C4S - Someone Lied to Us!

And it is actually a good thing. Let me explain. I have two proof points to back up the following claim: Point: The C4S is faster than Porsche's published numbers and faster than reported magazine tests. CounterPoint: Just my C4S is this way due to some factory fluke Case #1 - A so-called "expert" who sometimes visits this website recently told the owner of a 2002 Acura NSX and myself that the C4S is only marginally faster to around 60mph but that the NSX catches and passes the C4S by the end of the quarter mile on up. This was based on "limited" research consisting of reading magazines and believing what they say. So, striving to put this information to the test the owner of the 2002 Acura NSX and I hit the highway. I got on it and he attempted to keep up. From about 60mph up to about 110mph our cars were pretty even, but after 100mph I was pulling away up to 145+mph where I was certainly creating additional distance between us as the view of him fading in the rear view mirror was a testament to. Well so much for magazine tests I guess. Real world testing clearly showed the stock C4S to be faster than the stock NSX (2003 vs 2002) Case #2 - I spy a new 2004 C4S cab, seal grey, Nevada plates, on the highway today with its left blinker stuck on. So I weave a little traffic to catch up to him to tell him his blinker is on. Only problem is that he thinks I'm trying to race or something so he floors it and takes off. Ok, I stomp on the gas too. In no time I've caught him and passed him. He's smiling and giving me the thumbs up. I'm shouting that his blinker is on! He finally understands me over the wind noise I guess and turns off his blinker and gives me a friendly wave. Now I expect a C4S coupe to be faster than a C4S Cab, but according to all of the Porsche press materials there is supposedly only a minor difference in acceleration and performance, touting what a good job Porsche did with the Cab version of the C4S. I'm telling you that based on our highway dodging that my C4S coupe was significantly faster than the Cab, no ifs ands or buts about it. So, I'm left with the conclusion that either the C4S is faster than Porsche is letting on (also bolstered by my outdistancing an number of supposedly faster C2's at the track, but that's another story), or somehow I got some once in a lifetime act of God faster C4S from the factory, or maybe just a better tank of gas? Anyone else noticing this from their 03 or newer C4S coupe? Palting? Could it be the magical Orange Plug???

Ghost - The quality of gas makes a difference. A few years back on a high speed test track (4 miles, 37 degree banked corners) my Boxster S picked up 10 MPH top speed by changing brands of high octane fuel. I was amazed. The Cab you passed might have been a Tiptronic?

Maybe you got the x51 by accident :-)

A C4S Cab, Seal Grey... WTF they told me I had the only one!! You know one important point that you are overlooking is the skill of the driver in both cars. I would like to see the test conducted in a controlled environment with professional drivers. Some people loose their nerve at 145+ and back off some... JMTC. Now if you'll excuse me I have to paint my car Sea Foam so it's unique again

Some people loose their nerve at 145+ and back off some... JMTC

One cannot help but hope that Porsche engineers use a testing protocol that is more rigorous than two brief street races. Steve

Maybe a trip to the dyno for a few C4S and C4S Cab owners would be in order.

I don't remember the source for this (but it was reputable), and the information is at least a couple of years old, so I am not sure if applies to the water cooled engines, but Porsche dynos (at least used to) all engines and they must fall within a certain tolerance of specified output. If it is too low or too high, they are not used. I don't remember if they are remanufactured or what happens to them. In other words, the possibility of having a 911 which is significantly more powerful than other is unlikely. I will do a bit of a search, but I am sure there are other forum readers who may recall the engine spec info.

Each engine is allocated an hour, total, in the test chamber of which about 10 minutes is spent at various loads and throttle openings. HP tolerance is +/- 10% or the engine is torn down and parts returned to head of engine assembly. Your 320HP 996 could be as low as 290HP or a high of 353HP. But as for me I start to "feather" the throttle slightly, below WOT, above ~100MPH.

