Speed-shifting is a technique used during a drag race where the driver shifts as quickly as possible to match the rapid acceleration of the vehicle. The secret to performing a speed-shift on a manual transmission for a drag race is to know when your engine is reaching its maximum power during each gear and to shift accordingly.
Speed-Shift a Manual Transmission for a Drag Race
Use a dynamometer to figure out the correct power-band of each gear of your manual transmission. While many people believe that the engine is putting out the most power right before the red-line, the maximum power-band actually occurs somewhat before that. Most repair garages have a dynamometer and will perform the job for you.
Consider purchasing an outboard tachometer with a lighted shifting indicator, which can be adjusted to reflect the maximum power-band of each gear. Since you will be able to see the shift light indicator in your peripheral vision, you can keep your eyes safely on the road and still know the best time to perform your speed shift.
Implement the speed shift technique for your manual transmission by revving your engine before your launch from 2000 to 3500 rpm, depending upon the low-end torque of your vehicle (the more torque you have, the less you will need to rev your engine). Remember that the less you spin your tires, the quicker your launch will be.
Try to shift about 200 to 300 RPMs before you hit the optimum power-band for each gear. This will help to compensate for your reaction time to seeing the shifting indicator light, which may be as much as a second or even more.
Keep your foot on the gas during each speed-shift. This will cause your engine to rev high while the clutch is depressed, so you will need to make your shift quickly enough so that you do not approach the red-line, which can either burn out your engine or cause the rev limiter to kick in and shut off your engine. Either way, you will lose the drag race!