P31 DYNO
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Note to both of you, please be sure to bring a USB drive so you can take home the runfiles! I'd love to add them to my database of local C63s. I've got five cars so far.
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C63 AMG
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Not true for a C63. 5th gear is 1:1 and the gear you want to use on the dyno. If the car is not tuned and/or has a speed limiter, you'll need to use 4th gear to avoid hitting the speed limiter at the top of the pull.
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blilley18 - Congrats, very strong numbers. Thanks for posting the info from your dad's dyno session.
It is nice to see some P31 dyno results and these are the first I have seen. It will be nice to see more results as they become available.
cek, I hope that you make it to CarbConn and that they can make room for you.
Oh, I see they can take you! Good luck and have fun.
It is nice to see some P31 dyno results and these are the first I have seen. It will be nice to see more results as they become available.
cek, I hope that you make it to CarbConn and that they can make room for you.
Oh, I see they can take you! Good luck and have fun.
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Not to ruin anyones posts but here we have already a huge difference on numbers. One P31 car doing 425whp and 382lb-ft and another one doing 419whp/ 429lb-ft. We are talking about 47lb-ft difference
Last edited by C63newdude; Jul 17, 2010 at 06:29 PM.
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And, our car was running at 85-90 degrees outside. Also, we had to take a 120 mile drive to get there. The altitude is unknown to me, but in the Portland area I am thinking the elevation was around 200 feet too.
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If the dyno was done in 80 degree plus conditions the SAE correction should make the output HIGHER not lower.
The uncorrected numbers would be low and corrected numbers high
IE 379/359 corrected to SAE 402/382
SAE would take the dyno to the pressure of a column of air at 60F and zero feet elevation.
Not trying to create drama , simply saw your post listing the likely air temps which would certainly impact the uncorrected numbers
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I'm guessing it has something to do with the way PSI has their TQ calculations set. (TQ isn't really measured on a Dynojet, it is calculated based on HP).
In looking at a few of their other dyno videos, the TQ is coming in higher than what is considered common. (E.g. E60 M5 dyno)
I'd like to get a hold of the runfiles to see if there is anything obvious.
In looking at a few of their other dyno videos, the TQ is coming in higher than what is considered common. (E.g. E60 M5 dyno)
I'd like to get a hold of the runfiles to see if there is anything obvious.
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juice, corrected #'s are lower, not higher. super, all dynos measure torque using this~>horsepower = torque * rpm / 5252
below 5252 rpm, torque will always be more than horsepower, at 5252 rpm they will be equal, and above 5252 rpm torque will be less. a dyno never measures horsepower; it can only measure torque and then uses the above formula to get horsepower.
below 5252 rpm, torque will always be more than horsepower, at 5252 rpm they will be equal, and above 5252 rpm torque will be less. a dyno never measures horsepower; it can only measure torque and then uses the above formula to get horsepower.
Last edited by gOt BoOsT; Jul 17, 2010 at 10:56 PM.
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I don't know about that mthis. Because of the C63's engine running at a higher average temperature than that of other engines and the factor that in AMG mode that you are not suppose to give it full throttle until around the oil is around 190 degrees it might run better at higher temps. We should check this with some dyno run. And remember, me and my dad had to take a 120 mile drive to get up there. That might have made the engine run better.
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I don't know about that mthis. Because of the C63's engine running at a higher average temperature than that of other engines and the factor that in AMG mode that you are not suppose to give it full throttle until around the oil is around 190 degrees it might run better at higher temps. We should check this with some dyno run. And remember, me and my dad had to take a 120 mile drive to get up there. That might have made the engine run better.
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You've got some of the right data, but not the whole story.
Here's a snippet (below) stolen from a great dyno comparison article that simplifies the measurement/calculation on a Dynojet. On a Dynojet, RPM isn't part of the horsepower measurement/calculation. In fact, I've made several runs with out the tach sensor hooked up. When this happens there is no torque reading.
