Top Speed for a 996?

Hey everyone, love the forum. It's like instant access to a whole crew of experts all around the globe! I've got a question about the top speed for my car. I've got a 2000 996 C4 Cab that is all stock, no mods. I was at Watkins Glen (my favorite place in the world) for a DE over the weekend. On the back straight, I was in 5th gear and the rpm's were nearing redline at 135 mph. I upshift into 6th and noticed that my rpm's went down to just under 6000. I got up to 138 before I had to brake. I thought the top speed was supposed to be 178 mph? Could there be a 155 mph governor on the car I didn't know about? Thanks for any ideas. I hope there's nothing wrong with my car. Phil

well i believe the c4 is actually 161 top speed for some reason, ive had my 99 c2 cab to indicated 178 but the gps said 173 and it was still pulling but i was running out of nice desserted road

Well, you ran out of room before you could hit top speed. Just because you are on a race track, it doesn't mean you can reach top speeds. You probably need another few hundred yards to get there.

Wow ... you must be movin pretty good through the Ess's ... doesn't that just feel like heaven??!! I've never had the nerve to look just before I brake to go into the bus stop, but I have seen 135 mph not too far from the braking point. My speedo is off by about 10 mph {at that speed}, so that's 125 which seems to jive with the GPS which says 128 is my top speed {ie I picked up a couple more mph before I hit the brakes}. BTW, my best laptimes are about 2:27, this is in my 99 996 {the track car} which is totally stock with street tires {S-03's}. I have never hit top speed anywhere. I once had my 01 up to 145 but ran out of empty highway, it still felt strong like it was ready for much more.

Viken, sorry, I didn't complete my thought. My point was that I thought 178 was top speed. And, given my rpm/6th gear/138 mph, I didn't see anyway I could squeeze another 40 mph out. So, I started to question the 178 top speed. Pete, yep I was flying through there. Exited at around 120 or so. Looking back on it, Heaven is a good approximation. Though, at the time it was a little too terrifying to be Heaven I'm on street tires, too, and I just hit my best times this weekend. 2:25 was the best, with a whole bunch of others under 2:32. Boy was I surprised when people told me! By the way, there was a Jagermeister 962 there turning in 2:00 flat lap times. He was in the red run group and just flying past the race cars like they were standing still. In the Esses, no less. He was asked not to run again on the last day for routine "inappropriate passing"!

I managed 168 indicated before i had to back off (approaching slower traffic). There was a good cross-wind blowing which made it hairy, but the car remained predictable. Did it this weekend coming back from Monterey southbound 101 before Paso Robles.

No speed governors on Porsches, these are not Mercs My C4 on slight downhill (180mph)

Not a specific speed, but there will be a governor on RPM's which will translate into a speed. So I'm thinking the speed that your car is limited to will depend on the rolling circumference of your wheels. If your wheels are a little bigger then your top speed could be higher {assuming down hill with no wind etc}. Phil, based on the numbers you give ... I would guess you would be limited to 163mph. This assumes a rev limiter set for 7,250 {which is my guess based on my 99 ... no idea what it really is} my math: {(135/6000)*7250=163.125}

Besides not having "speed" governor/limiters (like the 155mph on MB/BMW that he mentions)... the RPM limiter will not limit top speed either since you can't hit the rev limiter in 6th gear, if you look at my video grab I'm only hitting 7k RPM at 180mph already (stock wheels), so the RPM limiter has nothing to do with top speed limiting, unless you fit a Cayenne set of 20" wheels In that slight downhill straight were the pic is from I was doing already 150mph in 6th gear when hiting 6000RPM, but then mine is a coupe.

A stock 996 can get close to 150MPH before braking at this spot. Maybe 145 with the cab. You'd need another half mile to see north of 160!

