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Old 08-12-2012, 02:19 AM   #1
orson250
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Default Compression ratio and quench height spreadsheet

Here is a little spreadsheet calculator that I made for calculating compression ratio and quench height mainly (or finding piston/rod/crank specs to achieve a desired cr or quench). The main reason I made this is because I got tired of re-entering values into online calculators over and over again and it allows me to compare different configurations side by side.

I know this is nothing too special, but it's a time saver for me, so I figured that maybe somebody else might find it useful. If anyone finds anything wrong or inaccurate about it, please tell me so that I can fix it. Any ideas for additions are welcome as well.

Download: http://www.mediafire.com/?m3z8dxx6t3xr8b6

quick screen:
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Old 08-12-2012, 03:10 AM   #2
ckyguy68
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Awesome. Thanks for supplying this.
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Old 08-12-2012, 12:12 PM   #3
wrxsubiemod
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Ow sweet!

Ill try it out and see how it works out.

Thanks
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Old 08-12-2012, 01:55 PM   #4
561wrx
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Cool stuff
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Old 08-12-2012, 11:57 PM   #5
orson250
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Thanks for the responses. Even if only one person gets some use out of it, it was worth posting lol.
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Old 08-13-2012, 04:03 PM   #6
ripman
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Is it possible to take it a step further for dynamic compression ratio calculations?
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Old 08-13-2012, 04:06 PM   #7
jkopinga
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Are you kidding me? It would be much too complicated as RPMs and Valve overlap as well as cam duration would throw a lot variables into this. This is where all the black art is. This is something you have to sort out based on what you want to do with the engine.

Jasper.
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Old 08-13-2012, 04:16 PM   #8
ripman
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I'm trying to make sure that I get the static CR in the right range for a kelford 264. I'm thinking about 8.5:1 should be close enough but would really like to confirm.
Trouble is the Kelford cam specs are advertised @1mm valve lift and the only info I can find from Subaru at the moment is advertised duration, so in effect it says that the Kelford closes earlier which isn't helping
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Old 08-13-2012, 07:19 PM   #9
orson250
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Quote:
Originally Posted by jkopinga View Post
Are you kidding me? It would be much too complicated as RPMs and Valve overlap as well as cam duration would throw a lot variables into this. This is where all the black art is. This is something you have to sort out based on what you want to do with the engine.

Jasper.
This. If I had some type of formula, it would be very helpful and interesting to implement. Trouble is, I have never come across one, and if I did, I'm not quite sure how much I would really trust it. Better option would be to search around for similar setups and see how they turned out.

Last edited by orson250; 08-13-2012 at 07:30 PM.
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Old 08-13-2012, 07:35 PM   #10
sense of nature
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In note #4 it says use neg numbers for dome & positive for dish.
But aren't 2,0 pistons dished & 2.5 pistons domed?
The numbers in the sheet show both as being dished pistons, but the 2.5 pistons have domes ,no?
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Old 08-13-2012, 10:58 PM   #11
orson250
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Any aftermarket forged piston that you will install in any forced induction subaru will be dished 99.9% of the time. But, even if you are wanting to use a domed piston in the spreadsheet, just change the value in the sheet. eg: 20cc dome piston means entering "-20" in the spreadsheet.
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Old 07-21-2020, 11:33 AM   #12
JimboBob
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Still works! thanks, really helped
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