"

Got some specs from a nice gentleman on this forum. They read as followed:

Intermediate: .0016 - .0043 thousandths
Oil control: .0016 - .0033 thousandths

Ring gap (installed in bore)

Top ring: .011 - .023 thousandths
Intermediate: .035 - .054 thousandths
Oil control ring .011 - .030 thousandths

He neglected to mention where the info was pulled, but he did seem like a knowledgeable fellow.

Click to expand...

Just glad to have gotten some knowledgable and congruent answers.....

I like the fact that Greg mentioned having seen one butt.

True that, brotha! Hey Greg, any other short block tips or secrets you would like to share with a mere common shade tree wrencher/slave? You can PM me or biggy if you want to keep them on the DL.