What's this about shifting?

[Auto_newb]

Ok, this is gonna be embarrassing...........But why do people let off the gas when they shift? I've heard of the term powershifting meaning you hold the gas down while shifting...

Does it waste gas if I were to hold the throttle down while shifting? If so, why do racers do it?
!!!!!!

[ales]

If you don't lift your foot then the engine, that is "freed" from any load when you depress the clutch, will simply rev past the redline to the rev limiter. Think about it: if you were to shift to a higher gear, let's say, at 3500 rpm, your rev limiter is at 7000 rpm, but when you release the clutch after shifting to a higher gear, the speed of the car requires the engine to be turning at, e.g. 3000 rpm. That is 4000 rpm that needs to be shaved off your engine speed, and all this punishment is taken by the clutch. Hardly adviseable. It's different in a race car in a race situation because the shifts are performed much quicker than in normal street driving, and also reliability of the components is usually not the primary consideration, they just need to last until the end of the race.

[Hemi99]

Power shifting is also when you let off the gas and don't use the clutch to put it in the next gear. It requires precise timing and is an art form if done right, if not, then it makes the most horrible noise you want to hear from the tranny. I take it you drive an auto, I would recommend that you try to drive stick sometime, it makes driving all the more fun! Just my opinion though!

[83-944]

"If so, why do racers do it?"

Which racers do that? Hemi99 has pointed out the way to get from one gear to the next in the least amount of time with the fastest power transition. Almost every professional race car (barring formula car) driver uses that method. It's taught at every racing school I know of.

[Auto_newb]

Power shifting is also when you let off the gas and don't use the clutch to put it in the next gear. It requires precise timing and is an art form if done right, if not, then it makes the most horrible noise you want to hear from the tranny. I take it you drive an auto, I would recommend that you try to drive stick sometime, it makes driving all the more fun! Just my opinion though!

Some people on this forum said power shifting is when you keep the throttle pushed down, which is which!?

Which racers do that? Hemi99 has pointed out the way to get from one gear to the next in the least amount of time with the fastest power transition. Almost every professional race car (barring formula car) driver uses that method. It's taught at every racing school I know of.

wth? Doesn't that destroy your gearbox?

[rubix777]

power shifting is shifting without the use of the clutch

[Auto_newb]

Meh, argue with these guys then http://www.automotiveforums.com/vbul...power+shifting

[Hemi99]

If you have ever tried to move the shifter when your foot is on the throttle, you will realize that it is extremely difficult to do, if not impossible. When your on the gas, the gears have a very heavy load on them that keeps them turning, i.e. the power from the engine. That force is extremely large and keeps you from trying to switch to the next gear. Power shifting is when you momentarily let off the gas and shift without the clutch into the next gear. If you watch NASCAR sometime, watch for the in-car view when they are accelerating, you will hear them let off the gas, then switch to the next gear and then get right back onto it. It doesn't destroy the gearbox necessarily unless you do it wrong. Granted that all manual transmissions nowadays have smaller gears called synchros (or synchronizers) that sync the rotational speed from one gear to the next to avoid grinding the gears. The clutch is primarily used to stop the power transfer from the engine to the transmission so as to remove the load from it and allow easier and more effective gear switching.

[Auto_newb]

I see, do they powershift from 2-3rd? 4-5th gears? Just wondering...