First Generation Firebird-L Mailing List
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Bob,
You've got to ask what they're doing with the transmissions. In drag
racing, it
can be an advantage to having fewer gears to shift, as each shift slows
the car
down as the engine leaves it's peak torque and horsepower point. But in
order
to utilize the 2 speed, the engine must have a sufficiently wide power
band to cover
only 2 forward speeds.
In street driving, the additional forward gears allow for a more
comfortable driving
experience. You won't taxing the engine quite so hard as you accelerate
to any
desired speed.
>I have heard stories of taking the 300 automatic to 120 miles per hour
by locking it in first gear.
I'm sure it's possible. Especially if you have a very tall rear gear
ratio. But what is the
point going 120 in first gear?
>I alss would like to know what the advantages are in using factory 3
speed transmission
>verses the 4 speed, if any?
I don't have a lot of drag racing experience, but I understand that in
some cases, many racers
report only getting to 3rd gear before crossing the last light at the
end of the run. This is
due in large part to the particular combination of rear gearing and how
quickly the car
moves through the gears through the quarter mile. So if you don't use
4th gear by the end
of the race, why have a 4 speed?
All 2 and 3 speed autos, and 3 and 4 speed manuals have a top gear ratio
of 1:1. So the
fewer gears between first and last mean that each gear in between must
have wider
spacing to bridge the gap. Torque producing Pontiacs, big blocks of all
makes, have
very wide power bands compared to say a Chevy 302 Z28 engine, and thus
can take
advantage of fewer gears, and fewer shifts in a drag race. Small
displacement engines
have more narrow power bands and work better with closer ratio
transmissions, needing
more gears.
But again, street driving is different. You aren't always driving at
WOT unless you're
Bjorn ;). So the additional gears allow for good acceleration, economy,
and less
engine wear. This explains why modern muscle cars often have two overdriven
gears in their manual transmissions. And many manufacturers are going
to 5, 6,
and even 7 speed automatics. Fewer gears means that the engine is
laboring a lot
more to get you to the desired speed. More wear, poorer fuel economy, and
maybe less enjoyable for the driver.
So in this case, what seems like a good idea for drag racing doesn't
necessarily mean
a great idea for a street driven car. Even a fast one. You can build a
very fast
car with a 3 speed auto , 4 speed manual, or something overdriven, and
beat the
guys with fewer gears at the stop light grand prix, and have a car that
drives well
and is not tiring.
I can say that after driving a 300 - 400 miles with the engine wailing
at 3400 RPM,
I was fairly worn out by the end of the journey, and a bit more deaf as
well. I'm
looking forward to the next trip with overdrive.
-Bob Cisneros
http://firstgenfirebird.org/show/closeup.mv?CarID=231
San Jose, CA
[EMAIL PROTECTED] wrote:
First Generation Firebird-L Mailing List
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This question is for Bob Cisneros. I am wondering about the 300st, 2
speed automatic transmission. I have a bunch of people in my area that will
pay more for a 2 speed automatic verses a 350 or 400 automatic. They use
these 2 speeds for racing. Is there an advantage using the 2 speed in,
lets say the quarter mile? I am sure that, if I was to get it on, it would be
less than a quarter mile. I have heard stories of taking the 300 automatic
to 120 miles per hour by locking it in first gear. I alss would like to
know what the advantages are in using factory 3 speed transmission verses the 4
speed, if any?
Thanks
Bob P
Portland, oregon </HTML>
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