I think my lower end, after 3 seasons of racing is tired. Lots of blow by and excessive crankcase pressure.. I assume from forced induction. Perhaps the TRW or Molly rings cannot take it anymore?

Anyway, whats a good blower piston/ring ?

-- Joe

 

There is a set of new gapless rings made for superchargered cars.

Friend of mine is running them and only had a 1% leakdown. He's running 22lbs of intercooled boost and they seem to be holding up fine.

Might want to look into those.

 

no offense.....but leak down percentage #s dont mean a whole lot when you look at the whole picture of what those rings do to the oiling issues of your motor

Do a little more searching on who is using gapless style rings and what their experiences are on both n/a and fi and i think you'd find there are more out there with bad experiences than with good. Not saying that some aren't lucky, but the majority have issues

Go with a good plasma-moly top ring set.....C&A is always good

 

off topic question. if there gapless rings how the heck do u get them on the piston?

 

when rings fail, the rings themselves are usually the last thing at fault. It can be a result of rod angularity, bore finish, usage vs. lubricant type, lubricant type, cooling issues, too little windage, and the most popular washdown. I doesnt matter if your A/F ration is perfect now, if it ever wasnt it can shorten ring life. I recommend against using gapless on blown or nitrous cars. I do recommend TRW pistons though. But as far as gapless rings, I was told that pressure can build up between the top and second rings causing them to pressurize that area and 1) lock in the bore, 2) try to separate the top and bottom halves of the piston by ripping it in half. I didnt believe it when I was told and did what I wanted. This is what happens, you will notice the beggining of this phenomenon on the piston pictured. when holding the piston you can definitely see how the top of the piston is lifted even though the picture it is not really extremely visable due to the angle of the photo. TRW's are the toughest (albiet heaviest) off the shelf forged piston there is. some of the manufacturers can "build" you a tougher piston with special ring spacing. this wasnt found until the end of season tear down. Leakdown testing was within specification. See piston result here

 

Tom, I swear i've seen this post from you before.

Some people at my shop (old timers) say its fine, that the pressure in the crankcase is not excessive. THat the fact I have no valvecover baffles is the cause of my oil consumption, and to "stop using synthetic oil". ugg..

THe oil doesn't really stink of gas, but it is yucky..

-- Joe

 

How do you know you have excessive blowby? Did you do a leakdown check? how fast is your car?

 

How fast? low 12s..

No I havn't done a leakdown. I dont have a gauge for leakdown tests, just a regular gauge.

 

my JYD ran high 11's on a 150 shot (Video) and it had absolutely the worst ring seal ever, the bores were trashed when I reassembled it. yes anethes it is a duplicate post but it applys when the question is also a duplicate I definitely agree you have to have alot of blowby before it becomes a problem and smoke out the valve covers must be "blasting" out before I would worry about it unless I broke the bank building it.

 

Well, all the money is tied up in cam, heads, lifters, etc...

THe lower end I could prolly rebuild for under a grand again when the time comes.

Thanks.

-- Joe

 

i saw this in a chevy performance mag. federal mogul has some new rings called(hellfire rings)don't know if anyone use them yet.you can check them out at www.federal-mogul.com

 

dont over-gap your rings either.

I was so worried about ring failure due to forced induction i ran .030 gaps top and bottom, and now i have freaking 11%-13% leakdown on my brand new motor. if i could do it over again i would have put about .027~ top and .025 middle because .030 is just way too much.

I know somone running gapless on a roots blown 383. only running 6 PSI though, but thats good enough for nearly 510 RWHP... its a very scary sight on street trim. going from 6 PSI to 10 PSI doesnt net much more power, either. more torque though. I think its because that little 144 blower cant keep up with the revs, but down low the things moves. Comp XE270 cam 110 LSA...

And I will be building another roots blower 383 in like a week here. Ill get some digital video of it and it will probably be using gapless rings.

 

Heh, i never checked the ring gap on my federal mogul molly race rings.

Did a compression test, getting 140psi in the cyls. didnt do a leakdown though.

Problem actually isn't blow-buy. My holley (M/T) valvecovers have no baffles, so at WOT it was spraying oil out my breather, and into the pvc. causing the plugs to foul.

Also, w/out the baffle it appeard to have excessive pressure, because the holes are right over the rocker.

In addition, the stalling condition that I was having was related to a cracked IAC valve. So with the combination of these, you can see why I thought the rings/pistons were gone. but after spending a few hours checking things it all started to make
sense.

Thanks for the replies. Hope my work will benefit others in the future.

-- Joe