Best way to launch a 991.2 7MT?
08-20-2021, 01:16 PM
#46
Burning Brakes
Wow, just wow! I don't understand the need for people to give such juvenile responses to the OP's question. I'm not here to defend the OP, but if he wants to launch the car, that's his prerogative. If you don't agree with it, don't click this thread, I know I hadn't until today.
To the OP, I was curious about your question, not quite the same, but this is what Car & Driver had to say about the 992.
To the OP, I was curious about your question, not quite the same, but this is what Car & Driver had to say about the 992.
Some of this blame can be placed on Porsche, though. To protect the driveline from catastrophic abuse, Stuttgart limits the engine to 3500 rpm when the car is stopped. Dump the clutch at that engine speed and the six bogs. Extracting the best from the car requires a careful slip of the clutch, which will undoubtedly shorten its life. But the small hit to acceleration times is an acceptable price to pay for increased driving pleasure.
Last edited by Speed2k; 08-20-2021 at 01:22 PM.
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circuiticon (08-21-2021)
08-20-2021, 01:58 PM
#47
For the manual, launch control wasn't built into that transmission. The manual is held to a soft limiter at 4k RPM at standstill and per the Porsche tech I spoke to when taking delivery of my manual '19 C4S in Atlanta, he emphasized NOT TO rev to 4k and dump the clutch. I have followed his advise and will continue to do so.
There is a previous forum thread of an owner who hard launched and dumped the clutch on his MT 991.2 and suffered damage, the clutch began slipping badly afterward, so he needed an expensive repair.
One is free to dump the clutch on any car one owns, but consequences may follow. Doing hard launches will wear items at a faster rate and if one is willing to accept higher maintenance costs and repair, go for it.
When deciding between a PDK or manual, I compared the fun of a MT minus launch control and power button to the PDK with launch control and the button. The everyday enjoyment of the manual won out over the occasional use of launch and button.
Everybody has different metrics.
Last edited by BSO; 08-20-2021 at 02:01 PM.
08-20-2021, 02:05 PM
#48
RL Community Team
Rennlist Member
Rennlist Member
What is this power button you speak of?
08-20-2021, 04:12 PM
#49
Three Wheelin'
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'til then, here's a rennlist-hosted copy.
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Last edited by jfischet; 08-20-2021 at 04:16 PM.
08-20-2021, 04:52 PM
#50
08-20-2021, 09:17 PM
#51
RL Community Team
Rennlist Member
Rennlist Member
Oh right, that, duh. I typically ignore it because switching to sport+ does the same thing, lol
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BSO (08-20-2021)
08-21-2021, 10:02 PM
#52
To all others, sorry... Not sorry. Get an effing life, mind your business and stop pestering the OP. This is a Porsche 911 forum. To hell with you and your stupid opinions that are not helpful and irrelevant to the topic. It's his car, he paid for it, let him do what he wants instead of debating him. Too much time being keyboard warriors. Go drive your cars and break the tires loose.
Seems like the common denominator in multiple threads is the same one or two people talking smack and debating for the sake of debating. I feel sorry for the people who have to live around this type. What a nightmare.
Seems like the common denominator in multiple threads is the same one or two people talking smack and debating for the sake of debating. I feel sorry for the people who have to live around this type. What a nightmare.
08-21-2021, 10:05 PM
#53
If you look up the numbers, you'll see that the .1 engines develop peak torque at a much higher RPM, around 5k and the torque numbers are significantly less than the 3L turbo.
Also the 3L turbo engines develop peak torque beginning at 1.7k RPM and hold it over a broad range. The 991.2 develops more power and torque at lower displacement in comparison to similar 991.1 models, it's faster.
Also the 3L turbo engines develop peak torque beginning at 1.7k RPM and hold it over a broad range. The 991.2 develops more power and torque at lower displacement in comparison to similar 991.1 models, it's faster.
08-21-2021, 10:07 PM
#54
What year was your Cayman?
08-21-2021, 10:10 PM
#55
God forbid I want to discuss improving the performance of my performance car on a performance car forum.
08-21-2021, 10:25 PM
#56
I'm not saying that doing a 5500rpm launch wouldn't take it's toll on the drivetrain (obviously it would), but I'm saying that if done properly, the drivetrain can handle it. Every other car I own can do it without issue, and my old 987.1 Cayman S did it countless times without issue. Unless they made the new transaxle etc significantly weaker, then I'd wager it would hold up just fine in the right hands. Hell, the PDK launches from a high RPM, and the 7MT is essentially the same trans as the PDK internally. I'm not convinced that the 7MT will explode meanwhile the PDK can be launched 50 times in a row without issue.
My guess is that you can grenade the 7MT (or burn up the clutch) if you do it wrong, and perhaps Porsche had too many warranty claims.
At some point, someone will unlock the stationary rev limit on the .2 7MT and prove it one way or another.
08-22-2021, 12:40 AM
#57
Oh, I'm well aware of that. the 3.0T will make more torque at lower RPM because of boost. Unfortunately, you don't really make boost while in neutral at a standstill. What I'm saying is that if anything, the 3.0T has LESS torque than a 3.8L 991.1 motor when you are comparing them both revving in neutral.
The only way to settle this question is to put a .1 and a .2 of identical configuration on the same dyno under identical environmental conditions and run them from idle to redline, then live with the results.
Everything else is anecdotal.
08-22-2021, 12:43 AM
#58
Launching a MT car is a dance with the clutch and throttle with literally countless variations of how quick you let the clutch out, and how much throttle to give as you release the clutch.
w.r.t. driveline destruction, every car will be different. My 04 Subaru STi would tolerate 5000 rpm clutch dumps (literally side stepping the clutch) and launch like a bat out of hell. The clutch was an upgraded unit, but it started slipping at WOT in higher gears (not holding the torque). My 93 RX-7 likes a high rpm launch, but the clutch is let out 'slower'. I have 'dropped' the clutch on my RX7, but it would then bog down.
I would rather destroy a clutch than the transmission. But best not to destroy either. Neither the Subaru or RX-7 are drag vehicles, and I only launched the Subaru a few times. The RX-7 saw a lot of hard launches on the street, and the only thing destroyed was the powerplant frame which cracked near the front likely in part due to wheel hop. Suspension upgrades (diff brace, solid engine mounts, and upgraded trailing arms) eliminated wheel hop completely and it hooks up and goes. Best upgrade was a set of drag radials.
As for boost, once the engine starts seeing load the boost builds as does the torque (noted on logging), but I prefer to keep my eyes on the road rather than a boost gauge when launching.
08-22-2021, 12:49 AM
#59
Just a note, from the above, when you state that when the .1 motor is "revving" it will make more torque that the .2 motor which also "revving". What comes into play here is that the .2 engine by "revving" will pump more air through the engine and as a result will spin the turbos faster and the engine will produce more power derived from the spooled turbos.
It doesn't work the way you think it works.
Go jump in your car, put it in neutral and rev it to 4k. Watch the boost gauge.
The only way to settle this question is to put a .1 and a .2 of identical configuration on the same dyno under identical environmental conditions and run them from idle to redline, then live with the results.
08-23-2021, 01:49 PM
#60
Rennlist Member
I still loved that car, but once it came off warranty, it was gone.