well ive tried searching and i come up with nothing but diffrent people claiming there right.
so i wanna see what you guys think about ring gaps.

im building a na d series at the stock bore.

but what im really looking for is the most comon used equation for finding out the ring gaps for both FI and NA.

and while were at it. whats a desired piston to wall clearence for both na and FI?

 

Ring gaps and piston-wall clearance don't really follow a "one size fits all" rule. Obviously the clearances will vary depending on being NA or under Forced Induction (to include nitrous), but also materials, design, and intended use.

Cast pistons usually allow a tighter clearance (~.0005-.002") than a forged piston, and even with forged pistons you have a 4032 alloy which usually allows a tighter clearance (~.002-.004") than a 2618 alloy (~.003-.006"). Rings gaps are the same way as you have to consider not only the material of the ring, but also how much heat and cylinder pressure it will be exposed to as well as how far up the piston the ring is placed in proximity to said combustion heat.

Luckily, the manufacturers of said parts usually know their **** and include recommended clearances for the ring gaps as well as piston-wall. I've always followed those recommendations and I've never had a reason to regret it.

 

well lets say for an oem rebuild im using oem pistons and rings.

 

Go with OEM specs. That's what they're for.

 

any clue as to what that is?

 

Buy a manual.

 

Not off the top of my head, but I'm sure someone has a service manual with those specifications. You may be able to find it if you try Google.

 

as per 1994 honda civic factory service manual
piston to bore .0004 - .0016 new, .002 service limit
ring gap top .006 - .012, .024 service limit
second .012 - .018, .028 service limit
oil ring d16z .008 - .028, .031 service limit

(all sizes are in inches)

 

thank you badway

 

I usually go with what the piston ring manufacturer recommends.

 

First let me start by saying I have searched and read dozens of threads here and on other sites for the past few days before posting.
If you can help, I am Looking for a little advise. After melting a piston several years ago from what I believe to be a bad tune, I am finally getting around to rebuilding my engine. I ordered new pistons/rings etc. The block was machined and honed to the pistons. The problem I have is after reading countless threads and talking to JE I am torn on the #2 piston ring end gap. When I received the rings, 2 of them were substantially larger than the other two. Resulting in an end gap of .028 in 2 cylinders for the 2nd ring. The other two are sitting at .021 and .022
I talked to 2 different people at JE and they keep telling me the #2 piston ring gap makes no difference as long as the end gap is large enough to avoid butting. They told me that they do not manufacture them and the manufacturer has a tolerance of .010 I believe is the number they through out.

If this were the case, why in both their literature and what I see online do most people suggest a clearance of .022 for the second ring.
I would really appreciate any advise.
The engine is tuned to 20psi and was making about 400whp on pump gas. Its bored 81.50 and honed just a tad looser.
I have searched countless threads with nothing that was a concrete explanation for this. I hate to rebuild just to destroy another engine over something so trivial.

Thanks for any help you may have!

 

Just put them all to .028.

 

Yeah, that seems to be the logical way to proceed, but I am looking for a concrete answer as to why its ok to go larger and what effects may result from doing so.