Q&A Porsche discussion

[Schwalbe]

^^^^ I think in the same direction as you nthfinity. I believe that you determined very well the problem. I read several similar report caused by high performance turbocharged engines who generate a lot of heat in engine bay. In spite of that, for a Gemballa of this price, I believe that it's normal to have a little more reliability.

[lakatu]

Originally Posted by lakatu Thanks st-anger for your reply. I don’t know about you but these PM we share back and forth are the best part of JW. I sometimes feel a little guilty though that everyone else is missing out on them . The data that I got for the 965 365hp was from http://www.bmwdeler.no/ 20,600 km 8,32 = 145 km/h Porsche 964 Turbo 365 ps, Sport Auto 1992. Do you think that this test for a 365hp 964 Turbo is the 911 Turbo “S� which you indicated was 380hp? Maybe this isn’t the Turbo “S� but a modified 965? I noticed that SA also tested the 964 RS but their time was slower 20,600 km 8,28 = 146 km/h Porsche 964 RS 260 ps, Sport Auto 1992 along with the WR time 20,832 km 8,15 = 151 km/h Porsche 964 RS 260 ps. Is WR that better of a driver or more familiar with NS than HvS to be able to post a 13s time advantage. Correct me if I am wrong but isn’t 13s a huge difference? On the cornering speed issue, I don’t doubt what you said, that less than 500 hp doesn’t make a difference on a track. (I am assuming that what you said applies to all tracks and not just to NS). Certainly, what you said that ALL time gains were due to higher cornering speeds fits the results of posted lap times. However, I still don’t understand why that is ? Maybe the way I am thinking about racing on a track is wrong. I figure the lap time is a function of average speed. As I have mentioned before it seems like the longest portion of the track is spent accelerating and the difference between taking a turn at 1g verses 1.25g’s is minimal (3mph at 50 ft radius for a car pulling 1.25g verses 1g). Certainly the speed is dependant on the radius of the corner but I think a 50 ft radius corner is a good approximation for a tight turn. The speed differential would obviously be greater for a higher radius curve for the car that had a 1.25g cornering ability verses 1g. However, at least as far as street cars go, the difference in cornering power is rather small. For example, comparing a 965 to a 996. The 965 Turbo “S� might corner at .9g (maybe higher I’m guessing it is at least .9g) and a 996 of .95g. Yet the NS times are huge, 8:32 for the 965 Turbo “S� and 8:17 for a 300hp 996. That .05g difference shouldn’t translate into that much faster of a cornering speed should it? Now I know that I am basing the cornering power measurement on steady state radius corner and that it will be different for different radius turns but I think the lateral g differential should approximately be the same. Now compare that small mph cornering difference to the mph difference due to acceleration. If you look at trap speeds at the end of a quarter mile they should be significantly higher for the 965 Turbo “S� than a 996. It looks like to me there is more time spent accelerating and the speed difference due to acceleration is higher. So a higher speed differential of acceleration over a longer period should translate into a higher average lap speed and time for the car with the most horsepower to weight ratio and that cornering speeds should be approximately equal if there is only a .05g difference. Certainly, aerodynamic resistance has to be a factor also at higher speeds for the much more aerodynamic 996. So again I don’t doubt what you said about power to weight ratios not being a factor until they are really extreme. I feel like I am missing something here but I don’t understand what it is .

Originally Posted by st-anger What i wnated to tell you is that cornering is that important because as you totally said right that most of the time the car is accelerating and stuff - you know it - BUT if you don´t have a 500hp car where you can gain from it´s engine power on the straights cornering speed is the most important factor, just see the GT3RS, only 380hp, very good power to weight ratio, very fast cornering speeds, so why is it among other things faster than a 500hp car, because you can enter corners earlier due to less weight, AND you can accelerate way earlier, so cornering speed goes together with speed on the straights and that´s why cornering speed is that important... and again, on the older tests i can´t provide an educated comment, since id on´t know circumstances - i know 13sec is VERY much on NS, with such drivers and such cars even 3 to 4 sec is quite a lot, but again, NS times are different, from what i know, i´d say "yes" WR is an outstanding driver, on NS i´m sure no one in a Porsche is faster than Walter, but again, conditions are the main factor on NS, it´s not unusual that parts of the track are completely damp, temperatures, maybe the one test took place in spring at 15°C the other one in Aug at 33°C ... to really compare cars on NS the same day, same time, same driver is required, and even then there might be huge differences, you simply can´t clock exactely the same lap times on NS, too long, too difficult and even drivers like HvS and WR make minor mistakes on a fast lap....NS is different, that´s the main point you should know and learn, so NO maths, no comparisons, no figures from other mags, etc ...

After I received this PM from st-anger I came up with a thought experiment that helped me better understand these concepts.

Imagine two identical cars with one expectation, car A is able to corner 2.4 km/hr or 1.5 mph faster in any corner than car B. Now imagine that you are timing these two cars on an unique race track which is essentially a high speed banked oval with one sharp corner.

The cars begin by accelerating from a standing start.

At the beginning the cars are side by side until they reach the corner. Car A then is able to negotiate the corner and emerge at the end of the corner traveling 2.4 km/hr faster than car B. The cars then accelerate around the track. Assume that the cars are able to continuously accelerate thought out this track at a constant rate i.e. they are not able to reach a speed where aerodynamic drag significantly affects the acceleration nor do they reach a top speed.

