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Discussion Starter · #1 ·
I am making a car simulation program, and it is mostly done, except I can't figure out what speed the tach moves at. Here is the situation: at any RPM, I can get the current HP and torque, and I have both the gear ratios and final drive ratio, and the circumference of the tires. My question is, what is the instantaneous change in RPMs of the engine with respect to torque or horsepower? Can anyone help me out?
 

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Discussion Starter · #3 ·
OK, like this:

The engine is at 4000 RPMs and the current (from a dyno graph) is 140 lb-ft. and is making 106 hp in 2nd gear. In the next, say, .001 seconds, how far forward will the tach move? 1 RPM? 2.678 RPMs? I need an equation.
 

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i dont know if this will work but you may just want to email Mazda and see if they will give you an answer. Just say something like you are doing a school project or something like that.
 

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As a start, you'll need to know how heavy the car is. Using the HP, gear ratio etc, you would calculate acceleration, velocity, etc. I thought about this for a little bit...looks like you'll need to do some sort of Calculus to figure out the incremental velocity change based on the acceleration generated by the torque/HP to arrive at the final result of speed vs. time which I assume is what you're trying to get to.

Good Luck
 

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Airboy said:
As a start, you'll need to know how heavy the car is. Using the HP, gear ratio etc, you would calculate acceleration, velocity, etc. I thought about this for a little bit...looks like you'll need to do some sort of Calculus to figure out the incremental velocity change based on the acceleration generated by the torque/HP to arrive at the final result of speed vs. time which I assume is what you're trying to get to.

Good Luck
Well, the computer can obtain a fairly accurate estimate by sampling the instantaneous acceleration numbers rather than trying to integrate a waveform.

Simple F=MA and other highschool physics stuff is all that's needed.
 
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