Nix's Engine Swapped Golden Nugget

The Jass side mounts are pretty simple & do a good job. My front clips never come undone as I’ve adjusted them to be quite tight. Also, I don’t know if I should say this, but the hard top whistles quite badly when you go quickly so a length of tape over the rubber seal stops it. 🤐

ooh it's update time, as I've been failing massively and not updating this thread.


well I threw the diff back in the car which is a crappy job as it weighs a tonne but it all went smoothly so no dramas. With the diff in for hopefully the last time I started on making the mock up axle. The MX5 axle is 24mm in diameter and the Audi axle is 32mm in diameter but has a 26mm bore so I was able to slide one inside the other. To get the axles to centre properly I plasma cut 4 pieces of steel that had a step in them to align and centre the 2 axle halves. So I threw the car on the ground set the inner joint so that it was about in the centre of its travel and then chucked a couple of tac welds on it. I unbolted the inner joint but guess what the outer joint had seized in place so I had to use the axle pusher plate thing that I made before




With the axle out of the hub I blasted it with the MIG welder and then once it had cooled down I pulled the axle apart to get measurements so I can get a quote and to get it ready to ship it off when I need to.



I was originally concerned that the axle would be substantially weaker at the MX5 CV joint due to its diameter but the Audi inner CV is only slightly larger in diameter so it shouldn't be a problem. Anyway with the axles sorted and out of the way I decided to finish the mounting the top radiator mounts.:



They're not the prettiest radiator mounts I've ever made but they do the job and the radiator is firmly held in place so that another job done. Annoyingly the mounts now clash on the underside of the bonnet so I'll have to remove some metal from the underside of the bonnet to get it fit and close nicely. Oh well gives me an excuse to add some lightness.

My custom clutch line and the stupidly overpriced circlip arrived so first up I threw them in the car



So the line connects into the back of the clutch master in the footwell then runs over the trans tunnel and through a grommet on the passenger side




The line is the perfect length and fits nicely, I may twist the line slightly so that it sits nicer but other than that its all good. Last thing to do on the clutch is find a reservoir and run a line to the master. After that I figured I'd go back to the radiator and finish up the cooling system. Normally on an E46 the coolant reservoir bolt to the radiator and has a bunch of connectors on the bottom for various coolant channels (Tee off the top rad hose, heater matrix return, block return, etc) the problem is that it won't fit and its plastic so I can't modify it. The M3's have a different setup with a separate coolant reservoir so I figured I'd do something similar.



I've had a random piece of 90mm aluminium tube for about 6 years, no idea why I bought it or what is was supposed to be for so I decided to use it on this project. I ordered a radiator neck and then when it arrived I started fabricating a reservoir. I plasma cut a top plate and welded the water neck into it then tac welded the top to the tube then cut the tube to length



I welded the bottom plate onto it and then welded the brackets onto it



I still need to weld in the fittings for the various in and outs but it looks pretty good if I do say so myself. I've never considered myself much of an aluminum welder as it's not something I do very often but I'm happy with that. So I positioned the reservoir far enough back that I could make it tall enough to make it the highest point in the cooling system to hopefully simplify the coolant bleeding process (Tailgate McNoIndicate make prarrie canoe cooling systems). I'll probably run the overflow to either the OEM Mazda overflow tank or I'll just leave it disconnected Nissan style

next up was the exhaust and I actually did do some exhaust work this time




That right there is 83 welds that need welding, each weld is 239mm long so that is 19.8M of weld that also needs back purging. That also doesn't include welding on the exhaust tip as I haven't decided exactly what I'm going with it yet.



I decided to chuck the tail pipe out the opposite side to what is standard for a couple of reasons:



1. I look to screw with people and it always confuses MX5 people when they notice its on the wrong side (did the same on my MK1)

2. It's a little nod to the Tailgate McNoIndicate as they all come out on this side



I'll probably weld some sort of exhaust tip on it at some point as 3 inch looks kind of small with the super aggressive bumper cut I've got on the car. I'll also change the ultra racing rear brace for a custom one with the a jacking point on it as well.