If this is the case then car B will still be traveling 2.4 km/hr slower as the cars complete a lap and will never be able make up that difference. So in effect the slower cornering speed is the determining factor in the average lap speed.

While 2.4 km/hr doesn’t sound like much it is the difference between the average lap time of GT3 RS 7.47 on the NS and the standard GT3’s 7.54

[lakatu]

Here is another series of PM between st-anger and myself these deal with the handling characteristics of the older verses new 911 models.

St-anger had written this in a previous message in repsonse to a question about the car control in my avatar:

st-anger wrote: …to answer your question: “is it easy?� well, yes and no, i mean with the older Porsche models it´s quite easy to powerslide and to control it, again for a skilled driver! i mean i´m quite often at NS and nearly every two or three days you hear or see about a guy who crashed his car, and kinda often it´s a owner of a older Porsche model who wanted to discover the limit of his car, BUT nordschleife is definitely the wrong place for that, when you enter a bend with 160kmh and you don´t know what´ll happen due to lack of experience...well, then you had a Porsche... again, a Porsche at the limit is one of the few remaining drivers cars, the older models more than the "younger" but also a 996 can be kinda trickey, i know many many ppl who´re saying that a 996 isn´t a true Porsche or sportscar any more, even their wife can push it to its limit...well, that´s definitely not the case, and those ppl haven´t even discovered the limit of their car themselves... in the end, it´s and endless discussion, so one needn´t be an expert to powerslide with a Porsche, but in that vid at that speed i´d say this driver knows what he´s doing so “yes� he looks like quite skilled, because it´s the speed that counts when driving at the limit…

I then responded by writing this message:

Originally Posted by lakatu The original question related to the 964 model and the ability to control a powerslide but in the answer you gave you indicated it was easy to powerslide in the "older models" and I was wondering if by "older" you where including the g series ( specifically 1984-89 911 3.2L & 930 models). Is it easy to induce and then control a slide like that in these models as well? The only visual powerslide like that I have seen with these models is in Fazsination with Roser at the wheel and he makes it look easy yet when you see the hand work involved I wonder how easy is it really? Also the frequent crashes you referred to on the NS of “older� models? What models are you referring to specifically? 964? G series?

Originally Posted by st-anger to answer your questions, well, again whatever you´re working on - btw sounds interesting - you can´t really say this or that model is easy to control, i know it´s maybe a bit hard for you to understand, i don´t know how much or if you ever had some track experience, but when it comes down to really sportive driving, and powersliding with that kinds of speed IS really sportive driving it´s all about the driver and his experience, period! that´s why i always say "yes and no..." sideways steff IS a pro behind the wheel, again i do not know him myself, but i know enough and SAW enough to know - you mentioned it: in "faszination" it looks all very easy and smooth - sure, he´s a pro driver, i mean .... pheeewwww....man it´s so hard to explain u know, ´specially in english, let take it from another point of view - the older models, yep, we can include G-series here, are quite easy to powerslide due to many factors, especially technically related ( suspension, tyres, balance, no electronic aids.. ) they´re just old fashion and not like modern, race car like suspension setup like on 996, 997.... so it´s quite easy to initiate a drift, and IMO it´s also quite easy to control it in such old cars - but again, some have the feeling for a car some not, so many´ll loose it even in low speed rage and only a very very small percentage of ppl will be able to control a slide to the limit of the car, it´s definitely like this, that the ppl are at first at their limit and not the car... on the other hand the newer models like 996 are more difficult to initiate powersliding but are then easier to control... ... in the end this is a endless discussion, I uploaded a vid feat. a GT2 driven by a good friend of mine, Mr. Vökl, he´s in the same test crew as i am here at EZW, AMS TV had been one of the first to show the new MKII GT2 so they got a GT2 and driver ( so no editor from AMS ) directly from EZW, in it you´ll see quite some driving skills, a ~500hp GT2 on wet pavement with lot´s of sliding....you´ll see when it appears in PC - but what i want to say: look at this vid and again we could discuss...looks easy - ??? - hmmmm maybe for some , but i bet 99% of JW members won´t be able to drive like shown in the vid - for most of them it would end in a 200k € disaster... so sorry m8 when i can´t help you on that, i really can´t - sure i could tell you but what´s legal for me won´t be legal for others and to say in general...well, on a certain level, i´d say for most of the ppl NO, to control a Porsche on a certain level isn´t easy... to quickly answer your NS question.... hmmm, i´d say mainly 964 and 993...

[lakatu]

Here is a exert from two PM’s between st-anger and myself. I think this is one of the more interesting and informative exchanges. Some of the others that I have posted were background to get to these. The second set is long but I think is the most interesting and is about the suspension and handling differences of the 964/965 models and the G-series(1974-1989) 911. I hope you enjoy these as much as I did .

Originally Posted by lakatu Thanks st-anger for the information. It is really helpful. So it sounds like it takes a lot of skill to control a powerslide or oversteer condition with a G-series car but can quickly become uncontrollable for the older G series models much more than the 996 models. I’m guessing quick reflexes and a feel for the car’s tires contact patches is the difference. But it sounds like for a skilled driver, a G-series 911 is controllable so that an oversteering slide is something a skilled driver can use to position the car or have fun without the fear of losing control of the car. Do I understand this correctly?