Carlos, Sorry I know I'm being a pain, but if {theoretically} you did fit a set of cayenne 20" {275/40R20} wheels on a 996, that would lower the RPMs at given speed. So down hill with no wind you are certain to hit well over 200mph!

well since atleast 2 of here have gone over 170mph pete im not so sure your math and a topspeed of what was it 163? really apply

Hey Phil, I was there too...in fact I think you relieved me on Saturday afternoon at the front gate so I could get my run in? Thanks again, even though you didn't have to stick around. That Jager car was unbelievable. Small world. regards,

The numbers you posted seem the indicate different gearing for your cab than on the standard 996 which I don't think is the case. There's no way you should be as high as 6k at 138 indicated (porsche's always read high). Also the cab probalby has a slightly lower top speed due to more drag.

The straight at the Glen is rather short for top speed runs. It also is an uphill climb through the esses before the straight. To give you a comparison, I run down the chute and shift into fourth then turn into the esses. I climb through the esses and shift fifth about midway through the left as we crest the hill. I accelerate fifth out almost to the redline, somewhere in the 150-155 mph range before the bus stop. This is in the neighborhood of how fast you can get my car on a track. Pocono full is a little faster at abotu 160. I did not get to do Pocono Nascar style, but with the full bowl, I could probably 10 mph faster. These speeds are lower than what the car is capable of, but you simply run out of track. Also keep in mind the entry speed on a track is key. Entering the esses 10 mph faster will make a huge difference at the end of the straight. Do you keep on the floor after the right turn into the esses or do you modulate your throttle? Other factors like aerodynamics come into play. The setting on my rear wing is supposedly worth 2-3 mph, you convertible top up verses down is probably worth 10 mph. Even open windows come into play.

Phil, BTW a quick C stock 996 at the Glen is around 2:10, last time I was up there, I turned mid teens. I believe the pole for a 996 cup car at the last event was 2:00 even. The 962 should be able to go abotu 10 seconds faster with a professional driver. He should also know not to pass is the esses at a DE. Its inappropriate behavior considering in 300 yards he has a straight and is gone.

Yo NiveK ... Just trying to figure it out. It's not "my math". 163 was based on the numbers Phil gave me. If the RPM's of a car are 6K {or just under} at 135mph and the rev limiter kicks in at 7250 RPM, then the top speed {rev limit controlled} is 163. End of story. I'm pretty sure the two cars that have gone over 170mph have RMP's well under 6K at 135mph, unlike Phil's car. Maybe I should be clear and state that I do believe the car is built for well over 163 mph. Hell there is a page in the back of the owners manual for my 01 with a graph that clearly states if the RPM's are 7K the speed should be 180mph in 6'th gear. Whether or not the car has the HP to actually do that on a flat course without a tail wind, I can not attest too. Either BRH986 is right and the RPM's were a lot closer to 5200 or the gearing/wheels are a different setup for some reason.

Not a pain, Pete and you are right I just re-read that, it obvious it should be the other way around... how about fitting a set of shopping cart wheels To add more to the speed/RPM relationship, my coupe at 138mph is doing 5200k in 6th gear and incidently around 6200k in 5th gear.

Carlos, I have to respect a man who can drive at 180 mph whilst taking photographs of the instrument panel!

I have to respect a car that one can drive at 180 mph whilst taking photographs of the instrument panel! Cheers, Uwe

But my wife didn't think that way when she saw it It was actually a video camera I handheld with the right hand, its on a video I posted, thats just a frame grab from it

I have a 2000 coupe with us m030, kumho track tires, and hawk blue. My best lap time at the Glen was 2:171 when I go flat out (pedal on the metal) after turn one and only lift for quick up shift. That would get me to about 140 before I brake for the bus stop. I don't think you need to shift to 6th at all at the Glen or any other track that I have driven. You will gain a few more mph if you don't up shift to 6th.

Carlos, You need to share your video with all of us! Mark P.S. Every man should have at least one vice that his wife disapproves of!

The top speed run is at the end of the video Right click, save as... 75MB/15 min version: http://members.rennlist.com/raptor/911-GSX-Raptor.wmv 10MB/5min lower quality version http://members.rennlist.com/raptor/SHORTER%20911-GSX-Raptor.wmv

Carlos, I can't get the links to work...is it just me? Right Clicking gives me an error

Hi I have a C2 tiptronic 1999 at last run i've got a 290 K/M (its about 175mi ) before i brake.

