[Nix.]

OK so I figured it was time for an updated and more detailed To Do List:

Run new vacuum line with check valve to brake booster
Run new vacuum hose to boost gauge
Run new vacuum hose to ECU
Install Core4 Speeduino in OEM ECU housing
Wire BMW X60004 connector into existing Mazda wiring
Wire Mazda X16 connector into new BMW harness
Wire Mazda ECU connector 1 into new BMW harness
Wire SGI-100BT to generate speedometer signal
Wire SGI-100BT to correct Tachometer signal
Reinstall wiring for reverse light switch
Install new main ground wire from battery
Install new ground strap from engine to body
Thin out unrequired wires from Mazda fuse box side harness
Tighten Diff to Prop bolts
Tighten and check rear suspension bolts
Tighten and check front suspension bolts
Remove, Paint and reinstall shifter adapter plate
Wire rad fans
Wire Wideband sensor into ECU Aux pigtail
Tidy passenger footwell wiring and reinstall kick plate
Tidy under dash wiring and reinstall dead pedal
Fill and Bleed Brakes
Fill and Bleed Clutch
Tighten turbo oil feed (turbo side)
Tighten hose clamps on turbo water lines
Fill engine with oil and prime
Fill engine with coolant
Assemble and install driveshafts
Reinstall interior trim
Torque wheels
Roughly align wheels front and rear


Again I'm sure there are things missing so I'll add them as I find them.

 

[Nix.]

So of course BMW use some crazy specific bolt to hold the diff to the prop shaft... and they want £27 per bolt.

Yeah fuck that for a laugh, I'll just modify a grade 12.9 bolt to fit as its essentially just an M10x25mm bolt with flat surface ground onto into it

 

[Nix.]

It was a good weekend of work on the car overall. I spent all of Saturday getting the BMW and Mazda harnesses integrated an overall it was pretty simple except that my engine is from an E46 which BMW still considers a "current" model so wiring diagrams are actively removed from the internet unless they are from the official BMW source (which is pricey as fuck!). Thankfully after consulting some wisdom on the BMW forums I found out that the Z3 which is classed as E36 had multiple different engines included the same M52TU that I have and the newer M54 so I was able to use the wiring diagrams from that instead.

I started getting everything integrated together and it was all going good until I came to wiring in the fuel pump relay. Every single piece of Mazda documentation including wiring diagrams as well as forum threads I can find says that the trigger for the fuel pump relay is light green. Mine is red and yellow. This had me stumped for a good while until I found some random pictures on the internet that showed the same wire colours.

Well with everything required to start the car wired it was about 1:30 in the morning and I was incredibly tired and I should have called it a day then but I thought it would be a good idea to try and start the engine... nothing happened, no start, no fuel pump, nothing; and its a bloody good thing nothing happened.

So at this point I called it a night and put the car back up in the air only to realise that the fuel lines weren't connected, neither was the starter motor. I also realised on the drive home that the engine had no oil in it! So here's some golden advice, if It's already gone past 1:00AM don't try and start your engine swapped car.

Well Sunday I came back with a fresher head and made a mental list of everything that needed doing before I could start the car. So I realised that I hadn't grounded the ECU (which is why the fuel pump didn't fire) so I started with that, Then I moved onto the starter wiring, I hadn't connected the trigger or the sense wire. I also connected up the knock sensors so I did that whilst I was there. After that I connected the fuel lines which is tricky as there is shit all space behind the engine but thankfully I opted to keep the standard push fit connectors so It's just a case of lining them up.

Next up I checked the turbo oil drain and tightened it down, tightened down the oil feed and tightened the turbo water feed clamps down. Then most importantly I filled the engine with the required amount of oil and coolant.

At this point I was confident I had everything ready to go so I connected my laptop to the ECU, corrected the displacement and Injector sizing (another thing I completely forgot the night before) then I turned the key on and off a few times to prime the fuel system only to hear the ominous sound of fluid dripping onto the floor.

With the car back in the air I found that the fuel was pissing out of one the fuel line connectors under the car (on the feed line) so I tightened that down and put the car back on the ground. At this point everything looked good so I disconnected the spark plugs and fuel pump relay and turned the engine over a few times to get the oil primed. I reconnected everything and it fired right up!

it then died about 5 seconds later. it did the same thing a few more times before I noticed that the ominous dripping sound had returned. I found that the return line was now leaking in the same place, I hadn't tightened that one either.

Now at this point I started the car a handful of times and it had run for a few seconds and then died, I thought that maybe I'd crossed the fuel lines so I disconnected them and swapped them then tried again. It ran for about 8 seconds before it died and wouldn't start again. I couldn't work out what was happening so I went through the settings on the ECU and found that I had entered the capacity wrong so I corrected it but no change.