Originally Posted by st-anger Do I understand this correctly? yep, u do [If you look at the video I mentioned before,] it shows a MKII GT2 driven by Mr. Klaus, some very nice drifting and some on board action what we´re doing "at work" - goes quite nice together with "reflexes" and "feel for the car" u mentioned... so, as u can see in this vid it´s not only the older models which require quite some skills at the limit, sure when ppl are watching the vid - some might say: "yeah spectacular driving, but it´s not that good, with some practice i can manage that too..." one word for them: BS.... to control such drifting and to manage such quick and precise steering corrections it requires a shitload full of practice practice practice...

Originally Posted by lakatu Thanks again st-anger for sharing that video with me. I can see what you mean by the skilled required and the difficulty of controlling even the GT2 at the limit. However, the wet conditions I think reduce the impact of the suspension and tire development of newer cars to improve stability but in the dry it should be easier to control. I know that it may seem like we just rehash the same thing over and over again. But each time we talk I get a little bit of a new prospective. Kind of like a jigsaw puzzle and each time I get a new piece . Each answer you give really helps because to me each question is slightly different and is directed at expanding my understanding in a particular area. So this leads me to my next question which concerns suspension improvements over different 911 models. I have been doing some research on the 930 verses the 965 by following your suggestion to check with Porsche owner chat forums and I have found that the majority of comments indicated a preference for the 930 over the 965 which I thought was rather strange. Some of the comments came from individuals that had owned both and they indicated that they preferred the 930 because it was lighter and seemed to understeer less than the 965. I wonder if their perception of greater understeer for the 965 was due to the 965 rear differential that provides 100% lock on trailing throttle. I have read that the 917 and the 934 & 935 had a similar 100% lock on over run so I would have thought that this shouldn't have been too detrimental to handling. To answer the question for myself I looked at the NS and HHR lap times: 1989 930 (300hp) NS=8:44 HHR=1:20.0 and for the 965 NS=8:33 HHR=? (I couldn’t find a HHR time for the 965). I think most 1989 930s weighed 2975 lbs (9.9 lbs/hp) and a 965 was about 3275 lbs (10.2 lbs/hp). So the slight power to weight advantage went to the 930 and the braking advantage with ABS and bigger brakes to the 965. As we have discussed before, any real lap time difference should be due to the handling advantages. Based on the times it would appear that the 965 was a better handling car and that seems to agree with commentary from car magazines that I have read. However, I have read some different things that have created some confusion in my mind concerning the suspension improvements of the G-series verses the 964 series for both turbo and normally aspirated. First, I’ve read that Dr. Porsche thought torsion bars where superior to coil springs and I’m not sure why, maybe this was before progressive rate springs? The racing derivatives of the 911 seemed to prefer the coil springs. The 934 used torsion bars and coil overs and 935’s used only coil overs. Also, I have read that for the 964/965 models, Porsche engineers tried to incorporate a Weissach effect, like in the 928 rear suspension, by building in rear suspension bushing compliance to create stabilizing toe-in under trailing throttle. However, Peter Falk (headed racing car development and head of production car chassis development at Porsche) said “It really didn’t work too well!� & August Achleitner (joined Porsche in 1983 as a chassis engineer) agreed that it was a compromise especially concerning noise intrusion. Finally I have read Paul Frere say that while others indicated that the 964 suspension improved the handling he couldn’t tell a noticeable difference. (I am not sure if he was referring to the 964 only and that he had a different opinion of the 965.) Yet in an article where Frere compared a Ruf CTR, which is based on the G-series, to a 965 he seemed to indicate that the CTR was a much more difficult car to drive although it wasn’t clear if this was due in part to the tremendous power of the CTR (see last paragraph on this page http://img10.imageshack.us/img10/625/965vsCTR7.jpg and the last two paragraphs of the article at http://img10.imageshack.us/img10/9031/965vsCTR8.jpg ) So my question is, based on your knowledge and experience driving 964s and G-series was the 964/965 truely an improvement to the suspension and handling? You indicated that the 965 was a special car and one of the few REAL drivers cars. Could you possibly explain what you meant by that? I have also heard that the 965 suspension was improved over the 964’s but I have no specific knowledge concerning any differences other than the typical turbo verse normally aspriated suspension upgrades. Maybe another way to ask the question is if someone offered you as a gift your choice of a pristine condition 930 or a 965 which would you personally choose? In a previous discussion we had about 964s you suggested not getting a 964 and going with a 3.2L instead http://www.motorworld.net/forum/show...154811&#154811 . In that response you indicated a personal dislike for the look and the handling of the 964 so that is why I thought I would ask you all these different questions. Do you feel the same way about the 965 as you do about the 964 because I realize it has a reworked version of the 930’s 3.3L and probably didn't have the inital engine problems of the 964?

