Software Newsletter #30 - April 17, 2006
Racing Computers and Software - www.iFamilySoftware.com
1. High MPH Throttle Stop Setup
High MPH Throttle Stop Setup --
are two types of Super racers, The Dialer and The Wheel Racer.
The Dialer is confident in his equipment and ET Prediction program. He sets his
car up honestly to run the number and can run it out the back door when necessary
without much fear of breaking out. The Wheel Racer always sets up quick
to get their first, and tries to "nose out" his opponent by taking the
least possible finish line margin. The Wheel Racer must have the better
reaction time because his ET is going to be based on his opponents performance
rather than his own. Any good dialer will tell you that he has the advantage.
Most wheel racers believe that they have the advantage. Go figure!
Dialer wants a car that is consistent and predictable rather than run a high mph.
The Wheel Racer must have the higher MPH car. The only problem is, with
the high MPH comes inconsistency and therefore an unpredictable race car. The
reasons are simple. Today, the high MPH car is an extremely high horsepower car.
Traction and throttle stop problems are big issues for high horsepower. Throttle
stop factors are effected by engine RPM (Coast RPM) but more importantly
by launch MPH which is not necessary equal to a specific Coast RPM!
Better traction, or "getting up on the tire" will increase the MPH at launch,
then when the car coasts on the throttle stop, the vehicle speed is different
than the base run. Multiply the amount of MPH difference by the throttle stop
timer duration and the effect on ET can be huge. The best way to try and eliminate
this problem is too launch the car softly and as consistently as possible in order
to leave the starting line at the exact same MPH each time. Then the throttle
stop duration must be limited to the least amount of time as possible. This means
you can't cruise at 5000 engine RPM. A car with 3 to 4 seconds in the timer duration
can only be consistent if the throttle stop RPM stays exactly the same on each
If you are not using a Family Software DataMaster computer, you
will never know if your throttle stop repeats or not. NO other data recorder
can see the minute changes in throttle stop RPM that the DataMaster can see. Looking
at graphs from a RacePak or other data recorder, you would tend to believe that
you have a consistent throttle stop, yet you can't run the number and your 60
to 330 foot times, and/or 330 to 660 foot times vary even with the same timer
duration setting. It's because your Coast RPM is varying and your data recorder
cannot see it happening. This is due to poor programming and low sampling rates.
The best way to increase your consistency is to reduce your timer duration.
An under the carb throttle stop cannot be used in most cases because the Coast
RPM will have to be set below the point of main booster flow. Therefore,
accelerator pumps are necessary when the throttle stop comes off. Because of traction
problems, and again to limit timer duration, the car should be in high gear almost
immediately into the run. This will remove .3 from the ET and reduce timer duration
dramatically. It will also help to eliminate any traction problems coming off
the stop. The best throttle plate and timer duration setting would be one where
the throttle is returned to idle, but the timer duration never allows the engine
RPM to reach idle. In other words, a short, controlled hesitation or cough. The
amount of ET you need to reduce may limit you from having the perfect throttle
Here is a recommendation for a starting point. Use a linkage
type throttle stop. Set your launch RPM to 4200 to 4600 RPM for consistent reaction
times. (The DataMaster is also the only computer that can accurately monitor Vehicle
Reaction Time.) The throttle stop goes on immediately. If your timer allows it
to start at .000 use that, otherwise use .001. Set your shift timer to two tenths
(.2) into the run. Set your Cruise RPM as low as possible and begin testing. Adjust
for the shortest timer duration where the throttle response is good coming off
the stop. If you don't have a DataMaster computer, make several runs with the
same timer duration setting. If the car will run the same STP ET (corrected ET)
three times in a row with the same timer duration, you have it right. Otherwise,
you still have work to do.
REAL World Technical Support --
With Family Software, you'll get better technical support than anywhere
on the planet. Why? Because, we design and/or use all of the products
that we sell. All of my 35+ years of racing experience and knowledge
is available to you and our other customers. Try to find that kind of
information at any one of our competitors. You won't be able to, I guarantee
it! Family Software cares about the racer and his/her success as a racer.
We also want you to get the most value for your hard earned dollars.
-- Secure Ordering
You can safely order directly from our web site. All of your information
posted on the web site. Our company is registered with the Public Eye for safe,
you have questions or topics that you would like to see covered in this newsletter,
please Email them to me.
Family Software - Drag Racing Computers and Software
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