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    is there a way to add x51 after the fact? How much would it run? I have a Cab 4S and a bit more power and PSE is intriguing me...


    Re: X51

    I think it will be too expensive and not worth the $$. Why not supercharge then?

    Re: X51

    Supercharging would invalidate the warranty, X51 would leave it in effect. I heard its like 15-20k for the X51.

    Re: X51

    Earlier this year I got a quote of $21K to do X51, including all parts and labor, from Auto Palace Porsche dealer in Pittsburgh.

    But that was around the same time that the factory had suspended X51 vehicle orders due to backordered parts or whatever there may be more wiggle room now for parts discount now that X51 supply chain is back up to speed.

    Re: X51

    Keep your car, trade in MY 2008 or MY 2009 when the 997 S is rumored to jump to 375-380 h.p.

    Re: X51

    If you already have the PSE the modification would be less. But, it is a reasonable thing to do after the fact,--and quite common for many to consider.


    Re: X51

    I got mine done after I got the car and it is definitely worth it, if you intend to keep the car. You won't add too much value to it but, if you do keep it, you'll definitely enjoy the additional power and the flexibility the X51 offers. Plus, you still keep the factory warranty in effect. I paid about $14500 including labor but I already had the Porsche Sports Exhaust in it when I ordered the car.

    Re: X51

    My C4S goes in on Monday (tomorrow) to get the X51 fitted. I already had the exhaust, but the kit is much more expensive to retro fit. I see the main advantages as follows:

    1) Much more bottom end torque. I find the car much too easy to stall.

    2) My impression is that the engine is low on torque. The kit releases much more midrange torque and a smoother power curve. The regular engine hits a little flat spot before t takes off, I'm hoping this will be less noticable.

    3) Peak power moves right to the redline, meaning that it's worth revving the car out. Currently the car feels slightly strained.

    4) And of course there is s slight power increase.

    The fitting is expected to take all week, so I'll report back afterwards. Have already had the car for 4 months, so will have a good idea whether this makes any difference.

    Re: X51

    Who's doing it?

    Re: X51

    Any difference with a regular 997 S will be felt upwards of 5000rpm's. You can't beat factory warrenty though.

    Re: X51

    Please let me know your impression of the x51 upgrade. It seems that $20K for PSE and X51 puts me in TT territory or close enough not to mess with it...

    Re: X51

    The local Porsche dealer is carrying out the work, so it's covered by Porsche warrenty.

    It's true that with what I've spent on the car it's damn near the same cost as a TT, but I don't want a TT. I'd have a GT3 or RS but the weather here is crap for half the year. Which left me with a C4S.

    Re: X51

    I don't get it, sell the car and buy a new TT... The TT includes many expensive options that are a must anyway, so the higher price is not as high as you think.

    Re: X51

    What's resale on a loaded '05 C2? Probably around $70K? Loaded Turbo should cost at least $130. That's $60K difference. $20K for X-51 retro fit and there's still a lot of money left over before you're in the Turbo price range.

    Re: X51

    SciFrog said:
    I don't get it, sell the car and buy a new TT... The TT includes many expensive options that are a must anyway, so the higher price is not as high as you think.

    But I don't like the TT. I'm not into Turbo cars. And to be honest I reckon much beyond 400BHP is too much. My last car was a TVR Tuscans S. It had roughly the same straight line performance as the TT (195mph, 0-100 8.0 secs), but with a 5 speed box. It was no fun to drive because the gears were over before you knew it, and that would be worse with a 6 speed box! First was almost unusable, second took you to over 100mph, I only revved it out in third once, never saw the power band in fourth, and only entered fifth once!!! Ended up driving everywhere in second, the same freakin gear all day every day LOL.

    Power delivery was so explosive that overtaking was about as appealing as being fired out of a cannon. Now I'm no wimp - one of my bikes will do a standing quarter in 10 secs... but a car is not nimble enough to be accelerating at those speeds on a public road. You can have too much of a good thing, just ask anyone whose ever dated a nympho LOL

    Personally I much prefer both the cleaner looks of the standard car. And the noise of the NA motor really gets the blood going.

    So for me the standard car has more character, is better looking, better sounding, and a lot more fun to drive. I would have loved a GT3, but the weather here is [beep] and this is an every (single) day car. So the closest I can get is the 4S with the powerkit. Thank You Porsche for making this car!

    If I ever want more power, and the car is out of warrenty, then I might consider a bolt on low pressure supercharging kit. But I doubt it...

