[IMS-340C]

Probably most of you guys used the sports displays at some point.

The ECU uses the engine parameters/sensors like boost/timing/AFR/Engine Load etc... to calculate torque/HP .

I wonder how accurate those numbers are compared to a real dyno? has anybody got the chance to compare those numbers with a dyno ?

Here's a chart I created from my ECU log and got these results:

[Wires]

I've heard if you are stock, the numbers are pretty close to actual. The power levels are interesting though. BMW does under-rate their cars, and those numbers listed would put a 3L turbo BMW about the same as a 3L turbo Audi (which makes sense from a competition standpoint).

[kern417]

The numbers aren't calculated. The ECU programming is load based, and BMW assigned load values (Torque) to certain combinations of engine parameters. So the numbers are whatever the tuner assigns them as. OEM will be more accurate than tuned since a tuner can set them to whatever they want. But if your car is pulling timing or running hot in the summer, it won't show different hp/torque values because the load requested by the DME will be the same for a given throttle position.

[IMS-340C]

If the ECU assigned values to certain combinations of engine parameters in my book that's some kind of calculation.

I also ran another map with higher boost and because of the low octane fuel the ECU retarded the timing and the ECU log actually showed lower torque numbers.

Originally Posted by kern417

The numbers aren't calculated. The ECU programming is load based, and BMW assigned load values (Torque) to certain combinations of engine parameters. So the numbers are whatever the tuner assigns them as. OEM will be more accurate than tuned since a tuner can set them to whatever they want. But if your car is pulling timing or running hot in the summer, it won't show different hp/torque values because the load requested by the DME will be the same for a given throttle position.

[GT500R]

I thought I read somewhere that HP is just a number and can be changed by the tuner but the TQ is the actual TQ requested at the flywheel (as this needs to be limited by trans) and is pretty accurate...

[kern417]

Originally Posted by IMS-340MP

If the ECU assigned values to certain combinations of engine parameters in my book that's some kind of calculation.

I also ran another map with higher boost and because of the low octane fuel the ECU retarded the timing and the ECU log actually showed lower torque numbers.

It's not a calculation. I got a BM3 tune and because all they did was reassign boost/timing to the same load functions, it said i still made stock power.

Instead of looking at the specific figure, think of it more like a percentage of max. At 100% throttle at the peak of the curve, they assign it 320hp. At half throttle, they reduce the requested load to 50% and set the load to read 160hp. It's not actually that linear, but you get the idea. It's all estimations based on hp figures and the desired output. They can assign whatever boost/timing/etc. they want to the load profile. So when your car makes more power in the winter, it'll still show the same load. Or when you're at different elevations, it'll show the same load. The car automatically changes boost and timing to try and compensate, but the ECU is pushing the same load values to the sports display.

In the absolute best case, BMW did dyno testing at various loads, plotted all of the hp figures, and updated their load values based on those charts. Highly unlikely, but that would be the only way to get it done semi-accurately. Because at the end of the day there is no way to calculate HP with engine parameters. Otherwise dynos would never be needed.

[IMS-340C]

Torque and HP are directly related so you can't change one and not the other at the same RPM.

HP=Torque X RPM / 5252

So to increase HP you either increase torque or RPM.

Originally Posted by GT500R

I thought I read somewhere that HP is just a number and can be changed by the tuner but the TQ is the actual TQ requested at the flywheel (as this needs to be limited by trans) and is pretty accurate...

[IMS-340C]

Unless they invent a small low drag dyno fitted on the flywheel, that would be cool.

Originally Posted by kern417

In the absolute best case, BMW did dyno testing at various loads, plotted all of the hp figures, and updated their load values based on those charts. Highly unlikely, but that would be the only way to get it done semi-accurately. Because at the end of the day there is no way to calculate HP with engine parameters. Otherwise dynos would never be needed.

[GT500R]

Originally Posted by IMS-340MP

Torque and HP are directly related so you can't change one and not the other at the same RPM.

HP=Torque X RPM / 5252

So to increase HP you either increase torque or RPM.

