Engine Swap - M6x

Not much compares to a V8. The thunderous roar, the pulsing of power at idle and all that wonderful, wonderful torque make a V8 an engine swap wet dream for many, which is why BMW fitted their M6x family of V8s into the bigger cars.

Fitting the eight-cylinder magnificence in an E30 engine bay is therefore a winning combination, and the engine swap of true heroes. But it's not to be taken lightly. But if you're up to the challenge, here's how to fit a monster 4.0 litre V8 M6x engine into your E30.

Overview

Taking on this challenge requires some serious guts, cash and lateral thinking. Before you buy a single bolt, bear in mind that the E30 pre-dates all BMW V8 engines; the earliest V8 is 1992. Therefore, some significant customisation will be required to squeeze the prodigious bulk of the M6x into the engine bay. The plus side of this is that any E30 can be used as a starting project, since none of the original components will be suited to the task anyway. Our favourite is to use a chrome pre-facelift shell, complete with the 316 badge on the boot lid, just for giggles.

The V8 comes in two distinct flavours; M60 and M62, with sizes ranging from 3.0 to 4.6 litres. They are almost identical in size, but the power output differs considerably; the 3.0's 215bhp seems almost anaemic compared to the 282hp of the larger 4.0 litre M60 unit. The M62 has similarly varying outputs, with the largest M62 kicking out an eye-watering 342hp - if you want any more than that, you're entering S62 territory.

Considering the complexity of the build, it's only worth doing if you use one of the bigger engines; either the M60B40, M62B44 or M62B46.

With that in mind, most of the running gear will involve replacing to cope with the dramatically increased power. Besides the engine, you'll also need to source a gearbox and clutch, propshaft and differential to get the power to the back wheels. Custom mounts will need to be sourced or built to hold it all together. Around the engine, changes need to be made to the radiator system, and the brake servo will need to be moved or replaced to accommodate the engine. You'll also need to find an exhaust solution. Another guarantee is the brakes; they will need to be substantially upgraded to cope, otherwise you'll crash at the first corner.

For a more comprehensive list, check out the parts list.

Parts List

The parts list is both lengthy and comprehensive. Click each part for more info.

• Full M6x Engine with all ancillaries (injectors, MAF, inlet, coil packs, alternator)
• Engine mounts
• Complete engine loom
• Gearbox
• Clutch
• Propshaft
• Differential
• Exhaust including manifolds
• Fan
• Radiator
• Universal Joint
• Gear bridge
• Brake servo

Engine

There's no point in doing this swap if you're not going to use a big V8. Both the 3.0 litre M60 and 3.5 litre M62, while grunty, will not justify the hundreds of hours and thousands of pounds that this swap entails - even if the engine is free.

Whether M60 or M62, all engines use an alloy block and head. After 1998, the M62 engines were fitted with VANOS. The engine options are:

• M60B40 - fitted to the E31, E32, E34 and E38
• M62B44 - fitted to the E38 and E39
• M62B46 - fitted to the E38, E39 and E53

Despite the M62 being the more modern engine, we still favour the older, simpler M60 lump. For starters it's a sturdier construction which doesn't suffer from the broken chains that the M62 is becoming renowned for. It also has a much simpler [M6x#Wiring|wiring]] setup.

If you want to make the best of both, a combination is to use an M62 4.4 litre block, coupled with M60 4.0 heads and chain, running an M60 wiring loom and ECU. This gives the best performance without compromising on reliability.

All engines install in the same manner; however, the later M62 engines will be fitted with EWS. This means you need the correct key and receiver for the car, or have the EWS disabled somehow.

Mounts

Left side engine mount

Because of the size, it's essential to get the M6x engine properly placed. This isn't just a matter of squeezing it into the available space, but also to ensure that it's not so far forward that it upsets the handling of the car.

Right side engine mount

To solve this, you can either buy custom mounts, or make your own. We do recommend purchasing them, with the kit from E30.de providing the best possible fit. If making them yourself, you need to comprehend BMW's bizarre decision to pass the remote oil filter plumbing through the left-hand mount. Because of this, we recommend keeping the original mount fitted to that side, and simply fabricating an extender to mate the original to the rubber bush on your chassis rail.

To help you keep things lined up, the distance between the engine mount centres measured across the subframe is 610mm exactly.

Drivetrain

Once you've fitted your engine, you'll want that power to be hitting the back wheels as efficiently as possible. With that in mind, you'll need to select the best combination for you from these three components; the Flywheel, the Gearbox and the propshaft.

