My current project - NC MPS conversion *Now with pictures! **& video!

I haven’t been around here much of late, been busy with life and work, however I thought it was about time to update people on a little project I have been working on, inspired by a few posts here to go turbo and also down to having no oil and ruining a 1.8L engine.

As the title may give it away I have put mazdas 2.3 DISI engine that is used in the mazda speed 3,5 & 6 as well as the CX7 - for those not in the know with this engine here is a link to the wikipedia page for it Mazda L engine - Wikipedia
Long story short it’s a 263 hp 280 lb-ft direct injected turbo engine.

I was planning on posting all about this as I was building it but got caught up and was/has taken much longer than I thought and progress was sooo slow at times I decided to post when it’s done. I do have some pictures but my phone broke and lost about a years worth, I did send most of these to other people so when and if I get them back I will post them here.

Well it’s not done but it’s something that I will finish, either in failure when the engine blows up or some government issue with MOT or its all going to just work, government approval. I am expecting about 6 weeks time to register the changes with 2 weeks of work left at my current progress.

As this an epic post, ill break it down into sections

If you have any question I will do my best to answer them.
I will be covering on what I have done with the car and the costs that I can remember to give an estimate of the total, these will all be without labour, that can be verry cheap to priceless, but needless to say many… many hours went into this.

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So where did this all start

As mentioned above I got this car many years ago and didn’t fully look after it - engine oil got low (though the pressure sensor still was showing fine!) and turned out piston #1 crankshaft bearing had got some damage and was making a noise (found this out after completely disassembling the original engine)

In the meantime I went and got myself a 2.0 sport version of the car and have been driving that since… Love these cars! before knowing the full extent of what the issue was I was pondering what to do with the car

  1. sell it sight as seen - I attempted this but no one showed any interest.

  2. put another 1.8 and sell it on - sounded like a lot of effort for a car that you can somewhat easily get

  3. put the 2.3 DISI MPS engine in - this appealed to me because it made it turbo’d :heart_eyes:

  4. put a crate 2.5 engine in - the quote for this was far too high in the end - I could have done what I did with the DISI and put it in myself - but still no turbo.

I chose option 3.

I did a lot of research before, attempted to contact everyone who had done this, tried to find out the pitfalls and issues around this but ultimately went ahead and did this option.

I would at this point mention that a lot more sane people over the internet whenever the 2.3 DISI swap came to question suggested to just put the 2.5 in! Throughout this project I wished I had listened to these people as all my research led me to one conclusion - it’s possible but being in the UK with a RHD is insanely hard! If anyone else is to go down this route I will list what I have done and what issues I have had.

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The premise of the 2.3 DISI swap.

Everywhere I read, all that was mentioned was that the engine would fit but there would need to be some heavy massage of the direwall for the high pressure fuel pump - this is a maybe… for LHD, for RHD seems to be much, much more than this.

So back at the end of 2020 I started working out what I would need, I would point out I have ‘zero’ mechanic knowledge at the time, and had bever even done anything like an oil filter change myself.

most I had done was get my brother to change my disk pads while I got him cups of tea :joy:

So planning on having this done in a couple of weeks I started to get some tools

some to note for being excellent (not sponsored by any of these and only posting from experience)

Halford advanced 200 piece tool set - £260, these have been worth the money, some have stopped working but the best feature about this set is their lifetime warranty, I have simply took the bits in that have stopped working (some have snapped, some have had their ratchet stop working) and halfords have exchange all of them free of additional charge and there are enough in this set that I could switch out to another socket size and not stop progress for the most part - downside is if halfords didn’t have that bit in stock you could be waiting a week for a replacement.

Ryobi power tools - I got myself their drill, impact gun, grinder & light, probably about £200 worth. these have been flawless throughout the project, I needed a cordless set as I was originally planning to do it away from my home and wouldn’t have a power point (live in a flat)

Note* I got third party batteries for these, it’s a bit hit and miss but at half the price of the official ones I ran on 2 x 5Ah batteries - I then got 2 more of these, they lasted in use time but their overall lifespan wasn’t great.

