Urge

I am trying to calculate the dome height for a custom piston order.

I take the Gasket thinkness into consideration correct? (I believe so)
Stock Head gasket is 0.6 mm correct?
What is the stock cylinder head volume?

I had my header ported and polished and they milled my head to get it back to stock head volume and I want to verify what that is?

Thank you...

WyattH

Free bump for you as I can use this info as well.

Sideways

I have used 53.6cc as the average size factory combustion chamber. It would be nice to see further reinforcement of these numbers.

53.6cc was from an article by Shawn Church a few years back: Combustion chamber volume on page two.

RWD_RCKT

[QUOTE=jurgento,Jan 12 2006, 03:48 PM] I am trying to calculate the dome height for a custom piston order.

I take the Gasket thinkness into consideration correct?

NEODYMIUM

what is meant by "dome height"?

Greenlight

I have checked 3 different cylinder heads. The combustion chamber volumes ranged from 53.1 to 54.4 cc's.

The "dome height" is the dimensional height of the top of the piston usually measured from the flat portion of the piston to the maximum height of the dome.

I have run high compression pistons with a dome height of 0.320" and 0.365".

The 0.365" domes required some modification so the piston would not hit the ground electrode on the spark plug at high rpm. I recommend that you always check the clearance between the piston and the head when you install an aftermarket piston or if cylinder head modifications were done. An easy way to do this is to place clay on the dome of the piston, bolt on the head and turn the engine by hand. Then remove the head and measure the thickness of the clay with a caliper, etc. and allow 0.040" as a bare minimum.

Urge

Thank you for some numbers, my head porter said they had mlled the head to create 54.4 cc chambers. I wanted to see if that was the stock volume.

Can anyone head confirm gasket thickness of 0.6mm and the fact you use that to calculate dome volume?

Thank you for the replys.

Urge

Any confirmation on gasket thickness?

Also, do you add this volume created by the gasket thinkness to the head volume to calculate Compression Ratio?

NEODYMIUM

By dome volume I assume you mean clearance volume, or in other words the volume left when the piston is at TDC. You would add the volume the gasket creates, which is about 3.57 cc's assuming gasket thickness of .6 mm after assembly, to the head volume. Keep in mind that this is just geometrically speaking as opposed to real world practices.

My questions: Why are the heads being milled down? Does the porting and polishing process increase the head volume thus requiring milling to compensate?
Also, I'm assuming your custom pistons have a different shape, so why would you mill the heads back to stock volume instead of a custom volume.If you mill to stock volume your compression ratio will be different.

RWD_RCKT

Assuming stock piston bore of 87mm. If you are going out to 89mm [custom piston?] calculation is:

PI*rsquared*height*conversion factor

Ex. 89mm bore

=3.14159* (89/2)squared* 0.6mm * .001 (conversion from cubic millimeters to cubic centimeters)

=3.82 cc's