1.5mm vs 2.0mm top rings and Hyper-u's

[Komeuppance]

The early style g54b used 2.0mm top rings, and later went to 1.5mm top rings by 83... so that would mean the 1.5mm top ring style pistons would have a thicker, and thus stronger ringland??

 

Apparently there are two styles of hyper-u pistons, 2.0mm vs 1.5mm rings... and I'm wondering which to go with.

 

-Robert

[Dad]

only .5mm difference basically .020 Not an issue IMHO

 

Dad

[Indiana]

One design change was to eliminate the large slot for the blowby gasses and change to holes. I'd say the more narrow rings sealed better with their new shape because they were easier to tilt and have less weight and the combustion pressure gets behind the rings to blow them outward to seal and less width at the cylinder wall would mean less friction. There was a design change in the shape of the edge of the ring too.

 

http://www.b2600turbo.com/images/IM000366.JPG

Edited September 9, 2011 by Indiana

[Tim_C.]

The pins were much lighter post '86 too.

 

Stock or forged are the only options for me after seeing 2 sets of hypers bust ringlands in a situation I took stock pistons to more times than I care to admit to. At least I didn't cry about it, but I'll never go near a hyper-u in a turbo app again. You can ask most turbo specialists and they say the same thing.

 

The probelm is the long stroke of the G54B. A little detonation is a lot more severe on our engines, thus they require a good tune, and good strong pistons. People can show their good results with hyper-u's, but it is only a matter of time before a fuel pump has issues, or an injector doesn't spray right, or any other fuel control problem that allows for detonation before you realize you need to get off the gas. A problem like that will melt a hyper-u, but not stock or forged.