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Re: Gear selection challange

To: Keith Turk <kturk@ala.net>
Subject: Re: Gear selection challange
From: William T Smith <WmTSmith@landracing.com>
Date: Sun, 24 Jun 2001 18:25:43 -0600 (MDT)
KT, 
What RPM peak Torque and how much
how much peak Torque at max power
With these two and your trans and RA ratios we can get 
this done and I bet it will not be in OD and I am just 
guessing ! wmts



Quoting Keith Turk <kturk@ala.net>:

> Thought I would share the joy's of running a 9" Vs a 
quick change....
> 
> I have been waiting on a dyno sheet to start 
selecting the right gear for
> speedweek..... keep in mind I have the axle's out and 
the Driveshaft out so
> it's an easy time to swap them out.
> 
> The motor makes it Peak power at 8300rpm ( correction 
from previous post )
> So we are looking to spin it around 8600rpm or so....
> 
> we have 3.25 gears as well as 3.07's..... and three 
sets of tires ranging
> from 26" .... 27".... and 28"
> 
> There are Two ways to play this game mathmatically... 
both of which are
> accurate and can cross check each other.....
> 
> 1.  Finding MPH
> 
> Rpm X tire height in Inches  divided by 336... 
divided by the gear...
> 
> for example.... 8500rpm X 26" = 221000 divided by 336 
= 657.73 divided by
> 3.25 = 202mph   then we could pitch the Overdrive 
into the fray by dividing
> that 202mph by the .91 OD which would give us an 
output speed of 222.393
> mph...... this just happens to be 3mph faster then 
the current record in
> the
> class.
> 
> 2.  Finding  Rpm
> 
> MPH X Gear ratio X 336  divided by tire hieght in 
inches
> 
> for example.... 225mph X 3.25 X 336 = 245700  divided 
by 26" tire = 9450
> rpm
> Obviously a bit much till we X it by the OD of .91 
which is 9450 X .91 =
> 8599.5 rpm
> 
> So that gets you through the Gas record..... we want 
to consider the Fuel
> record as well.... as that is where are best chances 
are with a Motor
> designed to run on Nitrous Oxide.   the record is 
230mph in that class...
> 
> Here is the challange ... come up with the best 
combinations and the
> reason's why..... I think I have already decided how 
we are going to do it
> and Beleive it or not the example I just gave isn't 
the best combination in
> my Humble opinion..... thou it's not a bad choice.... 
it just might not be
> the BEST choice as there are other things to 
consider .... such as Drag
> associated with running in OD and the Tire size/ 
wheel bearing speed.
> 
> I'll Give fella that comes up with the best choice a 
So-Al T-shirt...
> 
> Keith
> 
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