Hi

Torque will measure the actual power done by the engine using a physics calculation.

More information is on the wiki: http://torque-bhp.com/wiki/Horsepower

it is very important to enter the correct vehicle weight in the vehicle profile for this test (and to not spin the wheels)

Thanks. However, what you write on that Wiki page does not make much sense to me:

How is it possible to reflect the real "peak" value for wheel power at such a limited speed? For instance, my BMW 528xi is rated 245 HP at some 5-6k RPM - how am I supposed to accelerate from 10 to 55 mph? On a single gear? (my car is AWD, 8-speed AT)...

Please elaborate. Thanks.

Hi

It measures the max HP whilst accelerating - this can be done in any gear (though you'll probably want to do it in teh one with the most pull without spinning the wheels)

By actual horsepower, I mean practical, useful, horsepower at the wheels moving the vehicle. It's a straightforward physics (speed distance weight) calculation to get this information

You'll hit 5/6k rpm in most gears (you do not have to be in top-gear for this test)

Thanks, but I'm afraid your 55 mph testing limit is more influenced by your trying to make Torque users 'play safe', than by any technical reasons.

When I accelerate like this, the WHP max is some 60 HP. Even if I assume some 20% loss in the drivetrain, than translates to what - 80 HP at the crank? My car is supposed to have 245 HP.

Either I'm missing something, or...

You can calculate the amount of actual power needed to accelerate any object A to a speed X.

That's what Torque does. If you want a good reading, just start from a stop, and accelerate as hard as you can without spinning the tires.

Being M Sc in mechanical engineering, I know the laws of physics.

I'd just expect Torque Pro to display a realistic estimate of my engine capabilities. Sorry it's not up to the task.

Maybe this info will help...

http://torque-bhp.com/forums/?wpforumaction=viewtopic&t=3088.0

Thanks, I know this app (when I came across it contacted the authors and helped them rebuild it to the newest standards - losses in the state-of-the-art ZF 8-speed automatic transmission are much lesser than they used to be in regular, 3 speed autos used 15 years ago; also "cross-over" vehicles 4x4 is different in this aspect from the permanent AWD such as xDrive I have, Quattro etc.

And yet, the values shown by Torque Pro are way to low even if I convert them to CHP/CQT using this little guestimator.

Hi!

The accelerating from a rolling start is purely to reduce (significantly) the chance of spinning the wheels when you put the foot down. If you're an engineer, you will understand there is a far greater chance of doing this from a standing start, than from 10mph.

The to 55mph limit is because drag becomes a significant factor against the front of the vehicle, and every vehicle is different in drag given it's shape. You can go over this, but the accuracy may vary depending on the size/shape of the vehicle once drag takes a larger effect.

You do not need to be going ten bazillion miles per hour to correctly calculate HP or Torque. Low speed tests will be just as accurate for the above reason.

Have you entered the weight of the vehicle correctly (this must include driver and any extra fluids).

If you enter the manufacturers vehicle weight then it will be too light and will result in the HP value being significantly less.

As some vehicle ECUs are slow at returning PID information, only have the speed related displays visible on the screen for the test.
If you have too many displays for different sensors, then it slows down sensor information (more sensors, more time between polling each individual one).

(and make sure you have 'Faster Communications' enabled in the settings)

If you enter all the information and do the test properly, it is *very* accurate at measuring HP and Torque. Some people in the past have been disappointed by their readings (unfortunately, blamed the app as being inaccurate) then gone to a Dyno and had them confirmed.

Having a set of corner weights is really what you need to get it accurate. When my GTR is tuned on a dyno, I have to make sure every calculated variable is accurate, otherwise my readings go way out, including tyre pressures and suspension. Even having less fuel provides less weight for the rear of the car (and its strapped down at the front), and as a result the tyres can skip under high power and cause a poor reading.

Also take in mind that manufacturers always overstate the power figures on their marketing material. And when the engine loses compression due to wear it also decreases in power.

Personally, I always use dynos for my end figures and so far Torque matches the "at the wheel" power +/- 5% without tweaking (and that error can be attributed to innacuracy on my part no doubt)...

-D