Porsche 996.2 X51 Conversion Documentation

My 996.2 (3.6-L) engine recently needed replacement due to metal in the oil (more on that in a separate thread). I was fortunate to find a rebuilt 996.2 X51 engine at MB Motorsports for about the same price. This was only the block and cylinder head. I had to obtain the exterior components that couldn't be transferred from my old engine. Thanks go to Agnes and Martin there for using their network to source most of the needed parts (used at much lower cost than new) from the the US and Europe, and for taking most of the photos. It is well known that engines with the X51 Powerkit output more power, in this case rising from 315 to 340 hp (320 to 345 PS), due to improved engine breathing and a remapped ECU to take advantage of this. It has been openly speculated that the power may actually be higher, but the official Porsche number is lower to avoid competing with the 381-hp GT3. This jives with what some owners have posted about their 996.2 X51 engines. The X51 engines also have improved lubrication during high-G maneuvers due to the revised sump plate, where oil collects at the bottom of the engine. The 996.1 X51 conversion has already been documented here: http://911uk.com/viewtopic.php?t=602...er=asc&start=0 . I have Adrian Streather's 656-page tome Porsche 996: The Essential Companion . Its X51 conversion parts list (p. 161) closely parallels the 996.1 list, but says (p. 163) that the 996.2 uses the same formula, whereas I found the list to be shorter. Below I document what I have found is different on the 996.2, and compare it to the the 996.1. Below are the part numbers that I could find. Here's how you can tell whether you have a 996.2 X51 engine: My old engine's serial number above starts with "M96/03..." The new X51 engine's below starts with "M96/03S..." The "M96/03" indicates that this is the 3.6-L 996.2 engine. The "S" indicates that it is an X51. Following are photos of the engine being rebuilt and assembled. New crankshaft bearings Left: Kit intake camshaft. Right: Kit exhaust camshaft. Curiously enough, I could not find a separate part number for the exhaust camshaft. Camshafts Block before bolting on the heads Heads before bolting on to the block Intake port Exhaust port. The X51 size is the same as the regular port size, even though the header diameter is larger. Top of the engine. The oil cooler and oil-pressure sensor are visible. Intake headers. The X51 version is sand-cast aluminum rather than plastic. X51 exhaust headers. These are a larger diameter than the base version. Several views of the assembled engine before shipping to me for installation. A new cylindrical IMS bearing was installed. The reason for the rebuild is failure of the LNE ceramic bearing's steel races after about 30 kmi, so no more ceramic bearings for me! A photo from the 2003 Porsche Exclusive catalog (p. 13). This shows the aluminum intake manifold. It also shows an oil line on the right side running from the front of the engine to a tandem oil pump at the back. This is actually an option, not standard.

Very nice! so your old engine had the LN bearing retrofit that failed in 30k miles after install? Was the original bearing in good shape and the engine was healthy before the retrofit?

I had my local mechanic preemptively replace the original IMS bearing with the LNE ceramic bearing in 2013 at 54 kmi. They inspected the oil and filter and everything was fine. After that, the magnetic drain plug was clean (just microscopic fuzz) at each oil change until I did an oil change on in March 2015 at 86 kmi, when there were lots of metal flakes up to about 0.8 mm long. I cut open the oil filter and saw the same thing. The car ran fine and made no unusual noises. I had it removed and sent to MB Motorsports, where they disassembled it. Metal from the IMS bearing had gotten to the crankshaft and damaged its bearings.

That's quite a story. Any photos of the teardown or the failed LN bearing? Also, do they offer any warranty on the rebuilt X51?

I put the photos and details of the failed bearing on the failed IMSB thread at https://rennlist.com/forums/996-foru...l#post12217659 MB Motorsports gives a 6-month warranty. They also said that if the roller bearing ever fails, they will take care of it. I hope I don't have to take them up on that one!

Thanks for the info. I found it interesting that the ceramic ***** are indestructible but the bearing races are the next weak link.

Thank you for posting, especially the comparative parts list. Enjoy the car, it’s such a fantastic package!

Sounds nice, get it to a dyno and see how its performing.

Quotes source posts: 12217511, 12217659

If you read the linked Thread below after about post #121,you'll have an indication of a new theory of why the bearing may have failed and why the new roller may fail prematurely also. I hope the IMS Guardian is working well in the new engine? I hope I am totally wrong and the roller is a success. but since we do not know the cause of the failure of the hybrid bearing,it is just a heart-felt wish. I have just been rebuilding my M96 at home ,so I understand the pain.

Quotes source post: 12230949

Schnell, the OP is not rebuilding the failed engine. He bought another 996.2 X51 rebuilt engine so I'm not sure the relevance of the misalignment of the old engine.

Quotes source post: 12230993

That's right. A low-mileage 996.2 X51 engine came into MB Motorsports with--you guessed it--IMSB failure. Martin rebuilt that engine and installed a roller bearing. The photos shown of engine rebuilding are of my new X51 engine.

What DME map will you run? Original factory x51? You may already know, but anyone with a PIWIS can recode your DME for the x51 flash.

Quotes source post: 12233224

I'll start with the standard Porsche X51 flash. My local independent Porsche mechanic said he can do it. Apparently he has to first install the engine, then read out the existing flash, send that information somewhere, then receive a file for the new flash. I don't understand why he has to send a file out.

Quotes source post: 12230949

When I discovered metal in my oil in January I was excited to read about the IMS Guardian: it seemed that if you just started to get metal flakes in your oil, the Guardian would tell you to stop driving just in time to replace the IMS bearing with one of LNE's upgrades. I called LNE and read their qualification process for installing the upgrade. They say that once there's metal in the oil, it's too late; you already need a rebuild. Thus, I don't see the Guardian as being very helpful. It just prevents you from getting stuck with a dead engine, allows you to schedule a rebuild when you want it, and it might save you $1000 or so during the rebuild if the crankshaft is not damaged.

Quotes source post: 12253862

The way I've done it is you need the DME and Immobilizer programming codes from PXN which a dealer may or may not give you for your car. With those codes you can use a PIWIS1 or PIWIS2 to directly flash the DME with the x51/OBDII/LEV flash map. Or pay the dealer the half hour of labor to do the flash for you.

I have heard the pistons are different? Paul

Quotes source post: 12256240

The best I can tell is that the pistons were upgraded for the 996.1 X51 conversion only. For the 996.2 X51, user "GT4" on the 911uk forum said that the 996.2 base model already had the upgraded pistons, so the X51 was not different. Also, my engine rebuilder could not see a difference when he was working on my new X51 engine. I was not able to find a different part number for the 996.2 X51 pistons.

Hello everyone, First post here. I am in the middle of doing an X51 conversion on a 3.6 and need to find the revised A/C line (intake manifold will not fit without this) and the revised Venturi tube. Does anyone have any additional information on how to source these parts? Thank you, -Brian

[QUOTE=earpig;17422840]Hello everyone, I am in the middle of doing an X51 conversion on a 3.6 and need to find the revised A/C line (intake manifold will not fit without this) and the revised Venturi tube. Does anyone have any additional information on how to source these parts? /QUOTE] You need to find a used parts place with a used 996.2 X51 engine. A few are DC Automotive, LA Dismantler, and Specialized German Recycling in Sacramento. Do a Google search. They might not list all of the parts they have because there are so many. Ask whether they have a 996.2 X51.

Thanks. I will check with them.