Porsche is know to underate their dyno ratings. It stands to reason that they underate the performance numbers as well. God job on the NSX! I posted a simillar episode a while back, that time with a 360 moderna on the track. This was a 2002 model, driven by an instructor, with track tires and track driving adjusted suspension. This was at the relatively shorter 1.6 mile track at BeaveRun. He did have a passenger, his son, with him in the car. I had my C4S, P-Zero tires, brake pads on their last legs. By all that's holy and known, I should not have had a chance. I let him line up ahead of me so I won't have to let him pass me so soon. Lo and behold, I caught up to him after several laps, then passed him. Did it consistently each run. I believe the advantage was exit speed, with the C4S ability to get on the gas much sooner than the 360. First time around, he and his son came around to check out my car, astounded that I was on street tires. Fourth run of the day, he made me line up ahead of him .

i've experienced this many times. what impresses me about our cars is the acceleration above 100 mph. the little bastard pulls pretty good right to 170+ i've been spanked by few cars above 100. a gt2 (very cool to watch him speed away) and an '04 e55.

winovin and juan, your positions seem to disagree can you rectify? I don't believe I somehow got a magically faster C4S from the factory, although the thought that I could have received an engine with HP on the higher end vs. lower end is nice. I would hope driver skill wouldn't play much into simply mashing the throttle and going in a straight line. True, on the track it makes a huge difference and that's where I enjoy 99% of my high speed driving, but since the NSX owner never comes to the track we had to use a vacant highway for testing, well almost vacant... i know i know... anyway the C4S continues to suprise and amaze me, another track weekend coming up this week! Woot!

Bob, what brand of high octane did you switch to? I use Chevron 91 and blend 100 oct (4 gal). The 100 oct is 76 brand. Maybe I should change my base brand to the one you found? Thanks

These cars get faster w/time, the fact that your MY02 beat a MY04 makes perfect sense.

You should make that your signature!

Juan's post has triggered my memory - I don't think the tolerance is +/- 10% - that is too wide a range, and frankly, I don't see such a variance being possible with the same components. +/- 10hp seems more reasonable.

It's +/- 5%, or so I recall being told once upon a time.

That sounds about right. I know I was catching up to a GT3 this past weekend at Buttonwillow, so I must have gotten a strong motor.

jyoteen, That reminds me I was playing with a GT3 in traffic one day and then on the highway, another user here, and I didn't have any problems keeping up with him.... hmmm must be a group of mystery C4S's out there.. I've probably got an extra factory supercharger stuck in there somewhere under the hood since my car was a late in the year build it was probably just an extra part laying around they decided to get rid of when cleaning house...

dyno it

I can see how an engine can make less than specified HP but it's not at all clear how it can make more. You can make a mistake in manufacturing and reduce performance but I doubt you can make one and increase it. I suspect by +/- 10 hp they really mean -10 hp. Just a thought. I don't mean to bust your bubble Ghost.

JimB, I think the way an engine can make more than it's rated power is if the rated power is conservative (i.e. stating the rated power as an average of observed outputs). Having said that, I still find it hard to believe that the variation could be more than 20hp (i.e. 320 +/- 10hp). Further, not sure if this was speculation or an explanation, but the original article I read about this said something about the stronger engines going into the heavier cars, such as convertibles and C4s. As I said, not sure if the article stated this as an explanation, or whether it was just speculation. Paul

the guys at mckenna porsche recounted a story of the meridian metallic carrera no one wanted, but every salesman that drove it swore it was faster than a 'normal' car. they dynoed it at 345 hp (3.6L) which is a little more than +5% ....recompense for a hard to sell color?

