Piston ring gap
- Thread starter bblock383
- Start date
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Southernman
Well-Known Member
When you purchase new rings, there should be a cut sheet included that will give you the minimum gap settings. Different ring materials can carry different specs, which are also based on application (i.e. blown, nitrous, etc). Read the sheet and check the fit.
Standard(ized) ring sets usually don't require filing, and, if you want to ensure the best seal possilble, you may want to consider file-fit ring sets, but they do take patience and a little more time.
Southernman
Standard(ized) ring sets usually don't require filing, and, if you want to ensure the best seal possilble, you may want to consider file-fit ring sets, but they do take patience and a little more time.
Southernman
The rings are from a rebuild kit they are just standard rings probably federal mogul. They are for 40 overbore but other than that I don't believe them to be anything special. So do I need to worry about gapping them or not?
i think the different gap that you heard about is depending on the piston material.
some companies, like the hyperutectic (sp) have a specific gap they recommend.
...either way you need to a least check the gap by putting the ring in the cylinder and
do a measurement. that will give you a number to work with.
some companies, like the hyperutectic (sp) have a specific gap they recommend.
...either way you need to a least check the gap by putting the ring in the cylinder and
do a measurement. that will give you a number to work with.
The reason you alter the ring gap from a Naturally Aspirated Specification IS:
With Forced Induction the Cylinder Pressure (and crankcase pressure) is Greater than with a completely Naturally Aspirated Engine....therefore a good Crankcase Ventilation system is required as well.
I just checked my Chiltons manual and it says....Small Block-Piston Ring Gaps.....010" - .020" for the Compression Rings, and Oil rings .015 - .062".
I suggest gapping the TOP Compression rings at the looser end of the specification....maybe even a tad over the loosest spec....at or around .022".
Reason being...Increased Cylinder Pressure over what the factory designed the rings to seal.
I have seen a few instances where guys building High HP forced induction engines set the ring gaps too tight...but within recommended specification, and hit it with 15 plus psi of boost....the pressure causes the ends of the ring to BUTT TOGETHER and lift the crown off the piston.
By increasing the gap the rings will not BUTT TOGETHER and not damage the piston or cylinder wall.
That is why. I am sure you have heard guys talking about setting an engine up either Tight/Loose for what ever reason and ring gaps and bearing clearances fall into those classifications.
I recommend Moly Rings and cylinder prep for boosted applications.
With Forced Induction the Cylinder Pressure (and crankcase pressure) is Greater than with a completely Naturally Aspirated Engine....therefore a good Crankcase Ventilation system is required as well.
I just checked my Chiltons manual and it says....Small Block-Piston Ring Gaps.....010" - .020" for the Compression Rings, and Oil rings .015 - .062".
I suggest gapping the TOP Compression rings at the looser end of the specification....maybe even a tad over the loosest spec....at or around .022".
Reason being...Increased Cylinder Pressure over what the factory designed the rings to seal.
I have seen a few instances where guys building High HP forced induction engines set the ring gaps too tight...but within recommended specification, and hit it with 15 plus psi of boost....the pressure causes the ends of the ring to BUTT TOGETHER and lift the crown off the piston.
By increasing the gap the rings will not BUTT TOGETHER and not damage the piston or cylinder wall.
That is why. I am sure you have heard guys talking about setting an engine up either Tight/Loose for what ever reason and ring gaps and bearing clearances fall into those classifications.
I recommend Moly Rings and cylinder prep for boosted applications.
Shaker223
Boost Rules
My Wiseco sheet says top ring = bore x.0050" and 2nd = bore x .0055" for "street-moderate, turbo/nitrous""
CUUDAK
Well-Known Member
What Prine said!!!
Under boost more heat will cause more expansion therefore causing butting. This in turn will cause the ring to seize to the cylinder wall.
I used Total Seal and confimed with tech that the .055x bore is Not sufficient. I went .028 on the top and .024 on the bottom and .015 on the oil rings.
Under boost more heat will cause more expansion therefore causing butting. This in turn will cause the ring to seize to the cylinder wall.
I used Total Seal and confimed with tech that the .055x bore is Not sufficient. I went .028 on the top and .024 on the bottom and .015 on the oil rings.
I did alot of research as regards which ring gets the larger gap on boosted engines, and found about a 50/50 split on opinions regarding putting the bigger gap on the second ring.
Anybody got any solid knowledge on that issue???? :study:
CUUDAK
Well-Known Member
I was advised to go .024 top and bottom by their tech. When I preinstalled the top rings in the cylinders they were at .028 unground so I left them alone a ground the second ring to .024 and left the oil rings at the .015 gap.
But for some reason tech harrased me about buying "Gapless" ring pack. I have read about MANY horror stories on gapless rings in boosted applications.disgust
Well the pistons aren't anything special just stock replacement. Still not sure who makes the rings but whatever is standard in a rebuild kit which is just federal mogul I think. I'm only gonna be running 8-10 psi regularly and maybe go to 12 someday once I get a hang on the tuning aspect. So is this enough to need to gap them? I guess I should measure them n go from there.
CUUDAK
Well-Known Member
My 2 cents,
Set them at .022 and .015 for the oil rings and go with it!
I have been told numerous times that "EVERYBODY" blows up their first turbo engine.:wack:
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