[chris-c]

I'm just wondering if anyone knows how these are calculated.
Are they accurate or just looking at a known maximum for the car and it knows to calculate back based on that?

I happen to have a couple of old videos with the dials displayed and I've taken a guess at the readings on them. They tie in rather well with what BMW claim as the max so I'd guess they are just set to max when the accelerator is at 100%

Pre MPPSK

335bhp / 445nm (at a really bad guess)
326bhp / 450nm (bmw)

Post MPPSK

365bhp / 510nm (at a guess)
360bhp / 500nm (bmw)

[chris-c]

Originally Posted by Incontinentia Buttocks

Gimmick. Next...

Why are dogs noses so tasty?

[Lorcan]

Gimmick. Torque measuring devices suitable for fitting to vehicles exist but they are very expensive. Your car doesn't have one.

[chris-c]

Originally Posted by Lorcan

Gimmick. Torque measuring devices suitable for fitting to vehicles exist but they are very expensive. Your car doesn't have one.

Do we know if its based on % of throttle or something else like the Torque app that measures acceleration VS weight of car and drag coef? If I floor it downhill will I get a higher reading than it should or will it just max out at the pre defined value?

[Lorcan]

I believe it just maxes out at a predefined value. My guess would be that it looks up a figure based on throttle position, boost pressure etc and possibly refers to actual figures from dyno testing of a development model. I'm not saying it's inaccurate, just that it's probably not actively measuring what your car is making.

[DThr33]

Originally Posted by Lorcan

I believe it just maxes out at a predefined value. My guess would be that it looks up a figure based on throttle position, boost pressure etc and possibly refers to actual figures from dyno testing of a development model. I'm not saying it's inaccurate, just that it's probably not actively measuring what your car is making.

I've had mine remapped and not had the dials coded any higher, the car now just maxes out on the dials, so I don't think it maxes out at a predefined value

[NISFAN]

Originally Posted by chris-c

Do we know if its based on % of throttle or something else like the Torque app that measures acceleration VS weight of car and drag coef? If I floor it downhill will I get a higher reading than it should or will it just max out at the pre defined value?

It's not throttle only, otherwise it would be a full immediate deflection in line with pedal position.

I imagine it works off the hot-film mass airflow sensor, which with revs you can approximate into power/torque reasonably accurately. Although probably adjusted to a known full scale, rather than blindly trusting a mass produced sensors readings.

[chris-c]

Originally Posted by DThr33

I've had mine remapped and not had the dials coded any higher, the car now just maxes out on the dials, so I don't think it maxes out at a predefined value

That is interesting.

I might have to go for a spin later uphill then downhill and see if it shows a different reading.

[evdok]

Total waste of a feature, crap IMO

[ak335dxdrive]

They are the modern equivalent of the electronic equalizer.
Useless but
Pretty lights to impress the girlies.

[JLR1969]

Originally Posted by ak335dxdrive

They are the modern equivalent of the electronic equalizer.
Useless but
Pretty lights to impress the girlies.

If your Mrs is over 30 then she wont be impressed, mine thinks I am sad for even looking at them.....

To be fair she thinks I am a saddo for lots of other reason too

[NanasBack]

Probably no less accurate than the speedometer...?

[Kal101]

Makes a decent enough screen saver.

[Junebug85]

I had mine set to hot key/radio key 6 for fun.

The novelty has worn off though now. Thought it was top dog when I got the car

[SkyJawa]

Never used them once!

[moff]

Well there is no dyno in the car

Total gimmick and just based on throttle and revs.

[Kiddy1]

Originally Posted by NanasBack

Probably no less accurate than the speedometer...?

Explain?

[Ajs_435d]

Considering that most modern ecu's are based on torque and load they are quite accurate, if you use them is another matter.

[McBeemer]

Originally Posted by Ajs_435d

Considering that most modern ecu's are based on torque and load they are quite accurate, if you use them is another matter.

That sounds really interesting ...... Could you enlighten further please?

[Darth Helmut]

Originally Posted by moff

Well there is no dyno in the car

Total gimmick and just based on throttle and revs.

Quite possibly but...

I have OBDLink LX running and the set up allows you to input factors such as frontal area, specific mass, Cd and wheel diameter as well as the usual stuff. Changing these parameters affects the bhp and torque values displayed. I datum'd mine on my last dyno run. The peak torque and bhp pretty much matches what I got on the dyno (recorded the runs on there as well as interpolating the graphs). I'm fairly confident that what I'm seeing on OBDLink LX is accurate to within 2-3%. Throwing up the 'sport dials', I'm seeing similar figures (up to their max calibrated values; standard 435d figures, despite a stage 1 remap). They do saturate out at the default figures but their values across the range seem to be quite accurate. So bearing that in mind, I think what is displayed on the dials is as near as 'technically' possible and isn't just a throttle position and revs output.

[NanasBack]

Originally Posted by Kiddy1

Explain?

Speedometer accuracy within British regulations is -0% to +10%
Calculated from roadwheel rotational speed and diameter.
The display is affected of course, by fitted tyre size and how worn they are.

MPG is calculated from fuel injector parameters.
Injectors have a specified fuel flow rate, at specific pressures.
Consumption is a calculation of injector timing and measured rail pressure.
Distance error is also subject to speedometer calculation.
Often seen typically within 2mpg of calculated figures, when in the order of 40mpg.
IE. 5%

Engine torque is calculated from fuel flow and a function of engine rpm.
There is no reason why the manufacturers function, specific to each engine model, should not be accurate. Affected by the energy density of the fuel used (diesel / petrol / air)

Engine horsepower is a linear function of Torque(Nm) x engine RPM x 9549

So 5% shouldn't be difficult to achieve, unless it's a well worn engine.

Probably far more accurate than a lot of rolling road dynamometers guess at engine HP.

[MackM4Comp]

Originally Posted by Darth Helmut

Quite possibly but...

I have OBDLink LX running and the set up allows you to input factors such as frontal area, specific mass, Cd and wheel diameter as well as the usual stuff. Changing these parameters affects the bhp and torque values displayed. I datum'd mine on my last dyno run. The peak torque and bhp pretty much matches what I got on the dyno (recorded the runs on there as well as interpolating the graphs). I'm fairly confident that what I'm seeing on OBDLink LX is accurate to within 2-3%. Throwing up the 'sport dials', I'm seeing similar figures (up to their max calibrated values; standard 435d figures, despite a stage 1 remap). They do saturate out at the default figures but their values across the range seem to be quite accurate. So bearing that in mind, I think what is displayed on the dials is as near as 'technically' possible and isn't just a throttle position and revs output.

Wow, you guys really need to get out more