Engine Upgrade To A '95 S50 3.0L DOHC 6 cyl
July 2009

If you are looking for the old page it's gone as this project has taken a turn in a new direction brought on by the STUPID California smog laws. I was planning on building the m10 4 cylinder into a 2.2L using the crank from a '88 s14 M3 engine. I had the crank and an idea for economical 92mm pistons but when it came right down to it with the header and efi conversion I would never be able to get it legal in CA so I started looking for a nice m50 engine and 5 speed to swap in, keeping it all stock to pass smog. I came across a decent deal on a '95 S50 engine and transmission on craigslist.org and decided to go with that even though it is about $1000 more than a M50 would have cost. It's hard to pass up 240 smog legal hp!



The engine came with the necessary e34 oil pan and pick-up as well as a new water pump, thermostat and aluminum thermostat housing. The A/C compressor and power steering pump were also with the engine.

There are a few things I will need to get to complete the assembly of the drive train. The most expensive will be a new clutch and flywheel. I've looked on Ebay and decided that a 16lb steel flywheel will be a nice fit. I don't need to go as light as the 11lb aluminum flywheels.

I have already installed the water pump (unbelievably cheesy thin sheet metal impeller!), the new thermostat and housing. The valve cover is getting blasted and prepped for a re-paint.

The m10 is out and gone, the 5 speed will be going in my '78 very soon. I will clean up the engine compartment, paint it semi-gloss black and get ready to install the S50 and matching 5 speed.

Aug 1 2009:

I have ordered a 16lb flywheel and clutch assembly, they should arrive this coming week.

I have installed a new water pump pulley and all new idler pulleys. The idler pulley tension mechanism that BMW uses on these engines is a pretty crappy piece - it's a spring loaded hydraulic cylinder that pushes on a lever arm to hold belt tension. They have a history of failure. BMW should take a lesson from any of the Detroit MFGs on this one and use a simple spring.

I'm trying to find a 6 rib serpintine belt the correct length, without power steering it's more difficult than it sounds. I measured the length with a piece of cord and came up with 41", well a 41" belt doesn't fit - it's a little short but it's hard to tell exactly HOW much longer the belt will need to be. I tried a 43 3/4" and it was too long as was a 43 1/8" belt. The folks at Kragens have been very patient with me so far, we will see how it goes tomorrow when I come back for something near 42 1/2".

Aug. 05 2009:

The flywheel/clutch kit arrived today, they're the most expensive parts for this build so far (other than the engine/trans) at just under $500. The flywheel looks very nicely machined:




The clutch disk has a spung hub, the stock disks are solid hub and don't work well with NON-dual mass flywheels.



After trying 5 belts of various lengths I found a 42 7/8" belt #060423 (that number works with most belt mfgs) that works well without the power steering pump in place:



Aug. 09 2009

Here's a shot of the 4 speed shifter removed from my '78. It will be modified by extending the distance from the bottom of the pivot ball to the hole in the linkage pivot, the upper piece will be shortened slightly and a threaded piece fitted suitable for the aluminum knob. I will determine how much I will shorten the lever once the knob is in hand and I can get a feel for how long the shifter can be. Once the trans is in place I can determine how long I can make the lower piece to shorten the throw. I don't want TOO short of throw as the feel get's notchy the shorter you go. The shift knob should be a short reach from the steering wheel. I've seen a few cars with little stubs sticking up from the shift boot and the knob is quite a ways from the wheel. This wastes time moving your hand from the wheel to the shifter for each shift when driving "enthusiastically".



I'm making some progress figuring out how to interface the wiring from the engine into the car. When that's all sorted I'll post up a list of the wire pin numbers, colors and what they do and how to integrate them into an older car. All the info I've found on this so far is to integrate the engine into an e30 which uses similar harnesses and plugs that the e21 does not have.

Aug 10 2009:

Still working on the electrical side and plumbing but as I was installing the rear suspension subframe this evening I noticed something strange with the e36 exhaust down pipes that were laying nearby. The down pipes are different diameters-one set of 3 cylinders dump into a 2" down pipe and the other 3 dump into a 1.75" down pipe. Pretty strange to me that the factory would do that. I will fabricate new down pipes out of 2" for both, they need to be reworked anyway so they run under the passenger side floor rather than down the drive shaft tunnel.

13 Aug 2009:

I received some super custom made urethane engine and transmission mounts:



These were made by a member of Bimmerforums.com, Jester323. These are much better than anything else on the market. They have washers imbedded in them rather than just stuck on the surface like most. He also makes rear subframe mounts and some other parts.

