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-   -   DIY 318 - 325 Engine Conversion and M3 Full Replica (http://forum.e46fanatics.com/showthread.php?t=702327)

stuartjohn24 08-31-2009 08:16 AM

DIY 318 - 325 Engine Conversion and M3 Full Replica
Hi Everyone,

Ive been signed up to this forum for some time now, I will admit im shy dont ask many questions and read other peoples threads for the answers im after!

I have owned my 2000 reg E46 coupe for 4 years now and have recently completed an engine swap, from a 4 cylinder 1.9 M43 engine to a 2.5 M54 6 cylinder engine.

I have converted the body panels to genuine M3 ones, and re-sprayed the whole car in a white and black two tone theme.

I have done ALL the work myself, welding, painting, electrical, mechanical etc... start to finish.

I thought as I have been finding answers to the questions I needed on here over the past few years I think perhaps its time I tried to give a little back by answering any questions you guys may have on anything I have done. I will post photos on here if anyone is interested and a load of info on how to perform an engine swap etc....

Let me know Stuart.

Jake_928 08-31-2009 08:24 AM

Stuart post some pics, sounds like a cool project.

stuartjohn24 08-31-2009 08:26 AM

Thought I'd add some pics to get started:

1.9 M43

2.5 M54

wdeerfield 08-31-2009 08:29 AM

looks good. i was expecting an m3 engine in there. still looks great. good work. id personally paint the hood white and leave the roof black but thats just me.

stuartjohn24 08-31-2009 08:48 AM

M3 engine would have been nice!, unfortunately the price of them is ridiculous! that engine was approx 600 (900 USD) delivered with 80K miles on it.

I changed a few parts like all the rubber boots, hoses etc... and rebuilt the VANOS unit using besian systems kit.

*James* 12-26-2009 09:26 PM

I'd be extremely grateful of any info you could give me. I've pm'd you aswell!

Im getting excited after reading this thread haha.

bmw 318CISE 12-27-2009 02:59 PM

This is a very nice and tidy car, good job matey. PM me with any tips about forced induction kits, was looking at the bmc cda. I also have the 2.0 16 v engine and want it be a little fast but without replacing the engine. Any tips let me know please. Thank you. Neil

TiAgTouring 12-27-2009 03:02 PM

Very clean!! Why didn't you at least go with a 3.0L? Seriously an awesome project though, you clearly know what you are doing- it shows!

SweetBMW 12-27-2009 04:49 PM

Stuart.. in the UK do you have to approve any changes made to the vehicle? if so, can you please pm me with what changes you have made to your suspension, brakes, etc :)

would really appreciate it mate


stuartjohn24 01-03-2010 09:05 AM

Hi Guys,

Sorry for the very late reply, the thread didnt appear to get much interest so havent looked here in a while! I will try to answer as many questions as I can (I'm still learning too!)

To reply to the info regarding the conversion:

Well essentially the hardest part of the whole conversion is getting a complete ECU kit, i.e. the DME (or ecu) the MATCHING EWS unit (the ews and DME are coded together, either is useless if the other is missing!) and finally the MATCHING key for the EWS! dont listen to any rubbish about the key being paired with the DME its NOT! I have alot of information on the immobiliser for this car and I must say its a very clever system!

Mechanically as you know the engine will fit into the shell, there are unused studs and mount points some of which you keep others you now use.... (i had to look at alot of pictures!) You will need the 6cyl gearbox and the propshaft and gear linkage, i chose to keep the 318 diff and half shafts..... i was lazy lol! i have the 325 rear end parts in the garage still!

Some attention has to be paid to the cooling system, you will need two new radiator hoses (top and bottom) a new header tank (on the 16v 2.0 i think the header tank is the same as the 6 cyl) and another hose that is the return feed from the heater matrix, also you will need the feed and return pipes from the steering rack and the return pipe from the pas cooling ring in front of the radiator.

Air con is pretty simple, just one pipe is required that is a shorter version as the 6 cyl block is longer. and also a 6cyl anti roll bar or sway bar. I think thats about it.

All the engine bay electrics are different, they are simple factory harnesses that are easily sourced. The drive by wire need to be installed! thats 6 wires! and a few other wires for the cruise control as the DME controls the cruise and not the separate unit as before.

I didnt do the 3.0 litre as I couldnt find one for a decent price! the 2.5 set me back 500 and was a bit of a bargain!

With regards to approving changes.... it really does depend, the V5 registration certificate should be updated with the new engine details and capacity, this WILL change the road tax duty band! also the insurance company may demand the car is inspected (called an engineers inspection) this will check the quality of work done to the car, only then will the insurance company be happy to cover you, it really does vary with insurer though!

Suspension is still factory fitted AC schnitzer springs and shocks, its lowered about 30mm i think? Brakes are standard 318 front and back however have everything to convert to 325. any thing else you want to know give me a shout!


stuartjohn24 01-03-2010 09:17 AM

Some pics of the CAI I fitted at the end of the summer:


M3 Xenon bracket and cover, very cheap mod less than 10!


