89 L98 piston
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
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FWIW: I remember a poster or two suggesting 12cc's was the right answer recently, but it doesn't look like each indentation is enough to hold a teaspoon of liquid. Still, I could be wrong.
You also have to provide the distance "down in the hole"....which is the distance below the deck's surface. I think stockers are sitting down .025" when the piston is at the top of the stroke. And, the volume in the head chambers (IIRC) are 54cc's on an 89 with 113 heads.
The important thing is those look like stock 89 pistons to me -- which means you could simply look up the specs for 1989 compression!
If you are actually measuring, you could fill with liquid (until flush with the deck) suck it out, measure and convert to cc's.
Last edited by GREGGPENN; Apr 7, 2017 at 01:52 AM.
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 196
From: folsom california
Those are flat tops. IIRC, the valve reliefs (indentations) are 4cc's on a stock 89 L98. Basically, that means a teaspoon of water would fill all 4 of those shallow indentations.
FWIW: I remember a poster or two suggesting 12cc's was the right answer recently, but it doesn't look like each indentation is enough to hold a teaspoon of liquid. Still, I could be wrong.
You also have to provide the distance "down in the hole"....which is the distance below the deck's surface. I think stockers are sitting down .025" when the piston is at the top of the stroke. And, the volume in the head chambers (IIRC) are 54cc's on an 89 with 113 heads.
The important thing is those look like stock 89 pistons to me -- which means you could simply look up the specs for 1989 compression!
If you are actually measuring, you could fill with liquid (until flush with the deck) suck it out, measure and convert to cc's.
FWIW: I remember a poster or two suggesting 12cc's was the right answer recently, but it doesn't look like each indentation is enough to hold a teaspoon of liquid. Still, I could be wrong.
You also have to provide the distance "down in the hole"....which is the distance below the deck's surface. I think stockers are sitting down .025" when the piston is at the top of the stroke. And, the volume in the head chambers (IIRC) are 54cc's on an 89 with 113 heads.
The important thing is those look like stock 89 pistons to me -- which means you could simply look up the specs for 1989 compression!
If you are actually measuring, you could fill with liquid (until flush with the deck) suck it out, measure and convert to cc's.
hey, how about just measuring them? plus getting the volume of the deck height above the piston top in the bargain?
do as suggested above or do it cheap, quick and easy and no they don't do this in NASCAR; but I bet they would on Sesame Street; it'll be in the ballpark, its actually pretty accurate
(1) put the piston at top dead center
(2) pack the piston top, cylinder with modeling clay and smooth it out so everything is even with the block surface
(3) remove clay and roll into a ball
(4) take mic / calipers and measure diameter of ball (actually take several measurements at different points and use the average diameter) in cm.
(5) take one half the diameter = radius and plug into formula Volume = 4/3 radius cubed; i.e four thirds times radius time radius times radius equals the volume in cc's.
an advantage of this method is that it does require any expensive burets, etc. you can take a measurement in any position, up down sideways, upside down, doesn't matter
and its actually kinda fun.
Last edited by mtwoolford; Apr 7, 2017 at 10:01 AM.
