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      06-21-2011, 03:23 AM   #1
Mahmood07
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E92 M3 on Dyno Dynamics

So I got my car on a dyno last week to get a baseline reading before i do any tuning/cat delete. I am new to this, and it's the first time I got my car dyno'd. The only performance mods I have are Eisenmann Race Muffler and MS air filter running on 93 Octane.

The dyno was a 'Dyno Dynamics', and from what I hear, it reads lower than other dynos but is more accurate with flywheel torque(?). Anyways, here are the graphs, but I think they should have been stretched more to show the complete line:

Best run out of 3: 336whp, 325 ftlb
Temp: 64 F
Humidity: 64%









Can anyone tell me why the torque seems to be high? do the numbers seem right?
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Last edited by Mahmood07; 06-21-2011 at 03:34 AM.
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      06-21-2011, 03:48 AM   #2
Rshane
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The hp sounds right, but the torque is too high...only rated 295 at the flywheel...no way you would make 325lb/ft at the wheels.

Are you sure you didn't get a tuned 335i by mistake

Actually, after looking more closely at the second graph, your peak torque doesn't actually come in until around 4000rpm which shows just under 225lb/ft...which is about right.

I think there was some kind of error where it shows 325lb/ft @ 2800rpm then it suddenly dropped as the rpms climbed. Also, the first graph shows the torque holding about level the whole way across...it should peak at around 4000rpm and level off, not drop suddenly like the second graph shows. THey also dıdnīt take the motor up to 8400 RPM.

Something wasn't done right. But then agaın, I am far from an expert on dynos. Lıkely some of the folks here wıth the green user IDīs wıll chıme ın.
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Last edited by Rshane; 06-21-2011 at 08:15 AM.
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      06-21-2011, 05:02 AM   #3
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RPM Calibration is totally off. That's why the torque is wrong.

A complete waste of time baseline.
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      06-21-2011, 05:32 AM   #4
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Right. Should cross at 5250. Instead they cross at 6400. As a result, the dyno plot is inaccurate. Maybe the underlying data is correct in the computer and the dyno plot could be recalculated and printed. Ask the dyno shop.
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      06-21-2011, 06:19 AM   #5
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The crossing of the lines has nothing to do with anything. That changes as you change the scaling for the torque and power.

The graphs will only cross at 5250rpm if the scaling on each side is the same.

The problem is that the RPM calibration is totally wrong. So, if the engine is being revved to 8400rpm, it's showing as 7 thousands something.

The only thing you can do is to ignore torque and looks at road speed on the X -Axis for comparisons.

The power figure will be correct, but the torque wrong.
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      06-21-2011, 10:28 AM   #6
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Ya the HP sounds right but not the torque. Thanks Sal.
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      06-21-2011, 10:32 AM   #7
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Quote:
Originally Posted by Sal@Evolve View Post
The crossing of the lines has nothing to do with anything. That changes as you change the scaling for the torque and power.

The graphs will only cross at 5250rpm if the scaling on each side is the same.

The problem is that the RPM calibration is totally wrong. So, if the engine is being revved to 8400rpm, it's showing as 7 thousands something.

The only thing you can do is to ignore torque and looks at road speed on the X -Axis for comparisons.

The power figure will be correct, but the torque wrong.
Scaling for horsepower and torque appear to my eyes to be about the same. Maybe the torque scale is a few percent down from the power scale -- the hash marks don't quite line up with the numbers on the torque side.
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      06-21-2011, 01:08 PM   #8
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Quote:
Originally Posted by Sal@Evolve View Post
The crossing of the lines has nothing to do with anything. That changes as you change the scaling for the torque and power.

The graphs will only cross at 5250rpm if the scaling on each side is the same.

The problem is that the RPM calibration is totally wrong. So, if the engine is being revved to 8400rpm, it's showing as 7 thousands something.

The only thing you can do is to ignore torque and looks at road speed on the X -Axis for comparisons.

The power figure will be correct, but the torque wrong.
Huh? Horsepower is measured by torque at a given RPM. Therefore torque and horsepower should always cross at 5250.
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      06-21-2011, 06:50 PM   #9
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Quote:
Originally Posted by Muffnbluff View Post
Huh? Horsepower is measured by torque at a given RPM. Therefore torque and horsepower should always cross at 5250.
On a brake dyno HP is measured!! Then the RPM is used to calculate torque.

You are thinking of an intertia dyno.

Scaling of the graphs has to be the same for both torque and HP to get the graphs to cross 5250rpm.
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      06-21-2011, 06:52 PM   #10
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Graph scaling is not equally set on both sides.

One is -40 to 400 while the other is -20 to 400.

Of course the graphs cannot cross at 5250.

If the operator changes the scaling to 0-400 on both sides (or any scaling as long as it's the same) the HP and torque will cross at 5250.

A simple concept.
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