Ring end Gaps

[Steve.k]

Ive been noticing lately that a lot of ring and piston mfgs are wanting ring gaps on top and bottom a lot closer to each other. Years ago we used to set top and bottom in that .014 top and .010 bottom range on 4" bore. I see alot of mfgs suggesting in that .026 range or close top and bottom. A old superstock hemi builder told me once that on their all out Hemis they would not see a end of ring butt till north of .030 on end gaps. So since ive made my clearance on looser side. Albeit not that loose. Thoughts on that or use what works.

[blykins]

Mine always have wider gaps on the 2nd ring.

[rebelrouser]

Ring manufactures give specs for end gap per inch of cylinder bore, .004 per inch is the standard for stock engines, when you change piston materials, power adders, or very high cylinder temps like in an all out race engine you adjust that number to give wider end gaps. So I always check with the piston and ring manufacturer, as they are changing materials sometimes. So this spec is to prevent end gaps from butting and causing damage. By increasing the end gap on the second ring you improve performance at WOT, by relieving the blow by pressure under top ring trapped by the second ring, which can cause it to flutter at high loads and high speeds. The second ring end gap varies a lot by engine builder, and again on what kind of ring package you are using. If in doubt pick up the phone and call your manufacture.

[ProPower engines]

Ive been noticing lately that a lot of ring and piston mfgs are wanting ring gaps on top and bottom a lot closer to each other. Years ago we used to set top and bottom in that .014 top and .010 bottom range on 4" bore. I see alot of mfgs suggesting in that .026 range or close top and bottom. A old superstock hemi builder told me once that on their all out Hemis they would not see a end of ring butt till north of .030 on end gaps. So since ive made my clearance on looser side. Albeit not that loose. Thoughts on that or use what works.

The big questions here are
What bore size??
What ring type??
What ring width are you using?? .043 1/16 5/64 ??
Radial wall thickness?? How deep in the groove??
What application is the engine used for ect ect ect .........................

[Steve.k]

This is 4.05 bore. 1/16 comp rings and 3/16 oil. Total seal cr 1006 file fit. They call for same top and bottom. Its interesting to see all the way down even nitro application calls for same gap top and bottom.This is Drag gas deal.

[David Redszus]

Since ring materials are very similar, the real variable to which attention must be paid is temperature.
Of the bore and rings, while being measured and when running full blast.

The first is easy, the second, not so much.

[F-BIRD'88]

The alloy of the Piston matters. The rings position matters. The intended purpose and horsepower (heat load) matters.

[Steve.k]

Drag car forged 13.5 chi4v head dual 1050 on q fuel. I set them .026 top .024 second. Thats my preference give me your views. Top ring loose incase juice jug hits trunk.

[bigjoe1]

A big end gap does not seem to hurt power at al---BUT, too small and all kind of BAD things can happen




JOE SHERMAN RACING

[Steve.k]

Big Joe im thinking the same way. Plans change down the road. They seem to forget to tell ya.

[bigjoe1]

For years, I set the top at 014-015, second at 010--- Now is set the top at 020-022, second the same




JOE SHERMAN RACING

[Steve.k]

Hear that!

[David Redszus]

The alloy of the Piston matters.

Why would the alloy of the piston matter? It is the expansion of the ring that matters, not the piston.

The rings position matters.

The ring position matters only in the sense that position may determine the ring temperature.

The intended purpose and horsepower (heat load) matters.

Yes, but we are back to ring temperature again.

Ring friction forces, block expansion, ring heat transfer, all will have an effect on ring dimension
and ring end gap clearance.

[pamotorman]

A big end gap does not seem to hurt power at al---BUT, too small and all kind of BAD things can happen




JOE SHERMAN RACING

at GM they did a test on a NASCAR engine. they ran the engine to get base line HP then they took the engine down file filled the end gap of the rings to .125 and the engine lost less than 10 HP. blow by was up but the HP was still there

[In-Tech]

A big end gap does not seem to hurt power at al---BUT, too small and all kind of BAD things can happen




JOE SHERMAN RACING

at GM they did a test on a NASCAR engine. they ran the engine to get base line HP then they took the engine down file filled the end gap of the rings to .125 and the engine lost less than 10 HP. blow by was up but the HP was still there

Thank You, end gap is something that should be addressed but it is not as critical(unless too tight) in a race environment as many want to believe. There just isn't enough TIME.