flak monkey
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| posted on 21/4/20 at 07:37 PM |
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Mk1 MX5/Eunos Duratec Swap
Because I need another project.... obviously....
We have a really solid, rust free Mk1 MX5 which I have been doing a few bits on over the past couple of years. Was originally planning to stick a
turbo on it and call it done, but everyone does it and I have a bit of a dislike of turbos in sports cars.
So I had an idea to swap what is effectively a Mk3 on drivetrain into it - 2.0 duratec, 6 speed box etc. It's certainly not a common swap and
there doesn't seem much info about it on the web.
I plan on running it on Megasquirt and bike throttle bodies. Relatively basic build with 210hp spec cams which should be enough to have some fun in
the twisties.
I picked up a very cheap 2004 Duratec from just up the road - £100 as it had been partly stripped and then sat in the corner of a workshop for a few
years. Was worth a punt.
Stripped it down this weekend - bores and bearings were all immaculate with the exception of a bit too much crank endfloat for my liking. So I decided
to put a set of new main and HD rod bearings in and will be fitting ARP bolts to the stock rods. I don't need to rev it more than about 7250rpm
anyway.
Washed the block down, brushed out all the galleries, cleaned and measured the crank, rods, bores etc and all is good. No signs of wear on the
pistons.
Deburred everything on the block and main cradle too since these motors are full of sharp edges and unfinished stuff from the factory, drives me
nuts.
Cleaned everything up and am just starting to put it all together again. Once the short block is built I'll strip the head and clean that up
properly.
Oh and I'll be making one of my sumps for it too.
Sera
http://www.motosera.com
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roadrunner
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| posted on 21/4/20 at 11:38 PM |
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Looking good Flak.
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snapper
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| posted on 22/4/20 at 06:43 AM |
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Second photo, sensor in the middle of the block, is that a knock sensor?
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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flak monkey
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| posted on 22/4/20 at 06:46 AM |
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quote:
Originally posted by snapper
Second photo, sensor in the middle of the block, is that a knock sensor?
Yes, standard spot for them on the duratec
Sera
http://www.motosera.com
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wylliezx9r
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| posted on 22/4/20 at 08:06 AM |
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Awesome project and IMO much better than adding a turbo to the old lump.
I spent a lot of money on booze, birds and fast cars. The rest I just squandered.
George Best
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Golfedrocks
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| posted on 22/4/20 at 12:16 PM |
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Great work, will be good to see the progress.
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SJ
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| posted on 22/4/20 at 12:37 PM |
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Where do you find the time!
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flak monkey
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| posted on 23/4/20 at 06:09 PM |
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Not sure I know where I find the time to be honest! Even with the current global chaos work is just as busy as ever...
I finished assembling the bottom end with new bearings and ARP rod bolts so thats now bagged up, waiting for the head and sump. I'm waiting for
my local laser cutters to get back to me, but I'll be ordering a few kits for the sumps and some inlet flanges while I'm there.
Ordered an MS2 kit from DIY Autotune in the USA last Friday, it arrived Monday... great service by those guys as always. Probably the 10th system
I've had from them, and they are always bang on.
A few of the usual mods, rad fan relay output, PWM idle valve and 2 spark outputs. Although this time I have built an external igniter module using 2
BIP373's to see if there is any difference in the amount of noise on signals by having those high current drivers outside the MS case itself.
I picked up a bargain set of early R1 throttle bodies - these are the ones which also have vac slides in them - the thought behind these was to smooth
part throttle response, I'm interested to see how this works in a car and whether it improves MAP signal at low throttle openings as I prefer to
use MAP for load rather than TPS. They might be crap, but you don't know if you don't try these things. And I've been around the
block enough times now to have the inclination to follow roads less travelled.
This is what they looked like when they turned up.
Interestingly they have a wax stat attached which controls air bleed valves in each body - this appears to act like an air bypass for warm up, much
the same as an IAC would on true EFI. I'm not planning to retain it since they are (according to some google research) quite temperamental and
prone to seizing up. I'll be removing it and going down the electronic IAC route as usual with EFI.
I am planning to retain the injectors in the Duratec head, and for reference the ones fitted to the current 2.5l engine in the Mazda are around
300cc/min and super cheap (I got a set for $75USD shipped). These will work great for an engine with throttle bodies and 210hp spec cams. This leaves
the holes in the throttle bodies which I might use as the air bypass for the IAC, currently undecided. I'll make a new fuel rail for the Duratec
since I have a length of blank in the workshop, that way I can use the return system and add an external FPR.
Anyway, this is what they look like stripped of everything I'm not going to use. I will split them and re-space them to suit the Duratec inlet
spacing.
