Dyno Results

[edlms]

Here's the charts.
The mech changed up at 8250 (not 8400).

I'm not very mech/tech minded, and my reason for doing this dyno is to form the basis for my future mods.

As per my other thread on the GruppeM CAI and Exhaust, I've been advised to let the mods bed down for around 500km before doing another dyno test to show the improvements to HP and Torque (if any).

Cheers

Update - there appears to be a modest increase of 7bhp (at peak) and around 5-18bhp across the rev range.


ps didn't get the printout for hp at the wheels... sorry.

cheers

[gorun]

Is that good, bad or about right? All these dynos are different and the they come up with 3 or 4 power readings. Just cant make sense of it...

[SS32]

Beautiful! Look at that torque curve...I love it. I'm glad someone is taking the initiative to do a base line and then more after the mods are installed.

[lucid]

Originally Posted by gorun

Is that good, bad or about right? All these dynos are different and the they come up with 3 or 4 power readings. Just cant make sense of it...

The torque readings are pretty much in line with the results reported by RRI (see thread):

http://www.m3post.com/forums/showthread.php?t=136529

Download the detailed spreadsheet in PS and Kgm units and read the values from the Corrected Power and Corrected Torque columns, which take pressure and temp differences into account. Then compare those numbers to the corrected figures on the posted output sheet. You'll see:

Corrected Wheel Torque/Total Reduction:
RRI: 37.3 Kgm @3911 rpm
OP: 37.2 Kgm @3965 rpm

If you compare the wheel torque/total reduction readings over the entire rev range, they are in agreement, so I am assuming the OP's chart does not factor in any transmission losses for the torque reading.

However, there is something funky with the power figures. As you can see in the dissipated power reading, they are factoring in a %10 loss to "guess" engine power. If we bypass the engine reading, and just apply the temp and hum correction factor to get the standardize power reading from the 325.3hp figure, we get 335.8 peak hp.

Corrected Wheel Power:
RRI: 374.3 @7518 rpm
OP: 335.8 @7570 rpm

I don't understand why the wt numbers agree, but whp don't. I guess the wt numbers also include the 10% loss factor. In which case, the OP's numbers are about 10% off in general, which can be explained by:

1. RRI uses a hub dyno, whereas the OP used rollers.
2. OP's run was not close to steady-state (I don't know enough about the specifics of dyno run methodology to judge if a 5.8 sec run constitutes steady-state in this case).
3. Instrument differences.

[KINGLEH]

im still waiting for some dynojet results.....


we have one where i work.... but i dont have my M yet.....


i will be on the dyno the day mine rolls off the lot... then after brake in... then after each mod.....

[southlight]

Originally Posted by KINGLEH

i will be on the dyno the day mine rolls off the lot... then after brake in... then after each mod.....

That'll make you member of the year. I wouldn't dyno a car before break-in completed though.


Best regards, south

[KINGLEH]

i have a specific break in i do to all my new motors.... to seat the rings.... takes about a hour.. then a oil change..... then im easy on all the other parts that need to be broken in.. the tranny.. dif and such..... but dyno pull isnt hard on any of that stuff....


you can also brake in a motor on the dyno... ive done this over 10 times.... every one showing good reliability and very strong power....

[edlms]

Lucid - thanks for analysis. i don't fully comprehend the intricacies of dyno runs and the readings but you've enlightened me a fair bit, especially the differences between RRI's data and mine.

hope to see some HP improvements when i do my next dyno...

cheers

[PencilGeek]

Originally Posted by southlight

That'll make you member of the year. I wouldn't dyno a car before break-in completed though.


Best regards, south

I've always been curious how street car break-in differs from race motor break-in. I worked in the racing industry for a few years in my youth (still friends with all those guys) and we had a 1000hp Dyno. Whether street or racing motor, we broke them in on the dyno. According to us, the dyno was the best way to break it in because you could vary the load and run at different RPMs. Technically, a motor was broken-in when the rings were seated -- which is determined by pulling the spark plugs and looking into the cylinders with an endoscope. If the cylinders and pistons were dry (no oil), the motor was broken-in. Then we'd change the initial oil, and do the power runs. Same on street or racing motors.

