The Ultimate 24V Swap E30 Guide
This week might make a few purists rip out their hair, but this Ultimate BMW build list just wouldn’t be complete without an engine swap. We’re focused on the E30 this week, which means we have to ditch that old SOHC M20 and stuff in something with a bit more potential. This is Turner Motorsport’s guide to building the Ultimate BMW E30.
So, of course, there were more engine options in the E30 than just the M20. For simplicity’s sake, we’re going to focus on the M20B25 since that engine and the G260 transmission are one of the easier setups to begin a 24v swap with an M5X or S5X platform, but depending on your choice of transmissions, it doesn’t matter what E30 you start with. (Please no swapping of S14s from M3s, leave those alone, ok? Thanks.)
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Engine
There are a few common choices for 24v engine swaps in the E30, it just depends on what your budget is and what your ultimate goals are. If you want to turbocharge your 24v swap, the best engine choices are the M50 or M52 due to the cylinder wall thickness and the low cost of those engines. If you want to stay naturally aspirated and get the best bang-for-your-buck off the bat, we suggest choosing an S52. If you want to go overboard, the S54 is an incredible option but requires a bit more effort than the M50/52 S50/52 conversions do, so we won’t cover it here.
From your donor car or however you source your engine, you’ll need the engine wiring harness, ECU, fuel directional valve (definitely scoop this up because it’s NLA PN 13-31-1-740-281), engine mount arms, the driveshaft (depending on your transmission choice,) and the engine itself. Other than that, everything you need will come from either aftermarket sources, different donors, or should be sourced new.
Of course, when buying a donor car or engine, we always suggest running through everything on the front end so you don’t have to do a bunch of maintenance shortly after swapping the engine. It’s a good idea to buy a new valve cover gasket, spark plugs, coil packs, oil service kit, oil filter, oil filter o-ring, intake manifold gaskets, VANOS, water pump, thermostat, oil pan gasket, rear main seal, and a clutch kit. Other parts you might need are a new CSB, Giubo, coolant surge tank, fuel pump, and fuel filter, depending on the condition of what you have. | | | | |
The Swap
To perform this swap, you need to first yank out the old M20, the cooling system, the brake booster, distributor, charcoal canister, and wiring harness. You’ll use the fuse box, fuel lines, and brake master, but everything else needs to go.
Next, you’ll need either E28 535is engine mounts or one of the several aftermarket ‘swap mount’ kits available. Revshift and Condor Speed Shop both produce sets that are widely regarded as the best solutions since it is ideal to use polyurethane mounts to prevent any engine movement as the engine is physically larger and sits lower than the original E30 engine.
For the starter/flywheel/clutch, you have a few options. The first is to use the original M20 starter and flywheel, but you’ll need to have a machine shop turn down the raised portion of the flywheel for fitment between the G260 and M5X/S5X. If you choose to use the ZF or G260 gearbox from the E36, then you can just use an E36 starter, clutch, and flywheel kit. You can also use the E46 330i starter, flywheel, and clutch kit for a softer feel.
As you won’t be able to fit the brake booster from the E30 with the larger intake manifold on the 24v engine, you also have a few options. The most popular choices are the Porsche 944 ATE brake booster or the Chase Bays brake booster delete kit. I prefer the 944 booster since manual brakes are less than fun. However, you will need to modify the piston that attaches to the brake pedal assembly by shortening the length of the piston for fitment. You can generally eyeball this and will see how much to cut off when you go to install it. This will also require you to adjust the sensor on the pedal for the brake lights, otherwise, they will remain on or never turn on if you do not reset it.
You will also need to delete the secondary air pump system and EGR from the engine and seal those systems so you don’t have vacuum leaks.
The E34 M50 front sump oil pan, pickup, and dipstick tube are required for this engine to drop in and clear the subframe. You will need to purchase all three and install them in place of the M5X/S5X rear sump oil pan/pickup/dipstick tube.
