Help me understand, I am old school drag racer:

My M5 ran a trap speed of 118 mph, 500 hp, 4,125 lbs.

Now, "general rule" is you need 10 hp for every 100 lbs.

997tt weighs 3,500/ 600 lbs less but 20 hp less.

So, you would need 60 more HP (600lbs) - 20 HP (it's 500hp not 480) to make them even.

Total needed for M5 is 40 HP to make it even for a stock 997

Now the 997 Traps at 118-119 mph stock under good conditions...Say 119 mph..whatever. Why is this so slow for a weight to hp difference of 40 hp?

Why do THE TUNNERS that give you 79-90 hp only trap 2 MPH more at 121 mph? With 90 HP chip, it should trap 127-128 mph...AT LEAST 125 mph with JUST ECU and Headers and Exhaust/Cats should be 130 mph.

I know I am not nuts, the math is the math.. Please help explain to me...

Thank you,

I understand what you are getting at here and some ET vs MPH numbers that I have seen with other cars dont always translate directly to the Porsche platform. The only conclusion I can come up with is how the power is delivered. I know MPH tells most of the story about the power of a specific car, but I also know how power is delivered and RPM also plays a role as well. We have done some pretty extensive testing of our various performance systems on the drag strip. The baseline numbers that we got for a 100% stock 997TT was 12.27 sec. @ 117 mph. This was in AZ in less than ideal conditions. We continued to test each level of performance and the data is attached below in a pdf document.

We did see an 8 MPH increase between the baseline run and our 997TT with software, headers and exhaust. We had almost an 11 MPH difference with our EVT620. At this time, back in 2007, this EVT620 was the fastest 997TT in the 1/4 mile and the first 997TT to break into the 10's. I hope this information is helpful.

were the 1/4 mile times and traps on pump gas or race gas?

but great table explaining the differences

Most all of them were conducted on ~93 octane. In the AZ heat, testing on the track with 91 octane is worthless. We have found that on power levels up to ~ 600, there is not a huge difference in power from 93 octane to pure race fuel.

Another Example is the GT-R. on a 30 mph roll race..it's dead even until 120 mph. That is when the Stock 997tt pulls past. So the GT-R is just as fast in the 1/4 mile. Same HP, GT-R was about 300-400 lbs heavier given my extra passenger and 1/2 tank more than the GTR. I would have expected the GT-R to be a little slower prior to the higher speeds.

There is a lot more than weight and HP at play here. Not everything can boil down to weight and HP. During the heated debates of the 911 versus the GT-R, how many times did we hear Porsche owners cry "how can a 3800 lbs car with the same HP be as fast as my 911." Delivery of power, transmission efficiency, aerodynamics, driver skill, gear ratios...while the GT-R traps the same as the 911, it is over 10 seconds slower to 186mph. Sooner or later weight and HP will play a role, but in a short run, there are a lot of other factors that need to be looked at.

Gear ratio played a important role in 1/4 mile.

It is only 1/4 mile, longer race would show you the difference.

Some cars are designed to be fast in low speed while some are

better at high speed.

For one the times will be a lot different considering your M5 picks up harder down the track and gets its speed. Whereas the 997 gets speed from the jump due to AWD.