Compression Ratio?

[The Dan]

I used 5 different comp. ratio calculators, and they all gave me a different ratio ranging from 9.77 - 11.8.

Here are the stats:

Bore: 4.030
Stroke: 3.00
Deck: .008
Gasket:.0041
Combustion Chamber: 58cc
Piston Vol.: 2.7cc

Anyone with a valid calculator that can run this for me? Thanks.

 

[brianj5600]

http://kb-silvolite.com/calc.php?action=comp
10.24 with the pistons .008 out of the hole, but I assume you mean .008 in the hole so 9.8.

 

[Route666]

Yep 9.8, I just had to finally make my own Excel CR calculator and got the same thing.

 

[D.Hearne]

9.8 to 1 also. You have to remember to add the compressed volume to the swept volume then divide by the compressed volume.

 

[The Dan]

Thanks.

Yes, that is .008 in the hole. The only other alteration is the heads were milled .025. So I'm thinking that should put it to 9.9-10. In any case 10:1 was the goal, so I'm happy.

Thanks for the link, the others, like I said were all coming out different.

 

[Route666]

Yes, while surfacing the head's deck will reduce the chamber volume it also reduces the total amount compressed so it shouldn't effect CR as much as one would guess if thinking it over quickly.