Porsche X50 vs. X51 vs. X33 – What is it all about?

In the vast Porsche cosmos, there are numerous optional extras with a significant influence on a car’s value. Most of them, such as the factory turbo look (M470/M491) or Paint to Sample, change the appearance. However, only a few options have a lasting effect on performance. One of these is the so-called Factory Power Kit, or Werksleistungssteigerung (WLS) in German. Of course, it is difficult for the layman to understand at first glance what X50, WLS II or X51 actually mean. Hence, we shed some light on the factory power upgrades for Porsche 911s.

The first official Porsche Power Kits were available from model year 1983 in the 930 Turbo 3.3

Anyone who is familiar with Porsche’s history knows that there are numerous equipment options available today that were initially only produced on special customer request and later found their way into the catalogs. This is also the case with the Porsche Power Kits, i.e. the optional engine tuning directly from Porsche.

From model year 1983, Porsche Exclusive offered a Power Kit for the 930 Turbo 3.3 (MY 1978 to 1988) for the first time. It included a larger turbocharger, a four-pipe exhaust system, an additional oil cooler and a modified intercooler. Initially, the package was only available as a retrofit kit for around DM 25,000.

All Porsche 930 Turbo 3.3 WLS offered on Elferspot

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This first official Porsche factory Power Kit bore the equipment code SOW 020. SOW stands for Sonderwunsch, which is German for special request. It increased the power output of the 911 Turbo from 300 to 330 hp. From model year 1985, the WLS was available as an optional extra when ordering new cars. Unfortunately, it is almost impossible to determine the quantities. However, Turbos which were delivered with a Power Kit from factory are subject to significant surcharges.

The Porsche 964 Turbo was also available with a Power Kit

Porsche launched the 964 Turbo for the 1991 model year. However, with 320 hp and 450 Nm, it had 10 hp and 17 Nm less than the 930 Turbo 3.3 WLS. For the 1992 model year, Porsche followed suit and again offered a Power Kit for the top model with the new equipment code X33. This enabled the 911 Turbo, which was still based on the M30 engine, to achieve 355 hp and 471 Nm. This meant that the performance of the 964 Turbo 3.3 was on a par with the 964 Turbo 3.6, which appeared a good year later. 192 of these X33 models were probably produced in total.

However, the Zuffenhausen-based company also offered a factory Power Kit for the Porsche 964 Turbo 3.6, of which only 1,437 were built. A 385 hp version of the M64 engine was used in the Porsche 964 Turbo Flachbau (slantnose). Only 76 units of the 290,000 DM exotic model, which was only built in the 1994 model year, were produced. These vehicles had either the equipment code X83 for Japanese models with folding headlights or X85 for the rest of the world with 968 headlights.

The Porsche 993 was the first to feature a WLS kit (X51) for the Carrera models

With the last generation of air-cooled 911, the 993, Porsche offered an innovation labeled X51 from the first model year 1994. This was a Power Kit with different pistons and cylinders which, in combination with modified camshafts and an adapted engine management system, increased the power output from 272 to 285 hp. The torque increased from 330 to 350 Nm. Its price: DM 12,850.

But that was not all. Porsche Motosport offered the so-called Power Kit 2, which provided an additional 15 hp. However, that engine’s design was significantly more extreme than the one in the regular 993 Carrera X51. The use of mechanical rocker arms – as in the Carrera RS 3.8 – meant that a valve clearance check was required every 10,000 kilometers, for example. This point was omitted in the later VarioRam models from model year 1996 onwards, which also delivered 300 hp with X51.

WLS I and II available for the Porsche 993 Turbo – now being called X50

One year after the introduction of the Porsche 993 Turbo, namely from model year 1996, the WLS I kit was available for the Porsche 993 with 430 instead of 408 hp. This was made possible by the use of an additional oil cooler and a new engine tuning. It made the 993 Turbo WLS engine equivalent to that of the 993 GT2. The conversion cost DM 11,900 for a new order and DM 13,150 for a retrofit. Since this model, the equipment code for the factory performance upgrade on the Porsche 911 Turbo has been X50.

All Porsche 993 Turbo WLS offered on Elferspot

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In the last model year, 1998, Porsche offered a further WLS kit for the Porsche 993 Turbo for the proud price of DM 29,800. Vehicles with this option, called WLS II, have a further 20 hp more power and 45 Nm more torque. In contrast to the WLS I package, the final air-cooled Turbo expansion stage also includes two larger turbochargers.