Bracket fitted to Xenon unit


Trial fit of carbon fiber intake!



Measuring up for a haircut!





Intake tube was a bargain 30 from ebay, just required some chopping!

wilawok 01-03-2010 06:06 PM

cool project........ looks good !!!

Do you have any pics of when you did the rear wheel arches !!!

stuartjohn24 01-06-2010 11:51 AM

Hi Wilawok,

To be honest I didnt take many pictures during the conversion and it was almost 2.5 years ago so cant remember where they all are but I have found a few and put them up.

Hope they are of use, i went for changing the complete quarter panel as its the best way to get an OEM finish! this was time consuming and a bit of a pain to do in places but as long as you have a spot weld drill and some thin cutting discs its not too bad!


Before work started


Strating to cut away the passenger quarter panel, its a bit fiddly as its brazed on in a few places (under the light cluster, and the bottom corner of the rear window)



The car looks a bit of a wreck now! but it has to get worse to get better!


This was doing the drivers side, i managed to get a second hand brand new panel from a garage which bought it in for an insurance repair job on a real M3, all they done was cut a section out by the light! so I stripped the paint of the original panel and cut to fit flush, and seam welded, with a bit of patients it came out perfect!


after welding, pre prep work before spraying.

*James* 01-06-2010 07:13 PM

Looks very well done, second to none infact. I'd love to be able to carry out work like this to this sort of standard, maybe i will bite the bullet and just go for it, theres no way in hell i could do the sort of bodywork changes youve done with one of the reasons being that i cannot weld lol, but maybe the mechanical/electrical side of things are a bit more of my thing!

Did all the interior electrics function as normal? No fault codes being thrown?

I dont suppose you'd be intrested in selling it haha? [<< serious question]

Thankyou for sharing the pics and knowledge mate.

Flipe46d1722 01-06-2010 09:27 PM

Beautiful conversion, looks really clean

jreid 01-07-2010 01:41 AM

looks realy clean, great work!!!

stuartjohn24 01-08-2010 01:20 PM

Hi James,

Yes surprisingly pretty much everything worked perfectly.

The ECU and car electronics are pretty much completely separate and swapping the ECU appeared to have no affect whatsoever.

One to to bear in mind though is the instrument cluster will need re-programming to 6 cylinder spec. This is due to the temperature gauge, the 6 cylinder engines run significantly cooler then the 4 cylinder engines, from what I understand (read it somewhere) this is to improve engine emissions on the older 4 cylinder engine.

I originally thought this was due to the head and block both being aluminum on the 6 cly and needing to run cooler. but they should expand at the same rate being the same material! so its nothing to do with the head gasket as far as i know. the 4cyl 1.9 has an aluminum head and cast iron block so i would expect issues with the head gasket but after 80K it was still going strong!

Anyways im rabbling on a bit off subject here!

One important thing I would like to mention is the ASC/DSC my car in an early 1999 model, fitted with ASC.

The ECU/DME I fitted was designed to work with DSC, if any keen eyed spotters have noticed after around 2002 the ABS/traction control module was moved next to the brake servo on the drivers side. (and not by the engine electronics box on the passenger side!)

Im unsure about the reason for this, I would imagine its very difficult to change in its old location! anyways I thought the ASC would not work! I was proved wrong, luckily everything works! ABS and traction control!

It would appear the traction control and ABS messages on the CAN bus are the same for ASC and DSC so luckily all is ok! I must admit it has got me out of a few sticky situations before and im very happy I didnt have to retrofit DSC!

As far as throwing codes? none that are an issue, I had a couple to start with but they were because I plugged the oxygen sensors in wrong! :rolleyes:

Apart from that works really well, the ECU keeps itself to itself pretty much, the only communication it does with the car is via the CAN BUS which is between the ASC/DSC and the instrument cluster, this transmits information in digital format like RPM, engine temp, and the 'engine retardation' messages sent from the ASC/DSC to stop the engine revving or to reduce power output if the wheels spin up etc...

About selling.... well I have recently become a proud father and I'm after a more family orientated car so yes im willing to sell if the price is right! Im open to offers on the car and hope any offer that is made will reflect the amount of time I have put into this car and more importantly its a bit of a one off (very cheap insurnace for a 325... sorry 318! ;) lol)

*James* 01-08-2010 05:46 PM

Thankyou for that indepth explanation... appreciate it :D!

To tell you the truth after doing alot of research over the last couple of days and confident that everything will work ok, i think i may give it a shot and go with the s54 lump. Only reason being is that i have access to a donor m3 if needed for a VERY good price.

But i may still be interested in yours as its a very nice example, i understand the amount of work you've put into it, so pm roughly what your looking for it, i wouldnt want to offend with a low offer lol

cheers again...

RAFF112 01-08-2010 05:53 PM


Originally Posted by stuartjohn24 (Post 10544769)
Thought I'd add some pics to get started:

1.9 M43

2.5 M54

You should have done this

BDUB328I 01-29-2010 05:50 PM

yea if he wanted to add another 0 on the end of that $900 he paid for the engine he has

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