I also spent some quality time cleaning the e35 oil pan to get it ready for installation on the engine later this weekend. It will need a small plate TIG welded over the oil level sending unit hole in the bottom of the pan. I also had to chase the threads on the pan, apparently it's easy and very common to cross thread the oil drain plug on these newer engines.

18 Aug 2009:

I hit a milestone with the engine prep today. The 5 series oil pan and pick up are in place with new gaskets after a thorough cleaning and a little welding on the pan to fill the oil level sending unit hole. It's not as easy as it sounds.

The M3 pan uses a rear sump and pick up, the pick up tube crosses in front of one of the bolts that hold it in place so the pump must be removed to get the pick up off. The pump is held in place by 3 bolts but it still won't come out due to the oil pump drive chain. I had to remove the oil pump cover bolts that hold the pump to the main housing then pull the pump out slightly to get enough play in all the pieces to get the drive chain off the gear and the pump body out. With the 5 series pick up in place and a new gasket I re-installed the pump body, slid the pump back in and tightened it all up.

The M3 rear sump pan uses a windage tray that bolts to the block but it must be removed due to interference with the windage tray mounted in the 5 series pan. That part was easy.

The rear pick up tube also has a support that is attached to a main bearing cap by the cap bolts.



I was just going to remove the bolts and then the support but a little reading on the torque specs revealed they require a specific torque angle and I don't have a torque wrench protractor so I just broke the bracket off with some large vice grips as suggested on one of the e30 24v conversion forums.

Here's a pic of the pan in place:



The only significant thing left to prep the engine for installation is mounting the Sanden 508 A/C compressor and finding a belt to work with that.

As I was digging through the box of parts this evening looking for the oil pick up I came across the e36 emission charcoal canister and it even has the purge valve in place. I was a little concerned about finding one in a pick-a-part as ours doesn't seem to get e36's in yet.

21 Aug 2009:

The Sanden 508 air conditioner compressor arrived yesterday and it's really nice. I will get it mounted on the engine soon:



I held the front crossmember up to the engine mounts yesterday and found that it will take substantial modifications to get the S50 mounted, not a big deal though. I suppose it would be easier to mount it to a 323i crossmember but I don't have one. I DO have the skills necessary to modify the 4 cyl. crossmember.

Aug. 30 2009:

A while ago I removed the aluminum motor mounts for cleaning and bead blasting. The left side mount had two tabs on the side of the leg that I won't be using so I cut them off and ground down the areas for a cleaner look.

I pulled off the stock A/C compressor mount so I can fabricate an adapter to mount the Sanden 508.

Although I MUST retain the stock cast iron exhaust manifolds there is nothing that says they have to look like ASS. I removed them so I can grind down the casting flash, smooth them up, give them a through blasting and a shot of titanium color ceramic coating from Techline Coatings . Before pic:



During:



After:



You can see how close the forward manifold is to the aluminum motor mount. The sheet metal shield is there to keep the mount from getting too hot and cooking the rubber or in this case the urethane. The titanium color is a medium gray with a slight green tint. This stuff air dries so you can handle it without damage in an hour or so and fully cures with exhaust heat at 750*F. It should cut down some on the under-hood heat as well as keep the manifolds looking good for a long time.

TECH TIP: Notice the copper exhaust manifold nuts. NEVER use regular steel nuts on an exhaust manifold, the extreme temps cause them to corrode quickly and stick to the stud. The copper prevents corrosion and acts as a permanent anti-seize. They aren't very expensive and make life MUCH better if you ever have to remove the manifolds.

This project just saved me $150 by not having to send these out to have them done professionally. I almost forgot I had some of the coating left from a previous project (the race toaster) so I fired up my compressor and pulled out the small spray gun from a kit I got on sale at Eastwood tools:



Just this job paid for the spray guns and I'll use the larger gun to paint this car when the bodywork is complete.

08 Sep 2009:

I hit a pretty major set back a few days ago. I was modifying the front subframe by removing the 4 cyl. mount, seam welding a lot of it and boxing in the frame mounts, when I was done I held it up to the engine with the e36 mounts bolted up and found the mounts place the pads too wide for the e21 chassis. The e30 guys installing the 24v engines use the e36 mounts so their front frame members must be several inches wider than the e21. I could track down some e21 m20 mounts and see if they fit but it will be quicker to make some out of steel to the same pattern as the e36 mounts but a couple inches narrower on each side.

Here's the new drivers side engine mount:



That's about 3 hours worth of fabrication. I started with the original e36 aluminum mount and made a jig off that using steel plate. I made the base piece and the small end, bolted those to the jig and then cut poster paper patterns which were transferred to steel plate and cut with a band saw. The plates were fitted to the jig. Each piece needed bent and twisted to fit correctly. Only the two end pieces are straight and flat. After final welding I ground the seams, blasted it and shot it with some high tech industrial paint that actually contains 316 stainless steel. This mount moves the urethane cushion inboard 1.25" and keeps it in the exact plane that the original mount did.