I also have an alternator here from a Mazda 6 - bolts straight up, but it should be controlled by the ECU using a PWM signal to the D terminal to
control the regulator.
After a lot of research it seems that the PWM signal is ~1.3v at peak. With 0% duty cycle giving 0v output and 100% duty being ~18v output. I'm
planning to have a bit of a play around to see if I can trick it into charging at a constant ~14v like a normal alternator by building an external
regulator system. Why? Because I can and it will cost me nothing... if it doesn't work then the alternator goes in the scrap and I'll get
a little denso unit instead.
Sera
http://www.motosera.com
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ettore bugatti
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| posted on 23/4/20 at 08:54 PM |
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Racing beat makes a very nice exhaust manifold for the NC, well worth trying to fit that in.
Im surprised this swap is not more common.
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snapper
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| posted on 24/4/20 at 05:26 AM |
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Didn’t take long did it !?!
I was going to follow your build closely on my build and you go and buy a build it yourself Megasquirt and do all that fancy stuff with the
drivers.
I already have a Denso alternator, light flywheel, AP clutch kit and bellhousing for Type 9 so was considering a V6 Type 9 with longer 1st.
I will u2u for detail about where you got the injectors from if you don’t mind?
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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flak monkey
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| posted on 24/4/20 at 07:43 AM |
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quote:
Originally posted by snapper
Didn’t take long did it !?!
I was going to follow your build closely on my build and you go and buy a build it yourself Megasquirt and do all that fancy stuff with the
drivers.
I already have a Denso alternator, light flywheel, AP clutch kit and bellhousing for Type 9 so was considering a V6 Type 9 with longer 1st.
I will u2u for detail about where you got the injectors from if you don’t mind?
Doesn't take me long once I get started 
The V6 box has the longer input shaft if I recall? No big deal as they make bellhousings for it, as long as you have the right one. When I put the
Duratec in my GTS I put a BGH gear kit in it with a longer first and uprated layshaft bearings.
I got the injectors from Injector Planet
https://injectorplanet.com?ref:ODE5ODYuNTguODE2MTIuVA
The part number is 0280158156
Sera
http://www.motosera.com
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sebastiaan
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| posted on 24/4/20 at 10:16 AM |
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That alternator.... Bonus points for using the boost control PWM output from the megasquirt and cut the dutycyle to zero at TPS>90%!
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flak monkey
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| posted on 26/4/20 at 04:31 PM |
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Done a little bit more over the weekend, although have mostly been on gardening duties!
Stripped all the valves from the head, washed it down, checked it all over and reassembled with the standard valves and springs etc with some new stem
seals for good measure.
Got it bolted back down to the block with new standard bolts.
Made a blanking plate for the EGR too from a bit of 4mm aluminium offcut
Found a bit of fuel rail extrusion when I was clearing my workshop for moving a few month back, glad I kept it. The stock Duratec fuel rail
doesn't have a return, and they look like poo, so I made a new one. Luckily I spent a weekend organising my new workshop a couple of weeks back,
and I found all my special drills for doing the fuel rails. Just need the new injectors to turn up now...
Sera
http://www.motosera.com
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rusty nuts
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| posted on 26/4/20 at 07:40 PM |
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Why only half the valves?
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sebastiaan
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| posted on 27/4/20 at 06:02 AM |
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quote:
Originally posted by flak monkey
I picked up a bargain set of early R1 throttle bodies - these are the ones which also have vac slides in them - the thought behind these was to smooth
part throttle response, I'm interested to see how this works in a car and whether it improves MAP signal at low throttle openings as I prefer to
use MAP for load rather than TPS. They might be crap, but you don't know if you don't try these things. And I've been around the
block enough times now to have the inclination to follow roads less travelled.
Hi Flak,
In the interest of science and having nothing better to do, I ran a MAP line from the R6 (38mm) ITB's to the megasquirt yesterdays. My engine
idles at 60kPa, so probably a bit too high to properly run speed-density. This is a bone-stock Alfa 2 liter "Nord". so YMMV.
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flak monkey
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| posted on 27/4/20 at 08:31 AM |
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quote:
Originally posted by rusty nuts
Why only half the valves?
They are all there, angle of the photo makes it look like half are missing
quote:
Originally posted by sebastiaan
Hi Flak,
In the interest of science and having nothing better to do, I ran a MAP line from the R6 (38mm) ITB's to the megasquirt yesterdays. My engine
idles at 60kPa, so probably a bit too high to properly run speed-density. This is a bone-stock Alfa 2 liter "Nord". so YMMV.
