ring gap question
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 2,141
Likes: 2
From: Pittsburgh Pa
ring gap question
what is an exceptable ring gap on an engine that is what i would still consider a street engine that i would be se a good hit of nitrous say between a 150 and 200 shot. it is on my afr headed, forged 383 with 9.7:1 compression. i check a few top rings for their gap and they measured .020". is that around where it should be? am i being too picky? thanks
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by pr0zac
what is an exceptable ring gap on an engine that is what i would still consider a street engine that i would be se a good hit of nitrous say between a 150 and 200 shot. it is on my afr headed, forged 383 with 9.7:1 compression. i check a few top rings for their gap and they measured .020". is that around where it should be? am i being too picky? thanks
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 2,141
Likes: 2
From: Pittsburgh Pa
yeah i wasn't seeing that equation on the webpage so i was like this measurement can't be right. but then i figured out that you need to multiply them and i am right where i need to be.
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by pr0zac
thanks for the info. i had never really gotten that far into detail with an engine. i had mostly done heads and cams. this is kinda new.
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Melting Slicks
Joined: Dec 2004
Posts: 2,137
Likes: 5
From: Howard PA
As per the KB forged chart, nitrous motor, given a 4.030 bore .020 is dead on. My feelings, I open 'em a bit maybe like .025, why risk a butt? I'd rather have a bit of leakage than than a broken motor.
Burning Brakes
Joined: Aug 2000
Posts: 1,146
Likes: 2
From: Albuquerque NM
Originally Posted by Pete K
Bigger is less risky than small. I have run as much as .030 on a cast piston with no issues. If they butt 1 time it is all over. Fwiw, I usually go .024 on top and .025-.027 on second ring.
My pistons are wiseco protru and were gapped orignally to the upper end of their specs. However, I have a couple of considerations that led me to change the rings specs to lower than minimal specs. First and foremost as a street driven engine coolant temp of 150-165 is too cool and minimizes ring expansion. Secondly, the pistons were coated for lowered friction and top were heat reflective coated...thus keeping the temperature of the piston down. Third, the pistons were cryo-treated stabilizng the molec-structure and what I believe also added a more efficient heat transfer through the piston material.
every motor different I guess
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
My last motor had the kb hyper's. They called for .038 on the top ring. It made me sick to go that high. They claimed that it was nescessary to go that high due to the silicon in the piston. That motor always had poor ring seal.
