981 Cayman on its way

[Motorhead]

I know where you're coming from there Kevan. My first car was a 1963 Mini - all induction roar, rattling valve gear and horrendous gear whine..! I had a number of early Golf GTi's - Mk1 1800, Mk2 1800 8V and 16V - and have currently a Mk5. The early cars were great (but not without their NVH problems) but the engine refinement on the Mk5 is very impressive. However, it's completely characterless with no really dominant intake or exhaust sounds, a common feature of many modern engine installations. Now that cars are becoming more refined, manufacturers are aware that sound quality is of great importance to customers but that this also has to match the vehicle type - sports car, hot hatch, limo, etc. One area of importance is the interplay between the intake and exhaust and a considerable amount of time and effort is spent developing these items to produce target sound fields under different operating conditions, a typical example being that of Porsche's "Sound Symposer" for the 991. I believe that one manufacturer even resorts to playing synthesised sounds through the car's speakers.! And it will be interesting to see how manufacturers deal with the greater use of electric traction where there is either no, or limited, use of an IC engine to act as a sound source, where road and wind noise and transmission noise are thrown into prominance. More to the point, it's going to be interesting to hear what the press has to say about the 918 when it arrives. Looking to the future, it will also be of interest to see how quickly the technology incorporated in the 918 filters down to the other sports cars. And please Kevan, don't get me started on features that ought to be included as standard on a £50k car. Jeff

 

[Buddy]

Yes Jeff and mine was a 1962 A35 van with windows in the side so ditto, engine rattles from valve gear certainly improved once OHC using bucket tappets became the norm, it's one thing to have an engine sound for the driver since a lot of people drive as much to the sound and feel as to the rev counter and it is easy enough to rig an amplifier to do just that within the car and even to make it quite realistic but I'm sure that someone who sets sound level requirements for motor vehicles on the road is only considering keeping noise levels below a set maximum level, that is one thing but in interest of road safety it's about time that they make a minimum sound level as many cars and not all being electric make more noise from their tyres as anything else. But going a little off topic, it's also about time that they make it a legal requirement that pedestrians and cyclists have a level of responsibility for their own safety, in the past three days I've had one pedestrian walk out in front of me because he a) wasn't taking notice of anything and b) had earphones on. A pair of cyclists today were weaving around on the road and just rode straight out at a junction[8|] Darwin was right but try saying it if you hit one of these idiots. And in parting for the night, I had an email from the Sheffield OPC saying that they have the 981 Cayman Launch evening on the 8th March which is a Friday.[]

 

[Motorhead]

Strangely enough Kevan, I learnt to drive in my dad's A35 van (without windows!). What a beaten-up heap that was - my dad had an electrical contracting business and most of his clients were in the West End of London so, as you can imagine, it was extremely battle scarred. The mechanicals generally were OK (the brakes needed to be for London driving!) although the synchro on 2nd, 3rd and 4th was decidedly suspect but it was good fun to drive with it's light body and skinny cross-ply tyres. Happy days..! How vehicle technology has moved on in the past 50 years. Manufacturers certainly do have target interior sound levels for different driving conditions based upon experience and measurements from competitor image vehicles. But the emphasis now is on sound quality rather than actual sound pressure levels (SPL) or graphs, where actual aspirational sounds are generated based upon sound recordings of in-house and competitor vehicles (using a binaural head) which are then subjected to subjective and objective evaluation, including expert and non-expert jury evaluations. As we've both noted, as cars' powertrains become more refined and quieter, so wind noise, structure-borne road noise and tyre noise become more prominent, the latter even more so with low profile wide tyres with very stiff sidewalls. This is certainly a problem for interior noise but perhaps is even more so for exterior noise, where most of the noise certainly seems to emanate from the tyres rather than from the powertrain. The current vehicle pass-by regulations, where a car is accelerated from 50kph(?) through a controlled area and the measured SPL must not exceed a certain level, are targeting mainly powertrain noise but I believe that the test is about to change. Hopefully it will address the importance of tyre noise which will be the major source of noise for electric vehicles. Interesting that you should mention cyclists and pedestrians as, in addition to being a petrolhead, I'm a keen cyclist and walker. There was a very interesting and somewhat scary documentary on the BBC recently on the battle between car drivers and cyclists. Although it appeared to be a bit London-centric, there seemed to be a lot of stupid actions and aggression on both sides. Each has a responsibility to the other but being a good driver and a good cyclist requires a lot of thought, concentration and consideration; not always the case I'm afraid. And pedestrians are often their own worst enemy - oblivious to what's going on around them by listening to music, or worse, texting..! Still awaiting my PC invite to the 981 Cayman launch. My mate Rog, in particular, will be looking forward to the wine and canapes..! Jeff

