Thread: Motor Torque, where is it measured?

Engine torque is ment to be an at the flywheel figure

vehicle torque can be measured at the wheels or listed off of engine torque figures.

Manufacturer specs are flywheel figures, most chassis dyno figures are 3rd gear tests that give an unrealistic figure.
If your chasing more realistic aftermarket figures, ask for fourth gear dyno run results as it is a 1:1 ratio.

Originally Posted by aptfab

Manufacturer specs are flywheel figures, most chassis dyno figures are 3rd gear tests that give an unrealistic figure.
If your chasing more realistic aftermarket figures, ask for fourth gear dyno run results as it is a 1:1 ratio.

Agreed. All OEM figures for torque and KW are off the flywheel, and with no accessories! No fans, no pumps, all electrics, cooling and fueling is done off the engine.

If doing mods, dyno before, and then dyno after.

Interestingly my BMW E30 325i lists 160BHP, following extensive work, SM4 and turbo at 12lbs it could only make about 180 at the wheels on the dyno. So that theoretically is $x1000s to make only 20hp.

.................but then again it can really get down

Cheers

RF

Originally Posted by Rick Fischer

So that theoretically is $x1000s to make only 20hp.

G'day Rick,

Fair point, except for the bit about 160HP quoted as original (this would be at the flywheel). This would have equated to roughly 120HP at the wheels the day it rolled out of the factory and will have diminished somewhat over the ensuing years with mechanical wear. We are talking about a vehicle originally built in the 1980's.

A figure today of 180HP at the wheels today probably equates to a real world improvement of more than double what you started with. In that light while I'm sure the thousands weren't insignificant, neither was that gain!

I really love to see it "get down"

Cheers,
Iain

Thanks for the feedback,
So if you have a dyno figure you would have to divide it by the the overall gear reduction to come up with the flywheel measurement.
And by the same logic you can multiply the motor torque be the overall reduction in 1st low and move a planet!

TD

in very broad terms
"yeah, thats about right"

You need to factor in losses and a few other things but the concept is in the right direction.

Cept for autos... They can wind up with more torque at the wheels than the simple maths of torque X reduction gives you.

Originally Posted by RangieBit

G'day Rick,

Fair point, except for the bit about 160HP quoted as original (this would be at the flywheel). This would have equated to roughly 120HP at the wheels the day it rolled out of the factory and will have diminished somewhat over the ensuing years with mechanical wear. We are talking about a vehicle originally built in the 1980's.

A figure today of 180HP at the wheels today probably equates to a real world improvement of more than double what you started with. In that light while I'm sure the thousands weren't insignificant, neither was that gain!

I really love to see it "get down"

Cheers,
Iain

Exactly the point I was making and yes it is
89 E30 325 = in line six, manual box, rear wheel drive, the car "points" and still relatively LIGHT! Engine, braking, suspension/handling has so much in reserve. Is/was good project car, now fully restored and with no mods eg intercooler visible, and I love driving him.

Cheers

RF

Originally Posted by aptfab

Manufacturer specs are flywheel figures, most chassis dyno figures are 3rd gear tests that give an unrealistic figure.
If your chasing more realistic aftermarket figures, ask for fourth gear dyno run results as it is a 1:1 ratio.

Might be 1:1 in the gearbox but you still have the diff ratio to figure, standard rover 3.54, regards Frank.