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Gears, Gear Ratio And Acceleration


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Hi Im making a racing game for the XBox, I need some info on the following Gears, Gear Ratio and Acceleration, basically I want to know how a real car moves, if you are insteasted in testing the PC version then let me know

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i have the gear ratio's and acceleration and gear speeds for the ceilca.

I can measure the G-Force the car make in any gear..how much distance it covers in what gear, how long it takes and so on..

Let me know mate..

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I hope this will help, this is for a Canadian Echo with the C150 transmission and the 1.5L engine with 108 hp.

1st 3.545 to 1

2nd 1.904 to 1

3rd 1.310 to 1

4th 0.969 to 1

5th 0.815 to 1

reverse 3.250 to 1

Differential gear ratio is 3.526 to1.

The echo runs a 8.7 0 -60 mph.

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basically i need to computer(XBox) to do the calculations, so i need a formular, doesnt look easy it might be


 Ã(ù)Ggk     1  
F  =  ------------  –  crrmg  –  --  cdAñv2,  where  
 r     2  
F  =  net force acting on the car (N)  
Ã(ù)  =  torque function of the engine given an engine speed ù in s-1 (Nm)  
G  =  final drive ratio (no unit)  
gk  =  k-th gear ratio (no unit)  
r  =  radius of tire (m)  
crr  =  rolling resistance coefficient (no unit)  
m  =  mass of the car (kg)  
g  =  gravity (ms-2)  
cd  =  drag (air resistance) coefficient (no unit)  
A  =  frontal area of the car (m2)  
ñ  =  density of air (kgm-3)  
v  =  velocity of car (ms-1)  


v = 2ðrù/Ggk, where v  =  velocity of the car (ms-1)  
r  =  radius of tire (m)  
ù  =  engine speed in rotations per second (s-1)  
G  =  final drive ratio (no unit)  
gk  =  k-th gear ratio (no unit)  

forulars are a bit messed up on this forum

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heres the formular

speed=(radius of tyre*RPM*2*Pi*3.6)/(60*final ratio*gear ratio)

my algebra is not that good, i need to re arrange it to find RPM

so RPM=...

also revs going up is not constant, what affects the revs, what i mean how quickly does it got from 1200RPM to 6000RPM,(i dont think i will know this until i re arrange the formular)

is idle 1200RPM on most cars, my CDX is about 600RPM(when hot) 1300RPM when cold

I need to get the formulars working 1st before i have the ratios, ill let you know

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i'll help you to the end mate..

I know all the figures you need for the formula so it shouldn't be a problem.

I can send you a graph showing the acceleration though the gears.. I haven't managed to finish 6th yet because it does 140Mph in 5th.. I ran out of track (cough***cough)

The idle is 800Rpm but the graph starts @ 4K Rpm due to the launch point in 1st.

Heres the gear speeds. Sorry for the way it comes out. The HTML won't work on here.

RPM 1st Gear 2nd Gear 3rd Gear 4th Gear 5th Gear 6th Gear Reverse

800 4.03 6.22 8.61 10.94 13.93 15.65 3.92

1000 5.04 7.78 10.77 13.67 17.41 19.56 4.91

2000 10.07 15.56 21.53 27.35 34.81 39.13 9.81

3000 15.11 23.33 32.30 41.02 52.22 58.69 14.72

4000 20.14 31.11 43.06 54.70 69.63 78.26 19.62

5000 25.18 38.89 53.83 68.37 87.03 97.82 24.53

6000 30.22 46.67 64.60 82.05 104.44 117.38 29.44

6200 31.22 48.22 66.75 84.78 107.92 121.30 30.42

7000 35.25 54.45 75.36 95.72 121.85 136.95 34.34

8000 40.29 62.22 86.13 109.40 139.26 156.51 39.25

8200 41.30 63.78 88.28 112.13 142.74 160.43 40.23

8400 42.30 65.33 90.44 114.87 146.22 164.34 41.21

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  • 3 weeks later...

Good luck, and I'll happily test a PC version!

The formula can be rearranged so that:-

RPM = (Speed x 60 x Final Ratio x Gear Ratio) / (Tyre Radius x 2 x Pi x 3.6)

or (simplified slightly by dividing the 60 by 2)

RPM = (Speed x 30 x Final Ratio x Gear Ratio) / (Tyre Radius x Pi x 3.6)

I know that that Engineering degree would be some use after all!



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