Okay look, I know I will get beaten up over this because it has probably been argued over time and again. My question is this, what is the breakdown of bhp to crank hp? What is the figure most generally accepted for hp loss from the crank to the wheels. For anyone who has been following my story or had known me since I joined this fine group, I recently was informed my car is finally ready to pick up (going on Friday). On top of this RUF told me they looked through the records and could find nothing in the records here so they called Germany and BINGO they found it. It turns out that someone bought my car brand new and called RUF, who then flew over a few techs and they popped a RUF 550 conversion kit in.(this was before there was a RUF in Dallas) So now I have a freshly rebuilt engine with a fresh clutch to boot. On the RUF website and on the phone they tell me the car has 550 BHP, so how much does that mean the engine is actually making?

I see all over the forum that these engines are good to between 7-800 hp. It sounds like this engine is about at its limit before other mods would need to be made. (don't worry I plan on stopping with what I have) When I bought the car I knew very little about Porsche's, and since I have continued to learn about the brand, and am very glad I made the decision and that I was able to call my wife on the promise she made me. Some throw the newbie a bone and help me understand as much as you care to explain about the whole HP topic and how it losses HP between the wheels.

 

BHP or Brake horsepower is Crank horsepower. Our AWD cars typically have 18-20% driveline loss making YOUR car approx. 450 wheel hp.

 

Happy Veterans day. I'm happy to hear you are getting her back. I guess what you are asking is what is the diff between crank and whp? Well, it's debated, but 6 speeds lose around 15-20% and Tips lose as much as 25% to the wheels. Hope this helps and others will step in I'm sure. Have fun bro.

 

thanks guys. I appreciate it. Yeah I am just trying to figure out how much hp this car is making. If you look at the RUF site, it shows a graph for torque and hp, it might be difficult to understand, to the point some might think the upgrade is hp at the wheels, or is that correct, the graph is showing hp at the wheels?

http://www.racperformance.com/index.aspx?id=996-turbo

Let me know what you think. These guys at RUF are good guys, and I won't slam them a bit, they could have given me the shank and charged me out the rear, but they have gone out of their way to help me out and save me cash. I know I have seen a few posts about them that weren't great but all I can say about them is good stuff.

 

FYI,

The Ruf RT12 650 (997TT bodywork and aero) went about 189 mph in a standing mile
which is/was similar to several cars on this forum. They declare 650 minimum crank HP on their engine dyno at Ruf, Phaffenhausen. It is a 3.8 litre making a lazy 650 HP.

MK

 

RUF always quotes thier hp numbers at the crank (i.e., "BHP"). The dyno graph posted at the link above is an engine dyno (measures at the crank), not a chassis dyno (which measures HP at the wheels).

As has been said, your car is probably putting down around 450 to the wheels (considering 18% drivetrain loss), which is all that matters.

 

I believe RUF quotes metric hp or PS which is slightly less than imperial hp which we use in the USA. Thus 550 PS = Approx 542 HP (crank) as you would quote in the US. That would still be around 450 whp.