Some things to stay away from

Dewalt goggles - I got these half way through the build as my originals where old and scratched to the point it was foggy and couldn’t see out of them, the dewalt ones though had some breathing hole at the bottom and didn’t fit around the nose great - often getting bits flicking up in that small gap!

Another great place I used was autosiliconehoses.com - had 95% of all hoses I needed (I have ordered too much from these at times and due to the slowness of the project couldnt return these, will probably put all these parts up for resale once I have completed the project.) They look to be great quality, few issues with orders and they were always easy to work with and were very helpful.

My thought with most of these tools is if I decide to, I could sell them on later - keep in mind I was quoted approx £6000 for the 2.5 crate swap in a drive in and drive out solution.

Thus far on tools I probably have spent about £700 - 800

Once I started rolling the ball with the tools my next job was to find a DISI engine to put into this thing.

There was multiple options, getting an engine on its own seemed to be approx £1500 and that had the added disadvantage of having to get an ECU to run this setup and rewiring everything to piggy back from the mazda ECU or to completely replace the ECU - instead I found a donor car with the engine in, 90k on the clock and because it was a CX7 rather than the mazdaspeed range only cost me £1500! The clutch had gone because the guy had been towing a trailer but apart from that everything else checked out.

The benefit of this, it has the wiring harness, has the ECU its all mazda and while I saw some work ahead as the cars where made 1 year apart I was of the opinion that anything that had to be kept on the mx5 would be swappable or not much rewiring would be needed.

The first job - get the engine out and strip the CX7 down for parts - selling bits here and there I have made approx £700 back with lots of stuff available to sell, I have them in storage and haven’t really pushed selling some parts - I am estimating I will probably break even on the car once the rest are sold - so a free engine! (excluding mine and my brothers labour)

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Engine prep.

So a couple of things had to happen before I continued to put this engine in - first the balance shaft had to come out as the oil pan from the MX5 had to go on to fit in. this from what I have read is used to remove vibrations from the engine and give a smoother ride but shouldn’t be detrimental to engine longevity (again time will now tell)

Oil pickup also had to come from the MX5 as the CX7 was too long - this was the first issue I had, it turns out even though the 1.8 and 2.0 versions use the same block, the oil pickup has ever so slightly different positions. so the 1.8 version I had wouldn’t fit as the 2.0 and 2.3 shared the same bolt placement. I was expecting this to be done somewhat quickly so I needed a rush on the part and ordered it from my local mazda dealership, knowing how long it took I paid way over price for this.

while I was working on this I also fitted an uprated clutch from bofi racing, rated for up to 300 ft-lb of torque, and while there wasn’t any indications of an imminent failure, as I had everything out and was working on it I also got myself a new core for the turbo as there was reports of issues with these (no one had an exact reason but the consensus was a build up of ■■■■ from breather valve, that or too high oil pressure was pushing past the seals) - clutch was approx £260 and turbo core was about £80

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The disaster that was going 2.3 DISI
So this was all kind of going somewhat as expected thus far, small problems but nothing major. but then I had only just started and the hardest part was to come, putting this into the MX5 - me and my brother bashed the firewall a bit and was getting nowhere as we was in the street with limited options was working through the rain and by the time we tried getting the engine in it was pitch black - as getting the engine out through the bonnet opening was really hard we had detached the front subframe from the chassis, hoisting the car up in the air and was rolling out underneath, we had taken the old engine out just fine and had mounted the new one to the subframe with the gearbox attached, we had made a makeshift trolly from a shipping pallet with caster wheels on - this was the cheapest and best home made tool I had! never faltered and was able to much the subframe with relative ease - so we was both trying to get the engine in at 10 at night soaking wet, cold and miserable - trying to do it quickly we kept the exhaust manifold on, this kept getting caught on the body - took this off and the firewall was still nowhere near close to letting this beast in. - We gave in that night, coming back and trying again the next day where we could clearly see the high pressure fuel pump was going to be an absolute nightmare and bashing the firewall was not going to be enough!