On a dyno, 100% correct, but this is based on load values and flow.

[Wires]

One would need to quantify "calculation". To kern417's point, the DME has a 2D map that is RPM vs load that is populated with expected torque numbers. HP is a simple calculation as listed above based on TQ & RPM.

After that, there is a boat load of calculations that take that torque along with the readings from the MAF, MAP, TMAP, RPM, IAT, etc to create a boost target that the DME will use to throttle the wastegate with.

Long story short, the plot above is what BMW has hardcoded in the DME as their expected torque targets. That being said, there are a lot of OEM dyno plots out there, and it would be interesting to see if you dropped your numbers by ~15% if those plots overlaid perfectly with other people's wheel dyno plots.

[B58togo]

Point of reference. I was pinning the gauge on 460 with the 93 tune, and now I'm pinning it on 480 with the E30 tune. I think they should make the E30 tune read 500-510.

[Fuel-It!]

The sport gauges are imaginary, your tuner can set them to whatever you want. Sometimes I set them to 1000hp for customers to play a joke on them.

[jackstrath]

Dont pay to much attention to them... gimmick imo

[IMS-340C]

I didn't mean the sports displays specifically, I meant the ECU log as I think sports displays read from it.

Attached is part of the ECU log.

Originally Posted by Fuel-It!

The sport gauges are imaginary, your tuner can set them to whatever you want. Sometimes I set them to 1000hp for customers to play a joke on them.

Originally Posted by jackstrath

Dont pay to much attention to them... gimmick imo

[Skyhigh]

I am getting confused about what you really mean...

My understanding (which may of course be wrong) is the same as what most people here have been saying - the sport displays are only based on very basic paramaters (such as gear, RPM, throttle). They rely on values (mapping) for the combination of the above, irrespective of fuel type and quality, environmental conditions, etc. So by nature they are never too precise, but give a rough idea about what to expect.

If you tune your engine but not touch the Sport Display mapping it will still be showing the same power and torque for given gear, throttle, rpm.

[IMS-340C]

No confusion was just wondering how accurate are the sports displays as I found in the ECU engine log there are tons of parameters/sensors like RPM, throttle position, boost, ignition timing, ambient temp, engine load, AFR and much more.

With no tune and if the manufacturer is stating the true crank torque/hp numbers and if the sports display is acquiring data from all these parameters/sensors it should be quite accurate.

Originally Posted by Skyhigh

I am getting confused about what you really mean...

My understanding (which may of course be wrong) is the same as what most people here have been saying - the sport displays are only based on very basic paramaters (such as gear, RPM, throttle). They rely on values (mapping) for the combination of the above, irrespective of fuel type and quality, environmental conditions, etc. So by nature they are never too precise, but give a rough idea about what to expect.

If you tune your engine but not touch the Sport Display mapping it will still be showing the same power and torque for given gear, throttle, rpm.

[Skyhigh]

Except that it is not.
It will never show anything above (or under) the maximum speced power/torque when the basic preconditions (RPM/gear/throttle) are met, irrespective of ambient temp, fuel quality, boost, etc.

What you will find in the ECU is typically everything available (which is a lot). How this data is used and by which systems/features is a completely different question.

[IMS-340C]

True. No matter the conditions the Sports Displays always show 500 NM of torque.

Though the ECU compensates for the conditions like applying more boost when AC in on, but it definitely has it's limits.

Originally Posted by Skyhigh

Except that it is not.
It will never show anything above (or under) the maximum speced power/torque when the basic preconditions (RPM/gear/throttle) are met, irrespective of ambient temp, fuel quality, boost, etc.

What you will find in the ECU is typically everything available (which is a lot). How this data is used and by which systems/features is a completely different question.

[Skyhigh]

The AC is typically (temporarily) disengaged when max engine power is required. That's how it works on other vehicles at least.

[IMS-340C]

In my previous cars AC disengages above a certain RPM around 5000.

Not sure about my 340, but I noticed higher boost when AC is on and pulling at low revs.