So I've always wondered why a break-in needed to be 1200 miles -- when it could be as quickly as a few hours.

/PG

[PencilGeek]

Originally Posted by KINGLEH

i have a specific break in i do to all my new motors.... to seat the rings.... takes about a hour.. then a oil change..... then im easy on all the other parts that need to be broken in.. the tranny.. dif and such..... but dyno pull isnt hard on any of that stuff....


you can also brake in a motor on the dyno... ive done this over 10 times.... every one showing good reliability and very strong power....

LOL...I didn't read this before I wrote my response.

Ditto.

[PencilGeek]

Originally Posted by edlms

Lucid - thanks for analysis. i don't fully comprehend the intricacies of dyno runs and the readings but you've enlightened me a fair bit, especially the differences between RRI's data and mine.

hope to see some HP improvements when i do my next dyno...

cheers

So these were baseline figures -- not including the exhaust?

/PG

[ChitownM3]

Guys, the HP is lower than other dynoes because whoever dynoed the car let off before 8000 rpm. Looks like they let off around 7750 rpm. Doesn't this car make its peak HP at 8300 rpm?!?!?

[PencilGeek]

Originally Posted by ChitownM3

Guys, the HP is lower than other dynoes because whoever dynoed the car let off before 8000 rpm. Looks like they let off around 7750 rpm. Doesn't this car make its peak HP at 8300 rpm?!?!?

According to the dyno chart, it had already reached max HP around 7600. There's no point in going up to 8300 when you're already on the downswing.

/PG

[ChitownM3]

Originally Posted by PencilGeek

According to the dyno chart, it had already reached max HP around 7600. There's no point in going up to 8300 when you're already on the downswing.

/PG

If you look at the actual chart, it's obvious the throttle was cut at 7600 rpms, thats why the max was reached there. Look at the actual chart.

[PencilGeek]

Originally Posted by ChitownM3

If you look at the actual chart, it's obvious the throttle was cut at 7600 rpms, thats why the max was reached there. Look at the actual chart.

How can you tell the throttle was cut? That's not the way you dyno something on a motor dyno (vs. chassis dyno). I've been present for approximately 100 motor dyno tests. Granted, I've only witnessed a few chassis dyno runs...and therefore know much less about them...but the process was exactly the same when I saw it being done.

On a motor dyno, all power runs are performed at full throttle. You apply more load to the motor until the RPM reduces to the desired measurement point (2000, 3000, 4000, etc.). Once the RPM is at the desired location, you take the TQ/HP measurement and store it. Change the load, to the next desired RPM, take another reading. Continue this process through the entire RPM range until you find max HP; go a little beyond that...and call it a day. Since HP is a direct function of TQ and RPM, there's no point in pushing the motor much beyond the point where you found max HP.

/PG

[lucid]

Originally Posted by ChitownM3

Guys, the HP is lower than other dynoes because whoever dynoed the car let off before 8000 rpm. Looks like they let off around 7750 rpm. Doesn't this car make its peak HP at 8300 rpm?!?!?

Look at the charts from RRI. They have max hp at the wheels @7821 rpm. The max power at the crank could be achieved at a higher rpm, but the transmission losses go up with engine speed, so if the crank gains are very small between 7821 and 8300, the tranmission losses could trump them, and you see what these charts tell us at the wheels.

[lucid]

Originally Posted by PencilGeek

On a motor dyno, all power runs are performed at full throttle. You apply more load to the motor until the RPM reduces to the desired measurement point (2000, 3000, 4000, etc.). Once the RPM is at the desired location, you take the TQ/HP measurement and store it. Change the load, to the next desired RPM, take another reading. Continue this process through the entire RPM range until you find max HP; go a little beyond that...and call it a day. Since HP is a direct function of TQ and RPM, there's no point in pushing the motor much beyond the point where you found max HP.