Sep 11 2009:

And, here's the passenger side:



I made this one about 1.5" shorter and moved the pad towards the front of the engine by 1.5" for more clearance to the exhaust manifolds. There will still be plenty of room to the A/C compressor too. There is also a large gusset on the rear of the mount to strengthen the fore/aft axis. That's the great thing about doing this type of installation with custom parts, I can make it ANY way I want!

Mounting the A/C compressor will be next then installation in the car once the engine compartment renovation is completed.

Oct 12 2009:

I got the transmission mounted to the engine yesterday then slid them into the engine compartment for a trial fit and to see what it will take for motor mounts on the subframe. The engine is positioned with the bottom of the oil pan level and currently about 1" below the bottom of the crossmember, the final position will be slightly higher for steering rack clearance:



That's a pretty crappy picture so I'll replace it when I get a chance. BTW, you can see the A/C compressor is not mounted yet but there is a TON of clearance for it.

Here's a shot of the mocked up motor mount pad:



There will be little room for a brake booster/master cylinder:



Once the engine position is finalized I'll determine what will work for brakes.

The trans seems to have plenty of clearance other than by the clutch slave cylinder, that area will need a little "massaging".

Oct. 17th 2009:

The engine mounts are done and the crossmember painted:





The oil pan is slightly lower than the crossmember but it should be fine as this car won't be slammed, only lowered until the lower control arms are horizontal.



The front exhaust down pipe will be pretty close to the steering rack bellows, I will see exactly how close when the rack is mounted in place. The oil pan has a couple support ribs that run front to back that MAY be in the way of the rack mount and need to be trimmed slightly for clearance.



Here's a shot of the engine in place without the hoist holding it up!



The stock air box fits fairly well too, the fender will need slight modification to make it fit correctly though. If I could just run a cold air tube life would be easier but this will be a CARB legal swap so the stock air box stays.

I whacked the down pipes off the rest of the exhaust that came with the engine/trans deal. Why the BMW engineers made the cylinders 1,2 & 3 dump into a 2" down pipe and cylinders 4, 5 & 6 dump into a 1.75" pipe I'll never know:



I'll build the 4,5 & 6 pipe in 2" and hope the smog nazis don't notice the change.

Next up is the trans mount and then pull it all out for final finishing of the engine compartment.

Feb 24 2010:

Here's the new trans mount in place:



The new shifter mount is nearly complete then I'll fab up a double shear shifter rod to go with it.

I removed the stock coolant temp gauge sender to make way for the new sender to match the new gauges shown on the interior upgrade page. I had to make an adapter to go from 1/8" NPT to 14mm straight thread. I'll splice the wires into the original engine harness.

 

I bought an aftermarket e36 M3 aluminum radiator, fabed up a radiator shroud from aluminum and mounted a 16" electric puller fan to it.

 

There is not much clearance between the fan and the water pump and crank pulleys but just enough.



I've been working on the new exhaust quite a bit. Here's a shot of what I got with the engine/trans package deal. It's a cobbled up piece of junk with NON CARB approved aftermarket cats. It got through it's last smog test like this-I don't know how they managed that!

Earlier I showed the difference in the size of the two oem down pipes, here's a shot of the "Y" where they join. You can see the 1 7/8" pipe is pinched down even more - I don't know how those 3 cylinders could make any power at all. No wonder early U.S. spec M3s received bad reviews in the press because they were way down on power.

 

Here's what will replace the old junk stuff. The merges are from Magnaflow, I still need to drill the aft merge for the O2 sensor bung and weld that in place. The cats are also from Magnaflow and ARE CARB approved for '95 M3's. You can't really tell from the pic but I tilted the cats slightly so the smog referee can easily see the part number on the side of one of the cats.

The original M3 system used two very small resonators behind the cats but I wanted something more substantial and went with a dual in/dual out oval muffler. The only hang up was the off the shelf Magnaflow mufflers were 2 1/4" tubes and I need 2" tubes, the tube spacing was also too wide and the muffler body was too big sooooo.... I built my own!!

Here's the parts:

I cut the end pieces from a small sheet of .040" stainless, the outer shell is .030" stainless, the perforated tubes are from ebay as is the fiberglass muffler packing. The materials cost about $75 and it took 3 hours to fabricate it but I got exactly what I wanted. Here's the muffler core packed before TIG welding the shell on:

Here's the finished product:





I just received some V band clamps and flanges that will connect the exhaust sections together. I like the V band clamps much more than regular muffler clamps or bolt together flanges.

 

Stay tuned for updates.

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