g/s to cfm

[Greg Hermann]

>
>>
>>Yea I do that alot. One reason to find VE would be:  to convert to a
>>MAP cal, I need to know it going in right?
>>
>>> Like trying to develope fuel tables on a computer, without even having the
>>> engine running.  Ni being smart here just curious where ya going.
>>> Also, need BMFC for figuging fuel needed.
>>
>>Okay I'll bite.. BMF-what?
>
>Brake Mean Fuel Consumption.  How many pounds of fuel to make one HP.

Pounds of fuel used to make 1 Horsepower _for _one_ hour-- pounds of fuel
per horsepower hour is the unit of BSFC.

Horsepower is a unit measuring the RATE of doing work, a Horsepower-hour is
a unit of work. (1 Hp-hr. = 1,980,000 foot lbs. =  2546 BTU).

BSFC is a measure of an engine's efficiency. Say your BSFC is .40 lbs. of
fuel/ Hp-hr.
Say you are burning straight iso-octane, whose lower heat of combustion is
18065 BTU/ lb.

18065 BTU/lb. x .4 lb./ Hp-hr. =  7226 BTU heating value (of .4 lb. of
fuel) to produce 1 Hp-hour (2546 BTU) of work.

So--the thermal efficiency of your engine is = 2546/7226 =  35.2%

>Typically .35 (really good), .5 average, .6+(tirbo+other applications where
>fuel used to cool things.
>Bruce
>
>  the BMF part I think I'm guessing wrong

It's (properly known as Brake Specific Fuel Consumption--BS--F--C.


Regards, Greg