I then checked the fuel lines again and realised that I had them right the first time so put them back which was a massive pain in the arse as the plastic clip that holds the push fit connectors on just up and vanished. After about 10 minutes of searching I eventually found it between the block and the back of the starter motor. I reconnected the lines but didn't get chance to check.

Instead of finishing it I decided to watch the football... clearly that was an error in judgement

Hopefully tomorrow I can get it to run and stay running smoothly

 

[Zed.]

I decided to watch the football

I would have suggested doing anything BUT that, maybe sweeping the ocean or counting stars

Rich.

 

[Nix.]

Well I spent some time last night trying to solve the issues I was having. As I previously mentioned I left the car with the fuel lines swapped back to how they originally were so I started by trying to start the car and it fired right up and then died a few seconds later. It then wouldn't start again. I thought Initially that maybe the fuel pump wasn't running when cranking/after cranking so I jumped the relay to ground so that it was permanently running with the ignition on. I also changed all of the added BMW relays for spares in case there was an issue with them but again after starting it, it would run for a few seconds and then die and no amount of accelerator pedal action would save it.

Then it hit me. When I started tearing this car about several months ago the fuel tank was pretty much empty, I've since drained out nearly 4 more litres when I removed the old lines and goodness knows how much more spilled on the ground from the leaking lines and swapping lines over on Sunday. I chucked in 5L or so of fuel and tried again, it fired right up and then died however now at this point I was able to keep the engine going by giving it some throttle. The problem is that I hadn't connected the rev counter so I had no idea how high I was revving the engine.

So I figured it was time to wire up the Tachometer. Thankfully the BMW ECU outputs a tachometer signal but obviously that signal is not going to work on an MX5 Dashboard so I had to wire the signal through the SGI-BT100 which allows me to change the 6 cylinder input signal to a 4 cylinder output signal. Nice and simple, so I ran new wires to SGI-BT100 and then to the dash.

With that wired I was able to get it started a few more times and keep it going on the accelerator pedal but unfortunately the battery died shortly after putting an end to my evening.

Hopefully today I can charge the battery and start working on tuning the Idle settings to get the car to start properly.

 

[Nix.]

Well I've solved my idling issue, it now starts and stays running.

After doing some research and reviewing logs I took a punt on there being a lack of fuel for cold start so I bumped the Acceleration enrichment from 7% at 20 degrees C to 60% and then it started and idled until the acceleration enrichment started dialing down and then the AFR started hitting 18 and I turned it off. Out of the 30 seconds or so it ran only about 10 seconds of the log was useful as the wideband didn't finish heating and start outputting until after the first 20 seconds. However it was long enough to realise that the base map I have will not run my setup and that the VE table is way off. I'm not yet sure why the base map is so off, It could be the turbo/intake setup I have, The drop in compression ratio from 10.5 to 8.5 or it could be the 875cc injectors.

at present this is my VE table with the Idle section bumped by probably 80% over how it started.

you can see how out of scale the Idle section is with the rest of the table.

For now I need to wire the fans before I continue so onto that...

 

[Nix.]

OK so I think I've worked out the problem with the VE table being so far off. After some time reviewing the setup I realised that my injector/battery voltage compensation was off. So the battery in the car is pretty much dead and at present with the engine running it sits at about 11v and with the injector voltage corrections that were setup it would have been extending the injector open pulse by about 5-10% when it should have been extending it by about 40-50% according to the data on the injectors I'm using. Hopefully with the correct injector correction curves inputted the VE table will be slightly better.

So I've put the VE table back to how it was before then bumped the fuel up my 20% over all just to be safe for the time being. Hopefully I'll be able to get a new battery tomorrow as well and I can continue tweeking the tune.

 

[Nix.]

Righto so some more progress this evening. I tightened up all of the suspension bolts (will need to roughly align it later) but at least now nothing is going to shake lose when I can take it for a test. After that I got the fans wired on configured the ECU to turn the relay on at the right temperatures, installed a new battery and started tuning again to try and get the idle right.

Well I was on the right track with the Injector compensation, but something else I had done in the tune was throwing it off. So I loaded in the base map again, reconfigured the engine settings, reconfigured the injector compensation, changed the idle mode and then locked the ignition advance to 16 degrees whilst I set the idle. Initially it fired up and then died so I had a look at the ASE settings and bumped it by 30% across the board (I bumped the ASE as once the ASE turns off after 30 seconds I can see how far out the initial VE table is). Well with the ASE up 30% it was about the right AFR for idle and once the ASE was disabled it leaned out. With that in mind I bumped the entire VE table by 30% and then started changing the idle duty cycle to get it to idle at the right RPM. It now idles pretty nicely with a good safe AFR so I'm happy with it for the moment, I also had it fully up to temp and didn't spring any leaks so that's a bonus.

