Dyno Errors?
 

Ok, so check out this thread:

http://forums.pelicanparts.com/porsche-911-technical-forum/64638-dyno-experts-please-stand-up.html?highlight=dyno

In this thread, it is claimed that torque and HP are always equal at 5252 RPM. From the dyno results I've seen, this is not the case? On the C2Turbo site, there are many that are off...

What gives?

-Wayne

Wayne, the crossing will be at 5250 only if torque is shown in ft.lbs and power is shown in horsepower, and the x axis is RPM. If these are the units used, and the crossing doesn't happen at 5250, then there is an error in the data.

-Doug Clauder

Then there must be an error in all of the sheets that I have seen?

-Wayne

I have a dyno sheet that shows the "proper" hp, torque line crossover at ~5200 rpms (check the sheet on my P. Parts page below)

Best,

Kurt

They are equal at 5252 rpm just as Doug says if the units are correct.

Here is a tech article from Elephant Racing's newsletter that digs into the relationship between HP and torque. It gives the dirt on the 5252 number and why it is so.

http://www.elephantracing.com/techtopic/hpvstorque.htm

The equation is HP=TQ*RPM/5252, thus at 5252 rpm, HP=TQ*5252/5252, thus HP=TQ. Most dyno's measure one number and calculate the other from the above equation, so there shouldn't be any strange errors in the charts. Make sure you closely observe that the torque numbers corresponding to the HP curve are in lb-ft, and that they are using the same scale. Sometimes dynojet charts are scaled differently for HP and torque, for instance the left hand side of the chart will show a range of 0-400 for HP, but the right hand torque range for the chart will be scaled 0-600 lb-ft. This is done many times with cars that have a huge torque peak, but don't produce so much HP.

Brad