I've got a couple of days off work coming up so my plane is to get the intercooler piping done, then pull the engine out, weld the oil drain into the sump, paint the bay, finish the manifold welding and then start final assembly.



I've sent off the prop to be shortened and I'll be ordering axles this week so once that is all done that should be all the welding and everything mechanical out of the way. Hopefully in July I can get the ECU ordered and can start wiring. My goal is get the car drivable before the end of July but we will see how that goes. There will be some further bits that will need doing after but they can wait until I've recovered some funds

So after 83 welds on exhaust I decided that I hadn't got my fill of welding pie cuts so I did some more. 48 more welds to be exact



Nothing says racecar like pie cut intercooler pipes! So In reality I decided to pie cut the intercooler as it gives me far more flexibility than using an intercooler kit or mandrel bends and a length of 3 inch aluminium pipe is far cheaper than even a cheap ebay spec intercooler pipe kit. The hot/pre intercooler side is nice and short nd I was able to make it a single piece. The cold/Post intercooler side had to be 2 pieces it would not of been possible to fit it without either dropping the engine or removing the alternator which would not have been ideal.



I still need to weld in a port for the Idle control valve but I need to order the fitting so I'll do that when it arrives. I'm not going to run any kind of dump/blow off valve initially, however once I start to wind up the boot I'll chuck one in there somewhere.

I pulled the engine out of the car, removed the oil sump and welded a return fitting for the turbo oil drain (this was an absolute Canoe to do, between it being cast aluminium and having 20 years of oil absorbed into it, it didn't want to weld nicely); I'm still not entirely sure how well this drain setup will work but I can always revise it and switch to a scavenge pump later down the line. With that out of the way I painted the engine bay, front subframe, gearbox crossmember, prop bearing mounts and engine mounts. I also finished welding and then wrapped the manifold and installed it onto the engine prior to putting it back in the car as it would be near impossible to do otherwise. I threw a standard clutch and flywheel onto the engine for now as I plan on upgrading this later. I was originally gonna switch to a basic solid flywheel and new OEM rated clutch but it seemed as waste as I'd need to upgrade once I start adding more boost so I opted to run a stock one for now. I also gave it a bit of a clean off as it was covered in dust and crap.



Next up I threw some Aerocatch bonnet pins in as I need a way to hold the bonnet down now that the normal latch is gone. With all of the drilling and grinding done and bay blasted out with compressed air to get rid of any dust I threw the engine in for what I hope is the final time. I also threw the gearbox on and bolted that up with some temporary bolts (I need to order the genuine bolts).



So this week I hope to get most of the final assembly done and to finish off the last little bits on the list:



Fully weld wastegate pipe

Wrap wastegate and downpipe

De-Power steering rack/Weld pinion

Replace outer tie rod ends on steering rack

Wire up engine with Tailgate McNoIndicate harness and modify to work with existing Mazda harness

Change all fluids/Service engine, gearbox and diff

Install ABS sensor in front wheel hub to use for speedo

Wire up SGI-100BT to correct tacho signal and generate speedo signal for OEM gauge cluster



I've sent off the prop to be shortened already so that should be back in the next 1-2weeks and I've ordered the new driveshafts so they should be here sometime next month if all goes well.

^ saving on gym membership

I cut my PS belt while up the alps once....

I finished up the last bits on the exhaust, which involved finalising the fit up on the wastegate pipe, fully welding it out and then wrapping it along with the downpipe.



I also finished off the last of the painting on the car, started wiring up the engine with the stock Tailgate McNoIndicate harness and installed new spark plugs and reinstalled the coil packs. I did however find that the cable actuated cam on the throttle body is damaged and the clips that normally retain the cable have snapped off. This normally would be the end of the world as its a drive by wire throttle body with cable backup but I can't use the drive by wire function. A replacement throttle body is pretty pricey at £120+ and changing to one of the earlier cable only throttle bodies is going to be a pain due to them requiring an adapter plate and different connectors on the harness so I think for now I'll just modify/repair it so that it works.

