Piston ring end gap

[Capinoy123]

What are your theory's on piston ring end gap? What end gap do some of you use? (who build motors) .014", .020"? And why? The first motor i built had .017" ring end gap, seemed to work pretty good. But i herd some people run .20"+ on there 4G63T. Just want some input.

[Halon]

18 on top, 21 on bottom is what I used. Couldn't tell you why, just what I was told to use by a trust worthy resource.

[Pushit2.0]

You want the ring end gap as tight as possible without the ends hitting each other. Heat and bore size are the main things to look at while filling rings. If you bought aftermarket rings they should have a general sizing for ring gap, this much ring gap per inch of bore. If you have a turbo 4g63 with a standard .020 over bore and have a turbo bigger then a 20g and plan to run more then 25psi at some point ~18-20 on the top ring (compression) and ~20-24 on the second ring (scrapper) should be good. If you are planning on a bigger setup or more boost/heat then up the gap a little, or less take some out. Its a judgment call, if you do not know which way to go then you should not build your motor. Also most ring sets have a pre set oil ring end gap (based on bore size for the ring set), but its always a good idea to check this.

~John

[niterydr]

What are your theory's on piston ring end gap? What end gap do some of you use? (who build motors) .014", .020"? And why? The first motor i built had .017" ring end gap, seemed to work pretty good. But i herd some people run .20"+ on there 4G63T. Just want some input.

.20" on a 4g63?
Whiskey
Tango
Foxtrot

As John mentioned, most manufactures have recommondations of gap per inch of bore. What size pistons, what manufacture/type of pistons? What setup? Top ring? Second ring?

[Goat Blower]

I'm guessing he meant .020".

[Capinoy123]

yeah weisco .020" over rings and pistons

[Pushit2.0]

yeah weisco .020" over rings and pistons

Ok 1 more time for the record.

You have .020" over pistons with the matching ring set, you will need a machine shop to bore and hone the block to fit.

All after market piston makers sell there pistons with file to fit rings, some have the oil control rings pre gaped for a specific bore size or range of sizes.

It is needed to file to fit your rings, even if the oil control rings are "pre sized" its a good idea to check this to make sure.

There is a specific ring end gap per inch of bore, this varies a little pending ring type, make, and what the engine is intended for.

Most compression ring end gaps end up around .020", bigger if more heat is intended. Things that cause heat in the cylinder are: boost, compression, ignition timing, A/F ratio, exhaust manifold, turbo, exhaust, Nitrous, and what type of fuel you are using just to name a few. And less then .020" if you have more of a stock setup with no intentions of going to a bigger setup, but that brings up the question as to why build a motor then. The scrapper ring is normally set a little wider then the compression ring, but I have heard of people running them a little tighter, the idea being less heat makes it to the scrapper ring, they for less thermal expansion. Again you do not want to run to tight other wise the ring end gaps butt into each other and that is not good. So if you run a .020" gap on the compression ring I would run a .022" ring end gap on the scrapper.

Then there is what type of ring end gap cutting method do you use. Also be sure to de-bur the ends of the rings and most rings have a top and a bottom, so make sure they are installed right. And there is a specific place to put each ring end gap, so they do not line up after the piston is installed, the piston/ring company should have information on how to install the rings.

If you do not have a handle on EVERY aspect of building a motor, just do not do it. Plain and simple if you mess up on even the smallest detail it will cost you WAY more to fix it a 2nd time then to just pay someone to build it in the first place. There are a lot of reputable engine builds, ask a lot of questions and take notes.

Good luck with your setup.

~John