Originally Posted by st-anger maybe I took the wrong words or maybe it´s a missunderstanding, it´s definitely not a “dislike� I have about the 964 series, not at all, there´re some great rides in the 964 series, including the 965 , which is as I said one of the last few “men´s cars� nothing for the “boys�, don´t take that too serious, this doesn´t mean that the 965 is a nearly undriveable beast, definitely not, but compared to some “soft boiled� models it´s just a stunning machine… which one to take…3.2L or 965…!??? hmmm, kinda hard…but being a passionate driver I think i´d choose the Turbo …so why´s the 965 a special car, well back then it divided the men from the boyz… it´s been a Turbo with some old school behaviour, rear wheel drive only, rock-hard suspension - a car that only made sense once speed was picked up and what´s the most important thing: only the drivers foot stood between you and and a unscheduled one-to-one visit into the landscape, unfortunately though it missed the Carrera´s four cam – four valve technique, so it wasn´t really a refined engine as one´d have expect a “Turbo engine� to be – it was rather the well known “drive quickly� engine, demanding some massive k ´s to jolly along the car not to fall back into the kinda massive turbo lag, so unfortunately all this wasn´t the best partner for the brilliant new chassis, suspension and brake system that has been a major improvement to handling abilities because of better brake feel due to power assistance – that´s why some ppl are still sad that the circumstances prevented a better ( new ) engine, with that the 965´d have been a memorable car in history, not even in Porsche Turbo history… that sums it all up quite good IMO and goes together with the “skills� issue we´ve been talking about… besides that….just look at it, I mean just looking at that car and everyone´ll immediately know: this car means business… also her history is quite unique, as u know in the 80s a Fuchs wheeled, tea-tray like spoilered, brick sized mobile phoned 911 had been the must have car for any yuppie and when production of the 930 stopped in 89 it´s been clear that a new model won´t be far away… well, when stock market crashed at the end of 80s CEO Branitzki deep freezed a promising project named 969 http://www.motorworld.net/forum/show...=183967#183967 ( and codenamed 965 ) the 969 should have been a all new model replacing the Turbo and rivalling the other supercars from Ferrari, AM, Jag… so after a 16 prototype disaster, what´s interesting, it featured a 3.5ltr. watercooled twin turbocharged flat six, looking very similar to the bigger brother 959… to fill that gap, and to keep PAG at the top, a new car was needed, the 964Turbo… it had be be done really quick so that´s the explanation why there´s some trouble with the 964Turbo – u know the details ( engine, interior,…) in 89 the 969 project was cancelled by CEO Bez because by then costs for the model had been way above the Turbo, so it´s been a more or less unjustifiable option… so, to come back to the problems, due to lack of time to develop a very new engine PAG decided to use the 3.3 930 engine with the sportkit producing 320hp with modified cylinder heads, overworked induction and exhaust system and a catalytic converter. It´s wrong that it got a new Turbo, only the bigger, but lighter, turbine wheel in combination with the ~30% bigger intercooler boosted power… well, the result …well, the engine did little below 3000rpm, besides the car was something like 120kg heavier that the std. 3.6 C2 & 4, nevertheless it outran them easily as well as supercars like Lambo Countach or Ferrari 512 and it´s been known as the “most accelerative production car� it was also the first 911 Turbo with power assisted steering, it had ABS with new brakes from the 928 ( front discs and callipers ) and the 944 Turbo ( rear discs and callipers from the 944 front brake system ) well, most likely you know the details, so to answer your question: “YES�… …don´t know anything about the Frere test, but when he really compared G to 964 and realized no difference at all – well, then I have to worry what´s been wrong with mr. Frere back then keeping the answer short and easy is quite a challenge, because there´re many sub-questions in your main question i´d also like to answer – on the other hand I ´ll try to keep it as clean as possible to prevent information overkill well, as far as the diff-lock is concerned, it was definitely an improvement… the cars with the G50/52 tranny had stronger differentials and the 20/100 LSD, so 20%lock under load and even 100% on overrun… so the moment the driver lifts the accl, so without actuating the brake, the car provides 100% lock to prevent lift-off-tail-wag which is a major problem on cars with kinda massive turbo lag, it simply unsettles the car … imagine you´re in a mid or fast corner at certain revs and you have to lift the accl – without the diff-lock the car´ll get very unstable ( oversteering ) due to the lag effect, so not very helpful for a good lap time… back on the accl the rear end can be controlled quite easy… understeering in the 965 is caused by several issues, as u know the 930´s heavy duty differential “forced� the car to simply go straight under power, so it´s not like that, that the 930 is superiour in terms of not understeering that much, nevertheless, due to lack of time not everything was sorted out at the 964series, so understeering on C2, Turbo and especially C4 had been quite an issue, when talking about the Turbo some of this understeering may come from the new diff-lock, don´t ask for details, i´m afraid i´m not that familiar with both, the car and the tech stuff, to answer everything in detail, some more comes from a lift off tendency of the front inside wheel, this is a phenomenon we can see on quite some old Porsches, we apply threash-hold braking to compensate understeering then, a strut brace is also a kinda good solution for preventing understeering… …well, torsion bars had their advantages, no doubt about that, but soon they got replaced by springs, TBs were mainly used by Chrysler and Porsche back in the 60-70s because of their durability, compact, simple and light build, but on the other hand they were able to transfer loads very good, main disadvantage has been the absence of progressive spring rates resulting in a very undefined handling, especially on track, so PAG decided not to develop it further, there has been a attempt for the 934, it used some kind of experimental torsion bar system, but i´m not familiar with the details… so, 964 went away from torsion bars because of better handling with coil springs, also because of some construction changes like other diffs, drive shafts ( especially for C4 ) and mainly tranny, PAG left old Porsche syncromesh/915 behind and went to the Getrag/Borg-Warner syncromeshed G50 tranny which is bigger than the tranny in the G´s. with the use of coil springs one major handling advantage could be achived: fore and aft movement of the front suspension arms, resulting in a smoother ride when driving on track, e.g. over hard bumps. as u mentioned, the rear suspension had some kind of “passive rear-wheel steering� also known as “Weissach axle� because of toe-correcting rear suspension arm bushings. unfortunately all attempts to eliminate “toe out� whenever lateral braking forces were applied failed, this is a trailing arms phenomenon, and it couldn´t be sorted out till 993 series… it also featured improved control arms, reinforced chassis plates locating the trailing arms and reducing deflection of the suspension under load the rear suspension was also equipped with a special 22mm rear stabilizer bar operating with stiffer progressively wound coil springs, strongly degressive twin-tube gas shocks to improve handling. at the front the coil springs were good for a slight backwards movement of the weels, resulting in a more stabilized handling when hitting a hard bump, at the same time, negative scrub radius was incorporated in the front suspension geometry (the 3.2 had positive scrub). together with the assistance of the ABS, this gave a degree of steering correction when the front wheels began to slip. the 965 front suspension uses alloy lower control arms and MacPherson strut gas-filled shocks. the 21mm front stabilizer bar that ties the suspension arms together is augmented by a massive front strut tower brace. the upper shock tower mounts are reinforced to withstand the additional loads transferred to them by this brace. well, all in all, most ppl will say the 964/965 is simply the better car

