power shifting?
- Thread starter div
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- 24,344
- Midlantic Area
- GTP_Duke
Powershifting has no bearing whatsoever on GT3, since the manual transmission is sequential like a motorcyle transmission, and there's no clutch.
Powershifting in real life is when you don't lift off the throttle while shifting a regular manual gearbox. Normally you'd come off the throttle and allow the revs to fall when you put the clutch in. For powershifting, you stay on the throttle, clutch, shift, and let the clutch out. This keeps the revs up and gives the car a kick of acceleration when the clutch reengages. The trick is to be able to shift very quickly so that you don't overrev the engine while it is freewheeling.
Powershifting in real life is when you don't lift off the throttle while shifting a regular manual gearbox. Normally you'd come off the throttle and allow the revs to fall when you put the clutch in. For powershifting, you stay on the throttle, clutch, shift, and let the clutch out. This keeps the revs up and gives the car a kick of acceleration when the clutch reengages. The trick is to be able to shift very quickly so that you don't overrev the engine while it is freewheeling.
- 24,344
- Midlantic Area
- GTP_Duke
Heh, thanks. I'm just one of many though.
T13R, you weren't actually saying something stupid. Many racers upshift without clutching in order to shorten the length of time needed to upshift. However, to do that you need to lift throttle momentarily to unload the gears while you make the shift, then get back on it. In fact, most of the sequential manuals used in Touring Car racing work that way. The gearbox lever is moved manually by the driver while his throttle foot is held to the floor, but sensors detect the movement of the shift lever and cut the fuel and/or spark momentarily while the shift is in progress. All of this reduces the number of things the driver has to do during a shift and speeds the whole process up.
T13R, you weren't actually saying something stupid. Many racers upshift without clutching in order to shorten the length of time needed to upshift. However, to do that you need to lift throttle momentarily to unload the gears while you make the shift, then get back on it. In fact, most of the sequential manuals used in Touring Car racing work that way. The gearbox lever is moved manually by the driver while his throttle foot is held to the floor, but sensors detect the movement of the shift lever and cut the fuel and/or spark momentarily while the shift is in progress. All of this reduces the number of things the driver has to do during a shift and speeds the whole process up.
- 44
What!!!!!!!!
That is just crazy talk...
Many racers use the clutch when upshifting, the same way they use the clutch when down shifting. Have you ever driven a manual? If you had you would know that unless you are at the exact correct rpm for the next gear, all you are going to do by not pushing the clutch down(if you can get it out of gear) is tear up the gears in your transmission. Have a nice day tommorrow rebuilding a tranny. Now, with an automatic type shifter is is possible to not have a clutch, however, this would slow down shift times immensely. Every car today that is built with a non-continous transmission has a clutch, and every one, uses it every time it shifts, if it does not, after 20 minutes of driving it would probably not shift anymore, becasue the gears in the transmission would no longer have teeth on them.
So here is a test, take a car that has a stick in it, preferably a car that is not yours, or someone you care about, or someone who knows you and will beat you up, well maybe your car is best, so long as its a beater. Anyway, go and drive normally, but dont use the clutch when you make your first shift, see what happens... I suspect(meaning know) you will hear a horrible grinding noise and the shifter will shake violently. This is the gears in your transmission grinding against each other. Yea you will shift eventualy, but it aint fast or good.
In fact most sequential shifters used in touring cars dont work anything like that way, yes the driver doesnt have a clutch pedal, and yes he doesnt have to lift his foot off the gas. But here is what happens. The driver upsifts, the sequential transmission enganges the clutch, cuts fuel (not spark, you never cut spark unless you want to destroy your engine) and allows the cars engine to lower its RPM(the cars have light flywheels and driveshafts to make this go faster), changes gears, re-ingages the clutch, and the car is now in a higher gear. The reason the car cuts fuel is not so the car can upshift without a clutch, it is so the clutch does not get ruined by powershifting in a 500 horse power car(if has the racing flywheel and such such to make the rpm drop faster, which makes the shift faster, as the tranny has to wait less time for RPM's to drop enough that it can engage the clutch).
There is only one type of transmission that does not have a clutch, and that type cannot yet handle high horse power engines. This type of tranny is called a CVT. Or continously variable transmission. The transmission is made up of one concave cylinder cut in half and rounded at the top. A disk (or two) is placed between them and connects the two by simple friction. If car needs a low gear(close), it moves to the inside of the concave part on the engine side and the outside of the concave part on the wheel side, meaning one engine revolution turns the disk very little which in turn turns the wheels even less, if a high gear(wide) is needed the gear goes to the outside of the engine side disk and the inside of the wheel disk. This would be the optimal transmission for racing as cars could always stay in their powerband while the car was accelerating and there would be no shift times. However the transmission isnt, because when too much power is applied the conecting disk is no longer viscuss(sp?) enough and the transmission will no longer connect the wheels and the engine, meaning no power will be transferred. So right now, we still use 1 clutch sequential transmissions to get our racing done.
