QUIZ for you 996 Experts

Who can provide the following data for a 2002 996 manual (no aerokits)? 1. Gear Ratios for each of the six gears 2. Final Drive Ratio 3. Rolling Circumference of the Wheel (stock wheels) [m] 4. cdA Aerodynamic Drag [N/m2] 5. Rolling Resistance [N/m2] 6. Vehicle Mass (stock wet -- or dry if nothing else is avaiable) [kg] Thanks.

I can, but it'll cost ya! I'll take your BBS wheels as payment.

Here is 1. & 2.: General data Manual transmission G 96/00 and 01 Transmission ratios Z2 : Z1 = i 1st gear -- 11 : 42 = 3.82 2nd gear -- 20 : 44 = 2.20 3rd gear -- 31 : 47 = 1.52 4th gear -- 37 : 45 = 1.22 5th gear -- 41 : 42 = 1.02 6th gear -- 44 : 37 = 0.84 Reverse gear -- 11 : 39 = 3.55 Final drive Hypoid bevel gear drive with 12 mm offset Transmission ratio, final drive -- 9 : 31 = 3.44 3. 17" wheels were stock - 18" option. Would also be somewhat dependant on tires. 4. Coefficient of drag (Cd) 0.34 5. ? 6. Coupe curb weight: 2,959 lb./1,3450 kg. 5 out of 6 -- what do I win?

If you had gotten all 6 out of 6 the first time, I would have given you my car Since you gave me five out of six, drinks are on me when I head out to San Fran in June for business. Sound good to you?

OK, I just noticed that the answer to three was not complete (drinks are still on me), so, anyone, Bueller, anyone? I still need 3. Rolling Circumference of the Wheel (stock 18" rims PLUS tires) [in meters] 5. Rolling Resistance [N/m2] Thanks.

TD If you check the Tire Rack wesbite, you will find listed the revolutions per mile of just about any tire that will fit a 996 regardless of wheel size. Just follow the prompts and spec your car and tire. From the Revs/mile and a little algebra, you can calculate the effective rolling radius with enough accuracy for whatever you're needing. For help, rolling circumference = "PIE" x 2 x rolling radius. My usual consultancy charges will be posted to your Rennlist account. Cheers,

Hey Fred, the Tire Rack tip was great. The average revolutions per mile of the average of my front and rear tires is 830. Since there are 1609 meters per mile, this would suggest that the rolling circumfrence is 1.938, no? I mean, why would I need to make any further calculations? (although a rolling circumference of 1.938 meters seems pretty long).

1.973M for the 285/30/18 2.001M for the 225/40/18

TD, what the heck are you trying to figure out, anyway?

I was waiting patiently for this question. I have a data logger, a DL-1. It comes with default values, but I wanted to reprocess my data with the correct values for my car. I had found some values, but not others, and I wanted to see if everyone else had the same values. I am only missing one now (the rolling resistance), and I have no idea how to find the right number. BTW, the data is pretty cool. I am using trackvision software to overlay the data on my video, so you can watch both simultaneously. Maybe I will post it when I finish. So SRL, what's the answer?

Loren... Hail to the chief!!

I freely admit that I have no idea! (I think that may be an internet forum first! )

i have a feeling that Cw is way out from 0.34 964 had 0.32, 996 3.4 0.31, and i have a feeling that 996 3.6L is 0.30 or 0.29 0.34 get closer to turbos Cws.....930-965-993tt etc... please correct me if i am wrong

My data came from the MY2003 Press Release - Technical Specification MY03 Coupe and Cab - Coefficient of drag (Cd) -- 0.34 MY03 C4S and Turbo - Coefficient of drag (Cd) -- 0.31 MY03 GT3 - Coefficient of drag (Cd) -- 0.30 MY03 Boxster - Coefficient of drag (Cd) -- 0.31 MY03 Boxster S - Coefficient of drag (Cd) -- 0.32 interesting enough (since some are different) is the MY04 press info MY04 Coupe and Cab - Coefficient of drag (Cd) -- 0.30 MY04 C4S - Coefficient of drag (Cd) -- 0.30 MY04 GT3 - Coefficient of drag (Cd) -- 0.30 MY04 Turbo - Coefficient of drag (Cd) -- 0.31 MY04 Boxster - Coefficient of drag (Cd) -- 0.31 MY04 Boxster S - Coefficient of drag (Cd) -- 0.32 MY04 Carrera GT - Coefficient of drag (Cd) -- 0.39 MY04 Cayenne S and Turbo - Coefficient of drag (Cd) -- 0.39 I don't make these up they are "as published".

[QUOTE=TD in DC I am using trackvision software to overlay the data on my video, so you can watch both simultaneously. Maybe I will post it when I finish. [/QUOTE] Please do!