M4 dyno test by Sportauto 465hp/577 nm

[FogCityM3]

Incredible power production!! Also, think it looks pretty good for a turbocharged engine, probably about as linear as you're going to get.

[ASAP]

Is it just me or is the car making about 370 WHP? I have no idea what sort of dyno this is but I predicted 390-395 WHP on a DJ.

I can guarantee that if this is 390 WHP on a dj, this car isn't touching 120 MPH traps.

[CanAutM3]

How do they figure drivetrain losses ? 30% loss at max RPM seems awfully high to me (~135/465)

This is important to understand if the flywheel 465ps number is to mean anything.

[jc05e46m3]

Originally Posted by Boss330

Not quite...

P-Rad= Wheel HP
P-Mot= Flywheel HP
M-Mot= Torque at the flywheel

P-Schlepp = Drivetrain losses

Meaning that:

Pmot - Pschlepp = Prad
Prad + Pschlepp = Pmot

Thanks for correcting. I literally was guessing. Sitting at work causing trouble Your answer makes much more sense.

[Boss330]

Originally Posted by ASAP

If P-rad is truly WHP... I would like to see who else wants to argue the shift points here. Just like an N54, past 6K rpms... your power is dropping and you will shift around there. Once again, a function of small turbos.

The useless flywheel HP numbers match BMWs charts but the reality is slowly coming out.

AFAIK, you want to look at torque to the rear wheels when looking at shift Points. As long as you still are amking more torque at the rear wheels at 7000rpm in the gear you are in than at 5500rpm in the next gear, you still want to hold on to that gear.

Going by torque at the rear wheels all shift points are above 7000rpm, but quite a few are not at redline (more like at around 7200-7300rpm I believe).

[ASAP]

Originally Posted by Boss330

AFAIK, you want to look at torque to the rear wheels when looking at shift Points. As long as you still are amking more torque at the rear wheels at 7000rpm in the gear you are in than at 5500rpm in the next gear, you still want to hold on to that gear.

Going by torque at the rear wheels all shift points are above 7000rpm, but quite a few are not at redline (more like at around 7200-7300rpm I believe).

Where do you see TQ at the wheel?

[Boss330]

Originally Posted by CanAutM3

How do they figure drivetrain losses ? 30% loss at max RPM seems awfully high to me (~135/465)

This is important to understand if the flywheel 465ps number is to mean anything.

All I know is that they use a MAHA dyno that measures according to EU/DIN standards. But very valid question!

[E36toF30]

I'm confused. BMW says it has 400 lb/ft of torque starting at 1800 rpm. This graph says the full torque doesn't come in until 3200 rpm, and at 1800 it's not much more than 1/3 of peak torque. Something seems off, like they started the dyno run at 3000 rpm.

[Boss330]

Originally Posted by ASAP

Where do you see TQ at the wheel?

Torque at the rear wheels is:

Torque at the flywheel x overall gearing

For instance in 1st gear:

1st gear: 4,806:1 (DCT)
2nd gear: 2,593:1 (DCT)
Final drive: 3,462:1

5500rpm (577Nm at the flywheel):
Torque at the rear wheels = 577 x 4,806 x 3,462 = 9600Nm (1st)
Torque at the rear wheels = 577 x 2,593 x 3,462 = 5179Nm (2nd)

7000rpm (450Nm at the flywheel):
Torque at the rear wheels = 450 x 4,806 x 3,462 = 7487Nm (1st)


So as you can see, at 7000rpm it still makes 7487Nm at the rear Wheels in 1st gear, while it "only" makes 5179Nm in 2nd at 5500rpm. You still want to hold on to 1st until you reach that crossover point where you make more rear wheel torque in the higher gear (or you reach the redline). The S65 would allways make more torque at the rear wheels in every gear, which is why it allways makes sense to take it to the redline for maximum acceleration.

[Boss330]

Originally Posted by E36toF30

I'm confused. BMW says it has 400 lb/ft of torque starting at 1800 rpm. This graph says the full torque doesn't come in until 3200 rpm, and at 1800 it's not much more than 1/3 of peak torque. Something seems off, like they started the dyno run at 3000 rpm.

