is it true that the more power you try to put down, the more drive train loss you will experience? and also with most AWD systems inside the transfer casing you can disconnect the front wheels from spinning and dyno the rear wheels? thanks fellas.

 

I've heard that with a viscious coupling unit you can dyno one set of wheels.

 

What about the power theory?

 

Wouldnt you be dynoing the front wheels?

 

obviously, you wouldn't have as much drivetrain loss, and you would be sending all of the power through one set of half shafts or your rear drivetrain...

I would not dyno-tune my car this way imo.

 

Drivetrain losses are usually expressed as a percentage, so the more power you have the more you will lose.

As an example: assuming 20% lost through the drivetrain a car that made 200hp at the crank would see 160hp to the wheels (a loss of 40hp). While a car with 400hp at the crank would see 320hp (a loss of 80hp). The second car did lose more power, but it still made more.

The drivetrain loss percentage does differ from car to car though. For most AWD cars you'd disconnect the driveshaft and dyno on the front wheels. Much less work than trying to disconnect the fronts, but like VR-4ever said you really wouldn't want to do this. Going to an AWD dyno would be a much better solution.

 

AWD to RWD Right click, save as

For DSM's going to dyno, most of them use a welded center diff's, with that done you can remove the transfer case and eliminate the rear driveshaft.

Another option is a Viscous Coupling Eliminator, basically just eliminates any power to the transfer case.

As for something in the transfer case to remove, only thing i could imagine is taking out the shaft to it, but why not just elimnate the viscous, much easier

 

Yeah, all you have to do is get a ballpark figure of your powertrain loss in your particular vehicle, it all varies from powertrain to powertrain of different vehicles. Eng pretty much hit the nail on the head.

 

i know this isn't what you're asking but wrx AWD drivetrain loss is around 22-25%

 

Also Audi/VW/Volvo/Seat/Bugatti/Ford(Euro models *Freestyle and 500*)/Mercury Montego all use the HALDEX sytem

When coupled to a manual transmission is typically 15-17% driveline loss. Which is very low for AWD setup.