Carrera 4 handling dynamics

Does anyone know of a reference (book or internet) that describes the handling characteristics of a c4 as well as driving techniques, etc? What can you all tell me about driving a c4, how it relates to a c2, front engine car, and so forth? For instance, does the c4 hit you with throttle liftoff oversteer like the c2? Can you steer with the throttle while applying opposite lock with a c4? Thanks for the help guys!

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Only with the PSM off.

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isnt this the case for a c2 as well? The c4 was really designed for stability rather than an awd function. The c4 has a heavier steering and has more feedback on the steering wheel since it is also attached to the front wheels. You can throttle steer the car, but when you push the car beyond its threshold (by stepping on the brakes PSM will intervene (thats fine, if your on the brakes, you prob need the help anyway). The c4 has so much grip that its very difficult to break the tire free. The c4 has a maximum ratio of 40f/60r of power between the front and rear. More and more professional are being sold to the c4... Walter Rhol (Porsche Test driver) prefers the c4 of the c2 variant.

The C4 came standard with PSM - I understand that it was an option on the C2s... So it could be the case for a C2 as well.

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This doesn't answer much of your question, but it is something. http://www.youtube.com/watch?v=RYAkYe1Zylw This clip omits the bit at the end of the evaluation where they agree they prefer the driving characteristics the C2.

Yet the C4 was fastest by 1/2 sec.

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Exactly. The tight course put a premium on getting power to the road accelerating out of the corners, more than making up the weight penalty. I would think that on a course with fewer tight turns the C2 might be faster than the C4 simply because it weighs less.

So you agree the C4 is better. Anyway both are great cars!

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Since I have a C2, of course not! They are both wonderful cars.

In almost all the reviews and tests I have seen the C4 consistently beats the C2 in Lap times, particularly in the hands of a less experienced driver. And here in the hands of an experienced driver it still bests the C2. However, many prefer the feel of the C2, more traditional. Once your out in the wet or snow there is no comparison, the C4 will walk away from a C2.

For driving in the Colorado snow country, C4 w/ PSM is the only way to go! If I lived in Dallas or Atlanta it might be a different story.

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I've driven both. To quite frank, for the vast majority of the time, a C2 and C4 drive and handle almost identically, especially in the dry. The C4 is noticeably grippier when it's slippery. The C4 viscous coupling center diff was designed to give the AWD a rear wheel bias, the rear tires are so big and grippy, and the extra weight of the FWD is relatively small compared to the engine. Both C2 and C4 can exhibit trailing throttle oversteer, trailing brake oversteer, corner entry understeer etc..

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+1, but even if i lived down south I would still have a 4.

Pete: Great question! I've been trying to get an ansewer to that myself. I have attended several DE's, but have yet to have an instructor that understood the dynamics of an AWD car. I even enrolled for a Lamborghini driving event two weeks ago hoping that their instructors would be more familiar with AWD. Unfortunately, they had local instructors that didn't specialize in Lambos. My experience in my car is that I am able to get on the gas much earlier exiting the turns than the RWD cars. I can really feel the car pulling me out of the corner and can usually get a 1-2 car length jump on other cars. The downside is that the car tends to understeer through the turns. However, it is very controlled throughout the entire turn. As soon as I back off the throttle it hooks back up. I don't have any problem keeping up with similar powered RWD cars. Hopefully more people with AWD track experience will chime in.

Speaking from DEs/AX only. My C4 is setup pretty neutral, if it understeer (excluding slow corners) it is probably driver error on my part. With PSM off, it drives just like a C2. If I had to buy another Pcar, it would still be a 911 awd variant.

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I don't know of any book or expert opinion on performance specific to the C4/C4S. Personal experience is what we can offer. Yes, you can make the rear step out with throttle lift or trail brake, but with some difficulty due to those big rear tires. It's the same thing with the C2, though. IMHO, where the C4 outshines the C2 is apex and exit speed. Add the better brakes, the bigger tires, the wider tread, and the better suspension that come with the S (as in C4S), and the added performance surpasses the added weight, and you get a better performer. Typical with my experience on the C4S relative to the C2 is that I get into the turn with similar speed, but then I can modulate the gas to get the front end of the AWD to dig in and pull the front around the apex. I can get on the gas sooner and get to WOT sooner. The stiffer suspension helps, too. The resulting exit speed is faster, and that speed advantage is carried down the straight. I also can, if I wanted too, go deeper and brake later due to the better brakes, resulting in additional top speed advantage before braking at the end of the straight. It is very unlikely that you will notice any significant performance difference between the C2 and C4/C4S on the street. Not safely, anyway. You can somewhat get the idea, as the C4S feels more like it is on rails in corners. Are you tracking your car yet? Typing these things on the keyboard and reading about them is somewhat fun. Go to the track and find out for yourself. That, my friend, is the most fun you can have with your clothes on that also happens to be legal. Here's a vid: FUN . It doesn't really mean anything, other than it's fun!