That seems to be the description of a steady-state test. How long would that normally take? Not sure if they did that here. Note the acceleration time of 5.8 sec noted at the bottom of the sheet?

[ChitownM3]

Doesn't make sense to me. I thought drivetrain loss was just a percentage, so if the engine makes its peak power at 8300rpm then it should also make its peak power to the wheels at 8300rpm. I did take a look at the RRI graphs and it does seem like power drops off at 8k rpm. But if you look at the OP's graph, the graph reaches its peak and then drops substantially leading me to believe they let off on the gas. I think the HP coulda gone up quite a bit more if they went up to 8300rpm.

[lucid]

Originally Posted by ChitownM3

Doesn't make sense to me. I thought drivetrain loss was just a percentage, so if the engine makes its peak power at 8300rpm then it should also make its peak power to the wheels at 8300rpm. I did take a look at the RRI graphs and it does seem like power drops off at 8k rpm. But if you look at the OP's graph, the graph reaches its peak and then drops substantially leading me to believe they let off on the gas. I think the HP coulda gone up quite a bit more if they went up to 8300rpm.

Percentage implies a linear relationship between engine speed and loss. That is an approximation. I doubt that it is perfectly linear. At higher engine speeds lubricants behave differently (more heat to be dissipated), and friction losses most likely do not scale up linearly. I don't know this for sure though.

The power in the RRI tests peak around 7821 rpms--not at 8000 rpms.

It is possible that this was an acceleration test and they let go off the gas a bit too early. It would be good to have a few more data points after the peak to verify that the peak has indeed been experienced.

[lucid]

Originally Posted by PencilGeek

I've always been curious how street car break-in differs from race motor break-in. I worked in the racing industry for a few years in my youth (still friends with all those guys) and we had a 1000hp Dyno. Whether street or racing motor, we broke them in on the dyno. According to us, the dyno was the best way to break it in because you could vary the load and run at different RPMs. Technically, a motor was broken-in when the rings were seated -- which is determined by pulling the spark plugs and looking into the cylinders with an endoscope. If the cylinders and pistons were dry (no oil), the motor was broken-in. Then we'd change the initial oil, and do the power runs. Same on street or racing motors.

So I've always wondered why a break-in needed to be 1200 miles -- when it could be as quickly as a few hours.

1. In the dyno break-in scenario you've outlined, things are tightly controlled and monitored/measured by competent people. There is no way your average consumer can do that properly driving around on the roads. And if they make a mistake, the whole engine can be trashed.
2. Other parts of the drivetrain need to be broken-in as well, which can't be done on an engine dyno.
3. Race engines are for racing. Meaning, they are designed and built differently, and have a significantly different life expectation than passenger cars.

[08AWM3]

That red line is the reason I bought this car. Nice dyno.

[PencilGeek]

Originally Posted by lucid

1. In the dyno break-in scenario you've outlined, things are tightly controlled and monitored/measured by competent people. There is no way your average consumer can do that properly driving around on the roads. And if they make a mistake, the whole engine can be trashed.
2. Other parts of the drivetrain need to be broken-in as well, which can't be done on an engine dyno.
3. Race engines are for racing. Meaning, they are designed and built differently, and have a significantly different life expectation than passenger cars.

We all agree that street and racing motors are different. I guess I was making two other points, and probably worded it poorly.
1. On the dyno, we broke in street and racing motors the same. Same methodology.
2. Whether street or racing, we considered the motor broken in when the rings were seated properly -- as witnessed when you stick an endoscope down the cylinder and take a look.

Of course other drive train components need to be broken in as well. That's why I chose my words very carefully by only discussing the break in of the motor.

/PG