See my previous post: http://f80.bimmerpost.com/forums/sho...6&postcount=13

Also bear in mind that the Prad number at 1500rpm is extremely low (around 5hp), indicating a non full throttle scenario at 1500rpm IMO. This also creates that very steep rise from 1500rpm that you might not see in real world scenarios.

[JoeFromPA]

First off, let's get out of the way that dyno's are like track times. They aren't useful except as a comparison of change when other variables are controlled for....

This dyno is bizarre. First, it was ramped up around 3200 rpms. That's fine, some dyno operators ramp up at 2000, 2500, or 3000 rpms. Operator judgement, bit weird for a publication, but ok.

It shows a peak of 425 lb/ft of torque at the flywheel according to the translations provided here. But you can't calculate flywheel torque at the wheels, so that flywheel torque would need to already be adjusted to a loss percentage assumed from flywheel to wheels. What was the actual wheel torque? We have to calculate it ourselves based upon supposed wheel HP at a given rpm.

I wouldn't put alot of faith in this dyno is my bottom line. It's just too questionable and has no comparison. Put an e9x m3 on the same dyno at the same time, and we'll have something to talk about.

Second, the drivetrain loss at peak HP is showing >25% drivetrain loss. Huh?

[ASAP]

Originally Posted by JoeFromPA

First off, let's get out of the way that dyno's are like track times. They aren't useful except as a comparison of change when other variables are controlled for....

This dyno is bizarre. First, it was ramped up around 3200 rpms. That's fine, some dyno operators ramp up at 2000, 2500, or 3000 rpms. Operator judgement, bit weird for a publication, but ok.

It shows a peak of 425 lb/ft of torque at the flywheel according to the translations provided here. But you can't calculate flywheel torque at the wheels, so that flywheel torque would need to already be adjusted to a loss percentage assumed from flywheel to wheels. What was the actual wheel torque? We have to calculate it ourselves based upon supposed wheel HP at a given rpm.

I wouldn't put alot of faith in this dyno is my bottom line. It's just too questionable and has no comparison. Put an e9x m3 on the same dyno at the same time, and we'll have something to talk about.

Second, the drivetrain loss at peak HP is showing >25% drivetrain loss. Huh?

Yep... this dyno is off.

Originally Posted by Boss330

Torque at the rear wheels is:

Torque at the flywheel x overall gearing

For instance in 1st gear:

1st gear: 4,806:1 (DCT)
2nd gear: 2,593:1 (DCT)
Final drive: 3,462:1

5500rpm (577Nm at the flywheel):
Torque at the rear wheels = 577 x 4,806 x 3,462 = 9600Nm (1st)
Torque at the rear wheels = 577 x 2,593 x 3,462 = 5179Nm (2nd)

7000rpm (450Nm at the flywheel):
Torque at the rear wheels = 450 x 4,806 x 3,462 = 7487Nm (1st)


So as you can see, at 7000rpm it still makes 7487Nm at the rear Wheels in 1st gear, while it "only" makes 5179Nm in 2nd at 5500rpm. You still want to hold on to 1st until you reach that crossover point where you make more rear wheel torque in the higher gear (or you reach the redline). The S65 would allways make more torque at the rear wheels in every gear, which is why it allways makes sense to take it to the redline for maximum acceleration.

I see, you did it mathematically... I am just not buying what this dyno is showing, everything seems off. It's similar to when we put a tuned N54 on a load bearing dyno and it showed 100 LB FT less tq than HP. I knew something was up immediately... the misinformed dyno operator didn't even know what I was talking about.

[Inuyasha]

I'm confused - what is this in plain English. Is this engine underrated with power like most BMW TURBO engines of late?

[Boss330]

Originally Posted by ASAP

Yep... this dyno is off.




I see, you did it mathematically... I am just not buying what this dyno is showing, everything seems off. It's similar to when we put a tuned N54 on a load bearing dyno and it showed 100 LB FT less tq than HP. I knew something was up immediately... the misinformed dyno operator didn't even know what I was talking about.

The MAHA dynos are the most accurate out there and are used by OEM and approval authorities for verification of manufacturer numbers here in Europe. Agree that it seems like the engine isn't under load until around 3000rpm.

The mathematical calculation still is relevant because even though the actual numbers might be off, the torque curve even as provided by BMW (with more drop in torque above 5500rpm) shows that it's better to take it to the redline or at around 7300rpm (depending on gear) for maximum torque to the rear wheels.

