Jeff,
Indeed.
Ralph
Indeed.
Ralph
Another Pedal..
- Thread starter ralphmusic
- Start date
There was some interesting data on a German website recently covering gearing and in-gear acceleration of PDK v manual gearbox versions.
So the good news for those that don't like the manual gear ratios, maximum speeds in PDK in each gear, calculated using gearbox and final drive ratios and tyre circumference with my assumption on tyre growth at speed in 4th and above are below:
Obviously PDK 7th is theoretical.
It would appear that PDK is between 10% to 6% lower gearing thru 4th and this together with faster changes that don't unsettle the car in corners should yield benefits on more technical tracks.
So the good news for those that don't like the manual gear ratios, maximum speeds in PDK in each gear, calculated using gearbox and final drive ratios and tyre circumference with my assumption on tyre growth at speed in 4th and above are below:
Obviously PDK 7th is theoretical.
It would appear that PDK is between 10% to 6% lower gearing thru 4th and this together with faster changes that don't unsettle the car in corners should yield benefits on more technical tracks.
Well done for sourcing that Ralph. One thing to take from the figures is that despite the naysayers banging on endlessly about the manual’s high gearing - 2nd gear in particular - the car’s still good for more than the UK legal limit with PDK! In real world driving, rather than the track, I can’t see there being a significant difference.
Jeff
Jeff
I have been trying to see what my 3.8L PDK CS was like as I always ran it up to the auto change point on track but my efforts have been frustrated by data files lacking CAMBUS data to show Gear Selection.
The PDK GT4 accelerates from 0 to 100 km / h in 3.9 instead of 4.4 seconds. The sprint to 200 km / h takes 13.4 instead of 13.8 seconds.
Above 62 mph PDK is not faster, +weight, +10 Nm, -gear change time, or mainly manual at 125 mph being in meat of torque curve v PDK near max revs, if my table above is correct.
Above 62 mph PDK is not faster, +weight, +10 Nm, -gear change time, or mainly manual at 125 mph being in meat of torque curve v PDK near max revs, if my table above is correct.
Just another take on Ralph’s figures comparing the delta speed in each gear, 1st-2nd; 2nd-3rd etc.
Man: 34 32 21 23 28
PDK: 31 30 21 26 35
Can’t see much difference there in the gearing, although subjectively I’m sure progress will feel more rapid with the PDK owing to the shorter gear-shift times.
Jeff
Man: 34 32 21 23 28
PDK: 31 30 21 26 35
Can’t see much difference there in the gearing, although subjectively I’m sure progress will feel more rapid with the PDK owing to the shorter gear-shift times.
Jeff
Twinfan said:
10mph is massive at those speeds, you need a LOT more road to get 10mph faster at 100 mph. I am sure some one will do the maths. but you run out of road fast at these speeds, in fact it could add another 200 meters of road needed to rev it out in 3rd on the manuals.
My issue when I had my 996 GT3 and GT4 was running out of road space and thus never enjoying the engine :-( the extra 3 seconds it takes covers 220 meters !!! if it's 4 seconds that grows to 280 meters !!
the gearings **** no other word for it how ever you play it.
Brian_Innes
Member
David,
You are spot-on with that summary.
As a former hill-climb specialist in a previous life, I know only too well, just how big an effect a few mph of inter-gear speeds at max revs have on overall performance. I used to change the gear ratios on my racing Stiletto Imp's Jack Knight dog gearbox between hill climbs to gain vital seconds, not tenths, in competitive events.
Bringing this up to date, I noticed particularly at track days with my 718 CGTS PDK just how perfectly geared the ratios were for the power and torque curves of the engine. The difference in flow on the track was huge, and definitely not marginal. Even in normal road driving the closer, shorter ratios of the PDK made progress very satisfying indeed.
Brian
You are spot-on with that summary.
As a former hill-climb specialist in a previous life, I know only too well, just how big an effect a few mph of inter-gear speeds at max revs have on overall performance. I used to change the gear ratios on my racing Stiletto Imp's Jack Knight dog gearbox between hill climbs to gain vital seconds, not tenths, in competitive events.
Bringing this up to date, I noticed particularly at track days with my 718 CGTS PDK just how perfectly geared the ratios were for the power and torque curves of the engine. The difference in flow on the track was huge, and definitely not marginal. Even in normal road driving the closer, shorter ratios of the PDK made progress very satisfying indeed.
Brian
Hi Brian, hope you are well.Brian_Innes said:
I don't think people realise, as they are in the main "lifestyle " cars. When you "drive" them on track or hard on the road the longer gearing shows it's ugly head and for me ruins the cars, been an issue even from 996 GT3 days.
