Cayman GT4: Where are we up to now?

[Motorhead]

Thanks Frank. Some more useful details there including the fact that the side intakes are also used for engine cooling. Presumably some air is bled off before those large engine intake ducts shown in P10 of the document and I think that some air is also channeled from the underside for engine cooling. On my 987.2 the R/H side vent is used for exhausting air [fan-assisted] from the engine compartment but I'm not sure how this is accomplished in the 981 where both intakes feed the engine intake and cool the the engine. I don't think that fitting the transaxle is the problem since it's only modified internally, and therefore dimensionally identical to that used in the other 981s, but apparently it is the block which has had to be machined for it to fit in the Cayman's engine bay. Quite how our American friends have managed to shoehorn the 991S lump into the 981 I'm not sure; maybe a bit of "tin bashing" was required. As you say, our presumption that the bonnet vent provides a degree of downforce was correct, but there's no mention of it being used in conjunction with a centre coolant radiator. Maybe the race car version will incorporate a centre rad, like the GT3. Jeff

 

[fbr]

Ralph Surprised you are not tripping over the border into Portugal to see all the live action. Look on the PCNA for live updates https://www.pca.org/news/2015-03-06/cayman-gt4-first-drive-live-updates You seem to be in the wrong club . Jeff - looks like the centre radiator is in the usual place just below the number plate on bumper. Look PCNA G. red image SGO 1208. The side air intake lies above the induction intake on both sides and at least on the 981S/GTS models is thermostatically fan assisted on both sides. I assume it vents out through the wheels arches (note the negative pressure inducing flaps ahead of the "mudguards") and out round the rear diffuser. The description of the new rear axle and the fitting are given by Preuninger in one of his many interviews. Frank

 

[Motorhead]

Frank, If indeed that's what it is, well spotted re the centre rad. There's certainly something lurking behind the mesh. I'm assuming that the PEC Silverstone will have a GT4 this month or next, so I should get a peak when I'm up there for an R10 meeting. Porsche appears to have taken a different approach with the side intakes on the 981 compared with the 987 where the fan blows air out of the R/H side intake. Presumably it means that now there are 2 air filters rather than 1 filter to replace.....more expense.! Jeff

 

[ralphmusic]

Plus ca change? From April 2015 Octane magazine page 101 by Simon Kidston "On an Autumn day in 1972 the salesman from Porsche GB came to visit our house. 'We're making a special car,' he told my father. 'Only 200 will be built, and we're offering them to our best clients first as demand is sure to be strong.' They built more than 1500 in the end, and demand was so great that, instead of management to use them as company cars to use up unsold stock as expected, Porsche sold out the first batch of 500 immediately and had to build two more series." Demand forecasting on the 2.7RS before the Internet...

 

[Motorhead]

ORIGINAL: fbr The description of the new rear axle and the fitting are given by Preuninger in one of his many interviews. Frank

Frank, I may be wrong but I think that when Preuninger refers to the "new rear axle" he's referring to mods to the rear suspension rather than to the transaxle itself. Probably just German terminology at work there. Jeff

 

[chrisH]

ORIGINAL: Motorhead Frank, There's certainly something lurking behind the mesh. I'm assuming that the PEC Silverstone will have a GT4 this month or next, so I should get a peak when I'm up there for an R10 meeting. Jeff

I was at PDE on Friday and noticed a Cayman GTS manual had the middle radiator too, their rep.suggested it was due to the GTS PU styling but he admitted he was guessing. They expect to get pre-production GT4 and GT3 RS for track use only due to the demand. The CS manual I drove was quick and had buckets and PCCB, very impressive car, the buckets give the ideal driving position due to the fixed back rest and are very light to adjust fore / aft. The instructor said he prefers the GT3 as it is a more challenging drive than the Cayman, but he is a Cup driver. PS I know you don't like the 981 electronic handbrake, he told me just pull away and of course it disengages itself.

 

[fbr]

Jeff Try this link for more details: http://www.ausmotive.com/2015/03/03/porsche-cayman-gt4-in-detail.html I think there,s enough space in the back of the 981 to avoid "metal bashing" Frank PS If you look carefully you will spot the lightweight dump valves on the air inlets just ahead of filters. They seem to act to enhance the air ram effect on the side inlets They are linked to the MAF sensors and are used in full dump mode on the overrun to aid engine cooling. Do you think this accounts for the performance benefits associated with the side scoops/blades? PPS Chris - the electronic handbrake works just fine and used in the mode you suggested it acts better than the old fly off handbrake. It's the stop-start system that's the pain. It's function is not linked with the handbrake, so when you stop on the foot brake the engine stops, activation of the handbrake and release of the foot brake promptly restarts the engine. Next you speak to the salesman tell them you think the central radiator acts to keep the boot cool to aid the transport of perishable items. PPS maybe I should add a to the first PS before it's propagated by any enthusiastic car salespersons. Sorry for the edits but I'm sitting in a remote place with an iPad and enjoying a hot drink!

