Rings

We have a BNR 526 Hemi. We put childs and albert gapless rings in it and now the motor is blowing heaps of oil out of the pipes. It had a fresh hone job. We previously used child and ackerley rings with no problems. Any info or suggestions welcomed..........also what are the best rods to use and how many runs do most guys do. We turn this engine to 9200rpm and about 40psi boost (whipple blower).

 

we have found that the gapless rings seal up too tight sometimes. that will give you crankcase pressure, and throw oil out the pipes. save yourself some heartache and use a standard 2nd ring. we like a .031 top,1/16th 2nd, 3/16 oil ring, works well for us. i like the grp rods, seem to last a little longer than the others at higher rpm's. just my .02 cents

 

just a couple points. I have run both types of 2nd's. Won't get into that debate which is better. Make sure though that the ring is not upside down. Instant oil. I have seen that more than once over the years. If the engine just was honed, check to make sure the bores are round. I know this is simple, but don't assume anything. tried both types of rings in two engines. Ran identical mph

 

another issue is the relationship between leak past the top ring compared to leak past the second ring. I have seen guys run the second ring tighter than the top ring which causes the top ring to flutter and lose seal.

 

The top ring gets more combustion heat than the second and will expand more, so even if the second ring is fitted with a few thou. less clearance when cold, I don't think it will have less when making power.

 

Sounds to me like the 2nd ring is upside down. I would run a standard 2nd ring and open the gap to at least the same as the top. It will help the top ring seal better.

 

the second rings are definately not upside down. i spoke to bob today and he said it could be the intake manifold leaking or the seals in the blower gone.

 

Piston Ring Seal

Check the ring side clearance in the ring grove. Should be 0.003 - 0.004 If you have the pistons coated after the ring groves are machined they end up to tight and the ring can not float in the grove when hot. Also some (most) coatings are not totally smooth like a machined surface the same way glass beading ruins ring side seal. With reduced side seal the ring is not pushed against the cylinder wall with gas pressure.
Check back clearence in the ring grove, rings should never stick out of the groves when pressed in towards the piston with a straight edge. But to much back clearance and the gas pressure takes to long to press the ring against the cylinder wall. To much cushion and the rings flutter. You want as little back clearance as you can get but not have the ring sticking out of the ring lands. They make shims to reduce back clearance as it is a common problem.
I perfer a gapless ring of the overlapping style like the C&A but you must pay carefull attention to the gapping of the rings and make sure there are no burs on the mating surfaces and that they are not bottoming out on the inside of the overlap (both sides) after file fitting them.