- 24,344
- Midlantic Area
- GTP_Duke
I've driven a manual transmission for more than 20 years.
Touring racecars do have a clutch, used for launching and stopping the car. Most shifts on the fly are made without benefit of clutching; certainly without fully depressing the clutch. They don't necessarily have an "automatic manual" clutch like is available on the MRS. You are correct, you'd never cut spark without cutting fuel, but many EMSs do both.
Watch a NASCAR race some time - the only ones I watch are Sears Point and Watkins Glen, but that's beside the point. NASCAR stockers run H-pattern shifters, not sequential transmissions. When you watch the in-car camera pointed at the driver, you will see that they shift all the time without moving their left leg.
Touring racecars do have a clutch, used for launching and stopping the car. Most shifts on the fly are made without benefit of clutching; certainly without fully depressing the clutch. They don't necessarily have an "automatic manual" clutch like is available on the MRS. You are correct, you'd never cut spark without cutting fuel, but many EMSs do both.
Watch a NASCAR race some time - the only ones I watch are Sears Point and Watkins Glen, but that's beside the point. NASCAR stockers run H-pattern shifters, not sequential transmissions. When you watch the in-car camera pointed at the driver, you will see that they shift all the time without moving their left leg.
- 44
Yes, they may, but they still clutch, the car may do it for them, but they still cluth.
Are you sure that isnt a sequential? But even if it is an H box, the car still clutches, they would not shift without it.
Im sorry, but when touring cars shift, they use a clutch, there is no transmission that would get by without one. It may not go down all the way, but nor does one in any manual, the clutch only needs to go down far enough to disegnage the engine from the transmission, pushing it down any farther does nothing, any less, not enough.
Are you sure that isnt a sequential? But even if it is an H box, the car still clutches, they would not shift without it.
Im sorry, but when touring cars shift, they use a clutch, there is no transmission that would get by without one. It may not go down all the way, but nor does one in any manual, the clutch only needs to go down far enough to disegnage the engine from the transmission, pushing it down any farther does nothing, any less, not enough.
- 1,575
- GTP_T13R
Why not just use the clutch? If you are very good with it, it should make almost no difference. Just get a short-shift kit for your car, and you'll be shifting faster than a split second. Ive got one installed on my car, and i might me losing sumtin like 1 tenth per shift, but i dont see why Power Shifting would reduce that time down. Just need good interaction between leg and arm.
- 24,344
- Midlantic Area
- GTP_Duke
Well, yeah, I wouldn't recommend the technique for beginners 
Clutchless upshifting does require good knowledge and careful technique, which is why I don't do it. The method I've seen used most often is to pre-load the gearshift by resting your hand on it, but not hard enough to pop it out of gear. When you're ready to shift you quickly back off the gas, unloading the gears and allowing the lever to pop into neutral, then pop it into the next gear as the revs fall to the right point. It's not for the faint of heart or those who do their own transmission repairs.
Clutchless upshifting does require good knowledge and careful technique, which is why I don't do it. The method I've seen used most often is to pre-load the gearshift by resting your hand on it, but not hard enough to pop it out of gear. When you're ready to shift you quickly back off the gas, unloading the gears and allowing the lever to pop into neutral, then pop it into the next gear as the revs fall to the right point. It's not for the faint of heart or those who do their own transmission repairs.
- 807
I gotta go with Duke on this one. If you know your car, shifting without the clutch is pretty simple. The only time you actually need the clutch is going into 1st gear from a stop.
I drove a car for 8 years that had a notoriously weak clutch, so I often just didn't use it. Just like Duke said, all you do is let your foot off the gas, let the revs drop a little, and shift. If the engine is going the right speed, it'll drop right into gear as freely as it flops around in neutral. If not, you'll have to force it, and you'll grind the gears.
You need to remember that even if you do push the clutch all the way to the floor, there are still moving parts in the transmission that have to mesh together. That's how a transmission is designed to work. If you're within a few hundred RPM of matching the engine to the gear you're going into, clutchless shifting is much easier on the car than shifting when you please and letting the clutch sort things out.
I drove a car for 8 years that had a notoriously weak clutch, so I often just didn't use it. Just like Duke said, all you do is let your foot off the gas, let the revs drop a little, and shift. If the engine is going the right speed, it'll drop right into gear as freely as it flops around in neutral. If not, you'll have to force it, and you'll grind the gears.
You need to remember that even if you do push the clutch all the way to the floor, there are still moving parts in the transmission that have to mesh together. That's how a transmission is designed to work. If you're within a few hundred RPM of matching the engine to the gear you're going into, clutchless shifting is much easier on the car than shifting when you please and letting the clutch sort things out.
- 44
yea, if your good at it, and it is not faster than shifting with the clutch.
Simply, if your racing, you cluth
Simply, if your racing, you cluth
- 19,311
- Inland Empire SoCal
- SOLID_LIFTERS
I had an 88 Toyota pickup that had the second clutch blow out at 145,000 miles. It was a second vehicle for me that was used for "crap" work, so i didn't mind not fixing it. I sold the truck with 167,000 miles and the transmission ran just fine. Power shifting is very possible for a vehicle.
