Dave,
I don't understand Point 2
How can the wheel power be close to the same as you go
up the gear shifts when your mechanical advantage drops
so much with each shift. Is it because you dont have to
use full throtle to get the RPMs?
Also what were you giving an example of when your put
the trans ratios. what were the .625 .7 .785 was this
the percentage of total torque reflect by the part
throttle?
Quoting Dave Dahlgren <ddahlgren@snet.net>:
> Wide or close ratio has a lot to due with the power
curve of your engine.
> there
> have to be a bunch of e-mails about this in the past
too as i remember the
> discussion well. i was the guy with no clue about
what really works(at
> least the
> was the opinion of the old salts as i remember it
anyway). When i work on
> gear
> splits what i try to do is this.
> Launch the car as quickly as possible so as to not
waste any track length
> at the
> start.
> each gear change should result in 3 things happening
if possible and less
> important in the lower gears.
> The first and most important is that the new gear
selected is still above
> the
> torque peak of the engine. This is so if you have
trouble making the gear
> change
> or have to peddle the car and lose some RPM you are
falling back into the
> peak
> and not away from it. This will insure that you will
hopefully have the
> power to
> pull the next gear if there is a problem.
>
> The second is to have the new gear selected to have
the same amount of
> ft/lbs on
> the rear tires as the previous one. You can do this
if you have a dyno
> sheet for
> the engine. This will ensure 2 things happening.
first you will not have
> any
> problem pulling the next gear up as the power at the
wheels is the same as
> it
> was. second you will not shock the tires and lose
traction.
>
> To do this right depends on the torque curve of the
engine and whether it
> has
> nitrous or not and when you turn the nitrous on if it
has it.
>
> For a typical N/A car with 300 inches i would shoot
for 5 or 6 gears.
> something like
> assuming peak power at 8000 rpm
> 1 3.2
> 2 2.0 .625 X 8500S13
> 3 1.4 .7 X 8500Y50
> 4 1.1 .785 X 8500f73
> 5 1.0 .91 X 8500w35
> with this you should be in 5 'th about 1/4 mile
before the mile of interest
> and exit that mile at 8500 to 8800 rpm..
>
> My opinion and your mileage may vary.
>
>
> Bill & Dee Bennett wrote:
> >
> > Ok somebody explain to me why with having a longer
distance to run at
> > Bonneville using a close ratio transmission is
better. I realize that
> you
> > might experience to low a drop in rpm in the gear
changes using a wide
> > ratio. Is this the reason why or is it something
else. I would have
> thought
> > the 6 speed would be a good choice for the salt
given the ability to
> space
> > the ratios over 5 speeds and using 6th for
overdrive. If close ratios are
> > what are needed why not the something similar to
the old style Doug Nash
> > tranny with 5th being 1:1 and no overdrive. If
horsepower lose is the
> deal,
> > I don't think that matters to a few as already
stated over the past few
> > weeks. It seems to be no problem building the power
it is getting the
> > traction to use it.
> >
> > Bill
>
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