rs10

Now back to the interesting part - the significant differences. When the C4S was introduced, journalists seemed to regard it's handling as infinitely superior to the C4's, and I always wondered why. I presumed the shocks and dampers were basically the same - just a bit stiffer to handle more weight. I understood the mechanics of the 4wd were the same too. So the only things I could think of was the electronics, which I knew were different, and the width. And perhaps tire sizes? (Need to check that.)

Maybe the journalists simply never tried a C4 with the sport suspension and the 18" wheels? Otherwise, if the did - if the C4S really is much better - could the electronics be the reason? Or the width? Or perhaps I'm mistaken and the C4S suspension has nothing to do with the regular (-10mm) sport suspension? Or is there some other difference no one mentioned on this thread yet???

ditto

I think the reviewers bought into the faster lap times that Porsche fed them. The lap times could be 100% legit, or they could have been the product of something as simple as better tires. If the times were legit, going faster with the same engine but an additional 100 pounds requires good engineering. The C4S got bigger brakes too, they would be a noticable advantage on a track but all but invisible during normal driving.

Dennis C

I think it's the combination of upgrades to the suspension and brakes coupled with the wider tires. The C4S essentially shares suspension components with the turbo (with a few minor differences).

redridge

the C4's body is essentially a Gt3 frame and the C4S is a turbo body.... its AWD drive system is made for stability rather than for AWD... that is why you can drift with this system. If you ever drive a C2 vs a C4 it essentially drives similar. The big difference between the two is steering feedback... the C4 steering is heavier and has more feedback, being connected to to front wheels. Im sure you know about the viscous coupling Porsche uses.

rs10

It's not the lap times that won the C4S so much journalistic praise - at least not in the magazines I read (Evo and Car). It's the handling.

And it's not the brakes that make the C4S faster on the Nurburgring. The Nurburgring is not demanding on brakes. Also, the turbo brakes probably give it zero braking advantage over the C2. The C2's brakes are fully capable of braking at the tires' limit of grip. The Turbo needs bigger brakes because slowing the heavier turbo down from higher speed generates more heat - and bigger brakes enable the same braking with less heat. Since the C4S is also a bit heavier, it may also need bigger brakes.

And I'm not sure it's the suspension, because the C2 used by SportAuto had the 10mm lower sport suspension. And the C4S is said to have pretty good ride quality, so it's unlikely the suspension is much firmer. So if suspension, it would have to mean fine-tuned spring and anti-roll bar rates and higher quality dampers.

What helps the lap time is the width, slightly wider rear tires (295 vs 285), the weight distribution, and the 4wd. What hurts the lap times are the weight, drag, and 4wd. The shorter the track (or actually the shorter the straights and the tighter the turns) the more the advantages of 4wd outweigh the disadvantages. As a result, pretty much every 2wd watercooled Porsche is faster on the ring than it's 4wd equivalent, and slower on short tracks. (The C4S has no 2wd equivalent.) So if the C4S is faster on the Ring, it will be significantly faster everywhere else.

However, the C2 used by SportAuto didn't have the LSD and the tires may have been an older and therefore inferior model. I figure the LSD is probably good for about 3-4 seconds at the Ring; it's said to be good for ~1 at most tracks, but it will help less per km at the Ring for the same reason 4wd helps less - the turns aren't as tight.

In sum, the reason the C4S can do better Ring times than a C2 without LSD are the width, weight distribution, slightly wider rear tires, maybe superior suspension design (IF there are any real differences), maybe newer model tires, and maybe superior PSM - if von Saurma left it on or if the e-diff function remains on even when PSM is off - and maybe there is some other difference no one on this thread has identified yet ... . The reasons it can go faster than a C4 are the same, except weight distribution, and maybe the C4 didn't have the sport suspension - don't know.

rs10

I haven't had the pleasure of drifting any 4wd Porsches :-( A friend who drifted a 996 Turbo at a snow driving event didn't like it. Hard to control the drift, and generally huge angles. I remember hearing at least the bigger angles thing from other sources, and not on snow. Maybe the hard to control part is from the Turbo boost. (No clue whether the car was chipped, which might make the Turbo even peakier.) I can imagine the Turbo is also worse than other 4wd 996s because it's a lot heavier in the back. On the other hand, I just read an old article in Car saying the Turbo drifts wonderfully on track (presumably when trying to go fast, not when going for bigger angles). Still, if I were going drifting, the Turbo would be my last choice.

Should I expect the C4 (or C4S) to drift significantly better?

rs10

But interesting though lap times and drifting are, what I'd really like to know - along the lines of the OP's question - is whether the C4S is really so much better than the C4 - and also the C2. Which means, since I'm pretty sure it's the handling that impressed Car and Eco, whether the handling is really so much better. And if so, why? (Or did Car and Evo get it wrong? Perhaps they never tried C2s and C4s with the sport suspension, and the LSD (for the C2)? Perhaps others have different views?)

Ynot

Not useless but not as efficient as today's AWD systems. Most of the time it feels like a RWD car which isn't a bad thing.

KrazyK

Its a completely different car and suspension. Handling is much better than a C4 which is really just a C2 with AWD added.

rs10

I was wondering about this (about how the C4S suspension compares to the Turbo suspension). Are the parts exactly the same? If Porsche wanted the two cars to handle and ride the same, they should give the C4S slightly softer springs and dampers, due to lower weight, especially at the rear. And I've heard the Turbo has a rough low-speed ride, which I've never heard about the C4S. I'd quite like to know - if the Turbo has basically the same suspension, then I'll be even more tempted to get one. (Yes, I know the purpose of a Turbo isn't to go slow, but the route to the right roads is often over the wrong ones.)

On the other hand, are you sure the C4S suspension is substantially different from the C4 sport (-10mm) suspension (in terms of spring rates, damping, and anti-roll bar stiffness)? More than explained by the width (which makes an equal diameter anti-roll bar less stiff) and the weight?

alpine003

Um...no.

As someone said above, the c4 chassis is completely different than a c2 as the c4 is essentially the same chassis as the gt3 and more rigid. Most of the reinforcement comes from a revised front tub area in front of the windshield.

One of the reasons why I technically can't extract the most from my gt3 setup on my c2...

Dennis C

I'm not a Porsche engineer, so I'm only relaying things I've read about and things I've researched. The C4S suspension is very similar to that of the turbo, but there are subtle differences due to overall weight and weight distribution. It is very different from the standard C2 or C4 suspension. Many people (including Excellence Magazine) consider the C4S to be a "magical" combination of suspension, brakes and handling because it was really designed to handle the much more powerful turbo car. There are also aero differences to compensate for the difference in weight - this is the reason that the front splitter for the C4S is different from the turbo splitter.

rs10

Oops, forgot to include the quote, but can't figure out how not to post this, and can't figure out how to delete it either ... :- (

rs10

Interesting - would love to know if the ride quality is the same. I'm trying to find an opportunity to test either the C4S or the Turbo on local roads b/c I'm afraid the ride quality will be too harsh. If I knew the suspensions were the same, at least I'd only need to try one of them ...

Dennis C

The suspensions are not identical. They are very similar, but not identical. The damping rates are slightly different on the C4S. That being said, the ride quality is very similar.