custom Cp pistons
E85
800+hp
street car

are guys running tighter numbers using E85 compaired to gas? i was having issues with my catch can filling up anthing over 35psi and dont want that with this new motor. i wanted to know what numbers for top middle and bottom rings guys are using. also can you run a tighter p2w with E vs gas?

 

I am no seasoned engine builder, but have heard of guys running the same clearances as they did on gasoline for a high hp ethanol fueled engine and I have also heard of guys running tighter clearances. I asked a guy a while back what he was using and he said the same clearances as gasoline. His car made around 800whp.

I got ridiculed for running clearances suggested to me by an engine builder and CP Pistons themselves for my gasoline engine. Everything is looser than stock which has been known to handle 700whp quit frequently (K series), but people still say that I built it too tight.

Good luck with finding a good answer or medium to use as a guideline.

 

You can go tighter with E85 than gas because there is not as much heat.

 

I'd rather it be a little on the loose side than the other way around...

My opinion is 5-7 though P2W and .020-.024 top ring gap

 

I've done back to back testing and I had that same thought process on my new motor for this year. I wish I went even tighter because there is a measurable difference in blowby from gas to e85. You can safely go tighter on PTW and ring gaps.

 

Do you guys use any torque plate on the engine block when you take you measurement?

 

For the cylinders, no I did not. I know others that do not use a torque plate and build engines that run well.

 

i def plan to go tighter next time i up my piston size or have the chance too. I've been pushing the clearance window this year haha.

 

.007? Only if you are trying to make a baby rattle.

On alcohol you can run .004 with that hp no problem. The looser you go the more blow by and loss of power you will have. It puts less tension on rings as well.

 

I would not be the first person around here to run .007" P2W and the rattle goes away once up to operating temp. I am running .0065" now for my new setup but I will be running Q16. I started it up for the first time a couple days ago and couldn't hear any piston slap over the exhaust and stiff mounts/vibrations.

 

You can run .009-.011 with an up pipe and feel good about it. LOL.

If i cant hear it, maybe its not so much of a problem.

 

Yes, I run .012'' P2W with my 4'' downpipe and all is good.lol

 

HOLY ****!!

 

Holy **** is right !!!

 

Naaa you don't need those things there for the V8 guys

 

wow.

 

.012????? guess i must be building "virgin" motors then.....geez

 

LOL AT THIS.

 

i was also thinking the .004 area would be a good number. now as for top and middle rings what seems to be working?

 

On E85 0.020 top ring is safe and I would go 0.025 middle ring.

 

 

How are you getting that with .012 PTW clearance? Using custom rings? What pistons?

 

after your post on p2w im not reading anything else you have to say in this thread.

anyone running E that knows?

 

LOLOLOLOLOLOLOL

 

Come on. I was only joking about the fact that some guys run very loose clearances.
I personally run .003 PTW with CP pistons and I run 0.018 top and 0.023 middle.
I also use water/meth.