Piston Ring Gap Questions/feedback
Re: PISTON RING GAP QUESTIONS
Yea I was scared about my p2w being to tight. But I think it will be perfect at .004"
Re: PISTON RING GAP QUESTIONS
Ive researched this just as much as you have. At this point I personally wouldn't go any tighter than a .006 multiplier for 4-500hp.
My last engine made 450whp, 84mm bore. I used .020" gap (.006 multiplier) and didnt observe any crazy amounts of blowby or low compression test results.
Spawne and I talked about this offline. His thoughts are to keep it tight if its a street car bc it wont see extended periods of load to heat the rings up and make them expand. But as soon as you go the track (and of course you will), it becomes a race car and will see just as much load & heat. So it makes sense than you build it for the most extreme condition the engine will see, not the everyday. Idealy we want as minimal ring gap as possible but at the end of the day it doesnt seem to matter THAT much and the cost of it being too tight is your motor.
My last engine made 450whp, 84mm bore. I used .020" gap (.006 multiplier) and didnt observe any crazy amounts of blowby or low compression test results.
Spawne and I talked about this offline. His thoughts are to keep it tight if its a street car bc it wont see extended periods of load to heat the rings up and make them expand. But as soon as you go the track (and of course you will), it becomes a race car and will see just as much load & heat. So it makes sense than you build it for the most extreme condition the engine will see, not the everyday. Idealy we want as minimal ring gap as possible but at the end of the day it doesnt seem to matter THAT much and the cost of it being too tight is your motor.
Re: PISTON RING GAP QUESTIONS
well mine are high silicone pistons so they shouldnt expand as much as something with low silicon. What do you guys think about stepping up the gap on the top ring from .017" to .019"?
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Re: PISTON RING GAP QUESTIONS
If it makes you feel beter then do it. Remember a little loose is ALWAYS better than a little tight. If there been no sign of the ring ends touching on the next tear down then you know you can gap them a little tighter.
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Re: PISTON RING GAP QUESTIONS
Also the piston alloy has nothing to do with the ring gap clearance. The same way as the ring gap clearane has nothing to do with the piston to cylinder clearance.
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Re: PISTON RING GAP QUESTIONS
Re: PISTON RING GAP QUESTIONS
I understand that. But don't if you have a piston that expands more when it gets hot the ring gap will differ then it would on a piston that doesn't expand so much?
Re: PISTON RING GAP QUESTIONS
Re: PISTON RING GAP QUESTIONS
The decision has to be up to you, you have the facts laid out, you gotta decide whether or not what you have will actually expand enough to risk running .017. Remember, we are talking thousands of an inch here, both ways can end up in disaster.
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Your right, I'm wrong.
Re: PISTON RING GAP QUESTIONS
I think I'm going to go to .019" on the top
DO IT ON ALL FOURS
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From: IN Your Mind
Re: PISTON RING GAP QUESTIONS
This thread is still going? HAHA...
Piston expansion has absolutely nothing to do with ring end-gap. I get such a kick out of people talking about "how much more" a forged piston expands than a cast piston when they actually have no idea what they are talking about...
The coefficient of thermal expansion has absolutely nothing to do with how a piston is made. Forged or cast, it doesn't matter. The coefficient of thermal expansion is determined by the alloy used for the piston. A typical forged piston is made from low-silicon 2618 alloy. This alloy will expand about 13% more than a typical high-silicon (as much as 18%) hypereutectic piston. 13% of 2/1000's of an inch is only .0003".
Again, piston expansion has NOTHING to do with ring end-gap... How the piston transfers/absorbs the heat to the rings, as well as the ring placement, and cylinder pressures: YES! If you are having problems from piston exapansion and ring end-gap, you don't have proper backspacing to begin with.
Light Reading:
http://en.m.wikipedia.org/wiki/Piston_ring
In Depth Reading:
http://www.powermasters.com/heat_energy.html
http://www.enginebuildermag.com/Arti...orsepower.aspx
http://www.elstars.com.au/pdf/piston_rings_guide.pdf
Oil Loss From Ring Gaps:
http://www.kb-silvolite.com/article....n=read&A_id=56
Now I have just gone too far:
http://www.federalmogul.com/NR/rdonl...S200976080.pdf
Piston expansion has absolutely nothing to do with ring end-gap. I get such a kick out of people talking about "how much more" a forged piston expands than a cast piston when they actually have no idea what they are talking about...
