Power shifting (No lift shifting) in racing

[TRX250EX]

Hi everyone I was having discussion with some Manual cars owners about Power shifting if it's fine to do it when racing or drag racing for example in an Emira or Exige or not, some cars like Porsche have a system for this but Lotus doesn't and my question will there be an issue doing it for drag racing or something? Not that I'm gonna do it but just curious.

And if not why exactly? Both for track day and drag racing.

 

[d15b7]

‘Power Shifting’ a manual transmission is extremely abusive. It’s the fastest way to do a 1/4 mile but boy is it hard on a transmission. I had a best buddy back in the 2000s that had a 1989 Mustang LX 5.0 5sp that he drove to work every day and drag races on the weekend. It had light mods (cam/headers/computer and 3.73 gears). It would do a high 12 in 1/4 mile (very respectable back then). He took me for a ride one time and we did a full 1/4 mile pull out on the road. He power shifted all the way to 4th gear (foot to the floor no clutch just slam into the next gear as fast as you can pull the lever). It was unbelievably violent!!! (Like no kidding the glove box popped open and all its contents went into my lap!!!!!). It was fast but damn it’s abusive.

He’d make it through half a summer and explode the transmission (maybe 8 weekends at the street races). He always had two or three spare low mileage T5 transmissions ready to swap in that next day so he could drive to work.

No way I’d even consider power shifting an Emira even one drag pass. Too great a chance for destruction.

PS some cars (like my ‘20 ZL1 1LE 6 speed) have ‘no lift shift’ designed in. This is NOT true power shifting. You still dip the clutch in (but keep your throttle foot buried) and shift as fast as you can. As you do that, the ecu cuts the engine for a fraction of a second (stutters it) as you are moving the gear lever. Personally, I never do this with my ZLE. I always granny shift it. Tremec 6060 transmissions are very robust but are expensive and I don’t abuse my cars.

If you plan on drag racing do yourself a favor and buy an automatic or DCT

 

[TRX250EX]

‘Power Shifting’ a manual transmission is extremely abusive. It’s the fastest way to do a 1/4 mile but boy is it hard on a transmission. I had a best buddy back in the 2000s that had a 1989 Mustang LX 5.0 5sp that he drove to work every day and drag races on the weekend. It had light mods (cam/headers/computer and 3.73 gears). It would do a high 12 in 1/4 mile (very respectable back then). He took me for a ride one time and we did a full 1/4 mile pull out on the road. He power shifted all the way to 4th gear (foot to the floor no clutch just slam into the next gear as fast as you can pull the lever). It was unbelievably violent!!! (Like no kidding the glove box popped open and all its contents went into my lap!!!!!). It was fast but damn it’s abusive.

He’d make it through half a summer and explode the transmission (maybe 8 weekends at the street races). He always had two or three spare low mileage T5 transmissions ready to swap in that next day so he could drive to work.

No way I’d even consider power shifting an Emira even one drag pass. Too great a chance for destruction.

PS some cars (like my ‘20 ZL1 1LE 6 speed) have ‘no lift shift’ designed in. This is NOT true power shifting. You still dip the clutch in (but keep your throttle foot buried) and shift as fast as you can. As you do that, the ecu cuts the engine for a fraction of a second (stutters it) as you are moving the gear lever. Personally, I never do this with my ZLE. I always granny shift it. Tremec 6060 transmissions are very robust but are expensive and I don’t abuse my cars.

If you plan on drag racing do yourself a favor and buy an automatic or DCT

Thanks for the reply, I didn't buy Emira to drag race but we were drag racing Exige final edition to a Tesla Model 3 and someone wanted me to power shift which I said no way and he started saying he was doing it all the time in his Focus ST without any issues, and multiple guys were agreeing with him.....

I just needed someone with experience to show him a proof why it's not a good idea in a Lotus.

Thanks.

 

[JasonR]

The clutch is there for a reason. If it wasn’t meant to be used then it wouldn’t have one. There are gearboxes designed for drag racing, autos mostly but some sequentials that “bang” into gear.

Can’t understand why people would abuse a car like that tbh

 

[SteveB]

Although a different gearbox design (dog box with straight cut gears), in my Superkart the clutch is only used for moving off and stopping. No need to use the clutch for changing gear. However, a slight lift is needed when changing gear to reduce the pressure on the driven gears and allow them to slide relative to each other. Without the slight lift the driven gears are effectively locked together by the forces acting on the intermeshed teeth. Trying to change gear under full throttle without a lift will require a lot of force and cause a lot of damage (fragments of broken teeth which get trapped in bearings, other gears etc.). I imagine this will be a whole lot worse with a synchromesh gearbox with helical gears!

 

[FederGigant]

I just saw a video about a Golf TCR, which is a proper race car with a sequential gearbox, where the clutch is only used to get it moving. They are rebuilding the gears every 2.000 km

 

[Dabjbr]

I no-lift shift on my SS1LE and I don’t think it’s abusive at all. Then again, it was designed for it

 

[hagen111]

So what is a ’powershift’? My idea is you keep full throttle, and use clutch and shift at the same time. Engine will just run in its rev limiter briefly.

