[cfg83]

Hello -

I was looking at this Wiki :

Brake specific fuel consumption - Wikipedia, the free encyclopedia

Some examples of lower heating values for vehicle fuels are:

Certification gasoline = 18640 BTU/lb = 0.01204 kW·h/g
Regular gasoline = 18917 BTU/lb = 0.0122225 kW·h/g
Diesel fuel = 18500 BTU/lb = 0.0119531 kW·h/g

Thus a diesel engine's efficiency = 1/(BSFC*0.0119531)

and a gasoline engine's efficiency = 1/(BSFC*0.0122225)

Can someone state whether or not the above fuel efficiency statements are dimensionless or not? When I add units to the calculation I see the units in the divisor cancel out. For example :

Gasoline with 250 g/kW·h BSFC :
1 / ( 250 * 0.0122225)
= 1 / ( 250 in g/kW·h * 0.0122225 in kW·h/g )
= 1 / 3.055625
= 0.32725 "efficiency"

Is this the way it's supposed to be? Are there units for this?

Thanks,

CarloSW2