Ross Ring gap

[ckrell]

Its time to file fit rings. The guys at Ross said to do .020'' on the top ring with E85 or other alcohol. The top ring is stainless steel. My plan is to get the most out of my HX40 setup 40+psi and 70+ppm. Whats the most gap some of you have used. .020" just seemed a bit tight for my goals for the top ring. Please comment

 

[e85_4g63]

That does seem tight. I've seen and personally used 22 to 24 on sub 30 psi builds. 40+ psi and only 20 for the gap seems like an accident about to happen. Unless something is special about there top rings and allow them to expand a lot less then almost every other ring out there. I'd call them back and re-ask them again..

 

[BogusSVO]

Stainless steel top ring? First time I have heard of that.
Are you sure it is not a full chrome ring?

 

[ckrell]

My older piston kit had the ductile moly top ring. They said I really need to be using a stainless steel top ring for those boost levels and sent me 4 new rings. The originals were mostly flat black, the new ones are mostly shinny

 

[BogusSVO]

Seems we are both right, high chromium stainless steel top ring

I know them as chrome rings.

 

[5150DSM]

I would recommend a bit loose on the top 2 rings and invest in a good catch can/crankcase evac system. I would rather have a little more blow-by, rather than twist or snap a ring do to excessive cylinder pressure. I plan on running .022 top and .024 2nd on my DSMGreen set-up on E85, 32-35psi.

 

[JacksonAuto]

Listen to the folks that built the pistons. You don't need to get crazy with the gap on the top ring. The two main goals of the gap are to a.) not allow the ring ends to butt together and b.) to allow a certain amount of combustion gasses to pass through which allows the second ring to seal. Too much end gap will obviously allow excessive gasses past the ring which is not an acceptable compromise. There are zero gains from going with a larger gap, but there are negative consequences by doing so. The rule of thumb for high boost/high compression engines is .0057-.006" of gap per inch of bore. 3.366 x .006" = .020" gap. Perfect.

 

[ckrell]

.020" might be adequate but 25psi to some is high boost for others 35 for me it 45psi. The ring end gap should estimated more by HP per cylinder somehow or at least in the equation. I went with .024"top and .028" on the second my goal is 800+ HP at the crank but thank you all for your input. The shortblock is together