 

[Motorhead]

Excellent! Well done Frank for sourcing those tech details; the front centre coolant rad, ducting for the engine intake/cooling and the rear suspension mods in particular. I'm not quite sure what part you're referring to re the dump valves but does the arrangement actually differ from that of the standard cars? Regarding the reinforced transmission, in the EVO interview Preuninger says it features "a beefed-up gearbox from the Cayman GTS and a peak torque limiter inside that thing [???]" together with a lightweight dual-mass clutch system. Chris - I was a the PEC yesterday and spoke briefly with the manager there who reckoned he wouldn't get a GT4 until July. Interesting comments regarding the bucket seats. I drove a Cayman R round their handling track a few years ago and was suitably impressed with the buckets but I'm not totally convinced that they offer all that much over sport seats, even on the track. They look good though..! Electric handbrakes..? I can understand why manufacturers are fitting them since they free up a lot of space on the centre console but I just think that Porsche's implementation [location and mode of operation] is just a bit naff. Whether or not we like it, stop-start systems are here to stay...and at least they can be turned off if desired. Jeff

 

[ralphmusic]

ORIGINAL: Motorhead peak torque limiter inside that thing.. Jeff

I think you will find torque limiting is a standard ECU tune feature, look at Cayman S, GTS and base Carrera torque in 10Nm increments, the 3.4 is ECU constrained. Ralph

 

[Adam2S]

Another good review here by Georg Karcher (Automobile) with a 144 pictures! [] http://www.automobilemag.com/reviews/driven/1503-2016-porsche-cayman-gt4-review/ Georg also talks about the Boxster Spyder towards the end of the article, saying: "Overall, though, this is as close to a bargain Porsche as they come. Starting for $85,595, the GT4 is about $10,000 more than the Cayman GTS, but it undercuts its closest in-house rival, the 991 GTS, by around $30,000. Not a bad deal, but you’d better act fast. Fewer than 1,000 GT4s are coming to the United States. Those who miss out might want to put their name down for the 2016 Boxster Spyder, which gets a 375-hp engine with a manual transmission but none of the chassis parts that make the GT4 so special."

 

[MrDemon]

well all the main guys are driving the car on track today Dicky Meaden and Chris Harris plus the rest of the normal guys. will be interesting. I guess Chris will be on you tube 1st followed by the EVO in the next issue.

 

[fbr]

ORIGINAL: ralphmusic

ORIGINAL: Motorhead ...peak torque limiter inside that thing (???) Jeff

I think you will find torque limiting is a standard ECU tune feature, look at Cayman S, GTS and base Carrera torque in 10Nm increments, the 3.4 is ECU constrained. Ralph

Ralph & Jeff You've got much too comfortable with modern foolproof transmissions with their lightweight hydraulically assisted clutches. I think Preuninger was referring to the beefed up GT4 gearbox, clutch and a new/uprated (?) torque peak limiter and not the ECU. In truly "analogue" days it used to be sacrificial shear-pins that protected your transmission from overenthusiastic clutch release, leading to a box of loose coggie bits or broken half shafts. Those were the days! Especially if you mismatched engine power to transmission a la the "hot rodding" that Preuninger associated the GT4 development with. [link=http://www.schaeffler.com/remotemedien/media/_shared_media/08_media_library/01_publications/schaeffler_2/symposia_1/downloads_11/luk_k7_chap03.pdf]Here's a very boring German technical link that explains the operation of torque limitation in modern hydraulic systems.[/link]. I came across this especially for Mr D . Why compromise?

Frank ..Do we still need this strange two step with uploaded images? PS Winter back with a vengeance again today. Just right for the release of suitable boots for the GT4 - I might even be tempted espeicially since it has a hard top.. To ensure the Cayman GT4 is prepared for difficult winter driving conditions, Michelin is the sole supplier of the winter tyre option for the car too. These come in 235/35R20 92V XLTL Pilot Alpin 4 N0 and 275/30R20 97V XLTL Pilot Alpin 4 N0. Does anybody really intend to drive a GT4 on the road?

 

[clubsport]

C Harris, obviously likes it. He is spot on about fitting the GT4 into the Porsche line up and picks up on that gearing. Shame it's wet sump and 22% Lsd with it's track aspirations? https://grrc.goodwood.com/road/drives-and-rides/porsche-cayman-gt4-driven

 

[fbr]

Damned by faint praise?

 

[chrisH]

ORIGINAL: clubsport https://grrc.goodwood.com/road/drives-and-rides/porsche-cayman-gt4-driven

There are some great shots of the different colours here. What is your favourite?

 

[spyderman]

ORIGINAL: fbr Does anybody really intend to drive a GT4 on the road?

Not everyone has a trailer or a tow car!

ORIGINAL: chrisH There are some great shots of the different colours here. What is your favourite?

Shouty yellow for me please! Chris.

 

[MrDemon]

safe white for me... or Carmine red last minute change ... ;-)

 

[chrisH]

White for me with the satin black wheels and wing supports, red seat belts.

 

[Motorhead]

ORIGINAL: clubsport Shame it's wet sump and 22% Lsd with it's track aspirations?

What do you expect for £65k Paul? Given the restricted budget, adding the PTV Plus electronic rear diff lock used in the GT3 [different transaxle] and dry sumping the engine would have been much too costly. We'll have to see what turns up in the promised race car. Jeff

 

[clubsport]

ORIGINAL: fbr Damned by faint praise?

It's hard when the larger sibling with the motorsport engine exists. The car could have been so much more with a bespoke engine and diff or gear ratios, but then the price would be much higher. This does seem more of a Clubman's GTS, than an Motor sport car, which is no bad thing in the Porsche range. Interesting to see the perception of it a year on from customer cars being delivered......?