ring end gap factor

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GRAP6

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400 B Block stroked to 451 - platinum series Forged pistons. Do I use the .004" gap factor for a street engine. 440 source piston part number 5056? any guidance appreciated.
 
GRAP6 said:
400 B Block stroked to 451 - platinum series Forged pistons. Do I use the .004" gap factor for a street engine. 440 source piston part number 5056? any guidance appreciated.
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I am no expert, by any means, but on a bore that big, I would really be afraid that the ring ends would butt at anything much over a cold engine....

Just sayin'...

I have no experience with that, but jeesh... .004" is practically nothing...
 
I stated ring end gap factor ie - 4.000 x .004 = .016" clearance not .004 clearance
 
bOb shingler said:
if that motor in your sig pic is one you are building let me suggest you do little research into ring gaps and boost.
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We did...

I learned that, contrary to my previous opinion, the larger compression ring gap (according to all the "good" information I could uncover, for a turbo application) goes on the second ring, NOT the top one...

Like I said, I learn something every day.](*,)

We ended up with .020" on the top ring, and .024" on the second one.

Hope it's enough (3.465" bore.)

Thanks for your interest!;)
 
If the piston manufacturer doesn't specify, use the ring manufacturer's guide. Most are the .004" per inch of bore, so you'd be at .016 for 3.465. I add 20% to the first ring gap dimension for the 2nd ring gap spec. Some guys don't believe in it but it works well for me.
 
Bill Dedman said:
We did...

I learned that, contrary to my previous opinion, the larger compression ring gap (according to all the "good" information I could uncover, for a turbo application) goes on the second ring, NOT the top one...

Like I said, I learn something every day.](*,)

We ended up with .020" on the top ring, and .024" on the second one.

Hope it's enough (3.465" bore.)

Thanks for your interest!;)
Click to expand...

perfect
 
moper said:
If the piston manufacturer doesn't specify, use the ring manufacturer's guide. Most are the .004" per inch of bore, so you'd be at .016 for 3.465. I add 20% to the first ring gap dimension for the 2nd ring gap spec. Some guys don't believe in it but it works well for me.
Click to expand...

I don't know if that formula takes into consideration the additional gap necessary on turbocharged, supercharged, and N20 motors. All the additional heat generated by forced induction, changes the parameters for end gaps, I think.
 
bOb shingler said:
you did it correctly bill.
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Thanks Bob. We broke in the cam with some antique, worn out, 318 springs, and after running it at 2,500 rpm for 30 minutes, it's showing between 170 and 175 pounds compression pressure on all 6 cylinders, and we're happy with that, since it's a low-compression turbo motor.


I appreciate your input!
 
Bill Dedman said:
I don't know if that formula takes into consideration the additional gap necessary on turbocharged, supercharged, and N20 motors. All the additional heat generated by forced induction, changes the parameters for end gaps, I think.
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No, it definately does not. However, the piston or ring manufacturer would have those handy as with those extra sources of heat, the effect on a ring will be determined by both the boost level, type of boost, and piston design and material. What did those manufacturers tell you?
 
72ScampTramp said:
whats the purpose of filing the rings? Cant you just install them and go?
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The ring manufacturers don't have a clue as to what kind of a motor you are building; it may be normally-apirated, or it could be a nitrous-assisted, turbocharged, or a supercharged motor.

Rings "grrow" in length as they get hot from combustion..
The rings that are exposed to the heat from a Nitrous oxide assissted, or forced induction motor (supercharged or turbocharged) will tend to grow more than the ones installed in a motor without those power adders, and therefore, need different size gaps to take care of that added growth. If you don't have enough gap when they're cold, they can "grow" so much in length (and, this is a very real danger,) that the gap you had when they were cold, will totally close up.... and if they grow MORE than that, will cause all sorts of (bad) problems having to do with cylinder-wall scufffing (destroys ring seal) and ruining the ring seating (i.e. the delicate "shape" of the part of the ring that contacts the cylinder wall,) which is a very important facet of the cylinder sealing process.

If you DON'T file the rings to get the correct end gap, you can be either throwing away horsepower due to endgaps that are too large, and allow unnecessaary blow-by, or run the very real risk of having your cylinder walls and rings damaged, (right up to and including, having your engine seize, when the gap completely disappears from the heat)..... cause for an unnecessary rebuild.

Ring end gap filers are cheap and easy to use. Even I can do it!!!!:happy7:

It's good insurance for proper cylinder sealing.

Hope this helps!
 
moper said:
No, it definately does not. However, the piston or ring manufacturer would have those handy as with those extra sources of heat, the effect on a ring will be determined by both the boost level, type of boost, and piston design and material. What did those manufacturers tell you?
Click to expand...

Nothing. In fact, they didn't ask... so, I asked them.

I learned one thing; you ask 5 people what the proper end gap is for your particular engine (having given them the specs and all other pertinent parameters, such as the amount of boost, etc) and you'll get 5 different answers.

I just tried to hit the middle of all recommendations.](*,)
 
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