Some cars have this function as standard…when full throttle and touching the gear lever, ignition will be cut off for a split second and you can make the shift without clutching. It will also automatically match-rev under braking. It’s a great feature that works really well on track.

 

[TomE]

So what is a ’powershift’? My idea is you keep full throttle, and use clutch and shift at the same time. Engine will just run in its rev limiter briefly.

Powershifting is without using the clutch, just force the gearchange. Some cars are designed for it and where it’s not designed-in then some gearboxes cope with it better than others. The Emira isn’t one of them.

 

[VL3X]

Powershifting is without using the clutch, just force the gearchange. Some cars are designed for it and where it’s not designed-in then some gearboxes cope with it better than others. The Emira isn’t one of them.

Yeah, you can also float gears in some cars by slowly shifting without the clutch. It's pointless, but possible on some. I remember specifically being able to do it in a SR20 swapped Nissan 240SX. I would never try to "power shift" the Emira gearbox. I don't think anyone is drag racing these sort of cars.

 

[Nova]

Power shifting in the traditional sense is holding the throttle down to full, pressing the clutch, selecting the next gear, and releasing the clutch fully. When this is done, the engine goes to full throttle as the clutch is pressed, and there is a spike in acceleration as the clutch is released due to the inertia of the engine as it gets slowed down as the clutch bites.

Yes, it is very harsh on the transmission, especially if the higher gears were not designed to handle this since most people do not drive this way. Clutch dumps may be done in first gear, and even the second gear is usually beefy to handle the quick 1-2 shift.

There are cars designed for power shifting, which applies a slightly aggressive rev matching algorithm to the throttle electronically, giving the driver the convenience of keeping the throttle held down. This does *optimize* the power delivery during shifts so it *is* faster while limiting the stress on the transmission to an acceptable level.

 

[Nova]

Yeah, you can also float gears in some cars by slowly shifting without the clutch. It's pointless, but possible on some. I remember specifically being able to do it in a SR20 swapped Nissan 240SX. I would never try to "power shift" the Emira gearbox. I don't think anyone is drag racing these sort of cars.

LOL! I played with that in an old manual Honda Accord that I was driving around in my youth. Essentially, if you can match the engine speed perfectly to the transmission, you can get the car in gear without using the clutch. You have to be able to mentally map the current vehicle speed and intended gear to a desired engine RPM. In fact, this is what had to be done with older manual transmissions without synchros.

 

[TomE]

Or you had to double de-clutch, which I had to learn to do so I could drive some of my dad's vintage cars which had no synchro.

There is a story in Lotus circles of an Evora being used for passenger rides at a "run what you brung" day at a drag strip. After multiple repeated clutch-dump launches the teeth were stripped from 1st gear and the owner then continued to launch by clutch-dumping in 2nd gear, until the gearbox seized. The warranty claim for a new gearbox was politely declined by Lotus based on the history stored in the ECU.

 

[TRX250EX]

I think alot misunderstood what I meant by power shifting, what I meant is basically "no lift shifting", basically doing shifts as you will do normally but without releasing your foot from throttle pedal.

Like some mentioned also some cars have a system for that for example I tried in GT3 and in sport mode you can do it with the electronics cutting throttle the moment you press the clutch giving faster shifts as well as you only need to do 2 actions (clutch and shift), in normal mode this system doesn't work.

I already got the answer anyway, I just spoke to some guys been doing it for years in their cars without having this system and they say they never had an issue, I'm not gonna be doing it of course as I mentioned before but was curious with Lotus owners if anyone been doing it in a Lotus specially Emira.

And Off topic question: anyone noticed exhaust sound difference between Sport and Track modes? I thought after finishing break in or something it will be noticeable but tbh I didn't notice any changes, does anyone know the difference and why in screen it shows higher level for exhaust?

 

[CoryC]

I think alot misunderstood what I meant by power shifting, what I meant is basically "no lift shifting", basically doing shifts as you will do normally but without releasing your foot from throttle pedal.

Like some mentioned also some cars have a system for that for example I tried in GT3 and in sport mode you can do it with the electronics cutting throttle the moment you press the clutch giving faster shifts as well as you only need to do 2 actions (clutch and shift), in normal mode this system doesn't work.

I already got the answer anyway, I just spoke to some guys been doing it for years in their cars without having this system and they say they never had an issue, I'm not gonna be doing it of course as I mentioned before but was curious with Lotus owners if anyone been doing it in a Lotus specially Emira.

And Off topic question: anyone noticed exhaust sound difference between Sport and Track modes? I thought after finishing break in or something it will be noticeable but tbh I didn't notice any changes, does anyone know the difference and why in screen it shows higher level for exhaust?

I noticed it on my extended test drive... slight, but noticeable.