Interesting, thanks
Sera
http://www.motosera.com
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peter030371
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| posted on 27/4/20 at 10:50 AM |
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quote:
Originally posted by flak monkey
Stripped all the valves from the head, washed it down, checked it all over and reassembled with the standard valves and springs etc with some new stem
seals for good measure.
How did you clean the head? I guess you are adding a very mild cam which is the same route I am taking with my new head but at what point would you
consider a head skim is needed for a mild cam?
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flak monkey
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| posted on 27/4/20 at 11:26 AM |
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quote:
Originally posted by peter030371
quote:
Originally posted by flak monkey
Stripped all the valves from the head, washed it down, checked it all over and reassembled with the standard valves and springs etc with some new stem
seals for good measure.
How did you clean the head? I guess you are adding a very mild cam which is the same route I am taking with my new head but at what point would you
consider a head skim is needed for a mild cam?
The same way I clean all my engine parts.... a big tray full of kerosene and some hard work with a scrubbing brush or brass wire brush and bottle
brushes and a rifle cleaning kit for oil galleries . Kerosene is great at dissolving the gum which holds oil and carbon deposits on to all the parts
- it's also a bit less flammable/volatile than petrol, but still comes with a health warning!
I'm going to fit a set of Raceline 210hp cams when I have the money available.
You are limited to how much you can skim the head on a Duratec, otherwise the front cover doesn't fit any more. I wouldn't consider taking
more than a clean up skim off the head (0.25mm), but normally it's not needed unless the head is warped. If you need to up the compression, the
only option is aftermarket pistons, and it gets expensive, really fast!
Sera
http://www.motosera.com
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peter030371
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| posted on 27/4/20 at 11:41 AM |
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quote:
Originally posted by flak monkey
The same way I clean all my engine parts.... a big tray full of kerosene and some hard work with a scrubbing brush or brass wire brush and bottle
brushes and a rifle cleaning kit for oil galleries . Kerosene is great at dissolving the gum which holds oil and carbon deposits on to all the parts
- it's also a bit less flammable/volatile than petrol, but still comes with a health warning!
I'm going to fit a set of Raceline 210hp cams when I have the money available.
You are limited to how much you can skim the head on a Duratec, otherwise the front cover doesn't fit any more. I wouldn't consider taking
more than a clean up skim off the head (0.25mm), but normally it's not needed unless the head is warped. If you need to up the compression, the
only option is aftermarket pistons, and it gets expensive, really fast!
I've not tried cleaning the head yet, other things to sort out first, but I have a range of brushes so just need to get some kerosene
Was only thinking of a 'clean up skim' if needed after the clean.
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flak monkey
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| posted on 30/4/20 at 09:17 AM |
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Slowly making some progress.
Made a couple of odd little plenum things - one for MAP signal to the ECU and the other as the IAC distribution to each throttle body, but I might do
something else for the IAC, I haven't decided yet.
Intake manifold arrived yesterday afternoon, so I managed to get the throttle bodies re-spaced and offered up for test fitting.
Sera
http://www.motosera.com
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flak monkey
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| posted on 1/5/20 at 05:32 PM |
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Change of heart on the alternator. The original one would have been in the way of the steering column and would just make it difficult to get the
exhaust out of the 'wrong side'.
Picked up a cheap Daihatsu Denso 80amp unit and set about making some brackets for it this afternoon. Belt routing should work ok, though not with a
bit of rope 
It's all a complete mock up for now.
Sera
http://www.motosera.com
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Abe
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| posted on 1/5/20 at 05:58 PM |
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Man alive you blow me away with what you know and can do. Superb 👌👌👌
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SJ
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| posted on 1/5/20 at 07:25 PM |
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What's the top pulley driving?
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flak monkey
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| posted on 1/5/20 at 07:27 PM |
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quote:
Originally posted by SJ
What's the top pulley driving?
Power steering pump.
Planning to retain PS on the MX5
Sera
http://www.motosera.com
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flak monkey
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| posted on 3/5/20 at 05:40 PM |
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Done a bit more, but slowed down a bit.
One of the trickier things with the early R1 throttle bodies is getting a filter to fit. The backplates won't bolt straight up as the vac slide
spring covers are in the way. So my plan was to mod Pipercross PX500 filter and backplate onto them. I cut a new plate from some 1.5mm aluminium. 45mm
silicone hose pushed through tight fitting holes in the plate lets it clear everything. I'm just waiting for the trumpets to arrive which will
be pushed into the open ends and will serve to lock it all together.
The flywheel also turned up - standard NC MX5
Sera
http://www.motosera.com
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