I actually don't have a 996 yet, but I'm in the market for an earlier one(I'm currently in another liquid cooled Porsche, but one with the engine in the wrong spot!). The reason I ask, a friend of my dad's happens to have a 996c4 for sale, and he'd be willing to sell it to me for a good price. I've always thought I wanted a c2, but the availability of this one has made me second guess that and consider getting a c4, as a lot of what I've heard about the AWD has been positive. Aside from the obvious driveline differences, are there any other differences between a c2 and c4 (m/y 99)?

I think Palting best summed it up. Though the C4 doesn't have the bigger brakes or suspension as the S. It really depends on the track because the C4 shines in really tight corners. Very little rotation unless you lift and you can get on the throttle really early. When I am behind other cars and put the power down I make up at least a car length and exit faster then them. Exiting a low speed tight corner with a straight and the 3300 lbs 3.6l awd will blow by the lighter 2900 lbs 3.4l C2's and if will stay neck and neck with a 3.6l C2 down the straight. Tracks with no low speed turns are more geared for high hp cars. The C2 has the advantage, not because the C4 has loss of power with 5% going to the front wheel but because of the weight and it's only slight advantage of 130 lbs, the C4S on the other hand is 280 lbs heavier. So even the C4 has a advantage over the S.

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You really need to drive the c4 and a c2. I have always thought that one of the 911's great virtures is steering feel. On that, a c4 is very good; a c2 is even better. There are certainly circumstances where one will outperform the other. Only you can decide what is important to you.

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That was a good video. Thanks for sharing. I loved when you got behind that lotus @4:30. You know those handle awesome and the 4S was just crazy fast around that corner. The Lotus looked like it got out a shape and a rear wheel went off.

The funny thing is the Lotus didn't hit one apex, but i bet he thought he was going fast ..

nice vid palting, but without knowing who you're up against, we really don't know how we gonna wager for/against you. you're right though, that must've been fun cuz it was fun to watch. go pork4s!

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My track experience is that PSM does not activate if the rear is coming around, "has" come slightly around, the driver responds accordingly, with the correct, "opposite" stearing input, and the car is responding properly(***) to those stearing inputs. *** The line of "travel", motion, is in compliance with all of the directional control inputs. There are just two sensors that are unique to PSM(VSC), a stearing wheel rotational position sensor and a yaw sensor. Basically, provided the firmware is well composed the car can be sideways even as much as 30 degrees but as long as the direction of motion, line of travel, is in accordance with ALL stearing, directional control inputs, PSM need not activate. Amazingly CLEVER system....

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He was probably worried that vibrations from hitting the curbing would cause various plastic pieces to fall off his car.

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plastic pieces... let's not throw stones in a glass house.

Old thread, but the people posting seem to be VERY knowledgeable so I thought I'd write my question here in hopes that you are all still here to reply: Steering feel on C2 (vs AWD) My `99 C2 is my first Porsche. I tend to favor front engine, RWD cars and currently drive things like: Shelby GT350, Bimmer 328 RWD M-sport manual, `64 GTO. I do also love small, good handling cars like old Datsun Z's, Celica's and Miatas. So I bought the 911 last year, a dream car for me, and couldn't wait to really learn the master the dynamics and style of driving one (enter turns slow, exit fast, etc). So far, I do really like the car. I wish it was more powerful, but it's no slouch. It's just tough to get out of the GT350 and into the 996 and not feel the lack of power. But I digress. My issue is steering feel on the street. I think the front end gets too light, especially on the street on uneven, modulating surfaces. As the car's suspension absorbs the road, the steering sort of wiggles and squirms a bit as the car travels up and down over bumps. Can anything be done in terms of setup/tuning to help stabilize this? Or is this just the dynamic of a car with only 35% of the weight up front? The car has the factory 014 Sports options package (incl. 030 220 375 376) (Sport suspension, 10mm factory drop, LSD, Traction control ASR). TIRES: It currently has Hankook VENTUS V12 EVO2 tires with good tread. Cheap, I know (It came with these tires). Maybe better tires would help, but not sure it would change what I'm talking about. I'm thinking of trading for a 996TT in the future with AWD. . Will that help this feeling of flighty-lightness? Or am I better off tuning my current car, or just dealing with it? BTW, I did drive the car at Lime Rock on a DE day and enjoyed it very much under those conditions, so it's really more of a street thing than track thing that I have issue with. TIA for your input and experienced opinions.

