I'm building a twin 66mm 5.3 stock bottom, ls2 intake, zo6 cam, megasquirt, bla bla bla. Was wondering what ring gap should be used when running E85. I have seen .028" for gas, just would like to know what is safe. This stock shortblock is just my sacraficial tuning aid but I would like it to live long enough to get my forged bottom together.

 

I didn't mess with the ring gap at all. On stock engines I personally think it is overated. However, I do think a higher mileage stock engine helps. If has less than 80k in miles I would consider opening them up to .024. How many miles on the engine? How much boost you planning to run.

My current engine has a 180,000 miles on it and I didn't touch the rings. I run E85 from the pump, no intercooler and the engine has lasted several 25lbs of boost pulls, and about 3500 street miles and 7 months so far.

Most of the fast stock bottom end guys don't touch the ring gaps.

 

I set all my rings to 24 top and bottom, stock 5.3 pt88 turbo looking for 750rwhp on pump e85

 

^^^+1 I set mine at .024 as well, just enough to avoid problems and not too much to give up power. If the engine has enough wear or was originally assembled with them loose, you might get lucky. I know my engine with 68K only had .016, just one time getting the cylinder temp up and I would have been looking a multi piece pistons.

 

Thanks for the replies. I think I will open them up to .024, engine has 68k miles. I would like to run around 12psi until I get the forged bottom done, then turn it up and see what it will take till it bends rods.
The setup does have fmic's, one on each side of the radiator

 

FWIW, If it is a lower mileage engine I pull a piston and check the gap. My first engine I was going to gap and when we checked the gap it was already .024 so I didn't mess even checking the rest. Car ran great and lasted 7 months until I decided to try nitrous along with the twins. lol I personally think the nitrous killed it.

 

cool. I will check it out when I pull it to do the cam swap and headstuds. Do you run the stock 5.3 lifters? I have read all the back and forth about the ls7 lifters and with the little zo6 cam I don't think it is worth it. What are you running for cam and lifters?

Thanks for the info

 

The "ls7" lifters have been a stock replacement for quite some time now, and are used in all the non-vvt gen3 and gen4 engines currently. Early on, there appears to have been a couple variations of it....with reported differences of .050 plunger height. If you're going to the dealer for a set of stock replacement lifters, you'll be getting them anyway. Just make sure to measure pre-load no matter what.

 

cool, thanks. I think if the stock ones out of the 04 engine feel good I will run them. It may not last long anyway

 

Like I said. My current set up is with a 2000 5.3 with more than a 180,000 miles. I used the pushrods, lifters, everything. The only thing I didn't use was the cam. I put my old cam in it which is in my signature. I have it turned down to 15lbs right now but I have hit 25lbs of boost several times on long highway pulls and races. Hasn't missed a beat.

I now have a LS2 timing chain on it also. I am all about budget. However, I think a HUGE reason that I have gotten away with so much is because I run E85, low timing at full boost, and a fairly cool plug.

 

Thanks for all the info. I hope to get this running by fathers day for a rod run, its been a long on-off project.

 

Got the charge piping done from the ic's to tb. Now to mount the ic's

 

just seen 18psi on my stock 5.3 ls2 cam pt88, e85 18degs so far tr6 plug
damn this thing feels good.

 

that is cool! Wish I was closer to test driving mine. Got some of the ic piping done today.