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Author: Subject: Changing 2.0i 8v DOHC for an MX5 "ND" engine
voucht

posted on 12/11/21 at 09:28 AM Reply With Quote
Changing 2.0i 8v DOHC for an MX5 "ND" engine

Hi,

Some of you might remember me, I'm French and I built a Haynes Roadster when I was living in Sweden between 2011 and 2014. The car has been "IVA'd" there, it is registered and road legal. Long story short, now that I'm back in France, I can't drive it unless I take a series of tests, including pollution. Unlike in the UK or in Sweden, French authorities take the year of the car and not the year of the engine to comply with the Euroxx emission regulations. My car is from 2014, so I'll have to comply with Euro6. As my car is powered by a Ford Sierra 2.0i 8v DOHC from 1992, even though I have a catalyst converter, there is no way I can comply with Euro 6 emission regulation.

So I am considering changing the engine. Mazda MX5 seems to be a good option. To comply with Euro6, I need a ND engine. Do you Mazda fans confirm that?

There is one for sale with gearbox and all the auxiliaries, 38000km, for as little as 400:

https://www.leboncoin.fr/equipement_auto/2065175343.htm

I'm very tempted, but what else will I need for the conversion? I'm thinking:
- ECU
- Engine loom
- Dashboard with instruments
- obviously, looking at the pictures, I'll need a gear stick
- exhaust (not on the same side of the car as mine, so a complete new one with catalyst converter)
- new propshaft from Mazda gearbox to my Sierra 3.92 differential

What else do you guys think I'll need?

Thank you very much.





Sylvain
https://vouchtroadster.blogspot.com/
https://cafrazx550.blogspot.com/

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obfripper

posted on 12/11/21 at 01:43 PM Reply With Quote
Hi Sylvain,

This is the emissions data for the engine you have linked;

https://www.dropbox.com/s/au2d9qcq21sjt65/1.5%20skyactiv-g%20131ps%20p5%20engine%20emissions.jpg?dl=0

You would need a matching fuel lift pump, the ecu, the wiring loom, the original catalyst system as basic requirements, if you are able to get someone knowledgable to reprogram the ecu for no immobiliser then no further parts would be required.

If the immobiliser has to remain, then the instruments would need to be somewhere in the system, there is also a start/stop system on all models, and some models have a regenerative braking system (from the wiring diagram appears to be a large capacitor used to harvest energy from the alternator under braking, and the stored energy only used to charge the battery and possibly to assist during start/stop activation)
Getting the start/stop and regenerative system all working might be quite a challenge, i don't know how much technical data is available to help here.

A good engineering company should be able to fabricate a suitable propshaft without too much trouble.

There's definately quite a few things to work out, but it should be possible to do.


Dave

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Russell

posted on 12/11/21 at 03:47 PM Reply With Quote
I've got a 2016 MX5 ND ('Sport' model with the 2 litre engine). There is no start-stop and I'm fairly certain it hasn't got regenerative braking either.

Russ

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PorkChop

posted on 13/11/21 at 02:07 PM Reply With Quote
You need to take a step back. Just buying a Euro 6b compliant powertrain is no guarantee that you'll meet it when it's transplanted into a Roadster without modification.

First - are you certain that you need to comply with Euro 6b? There's a small window where you'd have to (if the authorities are insisting that you follow the type approval date and your IVA fell between September and December 2014), but if

your IVA (or type approval) was before September 2014

or

they are going off a "first use" date of 2014

then I would argue that you'd be needing to meet Euro 5b.

With that, then what exactly have the authorities told you to do to meet it? I'm assuming that you'll have to comply over the NEDC. You are not going to be able to check that without a rolling road and a very good, trained driver. And any mapping will unlikely be limited to tuning spark timing and AFRs.

I would be giving these guys in Germany a shout and see what they suggest as a starting point has they have been in your situation - https://www.cck-kempten.de/single-approval-according-to-%c2%a713-eg-fgv/?lang=en

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voucht

posted on 14/11/21 at 11:09 AM Reply With Quote
Hi,

Thanks a lot for the replies.

Yes, that gives me a lot to think about.

Regarding the start-stop and regenerative braking problem that I might meet with the ND, it could be solved by using an after-maket ECU such as Megajolt, no ?

@PorkChop,
You are right, I went back to the email conversations I have had with the French authorities in 2018, and they say that I have to comply with Euro5b, not Euro6.
But it does not change anything to my problem with my old Ford 2.0i 8v DOHC from 1992. I will not comply with Euro5b either, actually, the test centre dissuaded me to come with this engine, they are 99% sure I will fail.

