I got involved in a discussion with an S2K owner about my car...this is what I showed him. I find here on Honda-tech and elsewhere not too many people know about this stuff and get confused when it comes to gear ratios (shorter is better, LS transmissions suck etc).

Here's a dyno as of yesterday. LS Turbo-8psi 2" Downpipe, 2.25" Exhaust w/Cat, w/ AC, PS, Cruise



"198 ft lbs to wheels peak around 5300 rpm - transmissions only see torque
2725 lbs curb weight

GSR transmission in my car
4.40 Final drive
1st 3.230 - 4.40x3.23x198 = 2813 ft lbs of propulsion being sent to drivewheels
2nd 1.900 - 4.40x1.90x198 =1655 ft lbs
3rd 1.360 - 4.40x1.36x198 = 1184 ft lbs
4th 1.034 - 4.40x1.034x198 = 900 ft lbs
5th 0.787 - 4.40x0.787x198 = 685 ft lbs

S2kTransmission 99-03 S2000 - about 130 ft lbs to the wheels around 6600rpm plus or minus 5 ft lbs
Curb weight 2835 lbs.

4.100 Final drive
1st 3.12 - 4.1x3.12x130=1662 ft lbs
2nd 2.05 - 4.1x2.05x130=1092 ft lbs
3rd 1.480 -4.1x1.48x130=788 ft lbs
4th 1.160 -4.1x1.16x130=618 ft lbs
5th 0.970 -4.1x0.970x130=517 ft lbs
6th 0.810 -4.1x0.819x130= 436 ft lbs


Of course there's TONS of other factors involved...but you can see the affect of torque output through gear reduction and torque multiplication... mind you, i'm well aware that my torque curve is NOT flat...so at lower and higher rpms, the tq output isnt as near the peak output. Whereas, in any Honda NA setup, torque curves are rather flat, even in VTEC."

 

Well the math comes out fine, but the result is of no use.

You will accelerate proportional to net power being produced. Shorter gearing results in more wheel torque, so you get through the rpm range quicker; however the top of that rpm range is shorter in terms of car speed. In the end, area under the power curve vs speed will be very similar for two cars with (relatively close, but) different final drives; but when specific applications arise, there is usually gear ratio optimisation to be made.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by string &raquo;</TD></TR><TR><TD CLASS="quote">Well the math comes out fine, but the result is of no use.

You will accelerate proportional to net power being produced. Shorter gearing results in more wheel torque, so you get through the rpm range quicker; however the top of that rpm range is shorter in terms of car speed. In the end, area under the power curve vs speed will be very similar for two cars with (relatively close, but) different final drives; but when specific applications arise, there is usually gear ratio optimisation to be made.</TD></TR></TABLE>

Hmmm I didnt have time to do a whole spreadsheet of data..but yes I only concentrated on the peak outputs. Do u have a spreadsheet that does the proportional rate of acceleration?

 

the thing you want to do though, is pick a speed to where you're not going to be accelerating beyond. so for drag racers they want to barely top out 4th before finishing.

i'm surprised that the s2k has a 4.1 final drive. that's way low IMO. esp with the taller tires and higher redline.

 

Your numbers are right IF the power can be applied to the pavement without clutch slippage or wheel spin.

Thats wear the S2K has a definite advantage due to weight transfer. WHile it has less tq in first gear, it's able to apply most of it, you'd just be spinning at the mercy of your tires slip coef...........

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mista Bone &raquo;</TD></TR><TR><TD CLASS="quote">Your numbers are right IF the power can be applied to the pavement without clutch slippage or wheel spin.

Thats wear the S2K has a definite advantage due to weight transfer. WHile it has less tq in first gear, it's able to apply most of it, you'd just be spinning at the mercy of your tires slip coef...........

</TD></TR></TABLE>

of course