ring end gap ..
Thread Starter
Safety Car
Joined: Nov 2001
Posts: 4,424
Likes: 619
From: northern CA
ring end gap ..
According to the KB hypereutectic piston instruction sheet KB pistons run hotter due to their design in the top ring land area. Depending on usage (normally aspirated, race, nitrous, etc.) a numerical multiplier factor, .0065 - .009 per inch of bore in most cases, needs to be adhered to in order to arrive at the correct ring end gap for these pistons. This concerns only the top ring end gap, accordingly. The second ring gap is not affected as per the KB instruction sheet.
The spec in the GM resto packet calls for a second ring end gap of .013 - .025 .. Is it better to run a ring end gap perhaps closer to the middle of this spec range with consideration given to a street performance application .. ? .. At present I'm showing .015 second ring end gap.
John
The spec in the GM resto packet calls for a second ring end gap of .013 - .025 .. Is it better to run a ring end gap perhaps closer to the middle of this spec range with consideration given to a street performance application .. ? .. At present I'm showing .015 second ring end gap.
John
Race Director
Joined: Nov 2000
Posts: 10,350
Likes: 678
From: Beverly Hills (Pine Ridge) Florida
Re: ring end gap .. (mrg)
The more compression ratio, the bigger the gap needed to prevent the ring ends from butting (since more heat will be seen in the combustion chamber with a higher comp. ratio). Same reasoning goes to using a blower or nitrous (more heat, more ring expansion, and therefore more ring gap needed).
So if your on the high end of the compression ratio spectrum, go towards the larger gap. If you are running low compression, then you can squeeze it down some.
For the 2nd ring, I would try going towards the middle of the spec if the engine has been warmed up a bit (for street usage). But if your going to do some "racing", then perhaps larger would be better.
Just remember that you never want the ring ends to butt!
If you still have questions, try contacting KB directly.
Plasticman
[Modified by Plasticman, 11:48 PM 5/4/2004]
So if your on the high end of the compression ratio spectrum, go towards the larger gap. If you are running low compression, then you can squeeze it down some.
For the 2nd ring, I would try going towards the middle of the spec if the engine has been warmed up a bit (for street usage). But if your going to do some "racing", then perhaps larger would be better.
Just remember that you never want the ring ends to butt!
If you still have questions, try contacting KB directly.
Plasticman
[Modified by Plasticman, 11:48 PM 5/4/2004]
Thread Starter
Safety Car
Joined: Nov 2001
Posts: 4,424
Likes: 619
From: northern CA
Re: ring end gap .. (Plasticman)
The KB instruction sheet shows a pic of what can happen if the ring gap isn't set at the recommended clearance gap. There was a big chunk of top ring land and piston material missing. Following the instructions is IMPORTANT, no doubt. I think I just might shoot for a mid range spec end gap for the second ring as you mentioned. Thanks for your reply, Plasticman ..
John
John
