Small MX-5 mods

This is all rather in depth and quite impressive.

I really, really want to be able to want to do this myself.. If that makes sense. I'm just not ballsy enough. I suppose it's not THAT difficult for me. The mechanics are in place, I just need to get an ECU, sort the wiring, add, what, a MAP sensor and a wideband Lambda, and map it..?
 
It is in and it works!

I nipped to hellfrauds and bought a length of pipe to hook up the MAP sensor and took it for a spin.

I need to get to grips with the software but the car starts and runs like OEM with the AEM in. The calibration side of things I need to understand a bit better but on the whole, a very successful days efforts.

I decided that the post-cat bung location was a no-go. I'll need to nip the car into somewhere and have it done properly, which is a shame but it'll be much better for it.

I have got a slight problem in that the metal cover over the ECU will not go back in with the AEM wired up. I have an ABS computer where I'd planned to put the AEM and the loom I've built doesn't quite fit in how I had anticipated... I'll figure something out, I'm sure.
 
The O2 sensor bung was welded in today :D

I'm still waiting on a mounting bracket and a tensioner plate but my HT leads and pulleys arrived yesterday and I got the valve I needed from BMW so they are now (I think!) the only mail-order parts that I am waiting on! I've got everything crossed for them arriving before this weekend because that will give me some time before the RR day to iron out any creases.

Howard, I missed your post before. The ECU stuff will pay for itself really. If you go standalone via MegaSquirt then you'll need a MAP sensor and some form of intake temp sensor. If you go AEM piggyback like me then you don't actually need any additional sensors (the AEM has a MAP sensor built in) bar a wideband AFR to be safe. Regardless of the route, once you've bought and fitted it your increased fuel economy will probably quite quickly add up. Your current setup will be massively overfuelling to get a nice safety margin which you can pull back in so you're not simply pumping fuel into the exhaust pipe!
 
I've not gone down the cheap route by any means, but here is a quick summary of my costs so far:

Flyin' Miata Stainless Exhaust with 200-cell high-flow cat - £350 (not strictly needed)
AEM FIC - £300
AEM UEGO Wideband O2 sensor - £150
Eaton M45 (MINI) Supercharger - £200
TR Lane parts for the supercharger (inlet, outlet, mounting bracket, tensioner plates) - £370
R53 MINI Cooper S bypass valve - £60
Crossover pipework - £20
Bypass pipework - £20
Magnecor 8.5mm HT Leads - £70
Mazda RX8 420cc injectors - £100
I.L. Motorsport cam idler pulleys (for the SC belt tensioner) - £35
Other bits and bobs, some lying around the garage, some bought probably £50ish total?
Bung weld - £20
Fascia for the dials to be mounted - £10

Total: £1755.

Still to buy for completeness:

Boost Gauge - £120 (I want a nice AEM one, you definitely don't need to spend this much)
Oil temp gauge - £100ish
Colder spark plugs - £unknown


An off the shelf Jackson Racing M45 kit is £2700 and doesn't come with management, gauges etc.

It is possible to do this whole thing by being shrewd and picking up 2nd hand items or skimping on management etc for under £1000 but doing it this way I can pick and choose which corners I cut rather than having to bin parts to buy uprated stuff later on. You don't need to run bigger injectors but the standard items run out of puff very early and even at 180/190bhp you're running very high duty cycles and possibly leaning out slightly at high RPM.
 
Thanks for that. Certainly an interesting write up.

I've been tempted in the past by the idea of the supercharger for the MX-5, but I've ultimately always been put off by relatively small gains (50-60bhp or so?) for such a large outlay. Mind you, I'm comparing the bhp/£ against something like a turbo remap so it's not exactly a fair comparison I guess.

Still, are they really worth the money?
 
A stock 1.8 is about 140bhp. With a basic/conservative map (so the same as you would get from the crappy controller you get with the JR kit) and no cooling of the air whatsoever and you can expect 190-195bhp. Add in an intercooler for about £200 and you can safely hit 210ish.

Considering that you can do the basics for under £1k (and many have!), I don't think that is too bad value really. Plus it completely transforms the car. They really are quite underpowered as standard.

