Within the past month I've begun to look at the NASA TT classification system and trying to work out where the M2 would fit. NASA TX has a very competitive TT3 group and I had been hoping to
not be in it. TL;DR Looks like I'll be in TT3. Shit.
NASA uses a weight to horsepower ratio for classification. They take the base number and have modifiers on top of that that can add or subtract to that number. My hope was the weight of the M2 would offset its power, then with no aero and a street tire, I could squeak by in TT4. TT3 requires you to be above 10:1 with modifiers and TT4 is 12:1.
For power, the car has to do 3 pulls on a dynojet with SAE correction and smoothness level of 5. This ideally gives a relatively good comparison vehicle to vehicle. I figured this is where I should start and took the car to a local shop to get it dynoed.
Results look pretty healthy to me. This is a stock S55 with an Akrapovic Evo system. I find it pretty amazing how consistent all the pulls are with only the torque dropping off a little. For NASA's classing system, they use a calculated average HP which for me came out to
387avg hp. I previously had the car weighed and corner balanced with 165lbs of driver ballast and nearly a full tank of fuel, it came out to
3705lbs.
At that weight and power, that's a baseline of
9.6:1 lbs per HP. Here's how, best I can tell, the modifiers calculate out:
- +1 for running RE-71RS
- + .3for a tire that should measure less than 282mm
- + .4 for a car that is 3601lbs or more
- + .4 for BTM or no aero
- - .5 for factory DCT transmission
All of this brings me to a modified lbs to HP of
11.2:1 which is not great. NASA seems to favor 2 things—Hoosiers and aero, neither of which I'm going to have immediately, and heavily disadvantage the DCT and power. The rules around aero appear relaxed, so a large splitter and swan-neck wing are penalized as much as some basic OEM+ style pieces. All of this is apparent in the cars at the pointy end of the field—detuned Corvettes and M3s that run large splitters and wings on hoosiers. Of course have good drivers as well.
My next steps are clear. I've got to get the car weighed and corner balanced again and see how much weight I may be able to drop. I'll continue to look for a trunk lid to put my CS Racing wing on—it's likely to help a little bit but won't be nearly as effective as the larger wings on many of the cars. I've also been wanting to either make or find a true splitter that, even if just flat, goes to the front axle. Mostly, I'll try to get to both of the remaining NASA events and just drive the car and see where I land—I've already got some fresh RE-71RS sitting in the garage.