[german tarquini]

what ring clearance to use on mahle 2618 forged pistons
manufacturers data
top ring minimum 0,0070
second ring minimum 0,0070
oil ring rall 0,015

4000 example
top 0,028
2nd 0,028
oil ralls 0,015

what measure do you recommend?
i think the first measures are with little clearance and the second excessive

[oldman]

it all depends what you are doing, a street driver with maybe some mild track action can get away with tighter clearance vs something that is going to road race or run the Texas mile. 2nd, FI and / or meth and / or E85 can add heat load and will need more clearance. I forgot what I set mine at but it is FI and E85. .007 is way too tight off the top of my head. I think I set my top ring at .022 but I'll leave it to others who have build more LT1 and /or actually racing their rides.

My car does not seem to burn much oil say 1/2 quart between 5000 mile oil changes, street driven (but pretty hard on it). I thought it would burn more and have more piston slap with the forged pistons, but nope seems to run fine.

You really need a ring grinding tool, doing it with a vice and a file is pain and take WAY more time.

https://www.wiseco.com/auto/wiseco-a...bout-ring-gap/

[german tarquini]

thanks
i want to use it in mile races... centri ecs supercharger flex fuel 20% approximate 700 hp at wheel

kit
Mahle/Molnar LT1/L86 Drop In Piston and Rod Kit LSXLT1STD-KIT ..10.2 compression
https://www.lsxceleration.com/mahle-...lsxlt1std-kit/

[JANNETTYRACING]

Originally Posted by german tarquini

what ring clearance to use on mahle 2618 forged pistons
manufacturers data
top ring minimum 0,0070
second ring minimum 0,0070
oil ring rall 0,015

4000 example
top 0,028
2nd 0,028
oil ralls 0,015

what measure do you recommend?
i think the first measures are with little clearance and the second excessive

Tighter ring gaps will always produce best ring seal.

The ring gaps that are recommended with the rings, estimate how much growth you will have in that particular ring material and diameter due to estimated cylinder temp as a result of intended use.

That is why they use a gap calculation, X thousands multiplied by Bore inches.

It is safer to go on the big side of spec for your application if you do not have a Highly qualified tuner but you will give up oil control and ring seal.

A bad tune will overheat the rings and butt the gaps.

I can run on the tighter side of recommended gaps because I tune the cars myself and alway makes sure they have adequate fuel system components for the target Horsepower.

Everyone says ring gaps are the problem when an LT1 fails which is not the case.

It is and always will be a bad tune, lack of fuel or both.

We run Factory stock LT1 long block, up to 750 RWHP. or 860 Crank HP with no issues.

Ted.

[oldman]

I thought this was a good talk on rings, interesting that hypereutectic pistons need more gap vs forged 4032 / 2618. WEISCO and Jimmy Barton say to run more 2nd ring gap, especially on FI. so that would be at least .0057x 4.065= .023 for me, and you would be something like .0063 x 4.065= .0256, which to my mind is HUGE, but I only build daily driven street cars. Maybe a call to the piston manufacture would be good as you are actually building a racing engine running at high HP over long(er) distances.

As stated, my engine maybe burns .5 quarts between oil changes, maybe...

The stock ring gap and FI: while maybe OK for guys running on a dyno or 1/4 mile at a time, could be a likely failure point in mile and or road racing; but this extrapolating two extremes, assuming the engine is tuned correctly. Here let me put it this way, if somebody said hey I'm running 700 wheel HP FI on a stock engine what would be the quickest way to fail it, I'd say run the Silver State or the Texas mile a few times back to back or a long road race course over several weekends, I would say a likely failure point would be piston ring at the gap due to heat load. OK, take same engine increase ring gap and then ask what the most likely cause of failure would be... dunno burned intake valve or a burned piston as shots in the dark. Point being the LT1 is pretty strong but runs NA ring gaps on a cast high comp NA piston and just by increasing the gap brings a likely failure point to one a non-issue. Please understand that my labor is free and I'm not advocating everybody drop $2000 to tear their stock short bock apart. I'm just pointing out there is a big gap (pun intended) between OEM NA and a 2618 motor running mile races..


Here is a link to the pistons and you will note a 2618 piston is pretty exotic.
https://www.motortrend.com/how-to/na...iston-choices/