The coefficient of thermal expansion has absolutely nothing to do with how a piston is made. Forged or cast, it doesn't matter. The coefficient of thermal expansion is determined by the alloy used for the piston. A typical forged piston is made from low-silicon 2618 alloy. This alloy will expand about 13% more than a typical high-silicon (as much as 18%) hypereutectic piston. 13% of 2/1000's of an inch is only .0003".
Again, piston expansion has NOTHING to do with ring end-gap... How the piston transfers/absorbs the heat to the rings, as well as the ring placement, and cylinder pressures: YES! If you are having problems from piston exapansion and ring end-gap, you don't have proper backspacing to begin with.
Light Reading:
http://en.m.wikipedia.org/wiki/Piston_ring
In Depth Reading:
http://www.powermasters.com/heat_energy.html
http://www.enginebuildermag.com/Arti...orsepower.aspx
http://www.elstars.com.au/pdf/piston_rings_guide.pdf
Oil Loss From Ring Gaps:
http://www.kb-silvolite.com/article....n=read&A_id=56
Now I have just gone too far:
http://www.federalmogul.com/NR/rdonl...S200976080.pdf
Re: PISTON RING GAP QUESTIONS
This thread is still going? HAHA...
Piston expansion has absolutely nothing to do with ring end-gap. I get such a kick out of people talking about "how much more" a forged piston expands than a cast piston when they actually have no idea what they are talking about...
The coefficient of thermal expansion has absolutely nothing to do with how a piston is made. Forged or cast, it doesn't matter. The coefficient of thermal expansion is determined by the alloy used for the piston. A typical forged piston is made from low-silicon 2618 alloy. This alloy will expand about 13% more than a typical high-silicon (as much as 18%) hypereutectic piston. 13% of 2/1000's of an inch is only .0003".
Again, piston expansion has NOTHING to do with ring end-gap... How the piston transfers/absorbs the heat to the rings, as well as the ring placement, and cylinder pressures: YES! If you are having problems from piston exapansion and ring end-gap, you don't have proper backspacing to begin with.
Light Reading:
http://en.m.wikipedia.org/wiki/Piston_ring
In Depth Reading:
http://www.powermasters.com/heat_energy.html
http://www.enginebuildermag.com/Arti...orsepower.aspx
http://www.elstars.com.au/pdf/piston_rings_guide.pdf
Oil Loss From Ring Gaps:
http://www.kb-silvolite.com/article....n=read&A_id=56
Now I have just gone too far:
http://www.federalmogul.com/NR/rdonl...S200976080.pdf
Piston expansion has absolutely nothing to do with ring end-gap. I get such a kick out of people talking about "how much more" a forged piston expands than a cast piston when they actually have no idea what they are talking about...
The coefficient of thermal expansion has absolutely nothing to do with how a piston is made. Forged or cast, it doesn't matter. The coefficient of thermal expansion is determined by the alloy used for the piston. A typical forged piston is made from low-silicon 2618 alloy. This alloy will expand about 13% more than a typical high-silicon (as much as 18%) hypereutectic piston. 13% of 2/1000's of an inch is only .0003".
Again, piston expansion has NOTHING to do with ring end-gap... How the piston transfers/absorbs the heat to the rings, as well as the ring placement, and cylinder pressures: YES! If you are having problems from piston exapansion and ring end-gap, you don't have proper backspacing to begin with.
Light Reading:
http://en.m.wikipedia.org/wiki/Piston_ring
In Depth Reading:
http://www.powermasters.com/heat_energy.html
http://www.enginebuildermag.com/Arti...orsepower.aspx
http://www.elstars.com.au/pdf/piston_rings_guide.pdf
Oil Loss From Ring Gaps:
http://www.kb-silvolite.com/article....n=read&A_id=56
Now I have just gone too far:
http://www.federalmogul.com/NR/rdonl...S200976080.pdf