This particular swap was done for a customer at my shop and was finished in late 2019. This car was originally a RHD 1992 525i wagon, coming from the factory with a non-vanos M50, an automatic transmission which was showing it's age and an open differential. I swapped in an OBD1 converted S52 engine, ZF 320Z 5-speed manual transmission and 3.23 limited slip differential
I went to great lengths to maintain OE functionality and appearance, even going so far as to use a rotary tool to open up the stock intake box to remove the restrictions, to allow the larger engine to breathe a little better but while still looking stock and maintaining the factory intake ducting, which pulls in air from outside the engine bay
The work required is well detailed elsewhere, but I will go into detail in the related articles with what I did for the engine swap. The manual swap was a little more complicated than a normal swap due to it being RHD so I will detail the manual swap process here. Below is the LSD installed
The manual swap is fairly straightforward, requiring the pedals, master cylinder, clutch line, slave cylinder and manual driveshaft as well as a few minor electrical modifications. I initially tried to retrofit a LHD manual pedal to the RHD pedal box but quickly found that was not feasible. We ended up having to source a RHD manual pedal box specifically, as the LHD and RHD use a totally different setup for the clutch pedal return spring. The RHD unit imo has a much more favorable feel. It would have been impossible to use the LHD pedal regardless, as it interfered with the bracket
Here it is all installed... now time to move to the engine bay
The clutch line for a RHD manual E34 is NLA from BMW, so I took some measurements and bought some line and started bending some myself. This was one of the last test versions - I made just a few changes on the final version that is currently installed. I liked the fitment of this one overall but as you can see, it came up a little short
For the manual swap, we also had to jump the starter relay and install a manual driveshaft and that was that
As far as cosmetic touches, the M50 valve cover from the donor engine was in horrible shape so it was decided not to re-use it and to use the S52 valve cover and vanity cover instead. It took some custom work to get the S52 vanity cover to fit properly with the OBD1 engine harness, as the routing for the coils was different between OBD1 and OBD2. I trimmed the S52 vanity cover with a dremel, matching the OBD1 profile to get as clean a look as possible
I also wanted to re-use the stock intake box, so I used my dremel tool to remove some restrictions to allow a smoother path for air to enter the intake for the larger displacement engine. I did not get pictures of this internally but you can see it installed below as well as the modified vanity cover
