Torque measurement

[chicken_eyebrow]

Does anyone know what sensor the ECU uses to measure torque?

I had the Liquid Gauge plugged into another members vRS last night and we took it for a run, the most it made was 165ft/lb torque. Mine also does the same, usually somewhere between 165 and 169 ft/lbs torque even though it rolling roaded at 179ft/lbs last year and AFAIK they are supposed to be 175ft/lbs standard. The bhp figures on both our cars are good though, in the mid-late 180's.

I'm wondering if the LG is just crap or whether there is something wrong with how the cars are reading the torque :confused:

Edited 5 August, 2009 by chicken_eyebrow

[Lex Dysia]

I don't think there is a sensor to measure torque or bhp tbh. I think the lg uses calculations of airflow, fuel flow and rpm to guesstimate a rough figure, it is supposed to be pretty accurate though.

[freegeek]

The troque is obtained in diffrent ways depending on whether you are using it with a petrol or diesel.

For petrol it is calculated from the maf and rpm, for diesels it is taken directly from the engine ecu which provides it directly.

It is possible to reverse the methods for either petrol or diesel (see the manual) and you will see a difference, however I think the default methods for each are the most accurate.

[chicken_eyebrow]

Is it possible the MAFs on our cars could be a bit dodgy then?

If thats the case I would have thought the bhp figures would have been wrong as well as I thought they were calculated using MAF readings too?

Might get mine on a rolling road soon and look at the torque... 165 when it should be making 175 is a bit annoying!

[freegeek]

If the max bhp is right then it sounds like your maf is ok.

My mapped TT gives about 270lbft max on the TT while other are closer to 300lbft, I guess it is just the map I have.

Can you do a dyno run and post up the picture.

[chicken_eyebrow]

If I can get a decent enough photo of the screen I'll try and post one up tonight.

[chicken_eyebrow]

Ok as promised:

I did another run and got 189bhp and 165ft/lb. Peak boost pressure is 11.1 psi and peak command pressure is 10.8 psi. Outside temp was 18 degrees c.

The only modification to the car is a vented wheel arch.

[JohnRS]

I think the BHP on the liquid gauge is worked out by deriving the torque figure, which is measured from the ASR somehow. I done it with VCDS by logging the torque and putting it in a spreadsheet which will probably be how this works.

I hope this makes sense :confused:

[chicken_eyebrow]

I might get someone to do a VCDS graph on it then - if the torque is coming from the ASR then possibly the ASR is playing up? Not getting any fault codes showing :confused:

The other member whose car I ran it on has got ASR issues at the moment though.

[freegeek]

For petrol cars the bhp is calculated by MAF/0.8

Torque is then derived from the BHP and rpm.

Torque = BHP*5252/rpm

Thats it..

[chicken_eyebrow]

Is that right though? Because then the torque would be at it's highest when the bhp is at it's highest (as it is in my pic above) and I always thought that peak torque was around 2700-3000 revs and then tails off further up the revs?

(see below for torque graph of a standard car from a rolling road - not my car tho )

http://briskoda.net/south-east-skoda-meets/kent-rolling-road-day-27th-sept-merged-discussion/118131/10/#post1451097

[martziniuk]

I would take readings from these gauges with a pinch of salt. I have done a few logs with vag-com on block 120 and from the maf, they are quite a bit out compared to a RR. Chicken you look to be making peak power @ the highest rpm you reach, Our tubo cars normally make this around 5500-5700rpm iirc.

[chicken_eyebrow]

Chicken you look to be making peak power @ the highest rpm you reach, Our tubo cars normally make this around 5500-5700rpm iirc.

Might be to do with the dyno run on the LG being done in third gear?

When it was rolling roaded it was done in 4th gear and made peak bhp (188) at 5800 rpm IIRC.

[freegeek]

The formula is correct, "you canny change the laws of physics". But your plot is slightly odd they way the torque increase. It would be interesting to see some plot from other similar cars.

Stock cars are normally set up to have a flat torque which makes them feel like they have a contant pull close to the red line.

Mapped cars go for the max torque possible and have a peak at about 3k which tails off as the turbo runs out of puff.

Here is an audi plot of the 225 1.8T engine, I guess yours will be similar.

Compare that to a this hub coupled dyno.

And finally my mapped 225, which is probably the sort of thing you were expecting..

[freegeek]

I would take readings from these gauges with a pinch of salt. I have done a few logs with vag-com on block 120 and from the maf, they are quite a bit out compared to a RR. Chicken you look to be making peak power @ the highest rpm you reach, Our tubo cars normally make this around 5500-5700rpm iirc.

When was the last time you saw two Rolling Roads that gave the same results?

The liquid gives you consistancy so you know if you have improved something or of something is going wrong. I experimented with block 120 but decided against it as it give consistantly low torque figures, insted I went for the MAF method.

For diesels it is the reverse.

Edited 7 August, 2009 by freegeek

[freegeek]

FYI, the current version of software also lets you scale the graphs and gauges to 200,300,400 or 500 on bhp and torque independantly so that you can see more detial.

Let me know if you want yours updated.

[chicken_eyebrow]

Yeah that last graph of yours (on the Liquid) is what I was expecting to see on mine as it would have been closer to my RR graph, i.e. the torque shoots up to start off with and then tails off a bit, then tails off dramatically as soon as it gets to the high revs.

I'll see if I can get another member to let me try it on their car and get a photo of the graph.

I'd love an update if that's ok? Having two seperate Y axes for BHP and Torque would make it a bit easier to look at them.

[chicken_eyebrow]

Got a loony torque figure this morning...

300ft/lbs :eek: (this is a standard car)

Car seems to be running all right with no fault codes but I'm wondering if every now and again the MAF is giving a duff reading.

LG is being sent away next week for a software update and I'm going to try and get it on a RR before the winter just to check.

[freegeek]

Got a loony torque figure this morning...

300ft/lbs :eek: (this is a standard car)

Car seems to be running all right with no fault codes but I'm wondering if every now and again the MAF is giving a duff reading.

LG is being sent away next week for a software update and I'm going to try and get it on a RR before the winter just to check.

Data glitch.

[chicken_eyebrow]

Now discovered how to do it properly to get the right torque figure

Rather than doing it in third I did it in 4th and started at a steady 1500 revs then foot to the floor so the throttle plate was wide open. I stopped at just over 3k revs but by then it had made 175 ft/lb torque and the graph looked the same as a RR one

[banditbarron]

To be honest does it really matter what BHP or torque you are running at? I mean yes its nice to know but my Jabba Printout states 237Bhp from just an active map? Yeah rite i'm sure thats true LOL.

[chicken_eyebrow]

It does for me coz it's a standard car and if it starts telling me it's only kicking out 162 ft/lb torque then I'd start to worry that something was wrong with the engine :(