Anybody measure KB hyper pistons? Typical Undersize?
#1592829
03/14/14 02:28 PM
03/14/14 02:28 PM
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Joined: Jan 2003
Posts: 10,766 Central Valley, CA.
Quicksilver440
OP
I Live Here
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OP
I Live Here
Joined: Jan 2003
Posts: 10,766
Central Valley, CA.
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Typically...how much under standard bore sizes is a KB hyper piston typically? I know you have to measure the actual pistons used, but do they usually run .0015 or ? under the std bore sizes?(Std, +.030, +,.040, +.060, etc).
Is there a rule of thumb?
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Re: Anybody measure KB hyper pistons? Typical Undersize?
[Re: Quicksilver440]
#1592830
03/14/14 02:31 PM
03/14/14 02:31 PM
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Joined: Aug 2003
Posts: 43,157 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,157
Bend,OR USA
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Most pistons are under the size of the bores, not as big as the bore so the machine shops have to make the bore over size I've never ran the KB hypers, I don't like any cast pistons I have ran and used thier forged pistons They had the clearances built into the pistons
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Anybody measure KB hyper pistons? Typical Undersize?
[Re: Oyvind Mopar]
#1592832
03/14/14 03:27 PM
03/14/14 03:27 PM
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Joined: Jan 2012
Posts: 2,645 Stuttgart, Arkansas
rickseeman
master
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master
Joined: Jan 2012
Posts: 2,645
Stuttgart, Arkansas
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Just measured some Wednesday night. They were all .002 under. This is much better than the last 2 brands I measured which had .0015 variance between them.
2011 Drag Pak Challenger
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Re: Anybody measure KB hyper pistons? Typical Undersize?
[Re: Quicksilver440]
#1592838
03/17/14 12:45 AM
03/17/14 12:45 AM
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Joined: Jan 2003
Posts: 6,591 Canton, Ohio
Sport440
master
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master
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
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Quote:
Typically...how much under standard bore sizes is a KB hyper piston typically? I know you have to measure the actual pistons used, but do they usually run .0015 or ? under the std bore sizes?(Std, +.030, +,.040, +.060, etc).
Is there a rule of thumb?
They are tight because the pistons dont grow much. But the clearance is determined by bore diameter and intended performance. But still its a very tight perimeter.
.0015 to .0055 from small bore NA to large bore supercharged.
The clearance is measured at the skirt parallel to the balance pad height.
Whats even more important IMO, is the top ring gap. As it is closer to the top of the piston vs other type pistons that it requires extra top ring gap to prevent butting of the ends.
Example, NA 4.36 bore race gasoline motor = .033 top ring gap.
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