 

[chrisH]

Jeff & Kevan, Yes, my first car was a Mini Cooper so will always remember those days of every 3000 miles servicing and plugs & points needing adjusting after 1000 miles. Should we meet up on the Factory Visit this will be one for a few beers at least. As this has all got a bit off-topic I wonder if I can refocus you? Has anyone read your copy of the December Christophorus Magazine as there are some very nice pictures of the 981 Cayman and some not so convincing "marketing facts" about how its design is based on the 910 and the engine is only 30cm from the driver's heart and has a lower C of G, the bonnet and rear hatch is now made of aluminium. Strange this was never mentioned when the first Cayman was launched in late 2005 unless of course this was not true of the Gen I car[] I can't see how it can be that much different from the Gen II, or the Boxster 981 in particular and what about the 987 Spyder?[] Chris

 

[Motorhead]

Yes Chris, the usual Christophorus mumbo-jumbo but, as you say, some excellent glossy pics there. Very photogenic in yellow and it will be interesting to see the car in all its colours during daylight. An interesting combination of aluminium and high-strength alloy steels in the body construction. But apart from the doors, bonnet and rear hatch I note that there's still a lot of steel there. I don't think that the engine position relative to the driver has changed very much between the 987 and the 981 and the extra wheelbase has been used to increase legroom. The overall package dimensions for the Gen I and Gen II powertrains will be very similar too. Jeff

 

[Buddy]

Well I don't get the Christophorus magazine regularly although one does occasionally arrive though not this month as yet, I do question the lower CofG though as if doors etc are alloy and glass is still the thing to make windows of then they are taking weight out low down around the same height as the CofG and the glass I take it remains in the same positions or thereabouts which could mean a Cof G moving upwards, glass is heavy. Ok, I don't know the whole thing about the weights and distribution but it sounds like marketing talk. The bonnet was, after all, alloy in the Gen1. And yet, overall weight is said to be down compared to the earlier, smaller car so it's gone from somewhere so are the wings alloy?. From what I'm hearing most of the weight is relatively low in the overall dimensions of the car. Also, if the driver's heart is 30cm from the engine that must mean when the driver's seat is on the furthest forward position so given that the seat rails are longer in the new model to extend leg room then that means that in Gen1 & 2 we are closer and that as I have my seat well back then I'm closer to mine than I would be in the new model. I'd be more interested in how the new seat position effects the feel of the balance.

 

[Motorhead]

Looking at a pictorial material breakdown of the bodyshell Kevan, in addition to the doors, bonnet and rear hatch, there appears to be extensive use of aluminium in the platform. But high strength steels (micro-alloyed, multi-phase and boron-alloyed) are still used in critical areas such as the A-post, inner wings, cantrails/roof frame, door sills and door crash beams. It's not clear what material is used for the wings and roof but I suspect that they'll be steel. Porsche says that aluminium accounts for around 44% of the entire bodyshell and there's about a 40kg weight saving compared with the 987. Not great, but there's a 33% increase in the static torsional stiffness to 40,500Nm/deg compared with 30,100Nm/deg for the 987 Cayman. Jeff

 

[chrisH]

Jeff, Indeed these are the only real facts comparing the 981 and 987 but they dont explain how they achieved a lower C of G in the 981 although the whole car sits 10 mm lower in height so do you think maybe thats all there is to it? It would be interesting to see a side view of the 981 and 987 Caymans for comparison. Chris

