Values for Estimating piston dish volume with a rule / depth gauge!
Turbo Mini Forums

****Remember, these are only guidelines - it means you can easilly check the pistons assembled in an engine, or set of pistons without having to get the burette and water out (which a potential seller might not be too happy about!!!!)****


The following values are based on a bowl of OD 60mm, and the various depths measured at the centre (the deepest point).
These are only guidelines, and are assuming the same radius of curvature for the dish - ie not flat bottomed!

5mm deep: 7.15cc
6mm deep: 8.6cc
7mm deep: 10.1cc
8mm deep: 11.6cc
9mm deep: 13.1cc

If you measure a stock AE turbo piston (20831??) you'll find it is around 8.5mm.


For measuring flat bottomed dishes like the ones in forged pistons, i always use the formula:
[ pi * (Diameter^2) ] / 4 to find the area,
then multiply by depth to find the volume.
(use all dims in cm to keep units simple)

For taking into account the radius in the bottom of these 'flat bottomed' bowls, the following values are a good guide:

1mm round: subtract 0.4cc from volume calculated above
2mm round: subtract 1.6cc from volume calculated above
3mm round: subtract 3.6cc from volume calculated above

Hope this proves useful...

I moved this to the how to section, hope you don't mind dave

Edited by Jimster on 18th Feb, 2004.

Very useful, can i suggest that this goes in the 'how to' section.