efficiency formulas spreadsheet

[kerosene]

I am playing with the idea of a low fuel consumption (and low power vehicle)

Yesterday I was compiling different formulas for rolling and wind resistance into one spreadsheet.

File is attached - I am a metric man so its mostly in metrics - it does show you weight in lbs and speed in mph too - but inputs are metrics.

Let me know if you find it useful or if you have any suggestions to improve it or if you found errors.

Basically you input, cross section area, drag coefficient (or best guess), speed, weight, crr (rolling resistance coefficient), brake specific fuel consumption (g/kwh), road grade (uphill/downhill in %).

Lemme know if you have trouble using it.

if your guesses are close you should get pretty good idea of how much power is needed for overcoming different forces. Obviously its only as accurate as your inputs and it does not count for transmission losses - just gives you watts/hp of how much power is need for the traveling.

Cheers

[Daox]

You should have asked here first. Although, I see yours had an incline feature, nice add.

Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com

[kerosene]

screen grab of said spread sheet.

Wikipedia has some example drag coefficients to help.
Automobile drag coefficient - Wikipedia, the free encyclopedia

(note that many sports cars suffer from very wide tires - the bodies themselves are often much more aerodynamic than regular sedans but the coefficient ends up in similar numbers)

some info on rolling resistance:
Rolling resistance - Wikipedia, the free encyclopedia

[kerosene]

Originally Posted by Daox

You should have asked here first. Although, I see yours had an incline feature, nice add.

Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com

ha - you are right - the calculator is very nice much better than my spreadsheet.

I added the incline as the reserve power needed is dictated by how much do you want to slow down in uphills (or how fast do you want to accelerate).

[bgd73]

a math I havenot seen yet, as it crushes the japanese whirlwind of screaming inline fours....

the fantastic power for weight difference a 3 main boxer gives versus the yoyo counterbalance of an inline...same displacement needs gigantic air on the inline to be equivalent.

funny enough..there has never been a dyno for them. Through real life blogging and forums... I did take note the 1781 at 180 hp is playing with the 5 main subaru wrx easily... nearly 100% less power, and less than 500 pounds different. Ya know what I mean? A math for the engine and loss..does not ever equal the hp number written..all bad theory.

it is a sweet frustration for me.