Lastly, you’ll need to use the fuel directional valve from the donor car and plumb that sin to your fuel lines to adapt the E30 fuel system from the chassis to the 24v engine’s fuel system. | | | 
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Cooling System
Due to the larger size of the 24v engine, you’ll have to switch to an electric fan setup. We suggest a CSF radiator with either a Spal or Mishimoto 14” puller fan for the best results. Of course, run a new water pump, thermostat, and silicone hose kit as well. For the surge tank, the late-model E30 surge tank is the best option, but not the most attractive. You can find aluminum solutions that fit, but for the easiest route, the late-model E30 surge tank fits with everything you will have from the E36 coolant hose kit.
Finally, on the firewall, there are two hard coolant hoses from the heater core. You will need to use a punch, big screwdriver, or something similar to insert into the upper hose and carefully bend it away from the engine, towards the brake booster, so you don’t have clearance issues. They are easy to bend but also easy to break, so be careful. | | | | | 
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Drivetrain
You have a few choices for gearboxes, but it depends on what you want from your car. If you plan to boost your 24v, the G260 is out of the question. The G260 will only hold up to about 300hp, so, for the most reliable and easiest swap, use the ZF from the E36 M3. If you use the ZF or the G260 from the E36, you can just mount it up. Both will use the original transmission mounts, brace, and just need the E36 M3/328i driveshaft with the E30 CSB to work.
If you choose to keep the E30 G260, you have a few things that need tweaking, but it works fine, especially for naturally aspirated/lower horsepower swaps. The E30 G260 will need to rotate roughly 10 degrees clockwise to mate to the 24v engine, which means you need either an aftermarket swap brace and mounts or to modify your current transmission brace by raising the driver’s side to allow it to meet up to the transmission. You will also need to twist your shift linkage between the transmission and shifter assembly and spin the selector rod 180deg for it to work and sit in the appropriate location. With the G260 from the E30, you do not need to change your driveshaft, which is an appealing reason to use it if you will not be boosting your 24v swap.
For the clutch, it’s going to depend on your setup. If you use the E30 G260, you can use an E30 clutch kit but will need to either use the E36 starter and flywheel or use the M20 E30 starter and have the E30 flywheel machined down. There is a ‘raised’ portion that needs to be machined flat, which can be done at the machine shop. You can mix and match, but the easiest solution in my opinion is to use the E46 330i starter, single-mass flywheel conversion, and clutch disc/pressure plate. | | | | | |
Wiring
You can re-pin the engine harness to mate with the fuse box from the E30, which is fairly simple but does require confidence in your wiring skills. There are also aftermarket adapters available that make it a plug-and-play situation, which is highly recommended.
For the ECU, you’ll need to tune out the EWS system or get ahold of the original key, ignition cylinder ring, and EWS module from the donor car. Otherwise, the ECU will not allow the engine to turn over, as it will not detect the EWS system. This is a major pain in the butt, however, it is easily circumvented. Several tuning companies are familiar with deleting EWS. Wiring in the original key/ignition ring/EWS isn’t that difficult, either. In my swap, I wired in the original system and retained EWS.
You will also want to tune out the EGR and Secondary Air system since those are deleted, but you do not HAVE to. You will see fault codes from those systems when/if you scan your diagnostics system, but knowing they are deleted is fine. However, the right way to do it is to have them tuned out when/if you send your ECU out for EWS delete. | | 
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Exhaust
If you want to use the E36 factory headers, which are known to be quite good from the factory, you’ll need to knock the studs out of the flanges and replace them with nuts and bolts to clear the subframe. Additionally, if you want to mate your factory E30 exhaust, you’ll need to take the flanges from the E30 exhaust to the headers, cut them off, and make new downpipes that will clear the subframe.
An easier solution is to purchase ‘long tube’ E36 headers and ‘massage’ them with a hammer and some heat to clear the subframe, then weld them up to your existing exhaust or have a custom exhaust made for better performance. Unfortunately, there aren’t any off the shelf options besides Supersprint’s swap exhaust system, so if you don’t want to spend thousands on a pre-made bolt-on exhaust, you’ll have to do a bit of cutting and welding.
