On line head volume calculator.

Shop deals on ebay
shop deals on amazon
Advertise with us
Intlwaters

Help Support Intlwaters:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Terry Keeley

Terry Keeley

Well-Known Member
Supporting Member
Joined
Jul 24, 2002
Messages
7,124
Was making a coupla .21 heads and came across this cool calculator:

http://www.ambrsoft.com/TrigoCalc/Sphere/Cap/SphereCap.htm

Under "Spherical Cap" enter the volume you want in cc's under "Cap volume", then enter 1/2 your end mill diameter in centimeters (inch x 2.54 = centimeters) into "Sphere radius - R", and wala, it tells you how far to plunge the mill (Cap height - h)

In my case I wanted 0.13cc and I used a 3/8" ball end mill. So 0.187 x 2.54 = 0.475 cm. Cap height is 0.34 cm / 2.54 = 0.134" to plunge. I checked and it was right on.
default_smile.png


DSCN6078.JPG


DSCN6083.JPG


DSCN6081.JPG


DSCN6089.JPG


Yup, they're small. With the 0.01cc dish in the piston it puts the trapped C/R right at 15:1.

I'm gonna try it, I got some fast guys to catch in Mt. Vernon this summer.
default_ph34r.png
 
Last edited by a moderator:
Terry Keeley said:
Was making a coupla .21 heads and came across this cool calculator:

http://www.ambrsoft.com/TrigoCalc/Sphere/Cap/SphereCap.htm

Under "Spherical Cap" enter the volume you want in cc's under "Cap volume", then enter 1/2 your end mill diameter in centimeters (inch x 2.54 = centimeters) into "Sphere radius - R", and wala, it tells you how far to plunge the mill (Cap height - h)

In my case I wanted 0.13cc and I used a 3/8" ball end mill. So 0.187 x 2.54 = 0.475 cm. Cap height is 0.34 cm / 2.54 = 0.134" to plunge. I checked and it was right on.
default_smile.png


DSCN6078.JPG


DSCN6083.JPG


DSCN6081.JPG


DSCN6089.JPG


Yup, they're small. With the 0.01cc dish in the piston it puts the trapped C/R right at 15:1.

I'm gonna try it, I got some fast guys to catch in Mt. Vernon this summer.
default_ph34r.png
Click to expand...

Terry

Thank's for sharing !!!!!!!!!!!!
default_smile.png
:)
default_smile.png


Alex
 
You could even use it to calculate squish band percentage.

Using the "Cap base radius - r" figure out the area of the bowl. In my case 0.45 cm or 4.5 mm. 3.14 (pi) x 4.5 squared = 63.59

The area of the entire bore is: 3.14 x 8.2 squared (1/2 the bore) = 211.13

Subtract the area of the bowl from the total area to get the squish area: 211.13 - 63.59 = 147.54

Divide the squish area into the total area for the squish ratio: 147.54 / 211.13 = 0.699

Call it 70%.
default_tongue.png
 
warlokboats said:
Terry

Do you always make a flat squish with NO angle on your head buttons?
Click to expand...

Lately I have, apparently a flat squish band and sharp bowl to squish corner is the best to increase turbulence and squish velocity.

I've also learned from my SAW testing that crazy high (until now) C/R's can work if you feed it lots of fuel. To burn that fuel you need to run a hot plug and cut back on the water. If you tune to it (more prop, shorter pipe) you can go faster even tho the motor sounds like it's 4 cycling occasionally.

I forgot to include the squish area in my 15:1 calculation, with 0.010" head clearance it's actually about 14.7:1. The latest VAC 45's come in around 13.7:1.
 
Last edited by a moderator:
Very interesting. Thanks for the share Terry . Gonna have to try some things.

So what volume are you trying for in a total cc including the plug?
 
Cool. Bookmark now. Much better than the old cut it, measure, cut it again, measure, cut it one last time, **** IT, too much.

Thanks

Mike
 
warlokboats said:
Very interesting. Thanks for the share Terry . Gonna have to try some things.

So what volume are you trying for in a total cc including the plug?
Click to expand...

Looking for 0.13cc plus there's a 0.01cc dish in the piston. Plus the volume in a 0.010" squish band but that will shrink as the piston heats up and grows.

To be absolutely correct you should probably use the "Spherical segment" as the top of the chamber is actually flat with the plug (unless you're using a turbo plug). Then you'd havta add the volume of the plug hole.

I just used the total volume figuring the bit lost for the flat top would be made up by the plug hole and when I measured with a plug in it was right on.
default_smile.png
 
Last edited by a moderator:

Latest posts

Back
Top