Power in mechanical terms is the ability to accomplish a specified amount of work in a given amount of time. By definition, one horsepower is equal to applying a 550 pound force through a distance of 1 foot in one second. In real terms, it would take 1 HP to raise a 550 pound weight up 1 foot in 1 second. So to measure horsepower, we need to know force (in pounds) and velocity (in feet per second). Dynojet's inertial dynamometer measures power according to the terms just described. It measures velocity directly by measuring the time it takes to rotate two heavy steel drums one turn. It measures force at the surface of the drum by indirectly measuring it's acceleration. Acceleration is simply the difference in velocity at the surface of the drums from one revolution to the next. The force applied to the drums is calculated from acceleration using Newton's 2nd law, Force = Mass * Acceleration. Since the mass of the drums is know and acceleration has been measured, Power (horsepower) can now be calculated. Torque is then calculated using the horsepower number: Torque = Horsepower * 5252 / RPM.
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I don't know about that mthis. Because of the C63's engine running at a higher average temperature than that of other engines and the factor that in AMG mode that you are not suppose to give it full throttle until around the oil is around 190 degrees it might run better at higher temps. We should check this with some dyno run. And remember, me and my dad had to take a 120 mile drive to get up there. That might have made the engine run better.
I hope you're kidding...
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Check out the other P31 dyno post (Dyno Results :: Baseline Without Charcoal etc) as I think those results are more accurate than ours. HP figures between the two dynos are similar (420+ RWHP) so that may be a good average for P31's.
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For what it's worth my car made alot more TQ then HP on Dyno dynamic and he stop before 6k 433rwhp and 461rwtq
Ps to me Dyno numbers are just Dyno numbers. I seen my car on alot of diff dynos and all the people that run my car get diff numbers. Even on dynojet.
One guy figured out that the more fans we use the more power we make and I'm talking about 30-40rw diff.
Ps to me Dyno numbers are just Dyno numbers. I seen my car on alot of diff dynos and all the people that run my car get diff numbers. Even on dynojet.
One guy figured out that the more fans we use the more power we make and I'm talking about 30-40rw diff.
Last edited by mthis; Jul 18, 2010 at 12:07 PM.
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You need to do a bit more research.
You've got some of the right data, but not the whole story.
Here's a snippet (below) stolen from a great dyno comparison article that simplifies the measurement/calculation on a Dynojet. On a Dynojet, RPM isn't part of the horsepower measurement/calculation. In fact, I've made several runs with out the tach sensor hooked up. When this happens there is no torque reading.
You've got some of the right data, but not the whole story.
Here's a snippet (below) stolen from a great dyno comparison article that simplifies the measurement/calculation on a Dynojet. On a Dynojet, RPM isn't part of the horsepower measurement/calculation. In fact, I've made several runs with out the tach sensor hooked up. When this happens there is no torque reading.
Power in mechanical terms is the ability to accomplish a specified amount of work in a given amount of time. By definition, one horsepower is equal to applying a 550 pound force through a distance of 1 foot in one second. In real terms, it would take 1 HP to raise a 550 pound weight up 1 foot in 1 second. So to measure horsepower, we need to know force (in pounds) and velocity (in feet per second). Dynojet's inertial dynamometer measures power according to the terms just described. It measures velocity directly by measuring the time it takes to rotate two heavy steel drums one turn. It measures force at the surface of the drum by indirectly measuring it's acceleration. Acceleration is simply the difference in velocity at the surface of the drums from one revolution to the next. The force applied to the drums is calculated from acceleration using Newton's 2nd law, Force = Mass * Acceleration. Since the mass of the drums is know and acceleration has been measured, Power (horsepower) can now be calculated. Torque is then calculated using the horsepower number: Torque = Horsepower * 5252 / RPM.
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Here's another explanation, from Bristol Dyno that backs up the first data point I made.