Back to planning.
At this point I had neighbours complaining big time that I was making a mess or that we shouldnt be working on the car on the road/car park - the local council started giving us grief too, the plan was to have this done within a week and the wiring could be done after with little complaints.

Thankfully 2 days before the council had threatened to take the car away I was able to get a garage, too small to work on the car, couldn’t even open the doors and glad it was a convertible as to get out I had to jump over the top! but this gave me time to formulate a plan.

My grandad lived about a mile away and had offered to share his drive - so I now had a place to work on it.

After realising that bashing the firewall wouldn’t work, the only option… cut it out and reshape it, my brother had recently been able to obtain a free old welder that he had started practising on. the choice was to get this done by a professional, adding way more to the cost, it wouldn’t surprise me if this would of been around £1000+ that I don’t have lying around for the job - so I made a deal with my brother, he had his own project car but he wasn’t any good at electronics - I would do this and he would fab up a new firewall!





This meant completely gutting the front of the car of everything, and as I was replacing the entire wiring harness anyway, the entire car interior was stripped out, carpets, pedals, dash - everything!

The engine went in!

This took us a long time to do, working normal jobs and leading normal lives, I working weekends sometime and he can only do weekends, this took us around 2 months if not longer - we got it done, I was never going for pretty but as long as it was structurally fine and wouldn’t be an issue that was all I cared about - to that end I haven’t got an MOT for it yet but will hopefully do so soon, hoping nothing major shows up on that!
But we finally got the engine in, I thought this would be the end of the problems I had… but nope, they continued.

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RHD Turbo MX5…
Some of you are probably way ahead of me here and was thinking there’s only limited space for a turbo - I didn’t realise this at the time, I had saw BBS had done a turbo’s mx5 and all the reports I had read for the 2.3 DISI did not report any major issues… turns out that the swaps I had read look to all be in the USA , thus LHD!
There was no way in its current configuration that the exhaust manifold and turbo was going in from the CX7, as this point I had to research what options where available for the RHD turbo, thankfully a guy on here had just started doing a 2.0 Turbo - PDQ - he had shared valuable information and following this decided the best option was for a top mounted turbo with an exhaust manifold from a guy going by the name of kraken - while I have not been able to put this to test yet, everyone has given his stuff glowing reviews. but that was another £300 - however this leads onto the next issues, I had already reconditioned the CX7 turbo, the MPS turbo though has a unique flange for its manifold and downpipe flange.



The kraken manifold was for a garrett turbo, so this is where my computer skills came into play, I studied as a 3d computer artist, so I was somewhat familiar with CAD, so I designed an adapter to go from one flange to the other, I iterate this at least 10 times as the clearance between the turbo and the bonnet is near enough none exstant so had to make this as compact as possible.

getting a quote to get this fabbed was then was more than I was expecting., the design was at this point really simple but as it was a one of run, I was getting quotes of £100 for 2 flanges!
Step in a friend of my grandads, he is co-owner of a local company that made replacement parts for land rovers - got in contact with him, quoted £20 for each flange with all the holes threaded and countersunk!

by this point I had mocked up the intake, was to be a tight fit like the rest of this project, again the manifold intake was facing the completely wrong way, the intake is facing the firewall, the options again, find a compatible manifold that faced the other way, custom manifold or the least optimal but cheapest option was to have a snake intake, couldn’t find any other engine that would have the correct facing intake - so you guessed it, I went the jank way, intake now does a 225 degree bend coming from the intake down, back to the front and coming back up! this was accounted for in the firewall redesign, it’s so close that it’s touching the firewall and the firewall is so far pushed back that the glove box doesn’t release as normal, it’s a tiny bit stiff and slightly out of alignment (but it’s in and working and closes!)

