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      11-11-2008, 02:56 PM   #8
Got Track!!!!!!
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Drives: 08 M3 coupe
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Originally Posted by PencilGeek View Post
Let's not do this again please. I don't think you could be more wrong about how Dynapack works. When it's so easy to use the internet to do a little research, go to their web site, read how it works, it makes me wonder why or how this type of nonsense continues to propogate itself.

So, for the 20th time, here's how a Dynapack works. The Dynapack works on the EXACT same principle as a real motor dyno. It applies a hydraulic load onto the hubs to load the motor DOWN to whatever RPM you want to measure. It reads the torque at that RPM. The torque sensors are accurate to 1/10th of a foot-pound over the entire life of the product. Since there are no wheels to slip, no friction to maintain, no "smoothing functions" to select in the output screen, and the hubs attach directly to the hydraulic loader, there is no inaccuracy, no voodoo-magic, no F=M*A guestimates to infer horsepower based on mass and acceleration like you do with your intertial dynos. The Dynapack doesn't "read high" -- it reads accurate -- just like a real motor dyno.

You say the Dynapack "reads high" because it typically shows a 9-11% loss from crankshaft to hubs. But the roller dyno's read accurate when they show a 20-25% loss between crank and wheels. If a 20-25% friction loss were actually occurring, it would generate enough heat to boil the transmission oil and melt the gears. So what on earth makes you think these dynos -- that you swear by -- are even remotely accurate? Why wouldn't you trust a dyno that uses the exact same principle as a real motor dyno and is accurate to 1/10th of a foot-pound of torque?
Whoa there guy! I could careless what dyno is better at what.. What I posted is just my opinion, take it with a grain of salt, everyone here is grown up enough to make their own conclusions.. As far as the Dynpack i yet to find a competent operator to give me some decent #'s.. Both Dynapack I have been too have recorded 75-150 hp higher, so go figure where my optimism is coming from.

Thats why i always go to the track, to see if my "Dyno numbers" are true..
Your trap speed does not lie no matter how crapy a driver you are.

I also never posted anything about any dyno being accurate

I will keep your post in mind in the event I ever decide do go back and do a pull on a Dynapack.