Well I am the victim of racing ghost rider. I must correct Ken in his story as he was not correct. His story was slightly off and I appreciate ken's lie to spare me the emabaressment of our race. He beat me by 15 car lengths or more from 60-145. It was like my car was pulling a boat while racing ken., Clearly the nsx is a pos and has no business racing this car. I have only owned my 02 nsx for a month but have been beaten by many cars including civics,taurus,escorts and even a woman in a wheel chair who smoked me off the line. Not only did he smoke my car but after we got off the highway and stopped at the next light a hot woman jumped out of the car with huge ***** and hugged ken calling him the greatest while her ugly fat friend wanted me. lastly ken you mentioned that there is no skill mashing the throttle on the highway but clearly you are a better driver then me and other nsx owners. remember when you smoked the nsx in your auto g-35. My conclusion of you being a better driver then me starts with your probe beating my prelude/then your boxster killing my s2000 and now your c4s smoking my nsx. I assume when we are 65 your 4 volt motorized scooter will kill my scooter.your pencil is even better then mine and I believe your father can beat mine up I bow to your greatness. Well I got to get back to work

As far as I know Porsche does run every engine on the dyno for break in and testing. The Spec is minus 0 plus (something) percent. I am pretty sure the spec is -0 +10 percent. There is no way Porsche would sell an engine making less than its rated power. The rating is designed to allow for engines that are below some threshold and the advertised spec is set such than no engine is ever less. Given the degree of precision these days I am confident that the majority of engines in Porsche cars are above spec and it is the rare one which is at or close to spec. About Gas - I'm in Canada. It was a charity event put on by Pirelli. They recruited PCA instructors to take celebs around the test track at high speeds. They also supplied free tires which was a good thing. The track is an oval (you can see it at PMG.com), one mile on a side. The turns are banked steeply and you don't have to lift at speeds below around 200 MPH. Each "ride" was 4 laps. I was amazed at how much gas I used running flat out constantly. I could run about one hour before heading for fuel. The first tank was Gulf 92 octane and my car was clocked at 161.72 MPH average speed. The next tank I filled with Petrocan 94 octane and my speed went up to 170.93 MPH. I don't think heat was a factor it was a cool day and I got better speed after the first hour. I also discovered a trick about banked turns, get really really close to the wall and your car picks up speed. Some aerodynamic effect the car gets quieter and goes faster. My passenger (another instructor) remarked "Bob do you realize your mirror is only 2 inches off the wall?". He was right but no way was I going to look over to see it! This was in a 2000 Boxster S on fresh P 0 Rossos compliments of Pirelli. We learned one other thing than day, a 993 TT was capable of a sustained 300 KPH but don't try it on R compound tires. They are not designed for sustained high speeds! Oh year, how to freak out the celeb? Drive onto the banking and take your hands off the wheel at 170 MPH. Since this is a 996 forum, you'll be pleased to know that a 996 C2 press car was lapping at 179 MPH. Bothe the boxster S and the 996 exceeded specs in that regard. Best,

Paul, I would agree if I believed that Porsche was building engines with a 20 or 30 hp variation and that they picked a number in the middle to publish knowing that some would be high and some would be low. I seriously doubt that that is the case. I certainly hope it's not. With modern manufacturing techniques now in use, I suspect that 99% are within a 1% range and that the others are on the low side. Actually I would hope that 99.99% are within 1% and the +/- is caused by variation in the dyno. But who knows. Jim

sometimes, that additional power is made by the combination of the right parts. That's why a lot of race teams spend $$$$$ trying to find that elusive perfect camshaft or perfect piston, because by itself, it may not do anything, but a combination thereof may produce noticable gains. This is pretty evident in spec series, where a slightest advantage can mean running midpack or ahead of the field.

nsxtbone, That was pretty funny. As you know, this thread isn't about whose car is faster, but rather that published numbers, either from magazines, or even from Porsche don't seem to be jiiving in this instance, and of course how the so-called "experts" are often quite wrong... Bob Rouleau, I'm going to have the oppotunity to put this C4S on the high bank ovals of our local speedway in a couple of months. I'll report back my findings, although I might just have to remove my mirrors altogether so I can get even closer... There is an aerospace engineering term for the flow of air near a surface, and I suspect near the wall, I think it was called laminar flow and it had different characteristics, although that was 20 years ago and I don't remember much about those classes anymore... jyoteen, Maybe I just got the right parts! The NSX driver reported a puff of smoke out of the exhaust between 4th and 5th gears, don't know if that means anything or not, I'm still burning what I think is a higher amount of oil than normal for an engine with 5000+ miles on it now, but who knows, I still think it is the mystery "Orange Plug" upgrade that is secretly worth 20HP! All, A friend of mine got an R32 which I checked out yesterday, looks like a fun little car, can't wait to see it at the track.