In addition to the supercharger spending above, I have also spent:

£300 on the mk2.5 seats and door cards
£100ish on the style bar
£120 on a head unit
£30 on those brushed vent rings :p
£35 on a white dial kit
£60 on a mk2.5 centre console
£220 on Michelin Pilot Exalto 2 tyres
£200 on the Mazdaspeed MS-01 alloys
£200 on getting the alloys refurbed

With other bits and bobs like wheel nuts I'd call that about £1000.

Compared to that spending which gains me precisely 0bhp, I think it is blinding value :D
 
Seeing the costings of what you have done it makes me even more tempted to supercharge mine next year.

Were the TR Lane brackets bought second hand?
 
Nope, new from their site (their prices went up last week...). People quote £700+ for the kit but if you don't need the hoses, management or filter because you've sourced alternatives elsewhere then you're laughing.

TR Lane only sell that stuff so people can go to them for a turnkey solution. Other places do the stuff they don't make in-house for less money - a prime example would be the Supercharger Bypass Valve - you can walk into any MINI parts department and order one for £59inc VAT. TR Lane want £70+postage for the exact same part. They want £80 for the full set of pipework - I picked some up for £40 in total (and probably better stuff too, but that is a guess tbh).

If you are prepared to spend the time doing your homework (and there is a LOT to do and it is quite a steep curve) then there isn't much that is daunting about this project. You just need a reasonable level of skill with a few basic tools. If you lack those, TR Lane themselves will do you a turnkey solution for something like £1700 + a supercharger I think, but you'll then need to spend time unpicking what they have done with the management etc if you want to get some more power or better fuel economy out of it.
 
I was thinking about trying to do it myself with a megasquirt from reverant for management, as i'll know how it works a bit more then, and feel like i have achieved something!

Only thing that may change my mind is if TRLane start selling the turbo manifold and downpipe that is rumoured to be in developement, or a reasonably priced JR kits come up for sale
 
I know of a reasonably priced JR kit from a reputable seller, £1650 I think he wants for it, which isn't bad if you really don't want the hassle of building up a kit yourself :)
 
Not looking just yet for the supercharger stuff, but thansk for the suggestion anyway. I need to find someone who would be able to insure me with it for a reasonable price first!

I think i would only go for a JR kit if it was the M62 instead of M45 kit, otherwise i think the mini charger would work better for me
 
Seen those type of chargers used over in the states but there is no way that the stock injectors flow enough fuel to maintain 13:1 AFR at stock fuel pressure or reasonable duty cycles. People upgrade to 420cc RX8 injectors for a reason - and that is because the 260cc stock injectors (for a mk2 1.8, smaller on earlier cars) are struggling with 90%+ duty cycles past 6k rpm.
 
Loving the thread title, 'small mods', and here we are sometime later discussing a change to forced induction and standalone management/boost control for nearly £2k in parts when finished :D as fine an example of thread/project drift or 'mission creep' as I have seen! For that I must commend you! Hope to see it running at the RR day!
 
The thread title was deliberately sarcastic :D There is no way swapping an interior counts as a small mod either really :)

I bought the car intending to add more power at some point, having been out in Firestar_3x's SC'd and Freefaller's Turbocharged cars :)
 
Ever since being in Mark's supercharged MX5, I've wanted one as a 2nd car. Might actually have to fulfill that desire in the new year, so might be needing your input Mr DRZ.

Looking good so far, can't wait to see it in the flesh :)
 
paradigm said:
Ever since being in Mark's supercharged MX5, I've wanted one as a 2nd car. Might actually have to fulfill that desire in the new year, so might be needing your input Mr DRZ.

Looking good so far, can't wait to see it in the flesh :)
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When I'm done I'll head over for a Cat & Fiddle run :)
 
It's coming along well, I expect videos full of whining! This thread does not bode well for my savings plan :)

DRZ said:
When I'm done I'll head over for a Cat & Fiddle run :)
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I hope you like doing the speed limit then. Tis ruined bar the venue of course :(
 
Dup said:
It's coming along well, I expect videos full of whining! This thread does not bode well for my savings plan :)



I hope you like doing the speed limit then. Tis ruined bar the venue of course :(
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There is a short section that has 50mph SPECS cameras, on which you'd have to be going hell for leather for it to be an issue. You can go balls out on the stretches before and after and still have fun on the SPECS stretch as long as you're not regularly up in 3 figures on the straighter bits.

I drove it about 3 weeks ago and I didn't really feel aggrieved that the cameras were there, I was just a bit more mindful of my speed.
 
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