Since getting my MCS I've felt that its speedmeter seems to indicate that its going faster than it actually is. i.e. it tells me I'm doing 80 when I'm not really whipping past the other cars on the road. Anyway, to cut a long story short I decided to try and measure speeds in gears. I found that my speedo (and digital) read 70 at the top (i.e. 6,750) RPM in 2nd Gear (and before anyone freaks out, yes the car is run in).

So, doing a little math (please laugh uncontrollably if this is completely wrong):

Rim size - 17"
Tire size 205/45r17 - I understand the 45 to mean the ratio between the tire width (i.e. 205mm) and the sidewall is 0.45, so this makes the total outside diameter of the tire - 17+(2*CONVERT(205/1000,"m","in&quot) = 24.26".
Multiplying this by pi to get the circumference shows that one rotation of the wheel should move the car 76.23".

So working from the gear ratios - 2nd - 2.62:1, Final 2.74:1 we can determine that at 6,750 RPM the axel rotates at (6,750/2.62)/2.74 = 940.27 RPM.

So at the top of 2nd, the car should move 940.27 * 76.27 inches/minute, or 67.87 MPH.

If my math is close to correct, it looks like my speedo is pretty close.

So, question: is there any tech data published that shows what the top speed in each gear is supposed to be?

The real question: why am I such a sad geek that I put this calculation together in the first place????

 

Have you considered getting a hobby of some sort?

 

maddog,
I have such a bad head cold, that looking at your post makes my head throb! All of those numbers.....makes me want to sleep....24piu5nbgr v [forehead smashes into keyboard]

 

You could also use mile markers to determine if your speedo is right. Time yourself over a one mile stretch of highway at 60 mph. If it's right, it should take exactly one minute to cover one mile.

You really shouldn't be doing math without Trippy's oversight.

 

6-Speed Manual Transmission

Below are maximum speeds in gear calculated for 17" wheels---ADD about 0.6MPH [1.0KPH] for 16" wheels.

Gear RPM MPH
1.....................6750...............42.6
2.....................6750...............67.9
3.....................6750...............90.3
4.....................6750..............110.5
5.....................6750..............133.1
6....................(5500).............(135)

((RPM/Gear Ratio) * Wheel Circumference In Feet)*(Minutes Per Hour / Feet Per Mile)

 

So the car would do 150 if it had the horsepower and ecu limiter removed!! Only 5500rpm @ 135

 

I thought i would get some lite reading

HMMM so what does it take to get 150mph out of the MCS....a steep mountain

 

A GPS would be a better way of checking your speed.
Handheld or other. Good Luck