Re: Speed Application

["Marc A. Brown" <Mad_One@email.msn.com>]

Here are some more formulas:

HP = (Torque * rpm)/5250
Torque at output shaft = Torque * gear ratio
rpm1/gear1=rpm2/gear2, or rpm2=rpm1(gear2/gear1)

The last two formulas are the key in figuring correct shift points.  What
the last formula is figuring is where your output shaft speed is equal in
different gears using rpms and gear ratios.  I.E., it can show you where
your rpms will be when you shift from one gear to another dependent on the
rpms you shift at.  You can use the formula to compare gear 1 to 2, 2 to 3,
etc.  You must know the torque curve of your car though.

Also, the gear ratios on the 02A tranny are different for VR6s prior to
1997.

1994 - 1996 Ratios:
1st     3.300
2nd    1.944
3rd    1.308
4th    1.034
5th    0.838
FD    3.389
RV    3.060




-----Original Message-----
From: Adam Lindsay <adam@mindex.com>
To: GTI <gti-vr6@dev.tivoli.com>; jettaglx@igtc.com <jettaglx@igtc.com>
Date: Thursday, October 15, 1998 2:35 PM
Subject: Speed Application


>OKay....follow me here for a minute. I want to write an application that
>takes into account as many possible variables and calculates a realative
>distance, speed of a car run. Such an application could show prime shift
>points and speeds to expect at certain RPMs in certain Gears. I have some
>formulas now to get speed but I reliezied that Torque and Weight must be a
>contributing factor. Does anyone have these formulas laying around or know
>where I could get them.
>
>I know that there are some many factors that play into account that I could
>possible ever write an app that was perfect. The color of shirt affects how
>fast you can go. =} But I want to see how close I can get.
>
>This is what I have so far.
>
>MPH = (RPM * TireDiameter)/(Gear Ratio * 1000)
>TireDiameter = ((Section Width * Aspect Ratio)/25.4) * 2 + RIM
>Gear Ratio
>1    3.78
>2    2.12
>3    1.46
>4    1.03
>5    .84
>R    3.80
>F    3.39
>
>so sample
>205/50 R15 at 3000RPM in 3rd gear on a Jetta GLX
>
>TD = (205 * .50)/25.4 * 2 + 15
>TD = 23.08"
>MPH = (3000 * 23.08)/1.46 * 1000
>MPH = 47.4
>Real World showed pretty close results.
>
>But I want to study acceleration. So I need more formulas.
>
>