 

[Motorhead]

The lower overall height must help lower the CG Chris, but as Kevan pointed out, glass is heavy and the evidence seems to point there being a larger glass area (screen and rear hatch) in the 981 compared with the 987, which would have the effect of raising the CG. Have you seen any figures indicating how much the CG has been lowered? Even 1mm would have the marketing team making that claim..! Jeff

 

[Buddy]

I don't think I've heard of the 10mm lowering which in a 987 would lower the CofG but in the calc's it depends on what is where regarding the height and position of the various weights 44% of any car being aluminium must I expect be by volume of material since from memory steel is 0.27 lb/cubic inch while aluminium is 0.1 ok engine block, heads, gearbox cases and wheels take quite a % of the material used since these comprise the "big lumps" but then change the doors and a few other items and well it becomes a slight but reportable weight saving and since these items were already aluminium or light alloy then there must be a significant number of parts which have gone from steel to alloy or plastic to save weight. I don't recall what the weight of the 987 and 981 Caymans are but since the width at the front is increasing it would be interesting to see a breakdown of where the changes are.

 

[chrisH]

ORIGINAL: Buddy I don't think I've heard of the 10mm lowering which in a 987 would lower the CofG but in the calc's it depends on what is where regarding the height and position of the various weights 44% of any car being aluminium must I expect be by volume of material since from memory steel is 0.27 lb/cubic inch while aluminium is 0.1 ok engine block, heads, gearbox cases and wheels take quite a % of the material used since these comprise the "big lumps" but then change the doors and a few other items and well it becomes a slight but reportable weight saving and since these items were already aluminium or light alloy then there must be a significant number of parts which have gone from steel to alloy or plastic to save weight. I don't recall what the weight of the 987 and 981 Caymans are but since the width at the front is increasing it would be interesting to see a breakdown of where the changes are.

Kevan, Had a quick look on the Porsche website and it states 981 Cayman height as 1294mm whereas the 987 was 1306mm so the 981 sits 12mm lower. I think this is due to a lower roofline but as you say there is more glass area in the windscreen and hatch so who knows how much change there is in C. of G. Chris

 

[Motorhead]

I wouldn't expect a really significant change in the C of G position Chris and if you specify PASM the car is lowered by 10mm anyway; 20mm I think for the sport suspension option on the Boxster which will undoubtedly be offered on the Cayman at some time too. I'll bet that the improvements claimed for the 'Ring times are more likely to be due to the longer wheelbase and wider track of the new car rather than a slightly lower C of G. Here are some interesting figures for unladen weights obtained from Porsche's own car configurator: 987S 1350kg 987R 1295kg 981S 1320kg So according to these figures, the new car is only 30kg (not 40kg) lighter than the old model and the R is still 25kg lighter than the new car although I don't think that essential items like a radio and aircon are included. I note also the height of the R is given as 1285mm owing to it's lowered suspension. Jeff

 

[Buddy]

12mm lower in the roofline, by taking the doming out of the roof that would be sufficient, have ground clearances changed? To lose 30Kg between the 987 and 981 is significant since I expect they are comparing like for like or as close as possible. This talk of weight reduction does make me wonder if the volumes of materials have changed since the greatest reduction achievable is in as Colin Chapman put it "adding lightness" which meant removing metal and adding air. Use of aluminum can help as it is possible to make critical items using large cast or forged components to put more space into a design.

 

[flat6]

Some 981/991 comparison pictures here. (No great substance in the the thread itself) http://www.germancarforum.com/community/threads/official-2013-porsche-cayman.47617/page-3 http://www.germancarforum.com/community/threads/official-2013-porsche-cayman.47617/page-4

 

[chrisH]

ORIGINAL: flat6 Some 981/991 comparison pictures here. (No great substance in the the thread itself) http://www.germancarforum.com/community/threads/official-2013-porsche-cayman.47617/page-3 http://www.germancarforum.com/community/threads/official-2013-porsche-cayman.47617/page-4

Maybe, but worth a read and this quote from the thread says it all[] I'd definitely pick the Cayman over a base 991. 991 still looks good, but it has become more of a GT and less of a sports car in it's proportions.

