M5 dyno day!!!!!!!!!!!!
#21
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I also believe you need a large fan in the front to generate the cooling needed for max power, apparently the engine will protect itself if there is not enough air flow. See number 9 at the bottom of this link.
http://dinancars.com/whitepapersFile.asp?ID=6
They go into detail on the next page:
http://dinancars.com/whitepapersFile.asp?ID=8
Now that's a fan...
http://dinancars.com/whitepapersFile.asp?ID=6
They go into detail on the next page:
http://dinancars.com/whitepapersFile.asp?ID=8
Now that's a fan...
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Originally Posted by Centurion' post='247903' date='Mar 1 2006, 01:28 PM
Is 15% a sort of rule-of-thumb?
If so, these cars are dynoing (is that a word
) just slightly less than where they're suppose to.
If so, these cars are dynoing (is that a word
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I just spoke to one of the dyno guys here in Cincinnati. They run a Dynojet dyno. He said that an independant rear suspension car with a manual transmission will run 17-19% loss through the wheels. An automatic will run 21-23%, and a really good auto with a lockup converter will have 19-20% loss. These guys are talking about facts based on dyno results on the same cars, measuring rwhp on a rolling dyno, then removing the engine and measuring flywheel HP. A Mustang with a solid rear axle will lose 17%, and that's the best they've seen. The reason the independant rear axles lose more is because any joint in the drivetrain will reduce power because of friction.
So, you're registering 415 rwhp on an M5, and let's say they've done an fantastic job of reducing losses and are at 17%. That means your flywheel HP is 415/.83 = 500 HP. If you're running a 19% loss, your flywheel HP is 415/.81 = 512 HP. Let's say you're at 18%, so your HP with filter in is 415/.82 = 506 HP. With filters removed, you are at 425/.82 = 518 HP.
The other problem we have is that we can't run the car in 6th gear (closest to a 1:1 ratio) since the speed limiter will kick in. If the testing is done in a lower gear, say 4th, the HP will be slightly lower, and the torque could be slightly higher, but only by a percent or so. The other question I have is what octane gas were you running? You'll lose 10-15 HP running 91 octane instead of the recommended 94. If you're running 93, you'll probably lose a few HP, but not much.
If the dyno people know what they're doing, the numbers should all be SAE corrected for relative humidity, air temperature, and absolute pressure. There shouldn't be more than a few percent difference between runs with the same car on different days.
#23
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The other question I have is what octane gas were you running? You'll lose 10-15 HP running 91 octane instead of the recommended 94. If you're running 93, you'll probably lose a few HP, but not much.
Who sells 94 octane?
Who sells 94 octane?
#24
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Does one of those black M5's have an additional M badge added under the front grills by the radiator???? I could be seeing things but if I'm seeing correctly, why? Does he have a V10 badge under the grills on the side too? Really poor taste in my opinion. But who am I to say anyway????
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Originally Posted by wolverine' post='248476' date='Mar 2 2006, 10:15 AM
I just spoke to one of the dyno guys here in Cincinnati. They run a Dynojet dyno. He said that an independant rear suspension car with a manual transmission will run 17-19% loss through the wheels. An automatic will run 21-23%, and a really good auto with a lockup converter will have 19-20% loss. These guys are talking about facts based on dyno results on the same cars, measuring rwhp on a rolling dyno, then removing the engine and measuring flywheel HP. A Mustang with a solid rear axle will lose 17%, and that's the best they've seen. The reason the independant rear axles lose more is because any joint in the drivetrain will reduce power because of friction.
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Originally Posted by MichiganM5' post='248537' date='Mar 2 2006, 11:19 AM
The other question I have is what octane gas were you running? You'll lose 10-15 HP running 91 octane instead of the recommended 94. If you're running 93, you'll probably lose a few HP, but not much.
Who sells 94 octane?
Who sells 94 octane?
#27
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This is the very reason that Porsche is able to keep up with cars with much more horsepower. The further away from the drivetrain the engine is the more HP lost in getting the power to the wheels. Porsche with the engine in the rear has reduced their HP loss at the wheels be putting the power plant directly where the power is going. I read an interesting article about this a few weeks ago. I am shocked at the amount of loss to the wheels on the M5. I would expect it to be much better at the wheels.
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This is the very reason that Porsche is able to keep up with cars with much more horsepower. The further away from the drivetrain the engine is the more HP lost in getting the power to the wheels. Porsche with the engine in the rear has reduced their HP loss at the wheels be putting the power plant directly where the power is going. I read an interesting article about this a few weeks ago. I am shocked at the amount of loss to the wheels on the M5. I would expect it to be much better at the wheels.
#29
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Originally Posted by poleposition' post='248579' date='Mar 2 2006, 09:34 AM
Does one of those black M5's have an additional M badge added under the front grills by the radiator???? I could be seeing things but if I'm seeing correctly, why? Does he have a V10 badge under the grills on the side too? Really poor taste in my opinion. But who am I to say anyway???? ![Big Grin](https://5series.net/forums/images/smilies/imported/biggrin.gif)
![Big Grin](https://5series.net/forums/images/smilies/imported/biggrin.gif)
All the cars were running 93 octane.
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