There is only one certified test centre in France for IVA (RTI in French), which is the UTAC, located on the historical racing track on Montlhery, close to Paris. What I know is that the emission test consists of a combination of static, rolling road and driving tests, so it is pretty extensive. As you say, it is certainly a NEDC cycle on both rolling road and on track. They have an inboard device called PEMS for the emission tests in driving condition on the track.

I didn't know these guys in Germany and I definitely will get in touch with them, thanks for the tip.

But question: Do you think there is a big risk of not complying with Euro5b with an MX5 NB engine from 2016 with an adapted catalyst converter on my Haynes ?

Thanks.

[Edited on 14/11/21 by voucht]





Sylvain
https://vouchtroadster.blogspot.com/
https://cafrazx550.blogspot.com/

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obfripper

posted on 14/11/21 at 03:01 PM Reply With Quote
It does look like i-stop was only an option in the uk, the i-eloop is only standard from 2019 on models, but both were standard in holland, france and other eu countries from launch, although it's not clear if this was all models/engines throughout.

Using an aftermarket ecu is pretty much out as the engine is using direct fuel injection which is pretty much unsupported except with a few motec and link ecu's, and they are aimed at getting max bhp with no regard to nox emissions, which is not what you are looking for.

Roddisons in the uk can remap the ecus, they race the cars, and are most likely to know how to make the ecu work as a standalone, i don't know if they deal as much with the smaller engine but may be able to help you.

https://www.mx5-racing.co.uk/

In regards to the emissions, your vehicle will be approx 400kg lighter than the mx5 which should significantly reduce the energy required to move the car so reducing the emissions across the transient parts of the test, but the drag coefficient will be higher than the mx5, so the figures are likely to be higher in the faster parts of the test. These things are likely to balance out, and unlikely to change the overall figure by enough to fail , as it would take a 400% increase in nox to fail, but might change the tax classification - ie if the overall emissions went up 20% it would take you from 138 to 166g/co2 which would cost you more in tax but not stop you from getting on the road.

The other thing that will affect the emissions are the transmission ratios, you will have the correct gearbox, but will need to adjust the diff ratio and tyre size to match the output ratio on the mx5.

Dave

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voucht

posted on 16/11/21 at 06:11 AM Reply With Quote
Hi,

Thanks for the reply and the useful input.

quote:
Originally posted by obfripper

The other thing that will affect the emissions are the transmission ratios, you will have the correct gearbox, but will need to adjust the diff ratio and tyre size to match the output ratio on the mx5.

Dave


Yes, you have a point here. The engine I could buy (see first post) is sold with the original gearbox. My plan was to use my Sierra diff I already have on the car, which is 3.92 ratio, but it might be completely wrong. Fortunately, finding a Sierra diff with another ratio closer to the MX5 original ratio is not very difficult if needed.

To completely match with the output of the original MX5 drive train, tyres size have to be considered too. I have 195/55R15 on the car now.

Does anyone know the diff ratio on an MX5 ND engine, from 2016, and which wheel/tyre size it was equipped with?

Thanks.





Sylvain
https://vouchtroadster.blogspot.com/
https://cafrazx550.blogspot.com/

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obfripper

posted on 16/11/21 at 06:57 PM Reply With Quote
From what i can see, the 1.5 has a diff ratio of 2.866:1, and 195/50r16 tyres, that gives an increase in rpm at 100kph of 1300rpm assuming your diff ratio and 185/60r13 tyres.
The 1.5 gearbox has a 1:1 6th gear, where the older nc mx5's had an overdrive 6th with a higher diff ratio which would be closer to the sierra diff.

There isn't a sierra diff that is close to that ratio, that leaves a couple options, one is to use an alternative diff such as the matching mx5 one, or a bmw diesel one, if you have lobro type shafts they should bolt directly to a bmw diff and would leave only mounting to the existing pickups and the propshaft to sort out.

Another option is the mx5 based fiat 124/barchetta as an engine/gearbox donor, it uses similar gear ratios to the nc mx5 so closer to the sierra diff, and is only slightly higher co2 (148g), i can't bring up the rest of the details as i'm waiting for my workshop data licence to update, but is euro 6 compliant so should be similar figures to the mazda engine.

Dave

These are the emissions figures for the fiat/abarth versions.
https://www.dropbox.com/s/3n62cp7xe3ra1ja/Fiat%20124%20spider%20emissions.jpg?dl=0
https://www.dropbox.com/s/t8kkh5d6kxd9w06/abarth%20124%20spider%20emissions.jpg?dl=0

[Edited on 17/11/21 by obfripper]

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