…

[lakatu]

Originally Posted by lakatu The reason I ask you to compare the 930 to the 965 is I have learned that usually the lighter car is the better performer. Take the 911 2.7 RS. Porsche is still struggling to erase the memory of that extremely light weight car as the best Porsche of all time. So I figured that the 930 being 300 lbs lighter might be a better choice than the 965 in its sporting performance. Certainly there are some obvious advantages to the 965 over the 930. I know I don’t have to go into detail about those but basically it benefited from the 15 years between their designs. So it sounds like the 965 is a much better handling car and doesn’t understeer more than the 930? Also, the revised 965 suspension then was improved enough to offset any performance penalty due to the added weight? In regaurds to the 965 engine, I knew that there had been some compromises with the engine and that they went back to the 930’s 3.3L but where there any reliability problems with the 965’s engine? I was aware of engine problems with the 964’s 3.6L engine but I didn’t know that there were any problems with the 965’s 3.3L. Also, I wasn’t aware of any interior issues. Could you go into more detail about interior issues as well. Did the 965 have less turbo lag than the 930 due to the K27 turbocharger and less restrictive intercooler? Finally, concerning the engine what is your opinion of the 3.6L? I’m guessing you’d say “better but still not quite what the 911 turbo deserved as far as an engine� and that didn’t happen until the 993 TT. This may sound rather strange but for some reason I find rear differentials really fascinating. I didn’t quite make the connection to turbo lag and lift throttle oversteer though? If I understand correctly, the 100% overrun lock prevents oversteer by forcing both of the rear wheels to rotate at the same speed. And in a turn, due to the different radiuses between the inside and outside wheels it causes the car to want to plow straight ahead and not rotate into the turn. So doesn’t this reduce cornering speeds? I have always wondered if the 100% locking differential was a band aid that Porsche used to prevent it’s inexperienced drivers from getting into trouble but based on Porsche’s racing cars use of 100% overrun lock I am guessing that it benefits both the inexperienced and pro drivers. Does the 100% lock create massive understeer and if so why would the pro driver want it? If I remember correctly current 911s use 40/60 differentials. Why not 40/100% unless the 100% does cause too much understeer and the newer suspensions don’t require the full 100% lock to stabilize the car? Also I don’t know too many details about he 930’s limited slip differential other than it was optional at least in the US and that the brochure indicates that the self-locking properties have been limited to 40%. I assume this is under power but don’t have any idea what if any lock is on overrun. Do you know what 930 differentials lock on overrun was?

Originally Posted by st-anger well….another kinda hard point…NA or turbo… I mean with the modern cars like GT2, although it´s twin turbo charged there´s literally no turbo lag at all, it´s nearly like a NA car but with way more punch and power over the whole rpm band, they have their full power at 5700/3500rpm (hp/lb-ft) while e.g. a RS has it at 7400/5000rpm so a NA needs revvs – good example is again NS driving, there´re some sections u would love to have more power from a turbo at lower revvs in a e.g. NA - GT3, especially uphill when 2nd is too short, but 3rd already way too long, so u´ll loose some seconds because the engine needs much more time to revv up where the power is, with a GT2 u simply put in 3rd floor it and e.g. in a GT2 u have to watch out that u won´t loose it – uphill … lol, best car´d be GT3 RS with GT2 engine on the other hand – with turbo engines one has to deal with compromises all the time, so again, for me… i´d go for a NA car for track driving… ..well, the lightest car is nothing without the best suspension and definitely tyres, don´t forget to think about tyres as well, they´re the most important factor… so the 965 is hands down the better performer when compared to the 930, the 930 is definitely way too old when it comes down to chassis/suspension tyres – just everything… pheeew, i´m not that familiar with all this, but I haven´t heared of any major problems with the M 30/69 engine… well, interior…due to financial constrains little was changed over the previous 911 models, so ergonomics remained … well… kinda bad also quality level and overall looks isn´t up to 911 Turbo standard, non adjustable steering, horrible gear lever, …bla bla bla… …I believe yes, the 965 has less lag than the 930, opinion of 3.6- well, just hand me over a 993 when it´s a M64 engine , no seriously, definitely an improvement because of the M64 engine type instead of the M 30 type… the 100% diffs ruined the tranny, that´s why Porsche went to lower locking rates, don´t know every single detail, but over the years something around 40/60 seems to be perfect for both, handling and reliability… as far as I know 80% on overrun for the 930…