    It's Fitted :)

    Got my car back at lunchtime today. First the bad news... there's a Porsche instruction sheet provided with the kit, and it instructs you not to exceed 5000rpm for the first 300 miles. Therefore all I can tell you thus far is restrcited to sub 5000 revs, and I have yet to experience the extra 25 horsepower.

    But read on...

    I was expecting a barely discernable difference. Wondered if after a week in a courtesy Cayenne whether I'd be able to detect anything. WRONG. Immediately on pulling away from the forecourt the extra torque was obvious. Don't be embaressed if you've ever stalled a 997S, reckon I managed this at least twice a month, of not more often. Well it's the car's fault! The X51 adds LOTS more bottom end torque. The car pulls away cleanly without any clutch from tickover. The only thing harder to stall would come with an automatic gearbox. Sorted!

    Out on the open road the kit was a total revelation. There are masses more midrange torque. Previously i found that the 997 only really delivered useful overtaking urge above 5000rpm. Mid-range in gear overtakes were sluggish for a car of this power, and lesser vehicles could prove difficult to catch without dropping down a cog. Not so any more! The car now pulls cleanly from 2000rpm. Yes TWO THOUSAND RPM! There is a VERY noticable step in power at 3000RPM and for the first time you feel yourself being pushed back into the seat like a turbo would. Then at 4000RPM there is an even more noticable step and now you're reall starting to fly. Then just as it touches 5000RPM you hear the beginnings of something more vocal... to be continued...

    I already had the PSE fitted, and agree that it does get louder after 6000 miles. The new induction kit seems to add a noticably harder edged sound.

    Based on my experience so far, if all the kit did was deliver extra torque, and no extra power then it would STILL be worth it. That feeling of being pushed back into the seat from 3000rpm is addictive. Where the midrange used to be weak, it's now reminisent of a turbo charged car. Anything without a turbocharger would struggle to live with the new midrange urge. I reckon it's midrange is as strong as my TVR Tuscan S was.

    Everyone knows that the 996 was a great car, but people here will doubtless remember the shock the first time they experienced the 997, the thought of "WOW this is REALLY sorted". Well the X51 kit delivers something akin to that. It takes an already great car and makes it noticably faster. Going through my head was "WOW this has REALLY sorted out that engine".

    The retro fit cost me Pounds10,202.31. And I already had the PSE. Now it's possible to get a GT3 for that kind of spend... but my car is a C4S. So if you want the fastest and best 4WD NON-turbo car that Porsche currently makes, then this kit does fill a niche. IMO the Turbo has too much torque, enough to get it's chasis in a twist. After the X51 my C4S feels absolutely bang on. The perfect balance.

    So to me the kit was worth every penny. i would not consider ordering a C4S without one. It would be really interesting to compare the midrange urge of a GT3 to the X51.

    The 0-60, 0-100, and top speed figures do not tell the whole story. I would like to see some in gear 30-50, 40-60, 50-70, 60-80 etc times. And perhaps a G-meter to record the difference in accelerative forces through the midrange.

    I should have completed the 300 mile running in period by Wednesday. Will report back then as to what happens above 5000rpm.

    Re: It's Fitted :)

    Pleased that the kit is working out well. I just cancelled my TT order because I was dissapointed with way the car drives and handles compared to the fluid and flowing nature of my current 997S, and the sound was pretty blank considering I was going to be spending over $140k. So Im back to the drawing board and have been thinking of getting a new C2S with X51 when the 08's kick in mid next year.

    Look forward to your update later next week.

    Re: It's Fitted :)

    Sound like your already having too much fun!!!!!!!!!

    Re: It's Fitted :)

    Hi guys,

    Here's some pictures of mine in the UK. I had X51 fitted from new. Collected the car 29 September 06 & have only done 500 miles. So cannot comment on top end rev performance while still running the engine in.

    The car is outstanding at low revs & pulls strongly.

    Some pictures here in case of interest...

    Best Regards,


    Re: It's Fitted :)

    Interestingly there is an external cosmetic change due to the kit. Part of the kit is an extra radiator, which lives down in the centre of the front spolier. Pretty sure there was only a hole there before, and the radiator there looks brand new! The effect is very much like a front mounted intercooler, only tastefully done. I'm quite pleased with it. An when you open the engine cover instead of finding "some old washing machine", theres this nice bit of carbonfibre sculpture with a Porsche plaque. While personally I don;t get aroused by carbon fibre, have to admit this is an improvement. Have taken some pictures will post soon.

