318iS Drivetrain Donor - Options

[dc2100k]

I recently acquired an E30 318iS without a drivetrain and am starting to consider the best way to get her up and running again. The car does not have an engine (or ancillaries), gearbox or diff. It does have a prop and a set of half shafts, an exhaust backbox, and the original fusebox, ECU, wiring and fan are present. The shell is rolling but just for manouvering purposes and there are no brakes on the car. There is a full set of polybushes with the car, mostly still in the box. The car also needs a bunch of other things like a fuel system, screenwash system, seats, etc.

As I need so many parts I'm drawn towards buying a cheap donor car in order to pull most of the bits required. The car needs to remain 4 cylinders, and if it is 16V then it needs to keep the manufacturer's original fuel injection setup.

Option 1: early E36 318TI with the M42 engine, as this would allow me to use the engine box and diff (with E30 sump assembly and engine mounts, also exhaust manifold?) and should work with the ECU that's in the car without major headaches. I would also be able to use the rear suspension and brakes, and possibly also the front suspension and brakes (with modifications)? However, early 318TIs are thin on the ground these days.

Option 2: later E36 318TI or Z3 with M44 engine, this would be similar in principal to the above swap but I think it is slightly complicated by the change in engine type. I would have to use the M44 ECU with modifications. The M44 is also a slightly worse engine I believe as it doesn't have forged internals. M44 engined cars, however, are easy and cheap to come by.

Option 3: find a Z3 with the M43 1.8 SOHC engine and do a similar swap to the above but go for ITBs with some sort of custom engine management. A bit of a left field option but a Z3 1.8 is very cheap and it could be a fun project with the induction roar.

Option 4: Buy all the bits separately. This would allow me to get an E30 M42 with all the E30 specific bits on it, and probably also source a medium case LSD. Disadvantages are that it will cost a fortune to pick everything up separately, and there is no way to see all the parts working which you can if you are buying a complete running car.

Has anyone any opinions, particularly relating to the respective difficulty of the swaps. Thanks in advance.

[mike.bmw]

M42s and drivetrains are fairly cheap. I see them for sale around $400 occasionally on CL and FB marketplace. Rebuilding an M42 gets a bit pricey though!

Andrew325is recently swapped an M44 into a M20 car. Check out his thread here: https://www.r3vlimited.com/board/for...90-325is-318is

Where are you located?

[roguetoaster]

OP is in Scotland, and the M42 is way less common over there.

It certainly is a tricky spot, and depending on your regulations/licensing I'd seriously consider moving away from the M42 as parts are becoming a struggle to locate. While the M44 is an okay compromise, it's still a swap, so really, why bother with the trouble for no improvement? Whatever you do, don't make it another single cam 318, there are plenty of those already.

[dc2100k]

Thanks for the advice. Yes here in Scotland the M42 is quite hard to find now, and is almost certainly from an E36 necessitating some level of modification to fit the E30. The M44 is very common though, and in some cases can still be found with less that 80k miles on it for relatively low prices as E36 318TIs and Z3s are not popular here.

From my perspective swapping an E36 M42 is probably only slightly easier than an E36 M44, is that fair to say? On both swaps I will have to change the sump assembly and engine mounts, also exhaust manifold, right?

With an M44 swap I will also need to use the M44 ECU (and wiring harness?) - is that it? Or can I use the existing E30 wiring harness/Motronic 1.7 ECU without EWS with the M44 engine by swapping a few sensors?

Roguetoaster - what engines would you suggest moving to? It needs to be 4 cylinder for the motorsport class I want to use the car in (UK road rallies).

Cheers.

[roguetoaster]

So, the M44 theoretically has a lighter valvetrain, but has more components to fail, while the M42 is a very simple flat actuation system. In my mind the M42 is the better engine for motorsport use, especially if you go away from hydraulic lifters.

A late M42 should be able to use an E30 harness provided you swap intakes, fuel systems, and coils. An M44 should be treated as swap instead of a replacement basically because of the loss of the crank position sensor mount, but if you could add a bracket you could probably use an M44 with the same hardware as an M42, excepting the coolant port on the rear of the engine. I believe they all use the same exhaust manifold, but you'd have to check part numbers.

As to what other 4 cylinder to install, I can't say I know enough about the N/A engines there to say as we got almost none of those available to you. However, I'd look for reliability first, ease of install second, and a broad powerband/more power third.

