Power to weight calculation question

[BigKeyserSoze]

I feel stupid having to ask this but I will anyhow.

 

I have a Factory Five Roadster. If I run a 275 DOT tire with a competition weight of 2650 and no other adjustments, what is my power to weight allowed to be? I think it is either 8.5 or 8.9.

 

I see a +.4 adjustemnt for the tires and a -.6 adjustment for being at 2650 pounds or less. That yields a -.2 but I do not understand if I add that number or subtratct it from the 8.7 baseline.

 

The real question I have is what is my max HP. At 8.9 I believe 2650 pounds will allow me to run 297.75 at the rear wheels. At 8.5 it would be 311.76 at the wheels.

 

Please help so I feel less stupid. Thanks.

[Greg G.]

I feel stupid having to ask this but I will anyhow.

 

I have a Factory Five Roadster. If I run a 275 DOT tire with a competition weight of 2650 and no other adjustments, what is my power to weight allowed to be? I think it is either 8.5 or 8.9.

 

I see a +.4 adjustemnt for the tires and a -.6 adjustment for being at 2650 pounds or less. That yields a -.2 but I do not understand if I add that number or subtratct it from the 8.7 baseline.

 

The real question I have is what is my max HP. At 8.9 I believe 2650 pounds will allow me to run 297.75 at the rear wheels. At 8.5 it would be 311.76 at the wheels.

 

Please help so I feel less stupid. Thanks.

 

First, you are going to want to run the car at 2651 lbs if you are really right at 2650 lbs. That will allow you to have a slightly higher hp because there is only a -.55 hit instead of -.6.

 

So, assuming the minimum weight is 2651 lbs, then you can figure out your max hp as follows:

 

8.7 - .4 (tires) + .55 = 8.85

2651/8.85 = 299 rwhp

 

The check on this is:

2651/299 = 8.87 + .4 -.55 = 8.72