Gearbox

There are three gearboxes to choose from; either a 5- or 6-speed manual gearbox, or an automatic. There choice is entirely up to you, but what you buy will directly affect which differential you use. To explain; the auto box on an E32 730i V8 is a 5 speed, the A5S310Z with the 0.74 overdrive fifth. In comparison, a five speed manual V8 box has a direct drive non overdrive fifth so you'll need a nice tall diff to cope - a 3.25 M3 diff will be ideal. The six speed units on the 540i and 840i used the same ratios but with an overdrive sixth.

The 5-speed box can be found in the E34 530i cars, and is a stronger unit. The downside of using the 5-speed box is the requirement for a custom clutch, as the 3.0 litre unit simply can't cope with 4.0 litre power. It can also feel a bit over-revved at motorway speeds unless you've found a significantly low-geared differential.

The 6-speed from the 540i offers a final gear, which provides a faster top speed if mated to the correct differential. However, it requires a custom propshaft to mate up to the differential; no standard solution is available.

Unfortunately, gearboxes from V12 engines do not fit; they have the wrong bolt pattern for the V8 engine.

Clutch

You'll need the best possible clutch if you're going to make use of all that lovely lovely torque. Unfortunately, if you've opted to use a 5-speed gearbox then you can't use an off-the-shelf BMW clutch - you will have to contact a specialist clutch supplier. Helix can supply one if you ask nicely.

Propshaft

Your choice of propshaft is entirely dependent on your gearbox. If using the 5-speed gearbox then you will be able to mount the propshaft from the E36 328i, with the only modification being the fitting of an E30 centre bearing.

If you've chosen to use the 6-speed gearbox then you're committing yourself to a custom propshaft.

Differential

This needs to be chosen to match your gearbox.

Exhaust

Manifold

Being a V8, you'll need two manifolds - one to cope with each head. This doubles the complexity of the task, since both need modification to fit. There is a huge amount of discussion over how to solve this, not helped by the differences between LHD and RHD cars.

The left-hand manifold (passenger side for UK cars) is the simpler of the two, since there's not much else on that side of the car to interfere with except the starter motor. In this case, a BMW manifold only needs a bit of chopping and welding to fit, as in this picture:

Some people will say that an X5 manifold needs less modification, but no matter which one you choose you will be cutting and welding; therefore a standard manifold from an E32 or E34 will suffice.

For the right-hand manifold things are a lot trickier, with many resorting to a custom manifold. A good exhaust specialist will be able to fabricate one for you, but will need access to your car to do so.

If you are heading down the custom route, it's worth considering a tubular exhaust manifold. This system uses individual pipes from the head that meet at a collector further down the exhaust, rather than the standard BMW "log" type. Tubular systems have many benefits, the first of which is their relatively easy build from off-the-shelf pipes. Here's an example of a tubular manifold:

Brakes

Because of the sheer enormity of the M6x engines, you have next to no chance of retaining the brake servo in its standard place. You therefore have two options.

1. Relocate the entire mechanism to the other side of the passenger inner wing, so that it sits behind the headlight.
2. Remove the glovebox and fit the servo inside the cabin, keeping the master cylinder inside the engine bay.

Wiring

One of the most significant differences between the M60 and M62 engines is the wiring. The earlier engines used the traditional BMW route; an engine loom with integrated plug for the [M6x#ECU|ECU]], which then connects to the rest of the car using a standard BMW socket. In contrast, the later engines used BMW's Canbus system, which communicates with the rest of the car in an entirely different way. With Canbus, the ECU not only controls the engine, but also expects incoming signals from the gearbox, differential and braking systems in order to operate.

With the increased complexity of the M62 wiring, we highly recommend sticking to an M60 unless you're an electronics engineer. For the optimal hybrid solution, consider fitting an M62 engine with an M60 loom and ECU, although this will require some tuning of the ECU to get the best engine performance.

ECU

All M6x ECUs are interchangeable, although of course there will be fuelling issues related to the differing displacements of each engine. One of the most critical aspects of choosing an ECU is whether or not it is equipped with EWS. For the sake of simplicity we recommend a non-EWS setup. You'll therefore need an ECU with a number ending 404.

EWS

Main article: EWS

EWS is the immobiliser system fitted to BMW models with M60 and M62 engines from 1994 onwards. Its basic function was to check that the doors were unlocked correctly and that the correctly-coded ignition key is being used. If it fails to detect the right signal, it will disable the ignition circuit, the injectors and the starter motor, which is a right pain if you're trying to do an engine swap.

If your engine came from an EWS-equipped donor, then you will need the appropriate key, receiver and ECU to match.

Temp Sensor

E36 (left) and E30 temp sensors fitted to an M52

If you are running the E30 cluster, make sure you put in an E30 temp sender, as the E36 one will not operate the gauge properly. It is difficult to get to when the engine is in the car. Don't remove the existing one, as it also sends to the ECU; you will need to add the E30 one. If you are lucky there will be a blanked off spot to mount it in.