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Author Topic: Compression ratio vs. efficiency Excel program  (Read 10518 times)
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panic
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« on: December 06, 2009, 12:25:00 PM »

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?

* Otto cycle.xls (35.5 KB - downloaded 404 times.)
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pookie
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« Reply #1 on: December 06, 2009, 12:48:04 PM »

HUH...HuhHuh??    At least I did not need spell check for this one!!!!!!
« Last Edit: December 06, 2009, 12:56:25 PM by pookie » Logged
fredvance
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« Reply #2 on: December 06, 2009, 01:16:52 PM »

So if your thermal effeciency is 10% higher this meas what in terms of horsepower?
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Peter Jack
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« Reply #3 on: December 06, 2009, 02:47:00 PM »

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
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Milwaukee Midget
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« Reply #4 on: December 06, 2009, 03:20:58 PM »

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.
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« Reply #5 on: December 06, 2009, 03:22:46 PM »

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

FREUD
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panic
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« Reply #6 on: December 06, 2009, 03:56:53 PM »

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.
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panic
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« Reply #7 on: January 10, 2011, 11:41:55 AM »

Sorry, spreadsheet is not available.
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AHG
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« Reply #8 on: January 15, 2011, 02:17:13 PM »


Come on now, you know as well as I do, that sometimes funny things
just need to be shared.

undecided   smiley   shocked   grin   cheers
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« Reply #9 on: January 15, 2011, 06:36:53 PM »

Prof. Irwin Corey's kid?
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