Well in the copy you sent back in your reply the letters after 8500 seem to be
goofy. They did have the new rpm if you made the shift at 8500 rpm. The torque
will come out close to what you have as the rpm goes down the torque goes up. It
is all full throttle stuff. I use Ft/lbs at the rear wheel to do the gear
splits.. HP is a calculated # torque is what the parts really see.
Dave
William T Smith wrote:
>
> 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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