Compression ratios in the toy shop

[ernie]

Just to clarify, is not the capacity of an engine the swept volume?

 

[davidd]

Sorry Ernie,

You are correct. I should have sent myself to bed! I was thinking about John's project and trying to match combustion volumes and I conflated the compression ratio calculations with the combustion volume calculations with the swept volume calculations. And, swept volumes do seem to grow at Bonneville.

Thanks,

David

 

[litnman]

When ordering pistons from CP, they want a clay impression of the combustion chamber. They also want a clay impression of the valve to piston clearance and your required compression

 

[davidd]

Often piston manufacturers want an orientation for the wrist pin also. I have been using Mold Max 14NV to make combustion and port molds. It is quite strong and it does not need degassing like some mold materials.

The above is a mold of the racer combustion chamber. Below is a mold of a TPV 500 combustion chamber:

Molds are very handy when you get to the point that you can't remember what you had for breakfast.

Not a criticism of John, but those photos are not accessible to me. I know that even when the thumbnails work, they do not work the same in all browsers. It would be great if posters would just put full size photos in their posts. They seem to always work.

David

 

[litnman]

I'll try this again.