Maths bods question HELP!!!

[ilovelag]

how do i work out the power through the rev range of an engine????
theoretical power that is, before the losses from friction etc...
anyone done this for any engine because if you have that's my coursework done nearly.
please help

[Grim]

you go to a rolling road and they give you a graph.

hand that in for homework, and they will be impressed.

get richie to do it for you, and they will be amazed!


i think bren had a calculation for injector size engine size and something else, but it would only give a peak value

so give them a long and very technical answer. mention spool up times, injector duty cycle, uprated fuel pumps, spark plug temperatures, inter cooler dimensions, valve bounce frequency, flame front velocity, exhause bore and length, humidity, fuel octane rating, knock sensors, aspestos turbo hampsters, neons, throttle body diameter and weight of drivers foot.


did they not give you any clues during the lesson?

[ilovelag]

i've done a whole project on asbestos turbo hamsters so that bit is covered, i need the theoretical data from calculations (which is the bit i'm stuck on) and then compare that to an actual rolling road and then discuss the losses from heat, friction, drivetrain etc.

i need to know how to do the equation and what info i need and then i can calculate the rest!

[Ben A]

i did a project on this. i'll look out all the stuff you need to know, but i don't know how helpful it'll be to you.

so have you got a rolling road print out already, and your trying to find out what the car should have produced?

cos for my project i knew a shite load of stuff about the volume of air going in, the fuel consumption etc.

[Big_ReD]

Been thinking about how you could do this but i honestly dont know.
I did my project on feedforward engine control, trying to improve air/fuel ratio. I remember that for a graph of horsepower against engine rpm the engine would be held at say 1000, 2000, 3000 etc rpm and horsepower out put would be given depending on the air/fuel ratio. I have no idea what the equation could be but i think it will include lots of parameters.
good luck :wack:

[Ben A]

i did two. one was on a diesel engine where we loaded up the flywheel with different weights to produce different torques at different rpms, then from all the stuff i said before did an energy balance as to what was going in and comin out.

the second was on a petrol engine connected directly to a dyno and measurements taken at diiferent rpms. that gave a nice neat graph of torque and power at differnt throttle positions, and the point was to determine what was goin on there.

if i remeber the general findings were the air flow into your engine isn't as efficient at low rpm's as it is high because of the throttle butterfly being flat against the direction of air flow buggers it all up. (for lack of a better technical description!!!) :)