Ring gap

Mike,

As far as the information goes no problem, as to posting those instructions....I need to get a new set of glasses now

Richard Gavle

 

What about bigger gap on 2nd ring?

Another engine (non-blower, 600hp) I put together recommended that the second ring gap be larger than the top ring? Something about better ring seal? Anybody know if this is BS or what? Thanks for all the responses.

 

No need to save them. Hold the ctrl button and the mouse wheel will zoom in with internet explorer.

 

My last nitrous motor was built with the larger gap on the second ring. I asked the guys who dictated the build specs (a major distributer of small block Ford turbo engines) as well as another engine builder why the larger second ring gap. Both times the answer was the same, that the gap should be larger in the second ring to allow any combustion gas escaping the first ring to be allowed to exit the second gap and prevent ring flutter. I agree with both viewpoints, that the second gap should be bigger, but it seems to me that with both ring gaps set the same cold, then when the engine is operating under full load the 2nd ring gap will be bigger due to greater expansion of the top ring.

Just my 2 cent's

Richard Gavle

 

The following was found on the post that Mike sent about ring installation:

"NOTE: Most of the 2nd ring gap recommendations are larger than the top
rings. Recent testing has proven that a larger 2nd gap increases the top ring’s
ability to seal combustion. This larger “escape” path prevents inter-ring pressure from building up and lifting the top ring off the piston."

But if you look at the ring gap for Nitrous and blown, the first and second ring gaps are the same, as Mike is suggesting.

Here is a link to Mike's chart, it is a little easier to read for us old farts
http://dssracing.com/images/Articles/library/pistonring.pdf

 

I'm pretty sure that Total Seal still goes by larger at the top & a tighter second.

 

The reasoning behind larger second gaps is that once pressure gets past the first, you want to get rid of it. Several years ago Ford/Navistar discovered that this was a problem on their diesels and specified a huge gap on second ring. Just drove mechanics crazy, as no one could believe it.

As far as top ring end gap, if the rings show no sign of butting, you probably can go less. All motors are different, on blown alcohol, it will also change if you run a cold/hot tuneup vs. a hot/cold.