entropy
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posted October 28, 2009 02:07 AM
 Edited By: entropy on 28 Oct 2009 10:23
block-piston expansion with temp
I was measuring up a new set of JE's this morning in my FREEZING (63F, winter is here) garage. The measurements came up smaller than spec, so i went looking for the results of an experiment i did last year, i.e. Billet Block + JE pistons, heated 'em up, then measured em as they cooled down.
Thought I'd share that graph:
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Texas12R
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posted October 28, 2009 02:27 AM
It looks linear to me....
What do you suppose, is the max temp
that the piston will see ?
Are you still running the coating on the dome?
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ZRXDean
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posted October 28, 2009 04:32 AM
I like how parallel those lines are  Who needs warmup? (kidding)
GREAT data Karl, your OCD is a boon to us lazy bastids.
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kawasakijockey
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posted October 28, 2009 05:23 AM
I would like to know how the thermal expansion numbers go on the zx14. The spec clearance is .0008-.0019. Could make a hot running engine it seems.
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2007 ZX-14
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9.03 @ 149mph
8.95 @153 small shot n2o
8.68 @160mph 5lbs boost
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entropy
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posted October 28, 2009 06:21 AM
Michael
I also wonder what temps the piston sees; maybe Chin orJim or Doug or someone will help us?
The "coating" i use is not really a coating but a surface texture treatment with Tin impregnation. I don't think there is any thermal impact???
Dean,
I lost a motor to a well meaning but ignorant dyno operator (not Andy or JC) who put the boots to it before the motor was fully heat soaked. yes indeed, the piston/cyl was too tight (.001), but it was living just fine until he did his thing and seized a piston...
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tcchin
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posted October 28, 2009 07:41 AM
Piston temp depends on operating conditions (engine load, duty cycle, presence of detonation, etc.), but averages about 600F, or about half of the melting temp of aluminum. As the block is cooled directly by <200F coolant and the piston depends on mechanical conduction to the block for cooling, it stands to reason that the piston is always hotter than the cylinder.
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entropy
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posted October 28, 2009 09:24 AM
good info, Tim
i suspect there is a mighty strong T gradient between the dome of the piston and the skirts, eh?
what do you figure the delta T is brtween the skirts and cyl wall?
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dougmeyer
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posted October 28, 2009 11:51 AM
The skirt is relatively cool. I've got a chart around someplace - I'll see if I can find it, but the skirt temp is close to the oil temp when all is warmed up. That 600 deg is dome temp, right Tim?
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TRNorBRN6001
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posted October 28, 2009 12:59 PM
Just curious Karl, how have your piston skirts been looking?
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tcchin
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posted October 28, 2009 01:19 PM
Right, 600F is the dome temp, and thermal gradients are very steep near the dome, as a lot of heat energy gets transferred through the rings. The skirt gets enough oil splash that its temp is indeed very close to the oil temp.
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Texas12R
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posted October 28, 2009 01:50 PM
let me show my ignorance.....and I dont mean to thread jack
why do some engines use gas ported top rings
does anyone run a dykes pattern ring on a 4 stroke
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entropy
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posted October 28, 2009 08:05 PM
quote:
Just curious Karl, how have your piston skirts been looking?
the skirts have been looking really good since I went to the new style JE piston.
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tcchin
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posted October 28, 2009 08:47 PM
Ducatis and late-model Suzukis use Dykes-style rings, that I know of.
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Texas12R
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posted October 29, 2009 01:59 AM
Thanks Tim ! I should broaden my efforts
to take more manufacturers apart.... with
wrenches of course!
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Texas12R
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posted October 29, 2009 04:21 PM
Can I kill a thread or what!
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