I know how to get max acceleration from a manual: rev it up, and drop the clutch.

A slushbox auto, build up the revs against the torque converter, hold the car with the brakes and let loose.

With a pdk, what happens when you rev the engine with the brakes on? When does the clutch pick up? Is the brake only used to provide a signal to the clutch to engage or does it provide a load to the motor?

 

No different than manual, while your foot is on the brake the clutches are not engaged and when you let off it just uses special programming (aka the launch control) to slip the clutches optimally for the best launch.

 

How does launch control (optional and bundled with sport chrono on base and S models) differ from pressing the accelerator and brake simultaneously on a non launch control car? On cars with launch control, it is supposed to hold a particular engine RPM, and then modulate clutch engagement and throttle automatically for an optimal launch. I'm not sure what PDK cars without launch control do when you do this, and how it differs from those with launch control. I know Porsche advertises different acceleration times for cars with and without launch control.

 

Without Launch Control it behaves basically the same way but doesn't rev as high, and speculating that the programming of how it engages the clutches and/or other behaviour isn't the same as the launch control programming does it.

 

Ok, so I have now lived with PDK on my '22 boxster for a while. It does not have launch control. I'm generally happy with it, but there is one area where I think it is lacking. On a slushbox auto, when you need to get away from a light quickly, but without making a spectacle of yourself, you hold the brake and give it about 1500 or so rpm. You then let the brake go, give it more gas and get away quickly but without much fuss.

When you give it gas with brake on in the PDK, the revs go up a bit. You can feel the attitude of the car change, so you know the clutch is somewhat engaged. When you then let go of the brake and give it gas, you get a huge bog. Just going from brake to gas normally gives better results. My wife's DSG Alltrack behaves in the same way.

I still haven't had the courage to give it lots of gas or floor it while the brake is held. Has anyone out there tried this on a non-launch control car?

 

Do you have brake hold?

If so, activate it by giving the brake pedal a quick jab.

Wait for the light to go green and floor it.

That would be the alternative to SC car with Launch control.

I am thinking in cars without LC, holding brake and throttle might 'confuse' the car, leading to bogging.

 

I googled brake hold. Apparently, my car has it, but according to the description, it's more of a parking brake feature.

I will play around with it, anyway.

 

Has generally mystified me to be honest.

I have had it on multiple cars since 2006, and tried it a few times at Porsche events- most recently in a Taycan Turbo S which was astonishingly quick. I have four cars in the garage that all have the feature but never found a use for it not tried it. I suppose it is fun to try it once or twice. Can's use it on a public road without looking insane and it irrelevant for a track day. I suppose if you were racing from a standing start.

I am sure I am missing something so this is not at all a criticism, but what do people use it for?

 

I've gone on a back road and tried it just for the sake of trying it, it's definitely fun...if you're into impressing your passengers its a neat party trick...but practical purposes? Heck no.

 

Same, I’ve owned four cars with a launch control feature but never used it even once on any of them because I never had a use for it. On the street, I never want to launch as fast as possible from a stop light or sign because it would be silly (and sometimes dangerous), and on track I have no use for it either. I guess it could be used for a standing launch on the street in the middle of nowhere, or on a drag strip, or autocross.

 

This is the best I have read on the subject but is not definitive. One person talks about the lag when trying to get away quickly, which is what annoys me:

https://www.718forum.com/threads/lau...control.19502/