Compression ratio vs. efficiency Excel program

Started by panic, December 06, 2009, 09:25:00 AM

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panic

This is an .xls to compare changes in static CR (in .01 ratio increments) old vs. new as efficiency for each, an compares % nominal change and efficiency % change.
Based on the usual Otto math: E = 1-(1/CR^K-1), where K=1.4. If you need another value just substitute, it's not locked in.

Just use the spin buttons to input your CR (arrow = .01 ratio, open space = 1 ratio).

LMK if you think of any useful changes?

pookie

#1
HUH...????????    At least I did not need spell check for this one!!!!!!

fredvance

So if your thermal effeciency is 10% higher this meas what in terms of horsepower?
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Peter Jack

Panic:

Just so you know, when you try and open the spreadsheet on the MAC with Microsoft Office installed you get a message which says the spreadsheet contains Visual Basic macros and Microsoft EXEL for MAC cannot process Visual Basic macros. I can switch to a PC but some may not have that convenience.

Pete

Milwaukee Midget

Hey, Peter -

I had success by downloading it to my desktop and opening it with Appleworks, if you have that.

Thanks for the spreadsheet, Panic.
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Freud

Download OpenOffice.org for the Mac and it will open it instantly, after the virus warning.

FREUD
Since '63

panic

Assuming that the basic chamber shape isn't changed much (which will only be true with small changes, not going from 10 to 12, etc.) you'll get close to that as power.
Obviously, a dome intrusion or chamber masking will reduce the net.
This also does not compare engines re-optimized for higher ratio, such as different intake/exhaust bias, later IVC, narrower LSA, etc.

panic


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