The quickest officially recorded time for a stock cup car at WG is by Cory Friedman in the PCA enduro portion of the club race this past year at 2:00.0 as Ed noted(that was in a 2003 GT3 cup) IN 2000, JF Dumoulin officially clocked a 1:58.7 in a 2000 GT3 cup car in the 6 hrs of WG Grand Am race. This car had no modifications except shocks. Unofficially, stock cup cars run in the 1:58-1:59 range with fresh tires and professional drivers. Our Motec and Stack data recording sytems reveal that laps at WG in the 1:56 -1:57 range in the GT3RS and in the 2:00-2:02 range in the cup car do not achieve nearly the top speeds one would think(less than 165 even in the GT3RS). WG is actually the second fastest top speed circuit for Porsches in North America(in our experience)with with Daytona being the fastest. -Have not been at Pocono with these cars though-

Well, the reason I went to 6th in the first place was because I thought 5th was nearly wound out and I wanted to move back to the more powerful part of the torque curve. So, am I to understand that the rev-limiter will not kick in when I'm in 6th gear? I wish that someday I'd be able to find out first-hand, maybe in the Salt Flats in Utah!

No the rev limiter will kick in regardless of what gear you are in. When Carlos said: "...you can't hit the rev limiter in 6th gear" what I'm sure he meant by that was as long as you have stock setup and everything is working right, you would have to be going well over 180 mph before the rev limiter would kick in. I think most people agree that a stock 996 isn't capable of well over 180mph {at least on flat ground without a strong tail wind}. Phil, are you sure your RPM's were about 6000 at 135mph? Like I said earlier, if you check your owners manual, you will see that there is a graph in the back which shows for each gear RPM's vs Speed. For 6'th gear at 180mph a stock 2001 996 C2 should be at 7000 RPM's. Easy to check this on the highway by going say 60mph {rpms should be 2333} or 90mph {rpms should be 3500}. If you are seeing significantly higher revs then I would guess maybe your back or front {depends on where speed pick up is} wheels are smaller {overall diameter} then they should be. Check http://www.tirerack.com/tires/tiretech/general/size.htm for a tutorial on this. If this is the case Phil, you may indeed hit the rev limiter in 6'th gear well before 180mph.

Your clutch might be slipping!! Higher RPM but lower speed.....

Sorry, I don't know were the problem was, but it works OK now: 75MB/15 min version (recommended): http://members.rennlist.com/raptor/911-GSX-Raptor.wmv 10MB/5min lower quality version http://members.rennlist.com/raptor/S...GSX-Raptor.wmv

I can't get them to work either. I tried both versions too.

Use the links on the on this last post, they work OK.

I got it to work, Pretty damn cool Carlos

Thanks, it was fun making it

Carlos, I downloaded it today. Fantastic job! Charlie

nice job it's interesting to note that drivers in other countries respect faster traffic and merge right when appropriate. in California theres no shortage of *********--usually in lifted trucks--who try to pass you on the right, race you to the next stoplight or tailgate you at every opportunity. Letting faster traffic by is the last thing they'd ever do.

I agree 100%, its not only curtious and more efficient traffic wise, its also much safer: left lane yields to faster traffic and no right lane passing. I guess the polititians and burocrats are clueless when it comes to driving and traffic and ticketing for 5mph over the speed limit offers more revenue.

Higher gearing would not raise the top speed and might lower it, the car is already geared to hit the power peak in top not the redline. Aero drag versus engine power is the limiting factor.

<quote> Higher gearing would not raise the top speed and might lower it, the car is already geared to hit the power peak in top not the redline. </quote> You are probably right in most cases, if the higher gear is only to lower rpm's it would serve more as a overdrive to save gas than anything. one example is the old corvette ZR1, it used to get up to 180mph on 5th, but when you shift to 6th, top speed is like 176 or so. Likewise, the first gen viper can do 180mph+ in redline at top gear, but push it too long and you'll pop the motor. They probably set the gear to reach its optimal speed faster, rather than change ratio and lose more in the beginning.

Carlos, Great video!! Very cool.