[Top] [All Lists]

RE: Transmissions

To: Beth Butters <>,
Subject: RE: Transmissions
From: Beth Butters <>
Date: Fri, 23 Apr 1999 21:45:49 -0700
         I  really do understand what you are saying if  E.T.s made a 
difference  for trap speed but really they don't, of course that's what drag 
racing is all about. You can take any given car  and it will run just so fast 
in the quarter mile  assuming it didn't top out early because of being geared 
to low. Without touching the engine it is usually easy enough to lower the E.Ts 
with tires gearing traction aids ect. But without changing the tuneup, the trap 
speed is still a function of  the cars weight and the power to move it and it 
won't change but a couple of %. If  at the drag strip the race was won or lost 
with trap speed  60 foot times wouldn't mean a thing.  Sure if your car isn't 
capable of over powering the track surface, put lot's of gears in it and  run 
it as if it were an Austin Mini. But most of the cars I see run on the flats 
are perfectly capable  of braking traction when they enter the torque band in  
all the lower gears, so you have to  ease into  each gear  which waists much of 
the  mechanical advantage you have available to you.        Maybe  I can 
explain  speed verses distance the way I understand it , your engine produces  
a given amount of  total torque  in the time  it takes to go a distance and 
obtain a certain speed ,  weather it takes  20 sec. To do this or 25  it makes 
no difference   it's the same area under the acceleration curve, which is the 
total torque used to accomplish the task.  That is why the to tall geared , 
short geared car will match  the trap speed of  an identical car with optimum 
gearing  in the quarter mile.  So to my way of thinking that  as long  as your 
car is geared  so it will pull smoothly at W.O.T.  with the gears you have 
available , your going to  be going the  speed the car will go  at the  2 1/4  
mile.  Dos this only make sense to me  or what?  We'll knowing  all the 
different ideas I come up with that is probably the case,  I've only  thought 
about this for  35 years  and have rarely found anyone who could comprehend 
what I was talking about. None of this is t
can  at the  2 1/4  and still be geared  tall enough to make your target speed  
isn't  how you do it, atleast  with a  5 mile track.  Good Luck  Guys, Kvach 

From:  Dave Dahlgren[]
Sent:  Friday, April 23, 1999 6:47 AM
To:  Beth Butters
Subject:  Re: Transmissions

The real problem is that you run out of race track to play with.  Your
old 55 would go faster than 80 I hope. Mine did. The whole key point is
to keep the engine in the power curve . If yours is 5000 rpm wide and
flat then fine. Most are not. My years of experience tell me that the
power curve of most engines is 2200 rpm wide where things really happen.
The engine we run has am much smaller one than that. peak torque is at
8800 and peak power at 9900. When you are not there you are just burning
off the track distance. The faster you go the quicker you burn up the
distance waiting to get to peak power.  In my humble opinion you ought
to be at 90 to 95 percent of what the car is capable of at the 1/4 and
use the rest to get the last few percent. It has worked for me every
time. I do not even like the push off as it burns off at least a 1/4
mile that i could have used.  To me this is a drag race with a very long
timing trap. But only my opinion . I have tested this and every time I
am faster at the 1/4 I am faster at the end. The only thing you may not
like is the amount of time that the car is not accelerating at the end
of the course. if your car is accelerating at the 4 mile marker you have
left a bunch of speed in the trailer so to speak. Remember it is an
average speed the faster you go in to the measured mile the faster your
average. The only thing in favor of you way of doing it is that now to
my knowledge all the passes are in the same direction.  When it was the
same physical mile had to be really going early on so that when you run
in the other direction you do not get to the same physical spot too soon
going too slow.  Anyway I guess it is "po tay toes" and "po taa toes"...
i spend a day or too with the dyno sheet from the engine and the
computer figuring out the power available and the power required to go a
certain speed. correct all for the weather and altitude. If the car does
not break and slippage is in the range calculated car will go within 1
or 2 mph of what we expect off the trailer.  Have never made a 'warm up'
or 'test pass' since the first one when car was new .. that one was 179
on a 162 record...  Told Goodman to just leg it out through second gear
and shut it off on the short course so we could look it over before we
run it out the back door. Now it is off the trailer, pull the trigger,
go for it. you have to love the EFI the tune up is done when the engine
starts, the gearing is done before we leave, and if the computer says we
will not break a record we work on the car until it says we will, then
we haul the car out to make a pass or two.

Just my way of doing i am sure there are many that work, this one has
never failed though.
Dave Dahlgren

<Prev in Thread] Current Thread [Next in Thread>