I also at first attempted to re-use the CX7 intercooler but the outlet shape was a bit odd and would of hung low and possibly had other issues, decided to go for a new intercooler of ebay, again not tested but picked it up for £100

As per a lot of other people who have done turbo mods I cut a hole in the driver side front plate and hung the intercooler in front of the radiator.

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Knock on effects!

With all of these modifications and tight fits other things also had to move, one thing that happened during the engine lifting in/out was catching on the brake lines, so I decided to cut them under the chassis near the engine compartment, this turned out useful anyway, with the turbo and manifold in place the ABS pump had to move, this is now located on the opposite side of the car, again meaning I had to make all custom brake lines, joined them up under the car as I don’t want to start messing with the rear end (just yet)

with the intake pipes now going either side of the engine bay, the battery had to be moved, this is now located slightly to the right, not only that the intake would of interfered with the ancillary belt as it came too close to the alternator, this forced me to do something I was considering anyway but was going to probably wait until it was all done and had some more cash but it meant doing a aircon delete, this involved removing alternator where it normally is located on the CX7, getting a mazda 3 alternator and placing that where the air condition pump was


Due to the wire harness from the CX7, this limited some other choices, the ECU is now located over the top of the left suspension mount, the fusebox is a different shape but is near enough in the same spot

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Something went to plan!
I was lucky enough to find the full wiring diagrams for both the CX7 and MX5, in fact 2 for the CX7, neither matched up exactly to the harness I had, some of the colours were slightly out, it surprises me how many "Except UK’’ wire colours there where, there where slight variations, e.g with bose sound system and the options for the diesel version. All in all it took some planning to figure out the wiring harness, things like the door sockets were the same between the cars and had to slightly repin them to match the electronics inside the door. There were instances like with the airbag control unit, having the sockets the same but in a different order, for this I had to remove the airbag ecu from the CX 7 case and put it into the MX5 as the mounting point to the chassis was different.


but overall this went fairly well, I have tested as much as I can at this point and all the interior electronics work, swapped the harness over to use the MX5 heater control, I cut away a little bit of the dash to fit the clocks and all came on and worked, found I had 1 set of wires the wrong way around on the locking system so would continuously try to unlock, again a simple fix.

while the interior was out I also put down 2 layers of insulation under the carpet, try and keep some of the noise out unless I have the roof down.

the only thing I have not done yet on the wiring side is look into the remote boot release button, the CX7 didn’t have this, I have programmed the MX5 keys to work with the current setup but need to dig into the BCM to get that bit working, if I can’t I can alway unlock it with the key or the button in the cabin.

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What is left?

Well at this point, deciding to post here, im at the point where I am confident that I will be getting the project finished, as I said at the beginning a few more weeks,

There are only a handful of things left now, the downpipe is getting finalised with the O2 sensor ports being added



exhaust system gaskets need putting in place as it will now hopefully be the final time that stuff comes out

Tighten up some bolts and clips, some small modifications left to do to the wipers of all things as the high pressure fuel pump interferes with the wiper mechanism but shouldn’t cause me an issue once done

And last but not least the final few pipes, one for the fuel line, and 2 for the master cylinder to the abs pump, my first attempt at this did not go too well and got more pipe on order.

Then the effort of getting the engine swapped with the DVLA, they require a vehicle check essentially as I did it myself, my local mechanic said it’s something he can do and write the report.

Then finally the MOT But… there’s always a but right… this is only if it starts and doesn’t blow up in my face!

If the all of the \above works out well, ther will be a small shopping list of upgrades before i start to go push this beast
First will be a LSD, possibly just picking one up from a 2.0L sport, may go aftermarket depending on whats available and price
Engine bay strut brace, this might potentially be a difficult one with this mod as the brace plate for up the top of the engine bay has been cut out a little - this one might have to be a custom fab job.

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Hi just a question. Since each car registered after 1 March 2001 has emissions regulations related to the age of the car or let’s say the chassis registration date. My question is how are you going to pass the emissions regulations for the vehicle? Or are we talking about a different route for registration?