With that, pretty much all the difficult bits are taken care of. Everything left is just to attach hoses, fill with fluids, double-check wiring, put a battery to it, and fire it up. | | | |
Popular Upgrades
The 24v swap is a major improvement, even the mildest M50 is still a solid jump in power over the M20B25, but they aren’t exactly what we’d call ‘performance’ engines out of the box. However, with a few tweaks, they can be incredibly fun and more power than you’ll need to have fun in your E30. | | 
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M50 Intake Manifold
If your engine is an OBD2 M52/S52, the OEM intake manifold is not as free-flowing as the M50/S50 version. It is fairly simple to adapt the M50 manifold to the OBD2 engines for more power. The easiest way is with our conversion kit for that swap. I use this on my M52 and found it to be the highest quality option available. | | |
Schrick Cams
Upgrading the camshafts to more aggressive profiles will highly improve your top-end performance and offer more power. For M50/52 engines, the S52 set of camshafts is also a great upgrade but milder than Schrick’s options. | | |
Software
Our Shark Injector Software for OBD2 cars with the M50 manifold and M3 camshafts offers a considerable upgrade. It allows the engine to maximize the power gains from those two upgrades while also raising the red line and eliminating the top speed governor. | | |
Clutch/Flywheel
Regardless of the transmission you choose, upgrading to a lightweight flywheel, more aggressive clutch/pressure plate, brass pivot pin, and polyurethane bushings will give you an engaging and snappy shifting experience. The lightweight flywheel you choose will need to match your starter, though. If you choose, for instance, an E46 330i single-mass lightweight flywheel, you will need an E46 330i starter.
For the shift setup itself, my preference is the Z3 shifter assembly for reduced throws. If you use the E36 transmission options (G260 or ZF,) you could also use the Turner Motorsport Double-Adjustable Short Shift Kit for perhaps the best feeling shifter available. | | | 
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Steering
The Z3 Non-M 2.8 liter steering rack is perhaps the most responsive and fastest ratio for highly improved steering. You need rack spacers, will need to buy a specific kit for Airbag vs Non-Airbag E30 (depending on what you have), and will need the inner/outer Z3 tie rods. This is also quite engaging with a power steering delete. My personal swapped E30 has the Z3 rack with Condor Speed Shop’s power steering block off plate. I use the MINI Cooper S R53 drive belt for deleting power steering and A/C. | | | 
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Subframe/Rear Trailing Arms/Front Control Arms
It is highly suggested that you reinforce the front subframe. Both Garagistic and Turner Motorsport offer reinforcement solutions. If you are not comfortable welding yourself, Garagistic’s reinforced front subframe, rear subframe, and rear trailing arms are excellent options. We offer reinforcement plates for the front subframe. Superpro makes adjustable rear trailing arm bushings for rear camber/toe adjustment, which is highly recommended. Lastly, Turner Motorsport Monoball FCABs make your steering turn-in crispy. | | | | 
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Suspension/Wheel Hubs
If you want to stay with the 4x100 setup, you will either want to do a ‘cup kit’ for easy install with no welding. You can also 5-lug convert your E30 to use E36 coilovers. Otherwise, you will need to weld in coilovers in the front E30 suspension. CATuned offers pre-welded sets with new hubs/bearings in the front, which is good if you need to replace those. However, they are somewhat pricey. I use KONI yellow dampers, H&R race springs, E90 ‘drop hats,’ and Meyle HD upper strut mounts in the front and rear.
For 5-lug, you have a few options to convert with. You can use 1996+ E36 front knuckles/hubs, coilovers, and just need offset FCABs for the proper caster. You will also need the E36 M3 1996+ front brake calipers. For the rear, you can use 318ti/z3 rear trailing arms/hubs. You can also use the E30 M3 suspension. If you convert with the E36 M3 front and Z3 rear with the Z3 rear brakes, this is the easiest/least expensive and allows you to just use E36 coilovers and allows you to run 5x120 wheels. | | | |
Conclusions
One of the best things about the E30 is that it has so much potential. You can mix-and-match a bunch of newer BMW parts into it and take advantage of the updated performance mated to a highly responsive and lightweight chassis. This allows you to have the best possible version of an E30 you could hope for. Again, there isn’t one particular way to go about this. You just have to know what works with what and what the benefits/drawbacks are with each conversion. There are tons of awesome resources online that go in-depth on how to do all these mentioned upgrades, so you should have everything you need. This guide is just to show you what is possible and what combinations work from our experience. My E30 was the source material for this, as I have played with many of these different combinations to find what works best for me. So go out there, build your E30, and make it an absolute weapon in the corners and the straights. | | |
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