Piston Dome Volume

[David Nicholls]

Dear Members

Would anyone be able to tell me the Piston Dome Volume of a standard bore, 82.5 mm Mahle Nikasil Piston ?
The type that Stoddard sell.

Many Thanks
Regards
David nicholls

[Don Gale]

Simple to determine if you can find a used donor piston to make a mold from:

https://youtu.be/7v31wJ8FOl0

https://youtu.be/XasTH8lwVLA

CC the volume of the mold cavity.

I did a search for piston dimensions a few days ago and found one on a forum where the author posted a jpeg of a piston he sliced in half, and had some pencil marks on it with a few dimensions. Now I can't find the thread. If I could get accurate dimensions of the dome geometry and height and valve pockets, I could model it in SolidWorks and get an accurate volume.

[David Nicholls]

Dear Ron

Many Thanks for your reply, and relavent links to YouTube.

Meanwhile I did some measuring myself.

A Piston Dome Height of 5mm in a Cylinder with 82.5mm Bore gives a volume of 26.7cc
With a Piston in a Cylinder, it took 13.5cc of fluid to fill the space between the bottom and the top of the Dome.
26.7 minus 13.5 gives a dome volume of 13.2cc

I did each measurement quite a few times, it was quite accurate, and I averaged the results.

Happy Motoring
David

[Harlan Halsey]

That number sounds about right. The way I do that measurement is to grease the piston so as to prevent leakage, space the piston 1/4" below the top of the cylinder using a spacer on top of the piston and pushing it down with the plexiglass disk I use to measure the head volume with. It's pretty hard to fill just the space around the crown, but easy to calculate and subtract the extra volume above the piston.