[DJF1]

Originally Posted by lakatu Originally Posted by lakatu The reason I ask you to compare the 930 to the 965 is I have learned that usually the lighter car is the better performer. Take the 911 2.7 RS. Porsche is still struggling to erase the memory of that extremely light weight car as the best Porsche of all time. So I figured that the 930 being 300 lbs lighter might be a better choice than the 965 in its sporting performance. Certainly there are some obvious advantages to the 965 over the 930. I know I don’t have to go into detail about those but basically it benefited from the 15 years between their designs. So it sounds like the 965 is a much better handling car and doesn’t understeer more than the 930? Also, the revised 965 suspension then was improved enough to offset any performance penalty due to the added weight? In regaurds to the 965 engine, I knew that there had been some compromises with the engine and that they went back to the 930’s 3.3L but where there any reliability problems with the 965’s engine? I was aware of engine problems with the 964’s 3.6L engine but I didn’t know that there were any problems with the 965’s 3.3L. Also, I wasn’t aware of any interior issues. Could you go into more detail about interior issues as well. Did the 965 have less turbo lag than the 930 due to the K27 turbocharger and less restrictive intercooler? Finally, concerning the engine what is your opinion of the 3.6L? I’m guessing you’d say “better but still not quite what the 911 turbo deserved as far as an engine� and that didn’t happen until the 993 TT. This may sound rather strange but for some reason I find rear differentials really fascinating. I didn’t quite make the connection to turbo lag and lift throttle oversteer though? If I understand correctly, the 100% overrun lock prevents oversteer by forcing both of the rear wheels to rotate at the same speed. And in a turn, due to the different radiuses between the inside and outside wheels it causes the car to want to plow straight ahead and not rotate into the turn. So doesn’t this reduce cornering speeds? I have always wondered if the 100% locking differential was a band aid that Porsche used to prevent it’s inexperienced drivers from getting into trouble but based on Porsche’s racing cars use of 100% overrun lock I am guessing that it benefits both the inexperienced and pro drivers. Does the 100% lock create massive understeer and if so why would the pro driver want it? If I remember correctly current 911s use 40/60 differentials. Why not 40/100% unless the 100% does cause too much understeer and the newer suspensions don’t require the full 100% lock to stabilize the car? Also I don’t know too many details about he 930’s limited slip differential other than it was optional at least in the US and that the brochure indicates that the self-locking properties have been limited to 40%. I assume this is under power but don’t have any idea what if any lock is on overrun. Do you know what 930 differentials lock on overrun was? Originally Posted by st-anger well….another kinda hard point…NA or turbo… I mean with the modern cars like GT2, although it´s twin turbo charged there´s literally no turbo lag at all, it´s nearly like a NA car but with way more punch and power over the whole rpm band, they have their full power at 5700/3500rpm (hp/lb-ft) while e.g. a RS has it at 7400/5000rpm so a NA needs revvs – good example is again NS driving, there´re some sections u would love to have more power from a turbo at lower revvs in a e.g. NA - GT3, especially uphill when 2nd is too short, but 3rd already way too long, so u´ll loose some seconds because the engine needs much more time to revv up where the power is, with a GT2 u simply put in 3rd floor it and e.g. in a GT2 u have to watch out that u won´t loose it – uphill … lol, best car´d be GT3 RS with GT2 engine on the other hand – with turbo engines one has to deal with compromises all the time, so again, for me… i´d go for a NA car for track driving… ..well, the lightest car is nothing without the best suspension and definitely tyres, don´t forget to think about tyres as well, they´re the most important factor… so the 965 is hands down the better performer when compared to the 930, the 930 is definitely way too old when it comes down to chassis/suspension tyres – just everything… pheeew, i´m not that familiar with all this, but I haven´t heared of any major problems with the M 30/69 engine… well, interior…due to financial constrains little was changed over the previous 911 models, so ergonomics remained … well… kinda bad also quality level and overall looks isn´t up to 911 Turbo standard, non adjustable steering, horrible gear lever, …bla bla bla… …I believe yes, the 965 has less lag than the 930, opinion of 3.6- well, just hand me over a 993 when it´s a M64 engine , no seriously, definitely an improvement because of the M64 engine type instead of the M 30 type… the 100% diffs ruined the tranny, that´s why Porsche went to lower locking rates, don´t know every single detail, but over the years something around 40/60 seems to be perfect for both, handling and reliability… as far as I know 80% on overrun for the 930…

