Roof_991

Does anyone know a formula to figure outthe cc's of a snowmobile engine after having it bored

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JD8345RT

π • radius2 • height = cylindrical volume

This way will hurt your head less: Calculating the Volume of a cylinder

__________________
1993 Polaris XLT Special
1979 Arctic Cat El Tigre
1972 Arctic Cat Panther

kccats

What are you boreing?

RJ Gleason

Bore diameter times stroke length.
Add the percentage difference between the original and the new bore.
So. if the original was 67mm D x 68mm S, that would equal 4556mm volume.
over bore of 0.010 equals 45.56mm additional volume which added to the original equals 4601.56 cubic mm.

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BC_Dan

Volume of a cylinder is as JD stated or as follows

pi x bore x bore / 4 x stroke = volume.

so in RJ's example, 3.1416 x 67mm x 67mm / 4 x 68mm = 239744.9 cubic mm. Divide that by 1000 to get cubic cm and you get 239.7 cc.

Doing it JD's way

3.1416 x 33.5mm x 33.5mm x 68mm = 239744.9 cubic mm

divide by 1000, you get 239.7 cubic cm

That would be for one cylinder, multiply by number of cylinders for total displacement. There is a slight difference between calculating as above and using the calculator JD posted, is the difference in the value of pi used in the calculation.

Add a .010" overbore, that would look like this

Convert inches to mm

.010" = .254mm

67mm + .254mm = 67.254mm (new bore diameter)

3.1416 x 67.254 x 67.254 / 4 x 68 = 241556.1 cubic mm
Divide by 1000 to get 241.6 cc.

241.6 - 239.7 = 1.9 cc increase in displacement for a .010" overbore.

I know this is right because my 11th grader checked my work

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2007 Dragon RMK 700 155", 2008 RMK 600 155", 2006 RMK 600 144", 95 Prowler 550 2-up, 1990 Indy 650, Really OLD AC Cheetah

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JD8345RT

Now let's tackle dome heads and calculate the volume of a hemispherical combustion chamber!

__________________
1993 Polaris XLT Special
1979 Arctic Cat El Tigre
1972 Arctic Cat Panther

BC_Dan

I'll have my son get back to you on those

(seriously, the kid is crazy talented at math... he had already completed HS senior calculus before he was in 9th grade!)

__________________
2007 Dragon RMK 700 155", 2008 RMK 600 155", 2006 RMK 600 144", 95 Prowler 550 2-up, 1990 Indy 650, Really OLD AC Cheetah

http://www.avalanche.org/accidents.php

kccats

Cyl is easy. Just a piece of plexy glass with a small hole. With the spark plug in, put a little grease around the edge and set the plexy on it. With a gradeuated beaker or turkey baster, or suringe, add water till it starts to come up in the hole. That is the volume of the head!
Now with that volume and the volume of the cyl, you can divide them and get your compression ratio!

smallengineguy

Now my head hurts...

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BC_Dan

PPE. Wear a helmet when you do math, your head won't hurt

Or is that tin foil? I forget!

__________________
2007 Dragon RMK 700 155", 2008 RMK 600 155", 2006 RMK 600 144", 95 Prowler 550 2-up, 1990 Indy 650, Really OLD AC Cheetah

http://www.avalanche.org/accidents.php

Renagade

anything will help, while i pound my
head against the wall from confusion!!

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kccats

It's a tin foil helmet! Geez you rookies!

TwinsofMLB

Skip a step: bore x bore x stroke x constant x number of cylinders. Constant = 0.7854.

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1996 Arctic cat ZR 580- 6 inch risers, C+A powder skis, 99 ZR's front suspension, freshly rebuilt engine

1992 Ski doo mach 1 617cc (the beast)

Die hard polaris anti-fanatic!

Do the snow dance with me!!! We don't get enough in Vermont!

And God said: "Let there be snow."

TwinsofMLB

Using cylinder volume and compression ratio, it can be done! pi x 1/2bore^2 x stroke = the second number in the compression stroke (simplified).

__________________
1996 Arctic cat ZR 580- 6 inch risers, C+A powder skis, 99 ZR's front suspension, freshly rebuilt engine

1992 Ski doo mach 1 617cc (the beast)

Die hard polaris anti-fanatic!

Do the snow dance with me!!! We don't get enough in Vermont!

And God said: "Let there be snow."

kccats

Not times 2 times itself or squared

hosehoundfr86

My thought exactly,,,,