Thread: Fuel consumption

Short answer: Car 1 @2000rpm uses less fuel.
long answer to follow.

Originally Posted by Traveler

Short answer: Car 1 @2000rpm uses less fuel.
long answer to follow.

are they both assuming the two cars are Land rover discoverys?
More to the point, do these professors have any idea of the hp or torque curve/figures, the timing, etc etc for the 'simulated' engine?

Honestly, you really need to get a bloody life. If you spend a significant portion of your time trying to work out crap like fuel economy figures and which car will perform more economically than another is beyond comprehension. I can't believe you have two university professors wasting their time on this nonsense. Why can't you just get in your bloody truck and do what it was built for....exploring this great country of ours.

Originally Posted by Traveler

I have 2 professors at uni looking into this...
their is an answer... complicated...
answers tonight or tomorrow.

here is the question i asked them:
Hello again.
here is the problem.
their are no factors which may influence performance eg: wind, road surface, driver technique, type of fuel used,gear changes,optimum fuel efficiency point, etc.
point A to B is a flat surface.
both vehicles are at their given RPM speed constantly and in 4th gear between point A and B.{no acceleration, braking.}
Car 1 is doing 2000RPM constant throttle speed between A and B
Car 2 is doing 1750RPM constant throttle speed between A and B
Car 1 will reach point B in less time than Car 2.
Which car uses more fuel for the overall trip from A to B?

Now it is getting clearer. If you wipe out the acceleration and deceleration, wind etc, it should be able to be worked out.

I am interested in the result. At a guess they should be the almost the same given that the distance travelled is not great.

Is this for a uni assignment?

What a joke. Of course it can be worked out if all REAL WORLD factors are ignored.

BUT AFAIK, you still have to input some data on economy at speed points , and all the math does is fill in the gaps.
Car makers still use dynos to calculate Government mandated fuel economy figures.
That is why all dynos have correction factors for temperature, atmospheric pressure,and a host of other variables.
Funnily enough the Government will not accept computer models, and the Government specifies the correction data, to stop car makers "massaging" the data
Once you get on the road, its funny but those real world variables tend to affect the outcome to the extent that mathematical models are meaningless ( in exact mathematical terms), as errors would exceed say +-10%.
Regards Philip A

[QUOTE=001525;612190] If you spend a significant portion of your time trying to work out crap like fuel economy figures and which car will perform more economically than another is beyond comprehension.

thats an easy one:
narrow minded X 1 = 001525

Originally Posted by PhilipA

What a joke. Of course it can be worked out if all REAL WORLD factors are ignored.

BUT AFAIK, you still have to input some data on economy at speed points , and all the math does is fill in the gaps.
Car makers still use dynos to calculate Government mandated fuel economy figures.
That is why all dynos have correction factors for temperature, atmospheric pressure,and a host of other variables.
Funnily enough the Government will not accept computer models, and the Government specifies the correction data, to stop car makers "massaging" the data
Once you get on the road, its funny but those real world variables tend to affect the outcome to the extent that mathematical models are meaningless ( in exact mathematical terms), as errors would exceed say +-10%.
Regards Philip A

Philip you are confused. My question does not include any of your variables.

No Barry no association with anything i'm doing there. Sometimes i like to figure out things with pure mathematics. Cheers.