Check my math?

[Christ]

I was thinking about the basic fuel consumption figures in the OM636 Manual I have... the max figure is 215g/HPh (Grams per HorsePower hour).

I wanted to figure out how much fuel (in gallons) it would take to make 1 HP for 1 hour, using this figure as the basis...

So I found that diesel fuel has mass of 3217.6 grams per gallon.

In order to find out how many gallons of fuel I should use to make 1 HP for 1 hour (1 HPh),

215/3217.6 = 0.0668199901

Is that right?

Reversing the equation gives me:

3217.6/215 = 14.9655814, which I take as being 1/15 of one gallon per HPh. Dividing 1/15 out gives me:

1 / 15 = 0.0666666667, approximately the same answer as above... so which way is the correct way to come about the answer?

(The first answer is "It doesn't matter, as long as it's right." But this doesn't hold true in math. If you got the right answer, by the wrong equation, it's still the wrong answer. You can't "stumble on" an answer in math, and I want to know the correct way to do it.)

[jjackstone]

Christ,
As long as your known numbers are correct, use your units to verify the equation.

215g/1 hph x 1 gal/3217.6g = .0668gal/1hph which is your original solution.

I guess we have to assume that the 215g/hph figure includes whatever the nominal efficiency is for the engine.
JJ

[Christ]

215g/hph is the highest figure in the manual for fuel consumption. It's all I've got to go on.

[chembustion]

Originally Posted by Christ

215g/hph is the highest figure in the manual for fuel consumption. It's all I've got to go on.

My comment on the subject at hand is not the issue here. But I HAVE to say the line on bean counters is right on! The bean counters set GM up for a disaster ... beginning with R. Nader & the Corvair fiasco ... all the way to misreading the Toyota and Datsun invasion. Now, GM stands for Government Motors...and we'll see ( like who gets the next "bail-out" from the gov't? The gov't?).
We live in intere$ting times !!!

[Christ]

Originally Posted by chembustion

My comment on the subject at hand is not the issue here. But I HAVE to say the line on bean counters is right on! The bean counters set GM up for a disaster ... beginning with R. Nader & the Corvair fiasco ... all the way to misreading the Toyota and Datsun invasion. Now, GM stands for Government Motors...and we'll see ( like who gets the next "bail-out" from the gov't? The gov't?).
We live in intere$ting times !!!

Tasdrouille said it, I just quoted it. Thanks anyway.