Landracing Forum

Introductions => Formulas => Topic started by: panic on December 06, 2009, 12:25:00 PM

Title: Compression ratio vs. efficiency Excel program
Post by: panic 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?

Title: Re: Compression ratio vs. efficiency Excel program
Post by: pookie on December 06, 2009, 12:48:04 PM

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

Title: Re: Compression ratio vs. efficiency Excel program
Post by: fredvance on December 06, 2009, 01:16:52 PM

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

Title: Re: Compression ratio vs. efficiency Excel program
Post by: Peter Jack 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

Title: Re: Compression ratio vs. efficiency Excel program
Post by: Milwaukee Midget 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.

Title: Re: Compression ratio vs. efficiency Excel program
Post by: Freud 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

Title: Re: Compression ratio vs. efficiency Excel program
Post by: panic 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.

Title: Re: Compression ratio vs. efficiency Excel program
Post by: panic on January 10, 2011, 11:41:55 AM

Sorry, spreadsheet is not available.

Title: Re: Compression ratio vs. efficiency Excel program
Post by: AHG on January 15, 2011, 02:17:13 PM

http://www.youtube.com/watch?v=5hMAaOdNkgI
Come on now, you know as well as I do, that sometimes funny things
just need to be shared.  
:|   :-)   :-o   :-D   :cheers:

Title: Re: Compression ratio vs. efficiency Excel program
Post by: Stan Back on January 15, 2011, 06:36:53 PM

Prof. Irwin Corey's kid?