Piston Ring Questions

[sytyguy]

Trying to help some guys out with ring choices and have been presented with some questions:

- What oil groove do the STOCK SyTy pistons have? Deep or shallow?
- Has anyone ever used a 5/64, 5/64, 3/16 ring combo on a metric piston?
- Has anyone used the Total Seal 1274/2175 ring set for stock pistons?
- Has anyone had issues with zero gap second rings?

The last is my question, so I'll elaborate. We've had several engine builders in my area dyno SBCs (high rpm builds) with gapless ring sets. In all the tests using a zero gap second rings, they lost power. Reasoning? Compression builds up between the 2 gapless rings. This has only been tested (for me at least) on high rev'ing engines, so I wasn't sure if it directly applied to our builds due to the lower operating range. Your thoughts?

Thanks!

Hood

 

[JSM]

Most theories suggest just 1 gapless ring.

What can happen if you build up pressure between them, is ring flutter which then dramatically effects the sealing capability of the rings, lose compression, aka power.

 

[turbodig]

Most theories suggest just 1 gapless ring.

What can happen if you build up pressure between them, is ring flutter which then dramatically effects the sealing capability of the rings, lose compression, aka power.

I'm not sure why you'd use more than 1 gapless ring... as long as you get
a tight seal with one of them, the second ring is kinda wasted.

There's a lot of speculation floating around about multiple gapless ring
configurations, I don't think anybody really understands the true dynamics
of what's going on in there.

The only power loss stories I've heard came above 6000 RPM. Most of
us don't spin 'er that tight, so I don't think it applies as much in our
case.

Zero gap setups have a big advantage in that they don't degrade
in ring seal over time... so a 100k miler will run like a 2k miler.


Later,

Dig

 

[SY2455]

I had heard that the Gapless ring was to be use only on the top groove.

 

[bigtime]

Re: Piston Ring Questions

They make them for the second ring now so you can run a tool steel top on those high cylinder pressure engines.

 

[DanenGraham]

Re: Piston Ring Questions

The only downside i had ever heard was that some people have had problems with them snaping right where they thin out when they come together.