From my experience running a Porsche Motorsports diff at 40/80 lock rates on my race car yes the car has picked up understeer. But the importance here is trailbraking and exit speeds. What a lot of people fail to realize is that while the suspension technology on 911's is light years ahead from the original, the fact remains that a 911 is always going to be a 911. Driving a modern 911 with its real high limits can give you the false impression that 911's do not snap oversteer anymore... The difference here is that driving up to 9/10's for sure will give you that impression but when you explore that last 10th that is where the true 911 comes forward. The facts about any 911 driven SAFELY on the limit are:
1. NEVER LIFT! If you are in the middle of a corner on limit and you lift ,you will spin so fast that you will not have time to even wonder about it. Always be on throttle , sometimes if you feel the 911 sliding and you are on light throttle you will need to ADD throttle to stabilize the rear and exit almost powersliding...
2. ALWAYS BRAKE ON A STRAIGHT LINE. 911's have the weight in the back. When you brake naturally that weight wants to move forward. That is where a good locking diff comes into play. It stabilizes the rear as it gets light and you dont swap ends.
3. SLOW IN FAST OUT. Throttle stabilizes the rear. Again its all about weight transfer. After you are done with braking you need traction to negotiate the turn. By applying throttle you transfer the weight to the back of the car and you gain traction as if you leave the rear light that weight again will result to snap oversteer which will happen awfully fast ( ask me how I know )

By taking the above facts then you can realize why a proper differencial is so crucial to a 911 race car. In short a 911 on the limit will always understeer at the entry, stabilize by mid corner and oversteer by exit. While this may puzzle some people when you master is ( I still have a long way to go) its the most rewarding experience you can have! That is why 911's are so special...
Finally managing the oversteer is very relative to the tires you use as well. WIth the modern technology the limits are very high and some will let go really fast at really high speeds. The wonderfull thing about a 911 is that the chassis talks to you. So when the rear starts to get light you feel it immediately. If you follow the 3 "golden rules"" above and learn to throttle steer the experience will be a very fast, very safe and you will be able to anticipate most of the oversteer that will come your way.
If you are ludicrus with the brakes and throttle , dont pay attention to the rules then any 911 will bite back.....
Just my 02 cents!

[st-anger]

...nice to see ya back here DJF1

THX for ya lines

[DJF1]

Originally Posted by st-anger ...nice to see ya back here DJF1 THX for ya lines

Heh..Its nice to be back!!! In a few weeks I will have another track video for you from the 48 Hours of Sebring which takes place on February 11-14! I have a test day on the 22nd of January and I can't wait!!!!

Thx for the GREAT forum!!!

[st-anger]

Originally Posted by DJF1 Originally Posted by st-anger ...nice to see ya back here DJF1 THX for ya lines Heh..Its nice to be back!!! In a few weeks I will have another track video for you from the 48 Hours of Sebring which takes place on February 11-14! I have a test day on the 22nd of January and I can't wait!!!! Thx for the GREAT forum!!!

...all this is only possible because of GREAT members like u my friend...

...DEFINITELY looking forward to some more vids, reports, ..., whatever from u...

good to have ya m8, see u....

[lakatu]

Thanks DJF1 for adding your 2 cents. It is always nice to hear from you and get your prospective . Great comments and insight.

It sounded like the reason you went to the higher locking differential was to delay braking points and increase corner exit speeds. I can see how a higher lock rate would allow you to brake deeper into the corner without spinning but how has it helped exit speeds since the 40% lock is the same as stock under power?

Also with the increased understeer how has this affected actual cornering speeds did they increase after installing the higher locking differential or has it only allowed you to brake later?

Finally, I’m curious is the oversteer excessive and have you tried to correct it by increasing the front tires contact patch or through sway bars? Maybe it isn’t really an issue under track conditions as it sounds like you added the differential to allow you to brake later when entering into turn and I’d imagine that the understeer tendency is offset to some extent by the rotational momentum of the rear engine wanting to rotate around the corner.

[detltu6]

Wow I feel dumb asking this with some of the discussions going on here but: I know there were some changes during the production of the GT1 racecars and I know street versions were made but what were the production numbers and horsepower figures of each strassenversion. I can't find this info anywhere. I have found some approximate production numbers.

[DJF1]

Originally Posted by lakatu Thanks DJF1 for adding your 2 cents. It is always nice to hear from you and get your prospective . Great comments and insight. It sounded like the reason you went to the higher locking differential was to delay braking points and increase corner exit speeds. I can see how a higher lock rate would allow you to brake deeper into the corner without spinning but how has it helped exit speeds since the 40% lock is the same as stock under power? Also with the increased understeer how has this affected actual cornering speeds did they increase after installing the higher locking differential or has it only allowed you to brake later? Finally, I’m curious is the oversteer excessive and have you tried to correct it by increasing the front tires contact patch or through sway bars? Maybe it isn’t really an issue under track conditions as it sounds like you added the differential to allow you to brake later when entering into turn and I’d imagine that the understeer tendency is offset to some extent by the rotational momentum of the rear engine wanting to rotate around the corner.

Upi are correct on your assumption regarding the entry and exit speeds. The diff helps stabilize the car under braking so I can break more last minute so to speak. The by product of more understeer makes things worse at entry, again think of the weight transfer...After you are done with braking pretty much at the entry of the corner, then you are back on gas so that lightens the front. Now you do not have the engine up front like on ""normal"" cars so the front now is light and washes out initially. That is until the weight is stabilized and your chassis setup comes into play after the initial ""shock"" of a rear weight transfer. Then if you are setup correctly ( sway bars, spring rates, corner weights) the front regains some weight and the tires grab so to speak therefore by apex you should be in a nice state of a neutral car. As you realize now you have transferred some of the initial rear assigned weight to the front so the rear is at maximum adhesion as well. After the Apex you are looking at max exit speed, so you apply more power to accelerate. That is where the kind of stock rate ( which by the way on normal street cars is 20%) comes into play. Now you want the front to stick as well and as you realize by applying more throttle you bring some weight to the back again. SO now you kiss your nice and neutral state and again your setup comes into big play...but with less locking under acceleration the impact is not that great , instead you avoid some wheel spin which could be detrimental to your exit and usually that little bit extra weight you transferred back to the rear makes for a nice almost powersliding exit. If you overdo it you can end up swapping ends, if you apply as needed ( throttle steer) its very sweet and very controlled , looking most of the time like a 4 wheel drift. So that is pretty much why a motorsports diff is suitable for track use...

