TrackFan

Excuse my ignorance, but i've been buying/racing Corvettes for too long. I'm still trying to learn about Porsche.

Getting past the difference in price. Which would be faster on the track? I know the TTS is faster for acceleration, and top speed, but what about road racing? Is the AWD an advantage, or disadvantage?

Speaking of AWD. I figure there's more racers on this forum, so I hope you don't mind me asking here. Which would be faster on the track between the CS and C4S? I'm still stuck on getting a manual, and i'm thinking of getting a CS/C4S with manual, and modifying it for the track.

Thanks for any help.

mig7410

GT3 for the track
TTS for gran touring
Have you tried a DCT, your lap times will be better.

TrackFan

I need a more specific answer for the TTs. Why is not good for the track?

Horstair

Weight, Suspension, Heat (from Turbos), AWD...

991 3Turbo

The Turbo is made to go fast, yet give you some luxury as well as ride nice. I would like both!

GrantG

I think the TTS may be faster on the track (particularly at higher elevations above sea level), but it won't have the same hardcore feeling as the GT3. If you value laptimes over driver involvement (and don't mind the higher price and worse depreciation), get the TTS.

Modifying a Carrera for the track sounds like a good idea, until you realize you'd be far better off just getting a new or used GT3 (much better financially on upgrade and resale sides, if you intend to match GT3 performance and reliability).

If you like manual, get a 996 or 997 GT3...

TrackFan

I've been reading about the GT2 RS. Do they ever come up for sale? Altitude is a problem for me. I live at 8000ft, and the tracks are all over 5000ft.

That's why i've used the ZR1, but I want something new.

Part of my problem is i'm convinced the 991 GT3 is going to handle better than any older version. I don't want to go backwards.

mooty

TTS is faster.

TRAKCAR

TTS if we're talking 991's only, or a base manual C2S and go to town modding it.

Whats DCT?
TTS will be faster at the track.

Who cares, its fasterder.

Well the 991 GT3 is already a luxury coupe, might as well go faster right?

I think it will feel similar to a GT3, just faster. Now, I'm in agreement if you mean 996 997..

Now you're talking! GT2RS FTW!
The GT3 will handle much better than anything else before it, the TTS will be faster and I think will be less boring due to the boost surge. GT2RS for the ultimate thrill ride and the fastest of all in altitude.

No question about it.

GrantG

FYI - Supercharged cars generally do nothing to compensate for altitude like turbos. ZR1- probably loses ~30% of its power and torque at 8k ft just like a normally aspirated car. Turbo would lose far less (but lag is pretty bad at 8k ft at low revs).

tcsracing1

The suspension/uprights should be more track focused on GT3 along with the paddle shifter having more aggressive shifting and neutral feature.

The turbo is faster, but is heavier and has a more grand touring suspension set up. Not sure about TT shifter software when compare to GT3.

also not sure on characteristics/feel/balance of awd TT on track when compared to GT3.

NelsonF

The TTS's were always faster than the GT3/RS in the 996 and 997 versions. This will remain the same in the 991. Nothing new there, the major diff was driving feel given the turbo's awd and turbo vs n/a engine. Will they be much closer in feel now? I'd have my doubts- GT2/RS maybe but this is same as before right? I guess we will soon see.

TrackFan

I don't mean to argue, but that's completely wrong. Superchargers, or turbos increase boost which helps compensate for high altitude. It doesn't matter if the boost comes from a belt, or exhaust pressure. Boost is boost.

That's the reason you see superchargers, and turbos on airplane engines.

GrantG

Superchargers, because they are attached with a pulley and a belt spin at a fixed ratio to the engine speed. Their boost is directly proportional to revs (not absolute manifold pressure).

So, while adding a supercharger to a normally aspirated Vette would help regain lost power due to altitude, it does not help a ZR1 which is already supercharged compensate for loss of air density at altitude (it will have lost power at the same percentage rate as a normally aspirated engine - it just would have started at a higher baseline compared to a normally aspirated motor). So, the ZR1 would actually lose more HP than a base C6 (because it's the same % of a larger number).

A turbo car (or turboprop airlplane) on the other hand can spin the turbochargers faster as the altitude increases (it does not spin at a fixed ratio to the crank speed) - it will keep building boost, until the wastegate's threshold is reached (absolute manifold pressure target is the same at any elevation).

If you want to have the SC on your ZR1 compensate for power loss at altitude (compared to what it makes at sea level), then you need to use a smaller pulley (to increase the SC speed). Just make sure you return the stock pulley when you go to sea level, or you could grenade the motor due to detonation.

A turbo will also self-adjust when you drive between 5k and 8k, as you mentioned in your neighborhood - as in mine. This would be impossible (or very inconvenient) with the ZR1 (different SC pulley at top of hill from bottom of hill).

Superchargers can be used on airplanes, but check this out from Wikipedia (you wouldn't want to be prevented from using full throttle at lower altitudes in your ZR1, would you? This would be the result if your supercharger was designed to make full power at 8,000 ft). And your engine would still lose power over 8k ft:

"Since the size of the supercharger is chosen to produce a given amount of pressure at high altitude, the supercharger is over-sized for low altitude. The pilot must be careful with the throttle and watch the manifold pressure gauge to avoid overboosting at low altitude. As the aircraft climbs and the air density drops, the pilot must continuously open the throttle in small increments to maintain full power. The altitude at which the throttle reaches full open and the engine is still producing full rated power is known as the critical altitude. Above the critical altitude, engine power output will start to drop as the aircraft continues to climb."

http://en.wikipedia.org/wiki/Superch..._turbocharging

Turbos are self-regulating, because they spin independent of engine speed and the wastegate regulates (either closes manually with a spring and opens when absolute manifold pressure reaches a set level - same at any altitude. Or it can be electronically controlled with the same principle). The turbos will have to be properly sized to make full power at 8k ft (most fall a little short when stock, but not nearly as short as SC or n/a). And when the turbos are big enough to make full power at altitude, they tend to be laggier in the thin air. But, you can make full power anywhere from sea level to 8k - way more flexible than SC.

TrackFan

Lets get on the same page here. I used a ZR1, because being supercharged. It will lose less HP at altitude that a naturally aspirated engine will. Just like a turbo engine will. Of course the ZR1 is not putting out the HP it will at sea level. Neither will a turbo.

I'll use the GT-R as an example. Race it at sea level, and again at 5000 ft.