Porsche 993 with option X51, "RS light"...UPDATE!

Update 28-12-2014: Thanks all for contributing to this blog with info regarding the various X51 versions. Based on this I have updated the X51 blog. If you have any info about the X51 option or found anything not correct in this blog please contact me.

Anybody seriously looking to buy a Porsche 911 type 993 may have noticed some cars being advertised as a X51 optioned model. Besides increasing the price this option has many enthusiasts bounce up and down with excitement. Then why is this option so desirable and is it worth looking for a X51and paying the premium? A short guide to the mysteries of the X51 code for the Porsche 993...READ MORE>>>

Where to find proof of a X51 option

All options ordered by the customer were printed by the factory before assembly on the option sticker. This sticker should be present on the first page of the service manual and under the front hood. If the car has been repainted the hoodsticker is sometimes lost. Besides the chassis number, engine and gearbox data all options are listed by their 3 digit code. If there is a X51 on this list you have a winner, if not and the seller still claims a X51 engine then it may have been added later as the X51 engine upgrade was offered by Porsche as a retrofit kit ( list price, parts only: € 12.000 ). Interesting note is that the X51 option was not available in the US and Japan, not even as a retrofit.

Prices for an X51 upgrade varied per country but in the range of € 10.000 / $ 13.000.

Service manual option sticker with a X51 option ( besides many more options!!)

X51 for normal aspirated 993 engines

Any 993 including the Targa, Convertible and Turbo could be ordered with a performance increasing package ( called X51 for the normally aspirated 993 and X50 for the Turbo ). Basically the X51 kit compromised larger cylinders increasing the engine capacity from 3.6L to 3.8L, different cams and a different single pulley belt system. This increased power by 15 BHP raising the 270 BHP to about 285 BHP. When the Varioram system was introduced for MY 96 and base power increased to 285 BHP the X51 engine equalled the RS 300 BHP output.

X51 Werkleistungssteigerung for 993 ( 1993-mid 1998) modifications UPDATE

M64.05 and M64.06 (tiptronic) NON-Varioram engines with X51 option:

• 1993-1995
• Larger cylinders / RS camshafts and RS pulley if non A/C equipped.
• 210 KW/282 BHP 

M64.21 and M64.22 ( tiptronic ) Varioram engine with X51 option

• 1995-1998
• Larger cylinders / RS cylinder heads,camshafts and valves, modified X51 DME ( RS DME )
• 221 KW/ 300 BH

(Note that only ROW cars equipped with the 64.05/06 and 21/22 were offered with X51 option. M64.06/07 and M64.23/24 engine were USA models, X51 was not available in the USA)

An even more special, special 993 X51....(for the 993 aficionados...) UPDATE

Due to new emission regulations in Europe, Porsche in 1996 was forced to equip all 993's with the longer geared G50/20 transmission ( G64/20 for the 4WD models ). Until then the ROW models used the shorter geared /21 box that had a slightly better gear ratio. At the same time Porsche introduced the Varioram engine for the 993 with increased torque and HP. For about 8 months Porsche built a number of Varioram cars still equipped with the short geared /21 box. For the real 993 aficionado these are the best models, combining the increased power of the varioram with the better geared /21 box...now add a X51 option and you may have one of the rarest 993's available...

Turbo X50 kit ( WLS 1 and WLS 2 )

Turbo buyers were not forgotten and were offered the X50 option. This performance increasing package WLS 1 ( WLS= Werkleistungs-steigerung ) was introduced with the all new 993 Twinturbo. It consisted of ECU software tuning with increased boost pressure and power increased from 408 to 430 BHP. As of MY 1997 the WLS 2 package was available, this time Porsche went all the  way with increased capacity turbo's and twin plug ignition ( standard Turbo has single plug ignition ) producing a very healthy 450 BHP. This WLS2 package was standard on the Turbo S. Interesting note is that the US model Turbo S's were still only available with the WLS 1 package due to emission rules.

Wolfgangs own Tannengrün Porsche 993 Turbo S WLS 2

The rare X51 Non varioram 300HP engine

Motorsport 300BHP engine description

An even more desirable and mostly unknown option for 94 and 95 ( and thus non-varioram )  model was the "Porsche Motorsport Weissach" kit. Many specialists and even Porsche centers are not familiar with this rare bird but it was an option only available in 1994 and 1995 in Europe in exchange for 24500 Deutschmark. Where the X51 option is basically a powerkit for a standard 993 engine, this one is a genuine race bred engine probably based on the 964 RS 3.8 engine. It puts out a nice 299 BHP and 365 NM torque. Interesting about this engine is that it has mechanical valve tappets instead of the hydraulic ones introduced with the 993. A 10.000km service interval was therefore needed to check the valve clearance. The engine code for this engine is M64.05 R(ace...). It is recognizable by a Motorsport sticker on the intake manifold ( if it is still there after 20 years. The options sticker will only show X51 so the only way to be sure is to look at the engine number. SO far I have been unable to get factual information on the total number of these built. But I am sure there are some 993 owners unaware that they have a genuine Motorsport engine!

Be happy if this sticker is on your engine intake.

X51, an RS in disguise...?

It is debatable if the X51 can be called an RS engine. Just looking at the power it is tempting as they are exactly the same for Varioram models. However, if you dig deep in the parts list for both X51 and RS engines there are some differences. There are different part numbers for the camshafts for instance and also for the valves. The RS engine for instance uses a larger cylinder bore and different lubciration parts. The RS engine was developed by Porsche motorsport as a basis for a race engine that could be tuned and adapted by the customer. The X51 engine however was always meant as a power upgrade for the standard "street" 993 models. So while there are some similarities I would not consider the X51 an RS in disguise. More like an "RS light".

Performance

Although the power increase by 15BHP is not that much there is a notable difference in power between a standard and X51 993. Topspeed and 0-60 times are marginally improved but the power curve is different and it feels more lively and powerful in the mid RPM range. I have not yet had the privilege to drive the rare non varioram 300BHP 993 as described above but I can imagine it should be even better.

Rarity and premium

Looking at the used 993 market in Europe it is clear that the French Porsche salesmen were quite good in extracting an extra € 12.000 euro from their customers as the X51 equipped cars are far more common in France than in other countries. Also noticeable is the quite high percentage of C2S X51models. I have not yet found absolute numbers on how many 993's were ordered with the X51 package but it still is a very small percentage. Combine rarity with the "RS aura" and you have all the ingredients for an considerable markup in used car prices. Some car dealers advertise these cars as equipped with an RS engine (not good) whilst others do not even know they have something special ( bargain ). All 911's values are going unlike crazy, any special extra will add value, the X51 is one of those desirable options. 

Disclaimer

As with all my blogs, I do not claim to be 100% correct, in fact I welcome any corrections you may have! Just post a comment or contact me via info@flugplatz911.com

The above is based on literature from Porsche Stuttgart, checking out actual X51 models and help from a former Porsche mechanic. More information is highly appreciated, please contact me!

Documents relating to the X51 option:

If the X51 option was installed post-factory the DME had to be updated on tiptronic models because of the increased torque.