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Pistons and Rings
Building a 400 block, 4" stroke for the street but also planning on doing some open road racing. Might even try the Texas Mile or something similar. I do plan on driving this car a LOT. Trying to make some decisions on pistons and rings. It will have a Canton pan with the kickouts on both sides. I was thinking of using the Motion Raceworks catch can with breather tubes from both covers going into it to let it breathe. I called Total Seal and the guy told me either 1.5mm top and 2nd, or .043" top and 2nd and go with a 3/16" oil ring. He also said to use a gapless and gas ported ring. My intention is to have custom pistons made from 4032, coated, and maybe DLC coated pins. I want to make decent power and make it for thousands of miles. So longevity is important to me. Any thoughts?
In case you're curious...4.145" bore, Oliver 6.8 rods, KRE 290cfm CNC D-ports, Hyd roller w/ solids 234/[email protected] w/ .560" lift on a 112 lsa. RPM intake and an 800 cfm Q-jet. Planning on backing it up with a Tremec TKX and 3.50 gears out back. |
Talk to Paul K, he should be able to hook you up with some Racetec pistons with modern ring pack, coated, etc.
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I guess I should add that I'm mainly curious if anyone has experience with the thinner rings, gapless rings in a n/a application, or ported rings.
I can order pistons and rings myself. I know how to get all the math and info they need. I've always used the old standard 1/16", 1/16",3/16" ring pack or the factory ring pack and either Total Seal classic rings or Sealed Power. I just decided to put a LOT more thought into this one. This one is very special to me and I want to make sure it's as good as I can make it. No cutting corners on this one. |
I had Total Seal gapless rings in my 455 motor, the leakdown rate was less then 2% ran great but had a lot of reversion. I removed them when I refreshed the engine and the reversion went away. I was using a header evac system. Perhaps if I had vacuum pump it may have eliminated the reversion. I think gapless rings may work better with a vacuum pump.
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I had pistons with 1/16" rings and was going to just run Classic file fits and be done with it. But I got one of my 2nd Sealed Power rings gap too big and getting a hold of Sealed Power tech was impossible.
So I called Total Seal and they were able to sell me a single cast iron 2nd ring. BUT, I ended up buying a whole new ring set. They were back cut to reduce tension and the top rings are ported. So this will be new for me too. Supposed to be worth 7-12HP , why not. Its only money right ! |
That statement is a real stretch because I can't see how there's any logical explanation that would allow you can blame reversion on good ring seal!
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Far as i have seen; Gapless rings are for the experienced experts. |
We use thin ring packs all the time. It's a great way to add modern technology to our beloved Pontiac engines. Machining quality, finish and assembly become more important when using thin rings. They are a win-win at our shop. More power, less friction, less bore wear.
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I've built a few motors with the thin "LS" rings - no problems.
Back in the late 90's I used a set of the Total Gapless 2nd rings. They were basically an iron ring with a groove for 2nd ring (like an oil scraper ring) and you stagger the end gaps. I'm not sure if they even make those anymore, a gapless top ring makes much more sense to me. Anyway, that motor lasted maybe a year, and it was burning oil. One (maybe two, it's been a while) of the gapless rings had cracked. They also had nothing to keep the rings from rotating (maybe they've addressed that issue with their newer rings) and several of the other had rotated so that the gaps were aligned (so no longer "gapless"). |
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The Chids & Albert design was much better than Total Seals. |
Yea, my "lesson learned the hard way" was Total Seal's Gapless 2nd ring. Total Swill
Used the Chevy thin stacks in the 455 with good results. |
How many NHRA ProStock engines are running gapless rings,How many Nascar Cup engines are using gapless..I know the answer!
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How long they last is a big consideration. Also what's available at a reasonable price plays a factor in my world. Some of the metric rings are custom for some popular Pontiac bore sizes from one manufacture (I should say re-seller) and a similar set is considered a shelf item with another and it sells for almost half the price.
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I have used both Child’s & Albert gapless when they where around and Total seal and never had a issue.
As aways the needed bore prep and hood ring grooves for each type is paramount to good function. I have taken apart to SBC motors and a Buick 455 where gapless rings where installed on used cast pistons which ring groove clearance wise should have been s scrapped. These owners I can only assume where hoping a gapless ring would save them from there oil burning blowby problem. |
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I can't explain it all I know is what happened in my motor. Just the facts. |
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