ATDSM was started as a guide for those who purchased a
first or second generation dsm equipped with either an F4A22
or a W4A33 automatic transmission. It is a common misconception
that automatics are "slower" and "not good for racing."
The first "problem" is launching. You can't rev an automatic up to 5,000 rpm, then just dump the clutch. What you can do though is install a high stalled torque converter. A proper launch on an automatic can be just as quick, if not quicker than a manual transmission launch.
Another problem would be the rev potential. With a manual transmission, an engine rev's until you shift it. Although this makes more power, it can also be detrimental to parts. Over-revving an engine can lead to cylinder out-of-roundness, premature bearing failure, premature rod failure, and valve float. If more powered is desired though, there are "tricks" that can be done to automatic transmissions to allow them to shift higher in the rpm band.
These tricks can include a "manumatic" shifter, which is where you adjust the TCU (the computer that controls the transmission) to give full line pressure, then manually change gears by moving the gear selector. Another trick involves wiring switches up to the solenoids in the valve body of the transmission, which shift the transmission. These can be either toggle switches (the easiest), steering wheel buttons, or paddle shifters. The last option applies if you can get your hands on an eprom TCU. Just like reflashing the eprom in your ecu for fuel and timing curves; you can reflash the eprom in your tcu to different shift points, and higher line pressure.
After these steps are complete.. why is having an automatic so bad? You can launch the same, and unlock the power on higher RPM's. On top of that, there are no clutches to change every season, no mis-shifts blowing your headgasket or destroying your engine, and you also can achieve more consistent 1/4 mile times. If you would rather do something than press the accelerator, and like manually shifting the gears.. there is always the manumatic mod, or the pushbotton mod.
|Torque converter absorbs most of the driveline shock during launch.||Clutch transmits heavy driveline shock causing transmission,
transfercase, rearend, driveshaft, and halfshaft damage.
|Launch RPM can be raised to 5000 RPM's via high stalled torque converters.||Launch RPM is determined by when the driver lets the clutch out.|
|Electronics automatically shift the vehicle at a preset limit. This avoids
possible engine damage.
|Driver controlled shifting can lead to hard shifts causing gear damage; |
high RPM's during mishifts can cause rocker arms to be thrown out the valve cover,
and valve float at excessive RPM's can cause piston and valve damage.
|Consistent RPM shifts allow consistent ET's during bracket racing.||Driver has to watch the tachometer and shift at correct time to run consistent|
|Electronic shifting is quicker than even the shortest throw shifters.
Throttle can stay pressed the whole time, keeping transient boost between shifts.
|Even with NLTS, engine RPM must be cut back between shifts to help prevent |
transmission failure. This can lead to a slower ET and MPH, as both boost and
and power are lost.