To your last paraghraph... Given the above desirable results and effects from the diff as I mentioned setup is very very critical. The benefits of the diff are felt on really fast sweepers and medium speed corners. On the slow stuff I understeer like a dog, there is no way to overcome the initial wash out and only left foot braking mid corner helps to rotate a bit the rear end and help add some weight upfront for better traction... Again the generaL setup is very crucial. There is not one perfect setup for all corners. You win some you loose some and you pay attention to have a beautiful setup on the fast stuff and on corners before straights where exit speed is crucial... In the grand scheme of things what also comes into play is how you like your car to behave. Understeer is "safer" some love it some hate it and want an oversteering car. I like things in the middle so to speak towards more understeer especially on the fast stuff where you could be in a corner doing 100mph+ and things move awfully fast at these speeds... So general setup is accomplished by corner weights, spring rates, shock rebound, tire sizes and pressures, sways etc.. The corner weighting I thing is where everyone agrees... You want to have as much as possible at the center of the car a figure as close to 50% as possible. This will provide you with a neutral platform to start with. Then camber, toe-in etc are anyones game and it gets really confusing after that. By moving to a larger contact patch up front is generally accepted helping to balance the car more towards neutral as all 993's come from factory with understeer as the main characteristic. However like one racing legend said , � will stuff as much tire on the car as possible". So using the tires to balance the car is secondary, you want the fattest tires you can stuff under the fender wells and while that leads to increased contact patch ( read higher limits) it may or may not bring you close to your desired setup. That is where the rest come into play...So on my setup I strive for neutral setup. Therefore I'm usually almost full stiff up front and middle stiff in the rear. Then as I run a few laps I will adjust it to my liking and usually I soften the front to try and get rid of too much understeer in the corners that I want. Besides that you can play with the tire pressures which have an effect on handling... Lately I have also started to play with the triple adjustable suspension of mine and I'm still highly confused

I hope that explains a bit the madness My advise to all who have a 911 is that they should go out themselves and try these stuff, keeping in mind the golden rules. Only each individual and at a track envinronment can really understand by the seat of their pants how things work... I would also advise to keep things simple. In other words at first forget multi adjustable suspensions etc... Run what you brung , learn the character of the car and then make one chance at a time. For example..suspension...keep it simple at first and learn it. Then move into a diff. learn it, then add sways, learn it, then add fatter tires, learn it etc etc... This way every change you make have a profound effect on the way the car handles but because you know exactly what it was before you can make a baseline comparison now and figure it out better.. I see many people doing everything at once...that is wrong and very confusing as your baseline has gone bye bye and adjusting variables is just too much.... To be honest I'm guilty as well on not following my advise.. That is why I'm paying the price now with big time confusion when it comes to adjusting the suspension
Hope it helps!!

[TT]

I have a question about this car:



Spotted it today in Lausanne, coming directly from Monte Carlo...

I am just trying to figure out if it is a GT3 made "RS like" or a GT3 RS made less flashy!

No RS sticker whatsoever on the bumpers or sides, only "GT3 RS" on the back. No RS colored wheels, but it has the wing obviously, the Porsche logo on the bonnet is a sticker and not the metal one like in the normal GT3, it has the air intakes in the front bumper...

The only thing I am not sure about: on the back, inside, where the rear seats should be, there was a "GT3" trimmed, and I never paid attention to that detail in the RS..

Anybody has a final answer you Porsche gurus?

[lakatu]

I was hoping that someone that had more knowledge about he interior would have responded by now TT. I looked through all of my magazine scans, but there weren’t any of the rear portion of the interior. Based on your description, I think that may be the key as to whether it was a genuine RS.

When you think of it from a logical prospective I think it is probably an RS. It is kind of hard to imagine though that someone would pay all that money to convert a regular GT3 to an RS and then leave out the least costly item, the decals and painted rims. Also, purchased separately I would think that it would cost at a minimum $10k which is half the difference between a RS verses regular model. I think it is more likely that someone stripped the decals and paint off the wheels. IMO it looks a lot better that way and I am guessing that the owner thinks so also.

Thanks for sharing the pictures. Hope this helps. It has been rather quite in PC lately :roll: .

[dingo]

Originally Posted by TT The only thing I am not sure about: on the back, inside, where the rear seats should be, there was a "GT3" trimmed, and I never paid attention to that detail in the RS.. Anybody has a final answer you Porsche gurus?

After looking for some interior pics I had a brainwave - why not have a look at my 1:18 Autoart model of the GT3 RS (and I know you have one also)
Mine just has 'GT3' trimmed in the rear, so if we can trust Autoart then it seems this is what the RS's have
I hope that helps in some way