WLS X50 and X51 in the Porsche 996

The factory performance upgrades X50 and X51 were also available in the Porsche 996. The X51 Power Kit was available to 911 Carrera buyers for both the 996.1 in model years 1999 and 2000 and the 996.2 in model years 2003 and 2004. In the 996.1 Carrera 2 and 4, Porsche Exclusive used a modified intake system, modified cylinder heads, camshafts and exhaust manifolds which, in combination with new engine electronics, provided an additional 20 hp. However, this was reserved exclusively for drivers of manual 996s. Its torque of 350 Nm remained the same. The surcharge was just under DM 15,000.

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The face-lifted Porsche 996.2 Carrera was followed by the X51 power kit. An aluminum air intake, modified exhaust manifolds and camshafts, an additional water cooler – except on the Carrera 4S – and modified engine electronics provided an extra 25 hp. The 345 hp engines had the same torque as the other Carreras, but the 370 Nm were only available at 4,800 instead of 4,250 rpm. Porsche offered the X51 Power Kit for 9,727 euros, whereas the retrofit package cost 7,946 euros.

There was no rear-wheel drive 911 Carrera S in the 996 model series. 996 Carrera X51 are sometimes incorrectly referred to as Carrera S.

The Zuffenhausen-based company also offered a WLS package for the already very potent Porsche 996 Turbo. Bigger turbochargers, a modified intercooler and the appropriate engine tuning raised the peak output from 420 to 450 hp. Torque increased from 560 to 620 Nm. An additional 12,748 euros was charged for the WLS X50 in the Porsche 996 Turbo. The X50 engine was later also used in the 996 Turbo S.

WLS strategy change for the 997 – Turbo S instead of X50, X51 only in the Carrera S/4S

With the sixth generation 911, Porsche once again broke new ground in terms of factory performance upgrades. In addition to the Carrera 4S, Porsche decided to position a Carrera S as another sportier Carrera variant. The factory Power Kit increase by 26 hp to 381 hp, introduced from model year 2006, was reserved for the already more powerful S and 4S models. The difference between the basic Carrera and the Carrera S/4S X51 was a whopping 56 hp and 45 Nm of torque. With a price of 6.200 euros, the X51-WLS was a popular option back in the day. Incidentally, the X51 models were recognizable from the outside by a 4-pipe sports exhaust system.

The Porsche 997 Turbo introduced in 2007 no longer had a factory Power Kit as an option. Instead, with the model change to the 500 hp 997.2 Turbo, “only” the 997.2 Turbo S with 530 hp was added. On the one hand, this meant that Porsche was presumably able to realize greater margins with the higher positioned models than with the retrofitting of the WLS. On the other hand, this also marked the end of the X50 package.

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In the Porsche 997.2 Carrera S/4S offered from model year 2009 to 2012, however, there was still a factory Power Kit available. Now based on the new generation of engines with direct fuel injection (DFI), the upgrade amounted to 23 hp compared to the regular S/4S. The 408 hp MA1 engine anticipated the later engines of the Carrera GTS models available from model year 2010.

The X51 chapter ends with the Porsche 991

Porsche launched a new anniversary model with the 991 Carrera S 50th Anniversary Edition in 2013. At the same time as the special edition model, the Zuffenhausen-based company also introduced the X51 package for the Carrera S models at a price of around 14,000 euros. It again corresponded to the specification of the Carrera GTS, offering 430 hp.

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In the 991.2, the factory performance upgrade with larger turbochargers even made 450 hp possible! The Carreras thus entered performance ranges that ten years previously had been reserved exclusively for Turbo and GT models. But it also marked the last time that Porsche offered a factory performance upgrade as an optional extra. After the 991.2, new 911s could not be ordered with either X50 or X51. Instead, the Stuttgart-based company continued along the path of model series diversification.

Porsche 911s with WLS, whether SOW020, X33, X50 or X51, are something special – and therefore in high demand

The story behind the various Porsche models with factory Power Kits is an exciting one. Concrete numbers are rarely available. The only thing that is certain is that vehicles that can be proven to have been ordered with one of the coveted SOW020, X33, X50 or X51 packages when new are also more sought-after and therefore more expensive. It is therefore worth taking a look at the equipment sticker on your own car, if you’re lucky enough to own one. It is even said to have happened that owners of some 911s did not even know that they owned a factory-enhanced 911…