This is a modified repost of another one that I just made on another guy's thread. I have redone the numbers to work with Brian's situation here. This should be a much more accurate way to really get our crank hp numbers, especially those of us who know what our car put down on a dyno stock, as Brian here does.

I'm not trying to be a know it all here. But I want to suggest a different way of computation, that I think is actually the right way. Guesses at driveline loss, etc, are much more ambiguous and vague.

Givens:

You have to have a given as to what a car made at the wheels STOCK. 305.4 here.
Also, we will assume that 355 was the ACTUAL HP at the crank. In other words, we'll assume Porsche to be 100% correct.
We'll assume that there's no accuracy lost in the dyno from stock measurement to modded measurement, including environment or using different dynos .

Here's how you set up the math.

In prose layout, it goes:
"Stock rear wheel horsepower is to stock engine horsepower as modded rear wheel horsepower is to modded engine horsepower." Simple enough. This assumes a steady rate driveline loss.

So it is set up like this:

305.2/355 = 352/X

Work this out and you get that you now have 409.2 crank hp. A gain of 54.2hp (wow).

EDIT: I'm sure you all know how to work this out, but in case you're a bit rusty on algebra, you cross multiply... the bottom of one side times the top of the other, both ways. Then, you divide both of those numbers (here, 124,960 and 305.4(x)) by the number beside the x (here, 305.4). So, 124,960 divided by 305.4=409.2.

This equation removes the need for an assumed multiplier and makes it all based on your car's actual performance numbers (again, assuming Porsche was spot on with the 355).

Didn't change much with Brian's formula. The multiplier that you guys have all been using assumes that our cars all put out 304.72rwhp. Mine put out 308.2, so this would more significantly throw off the rest of my computations. And hey, those are expensive numbers, right? Very valuable!

 

Great number! Nice looking car also. Does Cargraphic sold the wings alone? how much?

 

Yes they do. I don't remember how much. I have a Cargraphic GT2 wing (which includes the deck lid) for sale. It's not the same one that you inquired about just now, but I thought I'd answer at least your first question immediately at least... Here's a pic of mine. I have more if you or anyone is interested. Just PM me. The uprights are raw carbon.

 

Grats on the numbers and beutiful car and mods. Since your in the area, I gotta see the car. Lets schedule a meet sometime soon!

 

Nice results, thanks for posting em up!

 

Awesome looking car. Glad you chose Softronic! Shameless plug - http://www.vividracing.com/catalog/softronic-m-390.html

 

I believe my sport cup wing was 3k... It has the carbon fiber uprights like Jared's as well and it is adjustable to modify downforce!

 

Mine made 317 rwhp stock, so either I have a good bit more than 355 or you guys had less. Either way, estimating crank HP after mods is a pointless exercise.

 

Thanks for letting us know.

 

410hp, sweet! How does it feel?

 

If you haven't added it already you should consider adding the center radiator.

I have it and it lowers my Oil temps, they run 10-20degrees less during hard running.

Not sure if it adds HP or not but it can't hurt and is relatively inexpensive at $200.

Yesterday afternoon (high 90's high humidity) I was running with a couple of Lambo's, Ford GT, Ferrari F360, Porsche Turbo 996, and Porsche 997 GT3 RS.

I never felt underpowered and my mods are very similar to yours.

 

Great looking car. Nice mods!