smokestack20

Guys,
Please settle a discussion I had with a friend. (Okay, It ended up being an argument!) How accurate are the listed top speeds for Porsche, in this case the 997.1S, 997.2S and the Boxster S? I'm saying the listed TS may be optimistic, but close.... he says not even close, 20-30MPH off! What say y'all

And no, I'm not taking the car out to try and prove him wrong!

Thanks, Ken 997.1S

mdrums

They are close...not 20-30mph off. At Daytona I've done 166mph down the front straight and according to gps data the speedo was right at 4mph optimistic.

At Sebring just before braking into turn 17 on the long back straight my speedo shows 141-42 all the time. GPS dats shows I'm at 139-40mph all the time.

pewter82

Top speeds are correct, also Porsche shows the wide body 4S a bit slower and the PDK is a bit slower, so they have done the testing.
Now about the 0-60 times ? Porsche is Conservitive with what they list. Why ? No idea.

Fahrer

I think Porsche is a bit conserative with the 0-60 numbers as they do it without abusing the car. Dropping the clutch like they do in the car magazine tests will generally drop roughly 0.5 second off the 0-60 time. I believe that Porsche also reports ralitic top speeds too but one must consider the conditions. If one is doing their own test at a different altitude, temperature , humidity,wind speed etc. results will vary. Finally, speedometers ( all brands) are pretty accurate and are generally 2 mph optimistic at most often used speeds but can be a bit more optimistic ( 10+mph) at higher speeds (e.g. 140mph)

Mike in CA

Top speed for my '99 996 was listed by Porsche at 174mph. On the Autobahn, flat out south of the Nurburgring I saw an indicated 177mph on the slightly optimistic speedo. Many magazines test actual top speeds instead of just using manufacturer's specs and Porsches numbers are consistently confirmed. You win the argument; your friend with his claim of 20-30 mph differences isn't even in the same country, must less the ballpark.

smokestack20

To elaborate further: He argued that Top Speed figures are usually obtained using "special cars". those that are factory tuned, lightened, etc. etc. I've heard of this being done by some companies to get the best possible results for a Road & Track article, but I'm thinking not so much for Porsche.

On a related note: which also came up in the debate, Sustainable speeds? What are the realistic sustainable, "Autobahn" speeds for the modern Boxster/911?

Thanks! mdrums, pewter, fahrer and all future posters.

Ken 997.1

Edgy01

Top speeds are realistic for Porsche. They always have been. I believe my 06 S is rated at 182-3 mph top speed and I easily hit 180 mph on the autobahn (indicated). I suspect the speedo could have been off by about 2 mph, perhaps. There was still plenty of pulling power remaining to get it up another few mph. (Frankly, at a mile every 20 seconds, I wasn't spending a lot of time looking at the speedo).

When you ask about sustained speeds, then you have another issue. Even on the autobahn, you can't expect to go 180 mph all day and night. First, it's completely unrealistic. With even occasional traffic on the autobahn, you will still have to drop down to 80 or 90 quite a bit. The other big constraint is cooling. At top speeds heat production is very high. You may exceed the capacity of the coolant exchangers if you attempted to drive 180 mph for an hour or so. Again, this is a car designed to be driven on the autobahn, under autobahn conditions. For those who track their cars they are never doing 180 mph--they may touch 120 occasionally, but never for very long.

smokestack20

Edgy, & Mike,
Having reached those speeds in Germany is proof enough for me! ( probably not enough for my buddy, if you know what I mean)
As for the sustained speed, its more a theoretical question.... What's the likely highest speed a modern Porsche could hum along without issue? Okay its a dumb question, but a little interesting.

Ken 997.1S

Mike in CA

I know manufacturers do sustained high speed testing but I don't recall seeing results for any recent Porsches. Just as a point of reference, though, my Carrera S PDK is turning just a shade over 2100 rpm @ 80mph in 7th gear. That would mean that at 160 it would be revving around 4300 rpm which is right at the start of peak torque output and well below the 7400 redline. The point being that the engine would hardly be overstressed at sustained speeds in that range assuming the road and traffic would permit. Hard to know of too many places in the world, though, where that would be possible short of a test track like the VW facility in Ehra-Lessien.

ADias

Any 911 can cruise at a stable 120MPH hours on end. I have seen it even on 100F weather. Few roads support that, of course.

Re top speed... The factory published numbers can be met by any production car under the same conditions. PAG does not tweak cars for review. Ferrari is known to do that.

allegretto

1) track racing warms cars up far more than high speeds. The revs are always very high, usually higher than can be reached in top gear. Motor deep in its power band producing lots of heat. The car is going slower so the cooling system offloads less energy. It is truly rare to see an overheated Porsche at the track, even a TT. Few other brands like that.

2) Owned a "press car". Other than abused it seemed like every other GT3

dasams

There's no way a pdk S can hit 160 in 7th. Not enough power at 4300 rpm to overcome the drag. But if you run full throttle in 7th, the engine will be fully stressed regardless of the actual speed. dave

Fahrer

120 mph easily. My VW Passat 1.9LTDI would cruise at 120 mph ( max speed) on the A45 in Germany. My friend drove me in his 2004 Boxster S at an indicated 272 kph (169 mph) on a section of the A2 but I am not sure what the claimed top speed is for a Boxster S of that year.

Mike in CA

I can't find a definitive test that shows speeds in gears for a Carrera S with PDK. The July 2010 issue of Car and Driver tested a PDK equipped Cayman S, down 65HP to the Carrera, and showed a speed in 7th of 171mph. I'm not sure I believe that; might be a typo. 160 in 7th is 26mph off the top speed of a Carrera S PDK, however, so it doesn't seem completely unreasonable. I'd love to see the actual numbers, as opposed to conjecture, that would prove it one way or another. In the old days the owners manual had a speed in gears chart, but not any more.

Even if 160 in 7th were possible, it would no doubt require full throttle so your point about a fully stressed engine is well taken.

smokestack20

Appears a white flag has been raised on the Top Speed debate. My skeptical friend just sent me a you-tube video "Porsche 911 Turbo- - Top Speed" showing the turbo reaching/exceeding the 193mph claimed top speed on the autobahn. (Top Gear video)
Thanks again to all, whats better than telling a good friend that he's full of sh*t!

Ken 997.1S