This is a genuine question since I was considering looking into swapping the engine in my NC with with a jaguar V6 3L petrol engine. However I’m not too sure whether the engine will pass the emissions regs for a 2010 vehicle.

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I am not 100% sure how it works, I have read multiple points around the web for DVLA stating that the tax is based on the chassis and not the new engine, my mechanic who is going to do the legit mot (not one of those who pay for a fake) said “it should pass” the only question he asked me was if the engines where the same year, and I said within 1 year of each other and that was his response, I will be seeing him tomorrow I will see if I can get any more details on how it works

More specific info I did read (unofficial) is if the power doesnt increase more than 50% then there wont be an issue, though my mechanic never men tioned this never asked the question about power and didnt seem to think it effected the outcome when I told him this would produce approx 90% more power

The only thing I have read against this, but it didnt really go into specifics so it still could be one of the same thing, but reading on the DVLA site or when I contactacted them a while back now they said that regestering the new engine they would work out the new tax.

so it might be the case that it should be ok regardless the engine, it might just mean more tax, tbh, im not 100% sure and emmissions is a real big point at the moment, the only reason I am not overly concerned is because my mechanic doesnt seem to be either

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Yes that is correct for cars registered after 1 March 2001. Anything before that was taxed based on size of the engine. Tax for newer cars is based on the emissions but that’s just money we need to pay to the goverment.

The issue is to get a valid mot with the “new engine”. The emission regs for the NC is fairly strict so passing the emission test is a concern especially if you have gone through the trouble of mating the car with another engine and making everything mechanically work with all the associated costs.

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Just done a bit of research, it seems the size of the engine doesn’t matter, it’s all about %, that is the emissions for a set year have a percentage of CO to other stuff, and again it seems to be based on the car manufacturing date than the new engine, so I assume here that anything newer will have tighter emmisions than cars before it.

Providing you have sufficient catalytic converters (ie size and type) as the engine your putting in was designed for then emmisions should be fine, yes it will spew out more stuff, but as a percentage it should be the same

I found this info in a post over on pistonheads with links to the gov.uk website
MOT after Engine Swap - Emissions rules - Page 1 - Engines & Drivetrain - PistonHeads UK

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that is precisely what I was on about, whatever engine you fit in the car it has to pass the emission test set with the limits for the vehicle when it was registered - and for the NC its the euro 5 standard

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Hmm, you had me concerned for a moment… it looks like some versions of the NC are euro 5 more specifically from what I can see with the parkers website that any NC SE versions are euro 5, however the none SE versions are euro 4, thankfully the CX7 I got the engine from is also euro 4, so im hoping the emissions wont be a problem!

Im not sure what SE stands for, I know there was 3 versions of the NC, 3, 3.5 & 3.75, could that be related to the later models after the 2011 change to euro 5?

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https://carfueldata.vehicle-certification-agency.gov.uk/

thats for my car
https://carfueldata.vehicle-certification-agency.gov.uk/search-new-or-used-cars.aspx?vid=840276

Just added some picture, I had loads more but I fear they are lost, I might still get some more and I will post them here if I do.

@ckleanth the link for your car doesnt work for me, sends me back to the main page when I click the link.

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Not sure why it doesn’t work now (probably because its the result of the search) if you go on the website select no 1 and enter your car first registration date and some further details it will show you the information. Initially it will only show co2 but once you click on the co2 value (or there about) it will show you all the emissions requirement values that the car needs to meet

You were right, this is an epic post.

Thanks for adding the pictures, they really help to show how much time and work this has been.

Really hope it all works out, should be a lot of fun to drive :slightly_smiling_face:.

Amazing work and congratulations. What yiuve done is to force a Mazda engine into an engine bay designed for a Ford engine.

Another option is ……

Low mileage 2.5L Ford Duratec from America about £1,000. Feels slow to rev but is better than the 2.0L Ford Duratec that NCs get from the factory. Add cams to make it feel quicker. Add turbo for 300hp a la BBR300. Given where the turbo has to go you must swap the plastic cam cover for an ally one.

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