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Should I open the ring gaps on a non intercooled E85 turbo 5.3L?
I am building a front mount 5.3L in a S10. The turbo is an On3 78/75 and I want to run E85 non intercooled. Looking to run 12-15#'s. Just wanted to ask some guys with experience if it would be worth opening the ring gaps. I know E85 cools the combustion temps, but running without an intercooler I could see air in temps between 2-300°F. Open to suggestions as to what you have seen work....
What are your current gaps at? If you don't know, I'd check them. I've seen as tight as .016 which I would say is too tight for FI... Esp without an IC. .005-.006 X bore is the standard for top rings and fine IMO. I'd error on the wider side with hot air stuff. (which I have zero experience with) Several of the successful hot air combo guys are pretty tight lipped about their setups. Maybe one will chime in.
I've talked to a couple reputable guys that run e85 with no intercooler and they all suggested .028-.030 to be safe. They run BIG boost too, like 25-30 psi.
Whats the consensus for the guys running intercoolers with E85..... what gap size are most running? I definitely will check the current gaps, and thanks for the help.
Whats the consensus for the guys running intercoolers with E85..... what gap size are most running? I definitely will check the current gaps, and thanks for the help.
As said above. I run .005 X bore is the standard for top rings. I've run over 30lbs on E85 intercooled with those gaps. On a 5.3 thats .019 -.022 gap. Never butted a ring...
What are your current gaps at? If you don't know, I'd check them. I've seen as tight as .016 which I would say is too tight for FI... Esp without an IC. .005-.006 X bore is the standard for top rings and fine IMO. I'd error on the wider side with hot air stuff. (which I have zero experience with) Several of the successful hot air combo guys are pretty tight lipped about their setups. Maybe one will chime in.
I just tore down an l33 that all the top rings measured .013. Second rings were all .024-.025. Glad I didn't just use it as is.
The consensus is to leave them alone if the engine has some miles on it (100K+). Less than that you should check. My 77k mike LQ9 was something like .015-.016 on some cylinders. I opened them to .024 and one by mistake to .026, which I shoved into the "problem cyl" #7. No blow-by or ANY oil in the catch cans!
Unknown miles, truck it came out of had a cab fire. The factory crosshatch was still very prominent though.
I believe .014 is the low end of factory spec. for the top ring. Sounds like a really fresh motor... Or someone rebuilt it recently. Get out the dykes and open that sucker up.
Thanks I am going to open them to .20-.22. I am still debating whether to run an intercooler or not. I want to be in the 600 rwhp range give or take. Its pretty tight on the front end of these S trucks, although I have seen a few people make it work. I've seen guys cut the bumper frame horns, which I didn't want to do being that this is more of a daily driver build and I want to keep as many safety features as possible.
Use a water-to-air IC mounted in the bed… A little more weight in the back can’t hurt. China stuff is cheap these days and would work just fine on a 600HP build.
I ended up with a 31x12x3 intercooler from a buddy of mines. The outlets were front facing which actually work out in this case. I was about to use to old core support for mock up and fit the intercooler in it with the radiator in the stock location. I plan to get the outlets shortened but thats about all i should need to do. With some 90° couplers it should wrap around and go through the core support under the headlights.
04-21-2015, 01:07 AM
Should I open the ring gaps on a non intercooled E85 turbo 5.3L? 