Hey no problem. Next time let me know ahead of time when you want to race rather then taking off while we are entering the highway and when almost I catch up claim I am getting smaller in your mirror? Also letting me know would give me time to roll up my windows, put my top on and turn my a/c off. Heck now I am excited that Acura must have lied to us owners about how fast our cars are also!!!!!!

NSXTBONE - thanks for keeping our collective big heads in check!

Better still, why not repeat the testing until definitive results can be reported? Based upon the conflicting reports I have heard about his contest from both participants, no one should have any reason to dispute published Road & Track test results for these cars.

FXHottie, If Road & Track were to be believed, the NSX should have caught and passed the C4S and that certainly wasn't true. The NSX did fall back in my rear view mirror, although I can't say if that is because he let off the gas, was applying some brake, needed to shift and didn't, had too much aerodynamic drag with his top open or what. The fact is that so many factors come into play (tire pressure, fuel, etc.) that magazine tests are usually pretty worthless and should never be quoted as a definitive source of information. I was actually more surprised at how easily I ran down the C4S cab given what Porsche advertising materials had said about it, although as one user above pointed out, I don't know if he had a tiptronic or a 6spd, even so, the margin of difference was surprising to me. Although these are only 2 instances from the street, I have several others from the track where the C4S has outperformed other cars that on "paper" it supposedly couldn't. Palting has found this to be true as well with his experiences with the Ferrari. C4S owners should rejoice! (Besides I think the C4S won the "best looking" 911 thread awhile back)

Perhaps Road & Track testing isn't as definitive as it could be. However, you still haven't established that your testing method, consisting of a single pass on a public road, was more accurate than R&T's testing methods. Moreover, it appears there are two different accounts of the results of your testing. Therefore, I was suggesting that the value of your data could be improved if you would repeat the testing several times, and perhaps try to secure a more controlled environment. An impartial observer might be helpful as well. BTW, the differences in acceleration performance between the NSX and the 996 reflected in the R&T testing were minimal, and probably statistically insignificant. Then again, if your testing truly reveals that your car accelerates significantly faster than the 2002 NSX, it could be that the R&T editorial staff was bought off by Honda and they altered the test results appearing in the magazine to make the cars look comparable. Finally, if R&T testing isn't a reliable source of information, and your test methods are reliable, then maybe you can start your own magazine. I'd call it "Good Killz" or "Street Racing With the Boyz".

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Ghost, Sorry I picked this thread up late. One additional variable is the "break-in" status of the engine, and the relative freshness of the tune. Another smaller factor is the fuel load. Guys who break-in the engine by hard use tend to have a looser engine with more power. For the most part, more miles also results in more power, if the state of tune is equal. The Road and Track extended tests frequently show their cars to be faster at 40,000 miles. Bob's conclusion from his gas experiment may be valid. But an hour running near redline may have completed the break-in too. Weight is also critical. The cab is certainly heavier, and add another 100 lbs if it's a tip. 10 gallons less in the tank also equates to about 70 lbs. If there is also a driver weight discrepency, the sums can get significant. I'm sure someone will correct me, but I'd guess that if all the factors were in your favor, you could be talking about a 300 pound difference compared to the cab. The Accura saga is hard to interpret since I have little NSX experience. It sounds like you went thru several gears, so speed in shifting may have had an effect. I'm presuming the NSX driver used the entire rev range, since that is another car that needs to wail to make hp. If I'm just wrong on all accounts, congrats on having a quicker-than-average C4. AS