E34 S52 Swap Overview & Manual Swap

The E34 is a great chassis which unfortunately came with some rather anemic 6 cylinder engines in non-M form. While the M50 is a stout and reliable motor, it leaves a little to be desired as far as performance goes. While forced induction is a great choice for many, others prefer the performance and feel of a stock drivetrain. Using the drivetrain from a newer model is always a great solution and on that note the S52 offers a large increase in displacement over the largest M50 available (3.2 vs 2.5L) as well as a big increase in power (240hp vs. 189hp). The swap will also require swapping to an M50 intake and M50 headers all of which will also slightly increase the power of the S52


(I'm not that messy - I have an outdoor shop and it was raining!)

This swap guide pertains specifically to the swap of an S52B32 from a Z3 M Roadster into a 1992 E34 525i wagon. The information should pertain to just about every M50 powered E34 but V8 or M30 models will find many things to be different and it is a lot of extra work to swap those engines to S52's.

It is highly recommended if you want to attempt this swap to start with an M50 powered E34. Starting with a VANOS M50 car will mean you need less parts upfront to do the swap, but also get the less reliable Getrag transmission unless you swap that too. I would recommend looking for a non-VANOS manual E34, so you get the ZF 5 speed from the factory and only need to source a few parts from a VANOS E34. I had a non-VANOS E34 525i sourced for this swap as a donor, the heart of which is pictured below



This particular swap was done for a customer at my shop, being the first major swap I have done, 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



And then a manual driveshaft and it was all good. It wasn't a ton of work, but the custom bent clutch line did take a few test runs to get looking nice


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