Any Rennlisters from New Zealand?
05-05-2015, 03:18 AM
Intermediate
Join Date: Mar 2015
Location: Auckland NZ
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I bought the Gembella equipped 964 from that guy , difficult to deal with , backed out twice on me , but I had just sold my 356 speedster and wanted another toy quick and his was the only C 2 manual even vaguely for sale - rang all the specialists and they all laughed when I told them I wanted a C2 manual , so I dug up all the old ads and got ringing. Looking at where prices have gone overseas , it was a good buy , have had it out at Hampton and runs strong.
I'm now running the fibre glass boot/wing off it haha.
05-05-2015, 03:29 AM
Walt Im not an engineer but the downforce on the new 991 GT3 and 981 GT4 is around 180lb rear and perhaps half of that at the front. If you look you will see the sidewall rating has increased for N rated tyres for those models over the Carrera S with 20" equivalent OEM wheels/tyres option. Additionally 991 GT3RS is now at 300lb rear down-force and front has increased too. The rear/front tyre wall stiffness has agin increased over 991 GT3/GT4 for the OEM Michelin N rated tyre the car ships on. All this is from memory so I cant quote down to the lb but at 200kmph rating PAG have found it necessary to increase sidewall stiffness of base model with same size tyre (assumes also similar weight and F/R weight bias). So aero is definitely a real component in the equation particularity for the newer performance models now that PAG are focusing on this aspect of their car design to ever lift the bar.
The GT3RS may be starting to get there but looking at your Carrera S vs GT3 example, and stirring in the P1 I mentioned earlier illustrates how other performance factors outweigh aero for torturing tyres on cars like ours.
Using your top speed at Hampton as a reference point, the GT3 is making about 60 kg of aero downforce at 230kph while the McLaren P1 is pumping out over 450 kgs at that same speed.
With the GT3, that force is on top of 750-800 odd kgs of car already over that axle - ie only 8 percent more downforce from the aero than from the weight of the back of the car. The 991 Carrera S has some aero downforce too so the actual difference in total rear axle pressure will be smaller than that 8% even at that speed.
At lower speeds it rapidly becomes a trifle of course, since downforce and drag are proportional to the square of the speed. The GT3 would make roughly 13kg of aero downforce at 100kph and about 50kg of it at 200kph.
So on to other factors then to explain the difference in tyre ratings from the Carrera S. The 991 GT3 is only a smidgeon heavier than the S, but I suspect that it's lower centre of gravity, wider track, higher top speed, 19% higher power output and expected heavier track use compared to the Carrera S work together (along with a small contribution from aero) to put much higher expected demands on its tyres, hence Porsche up-speccing them.
[Sorry Dave - maybe we should start a technical board but I'll just resume normal transmission instead]
05-05-2015, 03:37 AM
Rennlist Member
Fair points Walt. I was just bringing to the fore that aero is now an active component of manufacturers tyre specifications and that this will become more so with the advent of cars like P1, 918 etc which have significant active and passive aero built into the design.
When selecting a modern non N rated replacement for an older Porsche one must recognise that side-wall stiffness even on off the shelf sizes has increased with time to counter improved performance/power, weight and in some cases, as discussed, aero. Unfortunately the fact remains that performance road tyres in the 16 &17" categories are receiving only limited investment by tyre manufacturers these days who seem to be focusing their efforts more on the 19,20 & even 21" fitments.
P.S. I agree its a dry subject and we should allow normal transmission to resume :-)
When selecting a modern non N rated replacement for an older Porsche one must recognise that side-wall stiffness even on off the shelf sizes has increased with time to counter improved performance/power, weight and in some cases, as discussed, aero. Unfortunately the fact remains that performance road tyres in the 16 &17" categories are receiving only limited investment by tyre manufacturers these days who seem to be focusing their efforts more on the 19,20 & even 21" fitments.
P.S. I agree its a dry subject and we should allow normal transmission to resume :-)
05-05-2015, 04:22 AM
Instructor
Join Date: Apr 2014
Location: New Zealand
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He had it on buy now at one stage at ~ $33,000. I thought about the domestic ramifications of another car and decided it was too good to miss, but in the interim he had done another price change to $38,000. Sounds like I might have had some grief settling even if I had hit the low buy now. Great to hear it's running well.
05-05-2015, 05:22 AM
Good tyre grip wise and pretty quiet but they loose air, I've had to fit a tyre pressure monitor in my T5 to keep on top of tyre pressures.
My wife's old Polo had mew hankooks as well, same issues.
Michelin Extreme Contact DW on my Jetta are epic but like Macca says had to import them myself which might be an option for the Porsche.
05-05-2015, 06:07 AM
Burning Brakes
Join Date: Feb 2014
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05-05-2015, 07:03 AM
05-05-2015, 07:16 AM
Rennlist Member
I see 6 x 964 for sale on TM 35k-50k! What a damn shame there isn't a cost effective tipo to manual conversion for these :-). Even a software reboot with a lighter fly when could be devised surely to bring the tipo back to 21st century? Seems a shame given some are low km cars with decent spec...
05-05-2015, 07:29 AM
I see 6 x 964 for sale on TM 35k-50k! What a damn shame there isn't a cost effective tipo to manual conversion for these :-). Even a software reboot with a lighter fly when could be devised surely to bring the tipo back to 21st century? Seems a shame given some are low km cars with decent spec...
Even more so I remember a nice 77 911 getting all the way down to 12k before it sold
Must have been tough times for some.
05-05-2015, 08:01 AM
Rennlist Member
I have seen them advertised for 40k+ but I have not heard one selling for over 40k. Unless someone here has heard otherwise?
One of the Best 964 for sale IMO is the red race car of Seans on TM. The engine is a work of art. 350+ hp and a gearbox built to match with cup ratios. Jeff Knows how to build race 3.6s - one of the top builders in USA for 3.6 race units from memory it's upgraded all the way down to the crank including oil pump. Couldn't have that engine and gearbox built today for much less than Sean would sell it for...will make some racer a happy man
One of the Best 964 for sale IMO is the red race car of Seans on TM. The engine is a work of art. 350+ hp and a gearbox built to match with cup ratios. Jeff Knows how to build race 3.6s - one of the top builders in USA for 3.6 race units from memory it's upgraded all the way down to the crank including oil pump. Couldn't have that engine and gearbox built today for much less than Sean would sell it for...will make some racer a happy man
05-05-2015, 08:14 AM
Addict
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Join Date: Dec 2003
Location: Auckland, NZ
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There's a blast from the past. I was living in the UK and joined that UK 964 Smartgroups forum in 2000 or 2001 - then bought my first 964 - red C4 like John Miles in sometime in 2001. Good times - hard to believe they were only 10 years old at that stage.
05-05-2015, 04:21 PM
Rennlist Member
I see 6 x 964 for sale on TM 35k-50k! What a damn shame there isn't a cost effective tipo to manual conversion for these :-). Even a software reboot with a lighter fly when could be devised surely to bring the tipo back to 21st century? Seems a shame given some are low km cars with decent spec...