Hey Guys,
Piston ring gap seems to turn into a complex subject. First off this is the card I got with my rings that give you guidelines to where you should be at.
As you can see for a medium boost application of 15 to 30 lbs on E85 they recommend bore x .007. My motor is .020 over so my bore is 3.5720. If you take 3.5720 x .007 = 0.025 ring gap.
Well I've run 0.025 ring gap in the past and it tends to have a lot of blow by. It pushes a lot of oil out the valve covers. Even my turbo'd Honda's ring gap was .025 and it blew a lot of oil too out the valve cover. Like a catch can full a week when it was my daily driver.
I was asking around and some on similar setups/power as me say they run .020 upper and .022 lower. I wouldn't mind running that as I'm sure it'll have a lot less blow by but I'm concerned with going to small because of course if the rings expand and bind up you're tearing it all back apart and possibly reboring or looking for a new block depending on the damages.
Then comes the topic of how do you measure ring gap? and what about with or without torque plates?
The good news is almost everyone I spoke to measures it at the same depth. About an inch down the cylinder using a piston upside down to press the rings in square. Use either the wrist pin or an oil ring on the piston to act as a stop and keep the piston square in the hole.
The bad news is torque plates. Some say it makes no difference, but the majority of people say it does. My local machine shop says torque plates open up the hole about .0001 only. Problem is he also fed me so much other BS I don't know what to believe and what not to from him anymore.
Searching on google trying to find an answer I found everything from .0001 to .0004 and one guy said he even measured .0008 difference which seems extreme to me.
Some guys say if they're shooting for say .020 ring gap they'll just file to .018 or .019 because once the heads are torqued on it'll open it up to .020. While others actually file to .020 etc. Everyone has their own method.
So my point is when comparing ring gaps its become apparent to me everyone's doing it a little different and we're not even comparing accurate numbers.
Thoughts?
Piston ring gap seems to turn into a complex subject. First off this is the card I got with my rings that give you guidelines to where you should be at.
As you can see for a medium boost application of 15 to 30 lbs on E85 they recommend bore x .007. My motor is .020 over so my bore is 3.5720. If you take 3.5720 x .007 = 0.025 ring gap.
Well I've run 0.025 ring gap in the past and it tends to have a lot of blow by. It pushes a lot of oil out the valve covers. Even my turbo'd Honda's ring gap was .025 and it blew a lot of oil too out the valve cover. Like a catch can full a week when it was my daily driver.
I was asking around and some on similar setups/power as me say they run .020 upper and .022 lower. I wouldn't mind running that as I'm sure it'll have a lot less blow by but I'm concerned with going to small because of course if the rings expand and bind up you're tearing it all back apart and possibly reboring or looking for a new block depending on the damages.
Then comes the topic of how do you measure ring gap? and what about with or without torque plates?
The good news is almost everyone I spoke to measures it at the same depth. About an inch down the cylinder using a piston upside down to press the rings in square. Use either the wrist pin or an oil ring on the piston to act as a stop and keep the piston square in the hole.
The bad news is torque plates. Some say it makes no difference, but the majority of people say it does. My local machine shop says torque plates open up the hole about .0001 only. Problem is he also fed me so much other BS I don't know what to believe and what not to from him anymore.
Searching on google trying to find an answer I found everything from .0001 to .0004 and one guy said he even measured .0008 difference which seems extreme to me.
Some guys say if they're shooting for say .020 ring gap they'll just file to .018 or .019 because once the heads are torqued on it'll open it up to .020. While others actually file to .020 etc. Everyone has their own method.
So my point is when comparing ring gaps its become apparent to me everyone's doing it a little different and we're not even comparing accurate numbers.
Thoughts?