How do I calculate the torque of an Internal Combustion Engine?

[Mbenj]

TL;DR

How am i able to calculate the amount of torque a engine is producing by using factors other than horsepower. I want to make a engine simulator for the ios and only need rough estimates. The kind of factors i was thinking were Displacement, Intake Pressure, Volumetric Effieciecny, ect.

Hello all,

This is my first post on here so sorry if its not the greatest.

I am starting to make a car based video game for the ios in which you are able to customise cars and race them. One feature i wanted to include in this game was the ability to create unique engines. I don't want it ridiculously unrealstic but if they change small details like stroke for example, it will slightly change the torque curve. The original factors i was thinking were Displacement, Bore and Stroke, intake Pressure, Fuel Energy, Amount of Fuel and Thermal Efficiency. I've found new factors like Compression Ratio and Volumetric Efficiency, so maybe adding those will be a good idea.

I was hoping there was a specific formula to calculate torque, and in a curve as well(ranging through the rpm's), but i haven't had any luck looking through google and several other physics forums. I wouldn't expect just the one magical formula, because there's so many factors that go into specific torque outputs, but an estimate formula (or atleast part of it) that could at least give me a believable torque curve.

Thanks to all in advance, I appreciate any and all help
Regards,
Mbenj

 

[jedishrfu]

Maybe this will help:

https://carbiketech.com/engine-torque/
and this video with car stats:

 

[gmax137]

You can learn a lot from automotive engineering books, and from hot rod tuning books. In the real world though, people do dynomometer testing since formulas are just formulas.

 

[scottdave]

How are you going to use torque? How will this value affect the performance of your cars? I think the value that you are trying to arrive at is acceleration. In addition to engine characteristics, vehicle weight would be one factor which would affect that.

Perhaps (at least to start), you could go get a hot rod magazine which compares different cars and lists the factors. You could try to do a regression to come up with some sort of acceleration factor. Cars will not accelerate at a constant rate. Engines perform better at certain speeds. You see something like Max Torque at XXX rpm, for example. The the zero to 60 in __ seconds would give you an idea of how fast each car accelerates.

I imagine this project will take some fine tuning to get it to perform to your liking. Good Luck!

 

[scottdave]

The Motor Trend Cars dataset is a famous one used in teaching regression. It has comparison of 32 cars. There is no 0-60 time, but there is a quarter mile time. It might be something to play around with. If you install the R statistical programming package, the dataset comes with that.

You can see a description of the quantities here:
https://stat.ethz.ch/R-manual/R-devel/library/datasets/html/mtcars.html

and here is a listing of the data -

 

[cosmik debris]

If you really want to calculate the torque from basic principles you will need to calculate cylinder pressure from the chemistry of fuel and air. The Brake Mean Effective Pressure curve is congruent with the torque curve.

Cheers

 

[jack action]

This should be a good start: http://hpwizard.com/engine-horsepower-calculator.html