Now I'm kind of at the point where I need to be able to drive the car to tune any further but obviously I don't have any axles yet. So over the next few days I'll probably tidy up some of the last wiring bits and get the suspension roughly aligned after that it's probably gonna have to go on hold until I get the axles.

Hopefully they come in soon, stay tuned

 

[guitaristanime]

Great progress Nix. nice one

 

[Nix.]

I managed to get a little video of the engine running and a few little revs (the engine was still on the cold side so didn't want to go mad).

The video really doesn't do it justice, this things sounds absolutely mad and I can't wait to take it out for a rip

 

[Nix.]

So I just had a very exciting parcel show up at my door this morning. My axles finally arrived meaning I can finally "finish" this thing and take it out on the road. So over the past few weeks I haven't really done anything on the car and I had an absolute arse of a time trying to procure the correct outer CV joints. For some reason a lot of suppliers out there seem to have completely the wrong spec listed for the outer CV's for an MX5 (MK1, MK2 and MK2.5).

I checked about 3 different suppliers and all 3 of them had the outer CV listed as 28 spline outer and 32 spline inner which it is most definitely not. Eventually I managed to convince the supplier I was using that there information was wrong (after them sending me the wrong parts TWICE!) and managed to get the correct parts which if anyone cares are 26 spline outer and 22 spline inner (the same as several models of the 323). Anyway as I'd had a bunch of issues trying to get the CV's sorted I wanted to make sure that everything fit up nicely so I quickly threw one of the axles together to check and yeah it all fits like a glove.

The quality of the axles looks absolutely outstanding so hats off to GB engineering for that!

So over the next few evenings I'm planning on painting and protecting the axles and axle adapters as well as a the gear shifter mount plate which I never painted. There is also a few other snagging issues I need to sort out but if all goes well I've got this Friday off of work to start tuning and testing and then Saturday I'm going on a little road trip to see some friends so it will get its first real endurance test then... It's probably not the smartest idea but hey fuck it why not.

 

[Nix.]

So over the last couple of evenings I've been getting the axles prepped and assembled and tying up the last few bits that were outstanding. So I primed, painted and clear coated the axle shaft and because I had some left over I decided to paint the axles in the same colour as the car.

The axles went together without any dramas and they fit in perfectly.

Well that is pretty much everything that needed to be done to get this thing moving, so I took it for a test drive. The alignment is absolutely fucked so it handled like shit but it felt good enough to take it out of the industrial estate and out onto public roads. My first stop was the petrol station as this thing was running on fumes even before spending time tuning the cold start and idle last month.

Between it being pretty late and my speedo not working (I had forgotten to configure the speedo converter) I only got as far as the petrol station and back. I also noticed that it was running a bit warmer than I was comfortable with so I decided to call it at that. But man this thing is wild, It has so much torque and is so responsive even before you get into boost this thing feels fast and its running super rich at the moment so once its tuned it is going to be wild!

I have a feeling that the reason its running on the warm side is that the thermostat is toast, seeing as how in my infinite wisdom I decided not to replace it when I was working on the engine and the BMW stats are notorious for failing. I'll probably replace the stat and the water pump as well to be safe, if I can get the parts tomorrow.

 

[Nix.]

Well I've managed to get a new stat and water pump from the local motor factors so I can pick those up over lunch and can get those fitted this evening. I'll also have a go at getting it slightly better aligned as it is pretty horrific as it stands.

as the coolant in the engine has done a grand total of about 5 miles I think I'm gonna try and save as much of it as possible and put it back in. I'll probably recheck the axle bolts will the car is on the lift just to make sure that nothing has come lose yet.

 

[Nix.]

I was also doing some research and found that the thermostat on the M52TU doesn't open until the coolant reaches 97 degrees, which seems insanely high. So maybe it wasn't as bad as I thought it was as the ecu was only reading 99 degrees, I'm still gonna replace the thermostat and pump as I've already ordered them and it shouldn't be too tricky

 

[Nix.]

Well the overheating debacle continues...

So last night I changed out the thermostat and water pump which was surprisingly easy, I didn't even have to take the radiator or fans out. However it didn't resolve my issue. I know that these engines are an absolute nightmare to bleed when they are in a stock configuration as the water channels in the head and the heater matrix sit slightly higher than the water neck and bleeder.