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Not experienced enough to answer questions specific to your concern, but may be able to offer some suggestions. Weight bias is the big thing you are noticing. The front will "float" or even wander a little on road irregularities. The typical answer to this is to soften the front. This can be done by softening the suspension or lowering tire pressure. The latter, being the easiest and most practical approach. For the street, this is not necessarily a bad option. For the track, this will introduce more understeer. I would look at tire pressure first. Oh - that and alignment - but let's assume that is already good. If that is questionable - then that is the place to start. Something else you may want to consider, and it's not a typical street driving technique, is to try a little left-foot braking. This will put more weight on the front wheels and help them track more true to your intended path. If you experience this wiggle and squirm under acceleration, that is the weight bias at work. If it is more steady-state driving that you experience this, then softening the front is your best bet. One additional factor is your front tire width. The wider the tire is over the factory width, the more this issue will present itself. Are you running the stock configuration?

Good points, check the basics. I'm pretty sure the alignment was done when I had a new spindle installed, but I'll double check that. Otherwise, the car is stock rims and tire sizes (optional 18"). Only thing not stock is tire brand. I run the recommended PSI for partial load, but will play with that a little.

Couple things on my C4S. When i purchased my car bone stock it understeered BAD and felt uneasy at 100mph and over. It had sumitomo tires. Replaced thoses for michelins and that fixed the high speed feeling. I replaced the entire suspension and steering with fully adjustable and H&R sway bars. My car sits MUCH lower and has 2 degrees camber in the back and 1.5 in the front. I now dont have nearly as much issue with understeer. You would think the awd would help. Nope. Really considered doing an awd removal. Several guys on the turbo forum have done it and said they would never go back. The only reason i havent yet is my car never sees the track (hoping to change that) so it is rare for my awd to even get used.

The steering on my 996 does feel a bit light compared to my previous 986, but it still has great feedback and none of the issues you describe. I'd say check the alignment and change to good rubber. Porsche recommended pressures are high (for lower rolling resistance and better fuel efficiency) - I run 32 up front and 36 in the rear and have been getting very even wear on my Yokohama AD08Rs.

Just to circle back, I checked my PSI since that's an obvious first step. I have a TSB summary about correct PSI's from Porsche and they say that half load (2 passengers only) correct PSI is 33F and 36R. My tires were set much higher over the winter to help prevent flat spotting. When I set them correctly, the steering was definitely much improved. Overall, the car feels great. It seems to drive like a power boat, meaning, power and steering comes from the rear. I know that's not totally accurate, but it's pretty good imagery for me at least. It's just classic 911 feel vs the rest of my cars (all front engine, RWD). Bottom line: the more I drive it, the more I'm enjoying it. (Oh, and I have the LSD rear and sport suspension. fyi.) It's all good. Next stop: alignment and new tires. No rush on those items.

I�m new to Porsche and rear engine, so I�m slowly building my skills with it. HPDE would be great but I can�t fit in the car with a helmet at 6�6� tall. I was was attracted to the 996 by a day with 997s and 987s at a Porsche World Roadshow back in 2010. I love the fact that as I get on the power while exiting a turn (say at 45-65mph) that the back gets MORE planted, not less. The front gets lighter but it�s doing less work during this power-on-exit, so that�s OK! I need to learn a lot more but I�m on the street and don�t want to do anything stupid. I�m going to the next local PCA HPDE event as a spectator, to watch my local club colleagues as well as to borrow a helmet and see if I can make it work. If I can, I�ll sign up for the next one we have.