    Re: It's Fitted :)

    Great post Flash! One of the best explications I've heard so far. Be sure to tell us about the post break-in performance.

    Re: It's Fitted :)

    Glad you're in love with it. I know how you feel and can relate to how easy it is to drive with the extra torque on hand.

    Re: It's Fitted :)

    Congrats to the upgrade! Good review and writeup! Cheers

    Re: It's Fitted :)

    Nice pix, but why is your steering wheel on the wrong side???

    Re: It's Fitted :)

    I'm so annoyed mine can't be retrofitted with X51. One month too damn early in it's construction


    Re: It's Fitted :)

    BTW - does X51 constitute a 'modification' like a Ruf upgrade would? I'm just wondering what the jump in Insurance costs would be?

    From what I have seen it is cheaper to insure a Turbo than a modified Carrera.

    Re: It's Fitted :)

    Here's my attempt at explaining BHP vs torque... let me know what you think...

    You know those roundabouts you get in childrens playparks. They are a large wheel mounted on it's side on a central spindle. There are usually seats for the kids, and they either push themselves round or someone's father does it?

    OK so imagine the scenario where someone's father is pushing the roundabout. He does this by gripping the outer railing in his hands and pushing it along.

    When he first starts the roundabout is stationary. He has to push really hard to get it going. During the first batch of rotations he's grabbing and that railing and giving it big heaves. This is torque.

    Then once he gets the roundabout going and it builds momentum it starts getting harder for him to apply leverage, so he must gradually adapt his technique, and begins to apply quicker strokes with both arms. He doesn't have to shove so hard now because the roundabout is already moving very quickly. These quicker, lighter strokes really build up the speed of the roundabout, increasing it's RPM. This is power. Strictly speaking BHP is the amount of energy that must be imparted to the roundabout to stop it.

    Eventually he reaches the point where his arms can no longer keep up, plus one of the kiddies just puked over everyone. This is max revs.


    How's that sound?

    Re: It's Fitted :)

    Probably the dumbest question ever, but what I don't understand is why we don't throw away 'Torque' and 'BHP' numbers (at least for general public consumption) and just use a 'G'-meter reading when talking about a cars performance? Surely high acceleration 'G' is what we are all after?! I know Torque and BHP are major players in this but why can't we just cut to the chase here?

    Saying all that, I suppose 0-60 etc times are a direct reflection of this though, effectively giving an average acceleration rate over a period.

    I also find it odd that most BHP measurements are taken at the engine and not at the wheels. Porsche seem very efficient at not losing too much power between the engine and the wheels, whereas something like a Gallardo is less efficient (from what I have heard).

    Having 'G' readings would end a lot of my confusion in these ongoing 'power wars' where apparently if you don't have at least 500bhp then you just aren't keeping up with the competition! Hmmmmm....

    Re: It's Fitted :)

    Car A does 0-60 in 6.0 secs.
    Car B does 0-60 in 5.2 secs.

    Both cars race along the road side by side until each achieves 60mph. From that point onwards they maintain a steady 60mph.

    Car A is is ahead of Car B. Why?

    Answer - becasue Car A does 0-40 much faster than Car B, then crawls up to 60.

    The best measurement of straightline performance is the standing 1/4 mile, or even better the standing mile. A fact that seems to be better appreciated in the US than in the UK. Here in the UK very few magazines quote standing 1/4 times.

    However this does not tell you much about real world performance. My TVR Tuscan 2S would annihilate my C4S over a standing mile, but real world A-B the Porsche would [beep] all over it.

    I reckon that 'The Ring' provides a fairily good indicator of a cars real performance. It's not perfect but it's the best we have.

    Re: It's Fitted :)

    Sorry to continue going off at a bit of a tangent here but...

    I agree about the ring times being a more true measure of a cars performance but a lot of those times are dependant on the driver as much as the car. Also, the ring times are equally about the cars handling, somewhere that the 911 really comes into its own with its amazing chassis.

    But in terms of straight line performance it's difficult to know how a car will do by just looking at its torque/bhp/weight, and how it behaves in the real world for overtaking say. This is why I quite like Gustav's videos that I've been looking at recently as they give a rolling start and thus simulate real-world overtaking more.

    The 911 seems to have a big advantage over its competition from it's engine pushing down on the back wheels giving it more traction from a standing start. So it's 0-60mph and even 1/4 mile figures (to me at least) mask the real world performance of the cars. I don't really tend to do that many fast standing starts on the public roads myself...



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