So I've been reading through hundreds of posts on this forum to familiarize myself with the 911 Turbo and often, I see people posting about modding their car and others asking if the 550-hp or 605hp was at the wheel or crank.

What does this mean and which one is ideal and why?

Thanks.

 

Crank hp=how much power the engine is producing.

Wheel hp=how much power is being put to the wheels/tires.

Crank hp will always be higher than wheel hp.

 

There is a loss of power from what the engine produces to what reaches the wheels. In reading, I think most would say there's a loss of anywhere between 10 - 15% power mainly due to friction. Some opinions may differ, but you get the point.

 

Thanks guys. That helps.

 

No machine is perfect. When you are moving energy—there is always some type of loss. These losses can be due to friction, heat, mechanical and aerodynamic resistance ect. In the olden days---only Manufacturers had dyno’s. They would use them for engine development. These were machines that measured power right at the crank of the engine.
As time wore on, people wanted to measure their own HP. Obviously it’s not practical to remove an engine to see if an air box gives 5hp. So a need developed and was filled by machines that measure Power at the wheels. As you may imagine, if you measure an engines power at the crank—you may get 100hp…..now when that power has to go through a torque converter, it loses some energy to friction and heat…..then as it makes the gears in the tranny turn---It loses a little more….a little more when it goes through the transfer case and a little more is lost to actually turn the wheels. So when you finally measure at the wheel; your 100hp is now only 82hp. Different cars lose different amounts depending on the efficiency of their drive trains. The “general rule” is …

Standard 2 wheel drive car= ~90%
Automatic 2 wheel drive car= ~85%
Standard 4 wheel drive car= ~82%
Automatic 4 wheel drive car=~78%

 

That's very detailed and very helpful. Muchos thanks.

 

banned???

 

Is it a new record?