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 8500=5313
3 1.4 .7 X 8500=5950
4 1.1 .785 X 8500=6673
5 1.0 .91 X 8500=7735
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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