3.3 recommended piston ring gaps

[kamaro]

I got a low miles used 3.3 p&c set that are well with in the installation specs, Im using a set of new Mahle piston rings with them and right out of the box they all measured .016 for both top and 2nd rings, is that OK for a boosted 3.3? .. I'm planning to get close to 1 bar with that engine. Also since I'm using new rings, would you recommend de-glazing the cylinders with something like 400 or 600 grit?

[Flat6pac]

Deglaze with scotch brite and water with your hand.
600 grit is too coarse.
Bruce

[Turbo_pro]

Originally Posted by kamaro

I got a low miles used 3.3 p&c set that are well with in the installation specs, Im using a set of new Mahle piston rings with them and right out of the box they all measured .016 for both top and 2nd rings, is that OK for a boosted 3.3? .. I'm planning to get close to 1 bar with that engine. Also since I'm using new rings, would you recommend de-glazing the cylinders with something like 400 or 600 grit?

First, when I have the option, I always use the origin Goetze rings. The new Mahle rings are a cheaper product manufactured in Brazil.

.016" is too small.
I use the formula .006"x bore.
.006"x 3.8"=.0228" + or - .001 Basically .021 to .023"
The second ring should be .002" larger than the top ring. This allows the pressure that passes the top ring to escape unimpeded. If the second ring traps the compression, this will create pressure under the top ring that will damage the piston/ring land.

[kamaro]

Originally Posted by Flat6pac

Deglaze with scotch brite and water with your hand.
600 grit is too coarse.
Bruce

I will do, I always trust your opinions, Bruce

[Henry Schmidt]

Originally Posted by Turbo_pro

First, when I have the option, I always use the origin Goetze rings. The new Mahle rings are a cheaper product manufactured in Brazil.

.016" is too small.
I use the formula .006"x bore.
.006"x 3.8"=.0228" + or - .001 Basically .021 to .023"
The second ring should be .002" larger than the top ring. This allows the pressure that passes the top ring to escape unimpeded. If the second ring traps the compression, this will create pressure under the top ring that will damage the piston/ring land.

100% correct on all points.

[kamaro]

Originally Posted by Turbo_pro

First, when I have the option, I always use the origin Goetze rings. The new Mahle rings are a cheaper product manufactured in Brazil.

.016" is too small.
I use the formula .006"x bore.
.006"x 3.8"=.0228" + or - .001 Basically .021 to .023"
The second ring should be .002" larger than the top ring. This allows the pressure that passes the top ring to escape unimpeded. If the second ring traps the compression, this will create pressure under the top ring that will damage the piston/ring land.

I already have the Mahle rings so I guess I will just use what I have, after all it is Mahle, so it must be at least "decent".

So is it safe to go with .020" for the first and .022" for 2nd? .. I just took my 3.2 apart and all rings were at .016" so I guess the turbo engines needs a bit more gap to be safe, right?

[kamaro]

Originally Posted by Henry Schmidt

100% correct on all points.

I'm glad that you read my post, Henry, I really need your opinion here before I do a costly mistake, do I really have to throw away the Mahle rings and get Goetzes? .. I'm not looking to get 500+whp, just want a decent power out of a 3.3.

[Henry Schmidt]

Originally Posted by kamaro

I'm glad that you read my post, Henry, I really need your opinion here before I do a costly mistake, do I really have to throw away the Mahle rings and get Goetzes? .. I'm not looking to get 500+whp, just want a decent power out of a 3.3.

No, use what you have. They will be fine.
I think Jim was speaking to other builders looking to buy new rings. He didn't tell you to throw away your rings.

I really like the Goetze old school ring. I think it's an "old dog...new tricks" deal.
I even have custom pistons designed to utilize Goetze ring and you wouldn't believe the push-back I get from piston manufacturers.

[kamaro]

Happy to hear that .. thanks Henry

[rudedude]

Do you size naturally aspirated rings differently than turbocharged?

[dannobee]

NA engines don't need as much ring gap. If it's boosted, you'll need to add another 0.001" or so for each inch of bore because of the higher combustion temperatures.

As we used to say...

Big ring gap = big catch can

Small ring gap = big trash can

[Tippy]

I run my gaps looooooose now as I had them too tight during 1st rebuild and tore up the Nikasil and Total Seal rings.

Very costly mistake!!

No blowby after refresh.

[kamaro]

Originally Posted by Tippy

I run my gaps looooooose now as I had them too tight during 1st rebuild and tore up the Nikasil and Total Seal rings.

Very costly mistake!!

No blowby after refresh.

could you please share your before/after end gaps? .. I care of knowing about some real-time tests.

[gsxrken]

Originally Posted by kamaro

could you please share your before/after end gaps? .. I care of knowing about some real-time tests.

I’d like to know too. I assume Total Seal rings have a different spec if they’re gap-less ones but maybe they make standard ones too?

[Tippy]

Originally Posted by kamaro

could you please share your before/after end gaps? .. I care of knowing about some real-time tests.

I don’t remember the exact gaps (written down somewhere) but I chose gaps for 30 PSI/2 bar of boost.

[porschedude996]

What are the differences between the standard ring Mahle uses and the Goetze rings?

Originally Posted by Henry Schmidt

No, use what you have. They will be fine.
I think Jim was speaking to other builders looking to buy new rings. He didn't tell you to throw away your rings.

I really like the Goetze old school ring. I think it's an "old dog...new tricks" deal.
I even have custom pistons designed to utilize Goetze ring and you wouldn't believe the push-back I get from piston manufacturers.

[Henry Schmidt]

Originally Posted by porschedude996

What are the differences between the standard ring Mahle uses and the Goetze rings?

For years Mahle used Goetze rings. Economics dictated a change so Mahle started using rings made in Brazil. Made in Germany vs made in Brazil....seems an easy choice.
The difference would be design, materials and coatings. My guess, Goetze has proprietary processes.
I still believe that quality exists inexperience, and reputations are built on quality.