So I finished off the intake installation, getting the manifold torqued down and finalizing the Idle Control Valve feed off of the intercooler piping. After that I decided to try and finish off a couple of jobs that I'd been putting off starting with installing the wheel speed sensor to wire to the speedo. The reason I'd been putting this off is that when previously trying to replace the sensors on the front wheels both bolts sheered off and the sensors snapped in the hub. I opted to install the new sensor on the drivers side as I'd already gotten the sensor out previously and the bolt had snapped flush with the hub so was far easier to drill and tap. It was actually a surprisingly easy job and I got the sensor in without much of a fight.



After that was sorted I decided it was time to finally sort out the steering rack as I'd finally ordered to track rod ends. I'd been avoiding this as the last time I depowered an MX5 steering rack it fought me every step of the way. This one however was pretty painless and the most difficult bit was replacing the track rod ends. So I pulled out the pinion, stripped it down and cleaned it ready for welding.



So welding heat treated steels is a massive ball ache, thankfully this is not my first rodeo. I used a 312L filler road which a stainless steel filler for use on high carbon steel, tool steel and dissimilar metals, Its also used in cases where welding is required on heat treated steel that can't be re-heat treated.

 

With the pinion sorted I pulled the rack out of the housing and cut out the central seal. After that I started sealing up all of the old ports in the housing; previously when I've depowered racks I've just cut the ends off the lines and welded them up to make a bunch of plugs but it always looks like proper dodgy. This time however I wanted to do something different (also I'd thrown away all of the lines ages ago) so I grabbed a bunch of bolt, lock-tite'd them into the ports and then ground them off flush with the housing and then threw some paint on them so they don't rust.



I chucked it all back in the car and bolted everything back together, Unfortunately I was only able to change one of the track rods ends as the motor factors only had one in stock

So I haven't taken any pictures recently as there hasn't been much to take pictures of but I have been cracking on with the various jobs to get the finished. I've finished plumbing up the clutch and installed the reservoir, I've re-plumbed all of the brake lines including rerouting the drivers side brake line through the inner wheel arch instead of under the chassis leg as there is no room next to the exhaust and wastegate pipe. I've finished trimming up the underside of the bonnet so that everything clears nicely and I've run a new throttle cable and "fixed" the throttle body with some cable ties so that the cable stays in place. I also gave the chassis legs a healthy dose of cavity wax to try and prevent any future rusting.



I've also now started wiring!. I got the Tailgate McNoIndicate loom installed on the engine and I also stripped down the last of the Mazda loom ready to be spliced together. I've stripped the loom that runs from the rear of the car to the fuse box down to just the main power cable, the alternator sense wire and the reverse light switch as these are the only connections that run all the way to the back of the car. The rest of it along with the fuse box will get trimmed and reinstalled with a few modifications where required. The wires from the back car that normally run along the PPF will likely be run inside the car as without the PPF and with the exhaust routing I have there isn't anywhere to put them under the car. I'm considering upgrading the main battery cable as it looks a tad on the small side to be running the considerably bigger starter and everything else.



Joining the 2 looms should be relatively straight forward, of the 5 main ECU connectors only one them connects to the body of the car so that is the main connector that will need splicing. There are also a few secondary connectors which need to be wired in as well but I'm fairly certain they are just power connectors. I still need to review the various wiring diagrams to confirm everything before I proceed too far



I finally ordered the ECU today as well so when it arrives, theoretically I can start the engine once everything is wired and tightened down.



Currently everything looks like its on track for me to finish this phase of the build by the end of the month.

This cliffhanger is better than the penalties last night, that's for sure!

Damn this is so close, I would love to contribute but you sound like you have it very well covered. I've been fighting with a few left over electrical gremlins myself but nothing on this level, are you a sparky by anychance?

Also, @mods can we please, in honour of this amazing build, get rid of the silly B M W wordfilter that changes it to Tailgate McNoIndicate !!