Power shifting was a popular topic in my Auto Shop class in High School, and our teacher taught us all about the pros and cons of p.s. and it sounds like neon has a good grasp of the topic and racing technique.
Power Shifting I feel is a lost art with todays youth. I'm happy to see the young so willing to learn a racing technique that proves the user has earned the respect to be considered a racer. Just remember to keep it on the track.
Power shifting was a popular topic in my Auto Shop class in High School, and our teacher taught us all about the pros and cons of p.s. and it sounds like neon has a good grasp of the topic and racing technique.
Power Shifting I feel is a lost art with todays youth. I'm happy to see the young so willing to learn a racing technique that proves the user has earned the respect to be considered a racer. Just remember to keep it on the track.
- 10,309
- San Francisco, CA
- Vasco506
- Vasc0
Ah, so they shift without the clutch in the race cars? So that's why I always see them shifting so damn quickly, and being able to concentrate on the race...Would this be the same in rally cars, or would there be a normal road car sort of transmission (the normal way you have to use a clutch)?
- 19,311
- Inland Empire SoCal
- SOLID_LIFTERS
I see the Rally Cars mostly use the steering wheel padles, so no clutch. They do break down though so the gear shifter is still used when necessary.
- 44
Both touring cars and rally cars have clutches. They are automatic and are not used directly by the dirver, but they are there, and they do engange when shifting for you.
- 807
Huh?
You blew the clutch, and you didn't fix it, but the transmission "ran just fine" without the clutch? Did you have someone push it for you until you got up to 15-20 MPH and could put it into first gear? And what does any of that have to do with power shifting? It doesn't sound like you even know what power shifting is. Go read the explanation that's already been given in this thread.
- 13
the turbo doesnt go down at all if you line ur revs up but why bother? just work out what speed (approx) u need to change at and hit R2.
- 12,825
Formula Koenig race cars don't bother clutching when downshifting, either. The inbalance of RPM's dropping and climbing rapidly stresses the chassis too much - I know this for a fact.
They're H boxes. Point being you can do some pretty crazy stuff with gearboxes.
They're H boxes. Point being you can do some pretty crazy stuff with gearboxes.
- 24,344
- Midlantic Area
- GTP_Duke
In GT3, when you drive manual transmission, there's nothing involved except pushing the button to change up. It's already a "powershift" of sorts because you just hold the throttle wide open the whole time and punch the shifter button and the car changes up.
So what exactly are you doing that you call "powershifting"?
Real rally cars and most (but not nearly all) modern race cars use a sequential transmission, like a motorcycle - pushing the lever (or the paddle) one way shifts up to whatever the next gear is, and pushing it the other way shifts back down. There's no way to go, say, from 4th gear directly to 2nd without passing through 3rd. Paddle shifters are electrically or electric/hydraulically operated; lever shifters may also be, but can also be mechanically operated meaning the motion of the shifter is physically what makes the gears change inside the transmission. The gears are all racked up along a single axis, and the dog gear (which is driven by the input shaft from the engine) is simply shoved from one to the next. So the disadvantage of having to step through all the gears is more than made up for by the speed and ease with which the gearbox can be shifted, both for the driver and the transmission itself.
And ving, moit, go re-read my original post: I was saying there's no clutch in GT3, not on a motorcycle. I've been riding motorcycles for 25 years... I know there's a handclutch silly boy!
- 1,494
that concave cylindrical gear system certainly sounds like the future. isn't it already employed on things like electric trains or something? there was a time when auto gearboxes couldn't handle large torque, now look at the SL55...
anyway i've powershifted my car before, but not ever tried shifting without the clutch. though if i understand correctly, if u have to wait for the revs to fall, surely you can't powershift without using a clutch right?
and if u need to wait for the revs to fall, isn't it quicker to use the clutch and just shift without waiting for anything?
i saw this thing at a motorshow where the gearbox automatically engaged the clutch when u had the leaver in neutral and were about to move it to the next gear...
anyway i've powershifted my car before, but not ever tried shifting without the clutch. though if i understand correctly, if u have to wait for the revs to fall, surely you can't powershift without using a clutch right?
and if u need to wait for the revs to fall, isn't it quicker to use the clutch and just shift without waiting for anything?
i saw this thing at a motorshow where the gearbox automatically engaged the clutch when u had the leaver in neutral and were about to move it to the next gear...
- 24,344
- Midlantic Area
- GTP_Duke
Yeah, the MR-S has an optional "clutchless" manual, where it launches for you and does the clutching for you when you move the shift lever. It even gooses the throttle on the down shifts so you sound studly. It's a little slower than you can shift yourself, though.
Really, clutchless shifting is mostly done by racers who don't pay for their own cars and who have a big team of mechanics...
Really, clutchless shifting is mostly done by racers who don't pay for their own cars and who have a big team of mechanics...