In my setup I made the water neck and reservoir higher than the bleeder which makes the bleeder pretty useless once the rad is filled (didn't think about that when I built it). I'm also fairly sure that the water channels in the head are still slightly higher than the water neck so I think there is just an airlock somewhere in the head that is stopping coolant from flowing properly (which is pretty common for this engine). I did try jacking up the front end last night but it didn't seem to help.

I also remembered that the thermostat on these engines can be electronically overridden to force the stat open earlier than the mechanical open temp (I'm pretty sure it just uses a heating element to heat it earlier). So I did change the settings to force it open at about 88 degrees instead of 95 but alas it made no difference. There are a few other things I want to try today to get it bleed so we'll see how that goes.

I did however get my speedo sorted and working, I'd connected the wheel speed sensor incorrectly so after connected it up the right way it seems to work correctly. Just an the alignment to fix once the cooling system is working

 

[Nix.]

Well it now seems to be all sorted!

So I realised that I hadn't actually calibrated the Temperature sensors in tuner studio. I spent some time digging around online and found the correct values and input them. I also re-bled the cooling system again and this time I jacked the front of the car as high as I could get it and with the engine running the coolant level dropped a fair bit pretty quickly. So I think its safe to say that there was indeed an airlock somewhere in the head (which happens to be where the coolant temp sensor is). I got it all bleed and left it to idle for a while and it all looked good so took for another spin. when driving normally at 30-40MPH temps were around about 88-91 degrees, when constantly cruising on the dual carriage way at 75MPH temps were around 94-95 degrees so much improved over the previous temps.

I think I'll have a look at adding in an aftermarket gauge in as well so that I don't have to have my laptop plugged in constantly just to monitor temps. I'll probably also wire in the secondary BMW coolant temp sensor to the Mazda gauge just so that it somewhat works (I have no idea if the resistance curves are the same but I don't like having a gauge that doesn't work)

There are also a couple of other issues I need to work on but nothing major, hopefully over the next few weeks I can get everything dialled in nicely.

 

[Nix.]

So the car has been pretty much finished for the last couple of weeks, there are still a few things I need to tie up and a few snags I need to sort out but overall its in a good state. As such I thought I'd throw together a bit of a summary since its going to be a while before I'll be making any major changes.

Whenever anyone suggests an unusual swap on the internet , you tend to get 3 main response types, supportive people, Idiots that lack skill and imagination that insist its impossible and then muppets that insist it'll cost "£1700000" and "22 years" to complete it.

So to address the question of much it all actually cost and how long it all took

This includes anything that I've had to buy specifically for this project so, it doesn't include the cost of sheet metal, bolts or fittings I had in the workshop already. It does include any tools that I had to buy specifically for the project like the BMW specific tools and the kit to re-thread the head studs into the block. It also doesn't include any labour costs as I did all the work myself (If I was to estimate the labour costs at the rate we charge in the workshop then yes the costs would be astronomical)

The final cost came to £5577.90

I'm not gonna do a full breakdown as that would be boring and no one wants to read through that, but here are some of the most expensive things I ended up buying.

1. £462.40 - Time-cert head stud re-threading kit
2. £440.23 - Custom driveshafts
3. £328.60 - DIY-EFI Speeduino ECU
4. £315.00 - GFB EX44 External Wastegate
5. £270.00 - M52TU Engine, Gearbox and Harness
6. £257.20 - ARP Head studs
7. £250.00 - GT3071 Turbo (Legit Wuhan Whirly Boy)
8. £202.49 - Siemens 875cc Injectors
9. £152.97 - E46 Alloy Radiator
10. £150.00 - M52TU Decompression plate and head gasket

All in all this project took about 7-8 months of evenings and weekends but this includes time to fix the rusty chassis legs as well as some time waiting on parts so It could probably be done quicker If I'd been able to order all of the parts at the beginning of the project.

Would I recommend this swap to someone else?
Yes I would as its an awesome engine and with a turbo its pretty nuts, the caveat is that its not for everyone, there are definitely easier swaps but if you love a straight 6, don't mind pissing off the JDM purists and have the skills to do it then Yes.

What would I do differently if I was to do this again?
Well first things first the biggest Issues I had was clearance for the exhaust and turbo and how to run the turbo oil return, so I would definitely try everything possible to to top mount the turbo even if it meant notching the chassis legs or tube framing the front end.