 

[Buddy]

Agreed, I would buy a new Cayman S ( subject to the lottery ticket I need to check ) in preference to a 991 as I do not need more than two seats and for two going most places there is plenty of luggage room. It also satisfies all of my sports car requirements given the correct options are ticked so, what's not to like? I just picked up GT Porsche today where there is an article but no driving report as yet. I was concerned about the hatch arrangement but it actually does look good and suits the car admirably, the one aspect of this is that even more will now thing it's a 911, I've heard school boys passing my house pointing it out as a 911 turbo due to the side intakes![]

 

[Motorhead]

ORIGINAL: Buddy 12mm lower in the roofline, by taking the doming out of the roof that would be sufficient, have ground clearances changed? To lose 30Kg between the 987 and 981 is significant since I expect they are comparing like for like or as close as possible. This talk of weight reduction does make me wonder if the volumes of materials have changed since the greatest reduction achievable is in as Colin Chapman put it "adding lightness" which meant removing metal and adding air. Use of aluminum can help as it is possible to make critical items using large cast or forged components to put more space into a design.

There are some interesting comparisons between the 981 and 987 in these side-by-side pics Kevan: http://www.pistonheads.com/gassing/topic.asp?h=0&f=48&t=1158356&mid=0&i=260&nmt=All+New+981+Cayman+%2D+Out+in+November&mid=0 The lower and flatter roofline, more steeply raked (and larger) windscreen and raised rear hatch profile are clearly evident but the side profile below the top structure appears to have changed very little - similar ground clearance and wing height above the wheels for instance. The smaller front and rear overhangs are also apparent. Replacing lower stressed steel items with aluminium parts clearly has helped reduce the weight but, as I said previously, high strength alloy steels are still used to reinforce the bodyshell and doors in critical areas for crash impact/roll-over safety. However, the 987 also incorporates a significant number of these high strength alloy steel components too but material and manufacturing technologies have moved on since the Cayman's introduction in 2005 and I wouldn't be surprised if the equivalent 981 components aren't lighter and stronger. No doubt Porsche have also looked at taking weight out of cast and forged suspension components without sacrificing strength and durability. Some weight saving has also been achieved by adopting electrical assistance for the steering. Maybe the deletion of the PAS pump accounts in whole or part for the extra 5hp claimed for the 981 engine over that in the 987? Agree wholeheartedly with your comments on the 981 vs 991. I see that the Cayman badge on the hatch is a deletable item in the options list - perhaps it could be replaced with a Turbo badge..! Jeff

 

[flat6]

Hi Engine Connoisseurs [] I've just posted the Spyder and R power / torque graphs here http://www.porscheclubgbforum.com/tm.asp?m=719756&mpage=36&key=&#736902 . The Spyder is identical to the Cayman S. I'd like it if you would come over and comment on R's engine gains over the Cayman S engine. Many thanks Cecil

 

[Motorhead]

An interesting compararison Cecil since you've had plenty of previous Cayman driving experience in addition to that on your current Spyder. As you say, the R has slightly more power - albeit at higher revs - than the S/Spyder but they have identical torque figures. I'm sure that this is achieved by the R's revised (freer flowing?) exhaust manifold, which would tend to enhance the top end performance, and also by DME tweaks since the engine developers have so many tunableable functions which are controlled by the DME: 1) DFI - Fuel can be injected at dfferent times and in varying quantities throughout the power stroke; 2) Inlet valve timing and lift - +/- 20deg of crankshaft advance/retard in conjunction with low and high lift camshaft lobes; 3) Ignition timing; 4) Intake resonance manifold operation - to optimise induction airflow and boost mid-range torque. I suspect that Porsche have tweaked the first three to boost the R's power but have left the fourth option alone. Relatively small power gains are a regular feature of model year upgrades and are part of the normal development cycle. For example, Porsche have boosted the power of the 981 Cayman S by 5hp compared with the Gen II car. Jeff

 

[flat6]

Thanks Jeff[]. I've responded over on the Spyder thread.