Just curious as to whether this exists as a commercial option.
Standard MX5 motor is iron block and quite heavy: Engine including flywheel, exhaust manifold, alternator, clutch, intake manifold, and starter: 280 lb

Sigma/zetec SE/1.6 duratec with throttle bodies could be much lighter and produce similar power.
Short motor is 81Kg (180lbs) and fully dressed with throttle bodies under 100kg (220lbs)

Just day dreaming but this implies a Mk1 MX5, stripped of PS, AC, lightweight seats could be close to Elise Mk2 weight and power, but much cheaper and with nice gearbox....

Put it another way, this is the same bolt pattern as the Ecoboost 1.6 which can be tuned to >300bhp, albeit in a modestly heavier package...

You will be looking at custom bellhousing adapters, maybe custom flywheel with built in spigot bearing holder.

I know you're wanting to drop the weight but have a look at the Rocketeer project. All alloy v6

Or the mk3 mx5 is a 2.0 Duratec so go nuts with the 2.0 eco boost. Again retro ford is now using this box on there zetec's so it would give you ideas on joining them up.

There is a guy now making an adapter for the zetec to mk1 mx5 box. I don't know how far on he is.

To sum up anything is possible and the mk1/2 mx5 box wil be the next big conversion with boxes being available for £30 and up.

As for commercial viability. Not worth the bother unless it's a hobby and your making your self one with a few spares to help share the cost in my opinion.

[Edited on 12/2/19 by big_wasa]

Thanks.

Mk1/2 MX5 box has integral bellhousing, so yes, like the Rocketeer kit and Crapengineering's KL Mazda V6 conversions it would need a adapter plate and a solution for the flywheel and clutch, clutch release bearing etc. But I am not sure that the Zetec and the Sigma/Zetec SE /Duratec 1.6 share the same bolt pattern.

With some effort you can get a Mk1 MX5 down to 2000lbs so dropping another 60+ lbs off the front with a lighter lump is pretty interesting.
No panic, just dreaming.

cheers

Zetec E silver and black top use the old ford bolt pattern so can use type 9 with Sierra/Capri bell housing.
Zetec Se uses a different bolt pattern so needs bespoke bell housing (rwdmotorsport) for type 9 plus clutch has different spline to stock ford Sierra one so need to use a cortina/Sierra one.
Duratec is different again and needs new bell housing (rwdmotorsport) for type 9 but mx5 mk3 has same 2.0l engine so you can use that gearbox but there is an angle offset between engine and box.

For Zetec se either new bell housing and type 9 or go the rx8 box (same spline as stock Sierra) with adaptor plate. Rx8 box need a little bit of grinding to fit starter. Rx8 gears 2-6 are almost identical to quaffed clubman but is helical and will handle 9k rpm and 250hp/250ftlb as standards. Needs a new propshaft as spline is different to type 9.

If you are using the 1.7 Puma engine the spigot bearing cavity is not stock and needs boring out or the input shaft if the box grinding down.