And my fight from back in 2003 with the issue fell on death ears, it's only now jurno's moan about gearing lol !!! they are like sheep but no one said it in the 996/997 GT3 and it's the same in gear speeds all these years !!!
you post this on PH and people are happy milling about at 5k revs with the other half and nothing wrong in that of course. Porsche is the affordable "lifestyle" brand.
But owners always come back to me and say my 987 has long gearing and I get battered to death as no one ever agree's but the 9mph is massive, that's just maths.. So I give up with people some times. but as we both know 10mph and finding 300 meters of extra straight is impossible.
Very much looking forward to the GT4 RS PDK, not that any of us will be allowed one :-( as I hope the 2 big GT4 flaws todays will be fixed for the price it will be, ie lower gearing via PDK and that torque limit on the manuals :-( !
only car which works is the 991.2 Manual GT3, and the 3.8 RS with that short final drive with lower gearing and much much more BHP to allow you to get to these speeds in a shorter distance of tarmac, since you went in mine just for that tiny trip, I have fitted CUP LCA all round and that has bought back a ton of steering feels removing the rubber at all 4 ends and also removed a bit of weight with ti exhaust and lipo battery. It's a total weapon now and a rush to drive when you hit 6k. If you are about in 2021 for a tea I plan to at last take the car to Scotland and see what it's all about up there and with your local knowledge I'll be seeking advice for some great roads to explore
or the best over night stop off points. Happy driving D.
Brian_Innes
Member
David,
Always good to share opinions with people who understand the importance of gearing in relation to driving enjoyment on both road and track. Thanks also due to Ralph for posting a very illuminating table of the respective PDK versus manual gearings.
The advantages of PDK lower gearing compared to the manual gearbox is a subject I alluded to in both my 718 threads on this forum. PDK gearing suited the 2.5t 4-pot torque curves so well, and I'm sure the 982 GT4 PDK will also be an absolute rocket on track days. At both Oulton Park and Knockhill my 718 CGTS PDK raised more than a few eyebrows with its blistering track pace.
Good to hear you are planning a trip to Scotland in 2021. PM me when you are making your plans, and I'll be pleased to give you a few pointers towards choosing the must-do roads, stopping points, and the best time of the year for your trip.
Brian
Always good to share opinions with people who understand the importance of gearing in relation to driving enjoyment on both road and track. Thanks also due to Ralph for posting a very illuminating table of the respective PDK versus manual gearings.
The advantages of PDK lower gearing compared to the manual gearbox is a subject I alluded to in both my 718 threads on this forum. PDK gearing suited the 2.5t 4-pot torque curves so well, and I'm sure the 982 GT4 PDK will also be an absolute rocket on track days. At both Oulton Park and Knockhill my 718 CGTS PDK raised more than a few eyebrows with its blistering track pace.
Good to hear you are planning a trip to Scotland in 2021. PM me when you are making your plans, and I'll be pleased to give you a few pointers towards choosing the must-do roads, stopping points, and the best time of the year for your trip.
Brian
Just looking at whether 19" wheels would affect effective gearing. Given some can be specified with 19" or 20" wheels and aspect ratio to suit, these tables illustrate the very small difference in circumference.
The difference with the larger aspect ratio (40 v 35) will in principle be more flex in sidewalls.
The difference with the larger aspect ratio (40 v 35) will in principle be more flex in sidewalls.
Thread hijack warning!
PDK 718 GT4 on track video aka not another pedal
https://www.youtube.com/watch?v=yl8e9ReWRJ8
PDK 718 GT4 on track video aka not another pedal
https://www.youtube.com/watch?v=yl8e9ReWRJ8
Slower than Christian Gebhardt‘s May SportAuto lap of 1:53.9, different driver though....
In Germany, one PDK car for sale and 1Q build slots for mid-engined range seem very limited.
A video by John Teece of BGB in Ormand Beach Fl on their cold air intake system.
https://fb.watch/2u_Ivk9Xsr/
https://fb.watch/2u_Ivk9Xsr/
The End.
Sorry to see that you’ve left the Cayman fraternity Ralph, and many thanks for your forum contributions and input over the years.
A PDK 991.2 GT3 is an altogether different beast and I’m sure it’s going to be an excellent replacement for the GT4. In the best GT3 colour too!
Don’t be a stranger to this part of the forum.
Jeff
A PDK 991.2 GT3 is an altogether different beast and I’m sure it’s going to be an excellent replacement for the GT4. In the best GT3 colour too!
Don’t be a stranger to this part of the forum.
Jeff
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