I would also use a 6 speed gearbox from the beginning as they have better ratios (they actually have an overdrive gear! 6th is 0.83 whereas the 5 speed does not, 5th is 1.0) meaning I could use one of the oem BMW lsd options (all of which are like 3.9-4.3 ratios) and still keep a comfortable RPM when cruising. Obviously I can change this on my car in the future but it requires a different clutch, different mount and different prop shaft that in my case will need modifying again.

Use a pedal box! so the modified clutch pedal I made works just fine however it was such a pain to make and even more of a pain to get the feed plumbed in. I did consider doing this as I had a spare OBP pedal box in storage that I bought for S14 but I wanted to retain the brake booster as this is technically my daily

I'm adding this even though It's something that I still may do going forward, but use the oem E36 BMW axles. The BMW axles are pretty much the perfect length to go in the back on an MX5 and it should be possible to get a set of MX5 hubs re-splined to take the BMW axles. Another option is to get a set BMW hubs turned down to fit in the MX5 uprights (this would require switching to a BMW 5x120 stud pattern on the rear though)

So what's Next?
So aside from the snagging issues, I'm currently running at about 8-9PSI of boost on a very safe tune and this thing is already mad as hell and is considerably faster than my old turbo setup. As such the next thing on my list is Brakes. The car is in dire need of a brake upgrade before I start adding any more power. I haven't 100% decided on a course of action but I do have a couple of things in mind that I want to try out.

After the brakes are done It'll likely be, FIX MORE GODMANN RUST!, LSD Upgrade, Wheels, Tyres, Suspension, MO POWAH, Exterior

I'll likely post some other updates as I get chance to work through the snagging list but until my finances recover that is this project pretty much done

 

[BEN99W]

Great work. What sort of power do you estimate you are running now?

 

[Nix.]

Great work. What sort of power do you estimate you are running now?

At present I would hazard a guess at somewhere between 0.1 and 1.2HP... I broke it so the only power it makes at the moment is whatever I can muster to push its sorry ass into my workshop 😂

joking aside (although it is indeed broken at present) I have no real figures but based on driving it I'd guess at around the 300hp mark but as its a straight 6 the increase in torque could be misleading, once I have it fixed and dialed I will take for some dyno time if for no other reason then to find out how much power it makes.

As to how it broke well the answer is 2 fold, firstly I believe I mentioned previously that I'd had a run in with a few speed bumps and had munted the radiator bracket; well it happened again only this time on a far more aggressive speed bump (fuck you westgate leisure center and you're oversized speed bump!). It took a hit hard enough to force the radiator back toward the engine where it made contact with the crank pully and damaged the fan. The fan cracked and bent to the point that the fan blades dug into the radiator meaning it no longer spun and damaged the rad core, the secondary fan was still working so no immediate issue. This also however caused the lower rad hose to move enough that it was contacting something and tore dumping the coolant. I noticed long before the engine overheated and any permanent damage was done but the radiator, fan and lower hose all need replacing. With this in mind I decided that I may as well make some improvements so I'm changing the rad and intercooler mounted to angle the bottoms forward to give some extra clearance.

Secondly, well this is entirely my fault and is a direct result of my haste to get the car driving, I've cracked the rear subframe. I had to cut some material out of the subframe to fit the bigger diff but I wasn't concerned as the lower brace would of stiffened everything back up however the OEM one wouldn't fit due the routing of the exhaust so I had originally planned to take for a run and some basic dialing in and then make a custom brace, however in my haste and excitement I forgot. This isn't too big of a deal as I can easily weld it back up, reinforce it and install/reinstall the brace I should have installed from the beginning.

Hopefully I can source the parts I need this week and I can get everything sorted out next week

 

[Nix.]

So I figured it was time to update this, well its all working again. I changed out the e46 radiator for a e30/e36 variant radiator that is slightly smaller but with a much thicker core, I also put in a fan shroud this time as with the changes there was room. So far its all been pretty good, I did have an issue with the e46 rad hose quick disconnects leaking even with brand new seals so I cut them off the radiator side and changed them to the regular push on type. I also got round to sorting out the rear subframe. I welded up the crack and strengthened It a bunch where it was flexing as well as adding in the bracing underneath so there is no more flexing.

Fixing it has kind of been a bit of a nightmare and everything just took so much longer then expected. With all of issues that have cropped up, I decided to do the smart thing and relegate the car from "Daily" to "Weekend/Fun" car and bought myself another daily. And because reliability and fuel economy are overrated I decided to buy a BMW 325ci e46 (the same model car the engine came out of) so I could compare the different setups.

I'll probably do a proper update with pictures and such soon. I think next up on the list of things to do to the car is a few little maintenance tasks, fix the rust and then I want to make new tubular subframes for the front and rear.