Mahle Piston Rings

Drothgeb

Drothgeb

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Sep 18, 2010
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I'm using Mahle 286210 pistons in my new build. Had the block bored for .008" clearance, and plan on coating the pistons to get about .007" clearance. Pistons fit good. But with the rings that came with the pistons... the top rings just need a little filing to get a .028"gap. Oil rings are a little loose at .025". But the inermediate rings have over a .050" gap. I was planning on less than half that. Is this what Mahle recommends, or did I get the wrong set of rings with the pistons?

If I do need to buy another set of intermediate rings, I was giving thought to Total Seal intermediate rings. Anybody run these in a 800hp+ 12v with success?
 
Speak to Mahle tech then ask for guidance from the seasoned engine builders on your situation.
 
Drothgeb said:
I'm using Mahle 286210 pistons in my new build. Had the block bored for .008" clearance, and plan on coating the pistons to get about .007" clearance. Pistons fit good. But with the rings that came with the pistons... the top rings just need a little filing to get a .028"gap. Oil rings are a little loose at .025". But the inermediate rings have over a .050" gap. I was planning on less than half that. Is this what Mahle recommends, or did I get the wrong set of rings with the pistons?

If I do need to buy another set of intermediate rings, I was giving thought to Total Seal intermediate rings. Anybody run these in a 800hp+ 12v with success?
Click to expand...

second ring must be looser than first ring not to build pressure between them.
 
Just remember when building, your parts will not come perfect and like Leiffi said your main concern besides sealing is making sure you don't break the seal or damage ringlands. There can be that chance of one wrong piece picked for your order. However speak to Mahle and go from there.
 
Remember to base your ring gaps as well as the piston to wall clearance on how much heat and pressure your going to introduce on top of the piston. It's never one size fits all.
 
Brad, is there a good way to judge that? Maybe a rule of thumb that you go by when building and engine. I am
Going to run the same piston and was attempting to get the same piston to wall and the same ring gap on the top ring. None of my stuff is machined yet though so still can be changed


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97rada said:
Brad, is there a good way to judge that? Maybe a rule of thumb that you go by when building and engine. I am
Going to run the same piston and was attempting to get the same piston to wall and the same ring gap on the top ring. None of my stuff is machined yet though so still can be changed


Sent from my iPhone using Tapatalk
Click to expand...

too tight is bad, a little bit too loose don't have much effect but is safe.
 
Well that's a given man, I am looking for advise or a way to gauge this how much is typically needed for say 800+hp build


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what is too loose x too tight?

I went through this with the last engine I build and didn't find any opinions on here. just set it a few thou above stock spec.
 
I have good info on ring gap, just not piston to wall info
 
Fahlin Racing said:
Just remember when building, your parts will not come perfect and like Leiffi said your main concern besides sealing is making sure you don't break the seal or damage ringlands. There can be that chance of one wrong piece picked for your order. However speak to Mahle and go from there.
Click to expand...

I always check and custom fit everything when building an engine.

And I do plan on giving Mahle a call. But I've had mixed results from talking to manufacturers reps before. So like you said, I was hoping to get some input from some of the seasoned engine builders here on CompD. In doing some searching on it, I've seen a number of post on top ring gaps, but not so much on the 2nd and oil rings.

rockjeep73 said:
How much over .050 are they?
Click to expand...

They are .054"-.055".

Bponci said:
Remember to base your ring gaps as well as the piston to wall clearance on how much heat and pressure your going to introduce on top of the piston. It's never one size fits all.
Click to expand...

Brad, I know exactly what you mean. I'm actually building 2 engines at the same time. And have decided on a completely different set of build specs for each one depending on hp, rpm, intended use and etc. This one is a high hp street build that won't see much over 4000rpm. So for that, I was thinking if I held to, or slightly over max Cummins specs on piston ring gaps, it should be good. Especially since I'm coating the pistons. Planned clearances are .028-.030" top ring, .022-.025" intermediate ring, .022-.025" oil ring.
 
We've been getting away with 25-28 thou top ring 30-35 second ring and leave the oil ring as long as its at least 10 thou. All out build on monotherm's at 3 thou piston to wall.
 
Joesixpack said:
We've been getting away with 25-28 thou top ring 30-35 second ring and leave the oil ring as long as its at least 10 thou. All out build on monotherm's at 3 thou piston to wall.
Click to expand...

That sounds like a tight piston to wall, how did you come up with that number when building your engine
 
I'm guessing the tight clearance has a bit to do with the steal pistons as well.
 
Curious what are peoples thought on alloy piston clearances in 3rd gens? Assuming a non coated piston. I would assume coating would help a tad with expansion but nothing to back that up.
 
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