does anyone know the ring end gap for a mahle ring set# 4035MS-15 4.030"+.005" File Fit ,It has a 4.030 bore and the instructions were not in the box when it came back from the machine shop?

 

N/A .0055" per inch of bore
Boost/Nitrous .0065" per inch of bore

 

for both compression rings? you use this formula?
what about oil rings?

 

i thought top ring was one size then second was a tad bit bigger?

 

to prevent ring flutter the top ring is smaller than the second ring i did them at .018 on top and .022 on the second but i can change them it is not assembled yet

 

well my main studs finally came in so i am going to assemble this thing friday,Take a bunch of pics and show my 408 build step by step

 

just bringing this back...

My Mahle rings, which had the directions in the box, actually recommend the second ring be at a smaller gap than the top ring (NA was bore X .0045 for top, and bore X .0035 for 2nd). Thought this was a bit odd and asked tech support at Mahle and they said it is best for oil control, and the directions are mainly for someone who is simply rebuilding an engine for the first time, not a performance minded rebuild where the builder would already have the know-how and experience/preference on their own ring gaps. And he agreed that many people do build with larger second ring gap for higher performance, contrary to their directions' recommendations.

...unfortunately for me, I already filed my rings to have the top larger... Now I'm wondering if I should open up the 2nd ring gaps larger?? and how large is too large of a gap...?

 

I say for N-A .018 .022 bottom is perfect but if you open the top to .020 or real close to it still ok, however over .022 you'll spec more oil in the combustion chamber.
You can buy the top rings individually, as many as needed...

 

ah ok yeah.

I ended up opening up so all rings, top and 2nd, are right around .022. My 2nd rings were all around .016-.018 when I wrote the above reply and I was concerned with my top rings, and also the difference between the two. I think the biggest gap out of all of them was a .026 though, and I wish I could replace it....
I actually called Mahle customer service about it and the guy said I'd prbably be fine though and he was saying .022 would be most ideal, but I shouldn't pull my hair out over one .026.
And he also said that they only sell (supposed to go through a dealer) rings in sets per cylinder, not indvidually.

But anyway, they're all installed now, and the one with the big end gap is on cylinder 7, so I'll keep an eye on it and possibly test compression just for the hell of it. Oh, and the 2nd ring under it is a .022 though, so hopefully not too much more oil consumption than any of the other cylinders... what'ya think?

 

I wouldn't lose any sleep over it. I've torn down engines built by "pros" with wider discrepancies in the ring tolerances than yours that were running strong. I also would be compelled to correct it but you'll never know once it's installed.

 

I got this info from mahleclevite.com/publications. Gaps for the top rings,grey iron and steel: moderate performance: .004 x bore, drag racing: .0045 x bore, nitrous street: .005 x bore, nitrous drag: .007 x bore, supercharged: .006 x bore. Second ring grey iron and steel: moderate performance: .004 x bore, drag racing: .0055 x bore, nitrous street: .005 x bore, nitrous drag: .007 x bore, supercharged: .006 x bore. Notice: most of the second ring gap recommendations are larger than the top rings. Recent testing has proven that a larger second ring gap increases the top ring’s stability allowing for a better seal. This larger “escape” path prevents inter-ring pressure from building up and lifting the top ring off the piston allowing combustion to get by. many engine builders have reported lower blow-by and horsepower gains at the upper RPm ranges with the wider second ring gaps. also, almost every new car made is using this inter-ring pressure reduction method to lower blow-by and emissions and to increase engine output.

 

good info there