[dc2100k]

Thanks Roguetoaster. I think I'll probably end up going for the M44 swap to be honest. They are that much easier to find and tend to be much lower mileage (often well under 100k miles).

I've been offered the full drivetrain from a 1999 Z3 for next to nothing, would I be able to use this in my 318is? I can take the OBD2 harness and ECU plus all the ancillaries, steering rack, radiator, small case diff etc.

My main concern is that I believe the gearbox is 10 degrees off from the E30 - is this something I can overcome when installing it? I realise I'm going to have to get E30 oil pan and engine mounts.

[roguetoaster]

I believe that someone makes mounts to overcome the G250 offset, it might even just require the E36 arms, but I don't know. The only other issue with the Z3 might be harness length/position for the DME with the rest of the components being plug and play (slight modification for the rack if your 318 has an airbag).

[Andrew325is]

Yeah I put the M44 into my E30. It's a very nice engine for the E30. The right amount of power and weight distribution is fantastic. Far superior to the common 24V swaps IMO. The M44 is better than the M42 in almost every way so don't believe internet myths about the M42 being superior. I believe only the crankshaft is cast instead of forged, but I've never heard of anyone busting one, even under boost. Connecting rods are still forged as far as I'm aware. The low friction roller rocker drivetrain is a big improvement and you can use the new 5W-30 synthetic oils without a problem. The M42 flat tappet design needs heavier 10W-40. I required 2 donor cars for my M20 E30 (M42 E30 and Z3 1.9). I think you can use the E30 M42 wiring and ECU with the M44, but the engine will need some modifications like roguetoaster pointed out such as the crankshaft sensor. You could use the E30 intake, but you would also need the E30 valve cover and you would need to add the oil squirters to it from the M44 valve cover which would take some custom work. I decided it was ideal to keep the M44 unmodified and use the M44 wiring and ECU, but of course the M44 wiring harness needs to be modified for the E30 and it is complicated work. Far beyond the scope of what most people would want to undertake, especially with all the extra North American emissions components I decided to retain. It is brilliant having a modern low emission OBD2 E30 though. In the grand scheme of things it was still a massively simple undertaking. For example, restoring a Land Rover Defender ground up is several orders of magnitude more complicated.

[dc2100k]

Hi Andrew, roguetoaster. Thanks for your detailed replies. I have moved the project forward a little in the last week or so - mainly by jumping in and buying some bits that turned up cheaply & locally! I saw an M44 engine complete from a 1999 318TI come up for £50 ($60) so I grabbed that, and I also snared a Getrag 240 overdrive gearbox from an M40-engined E30 with propshaft, halfshafts and a 4.27 open diff - again for £50. I know this will be an unorthodox setup but should give good acceleration (useful for road rallies) and hopefully should get me up and running at least, and maybe later I can look for a small case 4.10 LSD (£££).

Andrew, I agree that the balance of the 4 cyl cars is better than the larger engined cars. I have started stripping down the M44 that I picked up and I am amazed at how easily it has come apart - no stuck screws or rounded threads! I have the M44 harness, ECU, manifolds and all ancillaries here too. The engine was apparently running fine and was on 140k miles; I'm not sure whether to use this engine in my car or whether to pick up another with fewer miles and use this one for spares? I am shortly going to pull the sump and rocker cover to have a look at the state of the engine internals - is there a guide to places of particular wear areas? I'm thinking valve gear, chains & tensioners, rod bearings, etc?

I am going to pick up a coil-on-plug conversion for the car, as there is no coilpack with this engine. I am as yet undecided as to whether to use the E30 M42 ECU and harness in the car, or go to the M44 ECU and harness. I'd like to use the original ECU and harness as this is in the car and has no EWS, but clearly the cam and crank sensors are different, the M44 has the DISA solenoid on the intake manifold, MAF, etc. so it's probably easier just to switch it and get an EWS delete from somewhere. I don't have any E30 M42 engine parts beside the ECU and harness unfortunately. Do you know will the M44 exhaust manifold fit with the normal steering linkage (RHD)?

Roguetoaster, as per above I have found an E30 Getrag 240 so that should get rid of any gearbox alignment issues. The clutch and DMF are still fitted to the M44 but I believe I need a new spigot bearing as they are different sizes between generations. Also, I understand for a fast road application I would be better ditching the DMF and getting an M20 solid flywheel & clutch.