[solstice]

Originally Posted by ASAP

Yep... this dyno is off.




I see, you did it mathematically... I am just not buying what this dyno is showing, everything seems off. It's similar to when we put a tuned N54 on a load bearing dyno and it showed 100 LB FT less tq than HP. I knew something was up immediately... the misinformed dyno operator didn't even know what I was talking about.

I would think Sportauto take some care here with a proper dyno setup since their Supertest enjoy a decent level of respect. But who knows, maybe it's some flaky equipment run by total amateurs. Impossible to know if they don't post that information.

[JRV]

Dyno not crossing hp and torque at 5250 RPMs shows it needs to be corrected/shifted.

[JoeFromPA]

Originally Posted by Boss330

The MAHA dynos are the most accurate out there and are used by OEM and approval authorities for verification of manufacturer numbers here in Europe. Agree that it seems like the engine isn't under load until around 3000rpm.

The mathematical calculation still is relevant because even though the actual numbers might be off, the torque curve even as provided by BMW (with more drop in torque above 5500rpm) shows that it's better to take it to the redline or at around 7300rpm (depending on gear) for maximum torque to the rear wheels.

Yes but it doesn't mean we sitting here are interpreting it correctly. Does that mean the MAHA dyno assumes a >25% drivetrain loss on a RWD platform and that is accurate? Cause that's how I'm reading that dyno. And why is torque already pre-calculated at flywheel levels? Is it reading it at the wheels and then increasing it to account for a 25% loss at peak levels?

[Boss330]

Originally Posted by solstice

I would think Sportauto take some care here with a proper dyno setup since their Supertest enjoy a decent level of respect. But who knows, maybe it's some flaky equipment run by total amateurs. Impossible to know if they don't post that information.

Sport Auto recently ran an article on their dyno sessions. I believe that they use the same dyno on each Supertest operated by TÜV or something.

I have also looked up a few recent Supertests and see that cars like the SLS Black Series and RS6 also show a similar power curve as we see for the S55.

The RS6 has a maximum drivetrain loss of 150hp and the SLS 160hp

[Boss330]

Originally Posted by JRV

Dyno not crossing hp and torque at 5250 RPMs shows it needs to be corrected/shifted.

The dyno reads metric numbers, not imperial. It's only if you use ft.lbs and hp that the curves cross at 5250rpm.

[s62]

Maha dyno does not assume anything. It measures the parasitic loss directly during the deceleration. This is how it arrives at the flywheel power.

The numbers are definitely legit.

Some of you would argue the numbers not because of the drivetrain loss but because of the torque peak arriving after 3000 rpm. This is normal. You can not load the engine enough on a chassis dyno to obtain the torque curve published by the manufacturer. The latter is obtained on an engine dyno at a steady state! For instance, the engine is brought to 1600 rpm, then it is tested how much 'braking' it overcomes, the number gets recorded. Then it is brought to 1700 rpm, then 1800 etc. all the way up to redline. The increments may differ, but when the resulting numbers are put on a graph it looks perfectly smooth, linear and angular. Yes, it looks so because it is obtained from egine dyno testing at a steady state!

The only way you may get maximum engine torque at 1800 rpm in the car is in top gear and full throttle starting at 1000 rpm trying to climb the Eiffel Tower. In other words, it would never happen!

[Boss330]

Originally Posted by JoeFromPA

Yes but it doesn't mean we sitting here are interpreting it correctly. Does that mean the MAHA dyno assumes a >25% drivetrain loss on a RWD platform and that is accurate? Cause that's how I'm reading that dyno. And why is torque already pre-calculated at flywheel levels? Is it reading it at the wheels and then increasing it to account for a 25% loss at peak levels?

I have no further info on the MAHA apart from that the numbers are according to European standard 80/1269 and that the MAHA is the preferred dyno for manufacturers and type approval authorities. Meaning that the calculations done by the MAHA dyno is approved and used to verify manufacturers power claims. I'm sure that manufacturers would protest if the type approval authorities used equipment that provides false numbers...

[JRV]

Originally Posted by Boss330

The dyno reads metric numbers, not imperial. It's only if you use ft.lbs and hp that the curves cross at 5250rpm.

Ahh yes, thx for catching that.