hey ht. ive got some mahle pistons going in a 81.5mm lsvtec. motor is gonna be boosted with a goal of 500hp.
mahle gave me a few different ring gap options. one for blown gas
and one for blown alcohol. im gonna be running e85 should i follow blown gas gaps?? or compensate for e85? thanks

 

Alc

 

also curious about ring gap recommendations. I have exactly the same setup as the OP. Mahle 81.5mm pistons, gsr block/ls crank, e85 4-500 whp goal

 

Considering E85 is 80-85% alcohol why wouldn't you consider their alcohol specs?

 

this is true. alc gaps would be .014 for first ring. .011 for second ring. oil ring says min of .015 i feel like these are really tight. but does this sound about right?

 

That's pretty oem-ish tight. I don't think at that power level I would agree with the numbers. Especially the second ring being tighter than the top. Conventional ring gap wisdom is to have a looser second ring to avoid flutter...although Mahle is a top tier oe/aaftermarket manufacturer. I wonder how they generate that recommendation.

 

Perhaps since the E85 burns cooler, ring gaps can be tighter?

 

just got off the phone with mahle and he said to run .018 top and .018 for second ring. much better than .011 haha. idk where they got that from

 

They're giving you gaps for methanol which runs cooler.

 

Yes. I know that...

 

I don't think you can use methanol ring gaps for an engine burning e85. between ethanol and methanol, ethanol burns hotter by a bit. add gas, and I'm sure it burns a bit hotter.

for what its worth, I run srp pistons and je rings and set my gap to .016 and .018 for 1 and 2. or maybe it was .017 and .019...

somewhere around there. I plan on boosting and hitting around 350-380 on e85.

oil ring gap isn't as important. I think mine were all .024 out of the box so I just ran with it.

 

my oil rings came out of the box at .023 too. and i ended up going with .018 top .018 second

 

I am going for 800whp before I did a rebuild on e85 I was running .018 top
And second ring was left at .021 did 640whp very well not much blow by
Know I am building my new block first ring was set at 0.23 on top but my second ring out the box was .031 wtf lol I may actually just run with it e85 or not I think at that power level I sacrifice a little blow by for some reliability I think