Force = Mass x Acceleration
That's one of Newton's laws. It's not important which one it is, because I don't remember. Force is one of the things that we're looking for. Force in the automotive world is called - you're supposed to shout it out..... torque. Torque is rotational force, and its most common unit for us is foot-pounds. Plain and simple, if you have a 12-inch wrench and you lean on the very end of the handle with 10 pounds, you're applying a force of 10 ft-lb. to the nut you're trying to turn.
The mass in our case gets a bit complicated. Mass in most cases is easy - how much does the object weigh that you're accelerating. In the case of the dyno drums, however, it's not that simple because we are not "moving" the drum, we're spinning it. We are not creating a "translational" motion on the drum, we are creating a "rotational" motion. To understand the difference, think of the actual dyno drums. Each one weighs 2700 pounds. It would take a pretty impressive force to push a 2700 lb. object across the floor. Now imagine just spinning those drums. The shaft going through the center of the drums rests on two hugely expensive bearings that I'm probably going to have to replace a lot more often than I want to. The drums spin with the slightest touch. To calculate away this difference, physicists came up with the "mass equivalent" of a rotating body, which is very similar to the "moment of inertia." I don't know the actual numbers, but let's just pretend the mass equivalent of the dyno drum is 50 pounds. That means that spinning the 2700 lb. drum is like pushing a 50 lb. weight across the floor (forget about the friction - you nerd.) Now I've heard some people say that this is not the correct way for calculating horsepower, but in this case - it is. Many of you are familiar with the hp = rpm x torque / 5252 formula. In many situations, that formula is the way horsepower is calculated. In the case of the Dynojet dynamometer, it is not. The Dynojet calculates horsepower even if there is no torque reading, and it does this in the manner that I am in the process of describing. Those of you that have had your vehicles tested at my shop and have watched the computer screen closely have seen that the computer plots out only the horsepower after each run, and I have to click the mouse a few times to get your torque. It does this because sometimes there is no torque reading, or the torque reading is faulty. This can happen because inductive and optical rpm pickups may not be perfect, and/or your ignition system may make things go a little haywire. If the rpm readings are not perfect, and the computer used the rpm x torque / 5252 formula, the hp reading would be inaccurate.
The mass in our case gets a bit complicated. Mass in most cases is easy - how much does the object weigh that you're accelerating. In the case of the dyno drums, however, it's not that simple because we are not "moving" the drum, we're spinning it. We are not creating a "translational" motion on the drum, we are creating a "rotational" motion. To understand the difference, think of the actual dyno drums. Each one weighs 2700 pounds. It would take a pretty impressive force to push a 2700 lb. object across the floor. Now imagine just spinning those drums. The shaft going through the center of the drums rests on two hugely expensive bearings that I'm probably going to have to replace a lot more often than I want to. The drums spin with the slightest touch. To calculate away this difference, physicists came up with the "mass equivalent" of a rotating body, which is very similar to the "moment of inertia." I don't know the actual numbers, but let's just pretend the mass equivalent of the dyno drum is 50 pounds. That means that spinning the 2700 lb. drum is like pushing a 50 lb. weight across the floor (forget about the friction - you nerd.) Now I've heard some people say that this is not the correct way for calculating horsepower, but in this case - it is. Many of you are familiar with the hp = rpm x torque / 5252 formula. In many situations, that formula is the way horsepower is calculated. In the case of the Dynojet dynamometer, it is not. The Dynojet calculates horsepower even if there is no torque reading, and it does this in the manner that I am in the process of describing. Those of you that have had your vehicles tested at my shop and have watched the computer screen closely have seen that the computer plots out only the horsepower after each run, and I have to click the mouse a few times to get your torque. It does this because sometimes there is no torque reading, or the torque reading is faulty. This can happen because inductive and optical rpm pickups may not be perfect, and/or your ignition system may make things go a little haywire. If the rpm readings are not perfect, and the computer used the rpm x torque / 5252 formula, the hp reading would be inaccurate.
