MX5 into MGB GT engine swap

[Not_Anumber]

Ive sucessfully bid on a low mileage MOT failure MX5 which will be donating its engine and gearbox to my B GT.

This will be a far less ambitious engine swap than MGB281's highly sophiosticated Jaguar V6 & RX8 gearbox transplant. Though there will be elements of fabricating and adapting some parts and problem solving on the fly, I have to confess this will be largely following a path laid down by others.

The plan is to use as many stock parts as I can including the injection system and ECU and then to document anything that has had to be modified. The rationale being that any future owner will be able to readily replace most parts with off the shelf MGB and MX5 parts (+MGF for the steering) and be able to replicate any parts Ive modified for the conversion..

[Not_Anumber]

The MX5 donor car has now arrived and at only 67,000 miles, it's VVT engine runs very nicely and the car is only let down by rust underneath.

[Not_Anumber]

Im removing the B series engine now as it sold immediately on Ebay. Not sure whether to remove it on it's own or with the gearbox.

I'll be selling the gearbox separately at some point so for now I’m just trying to decide if its going to be easier to remove the bellhousing bolts and hoik the engine or if it would be quicker to separate the propshaft, undo the gearbox cross member and pull both out.

[Not_Anumber]

The GT's engine bay is now empty awaiting the next step.

BTW my B series engine sold the other day for its buy it now price of £ 450 on Ebay. The starter motor has gone the same way for £ 45.
I'm currently waiting for bids on the overdrive gearbox but im confident that together they will cover my cost on the 67,000 mile MX5 donor.

[Bourne]

Are you documenting with pictures. Any chance we can get a look?

Merry Christmas!

[Not_Anumber]

Im taking photos as i go but im not sure if the forum software supports directly uploading them

[bluetr3]

Hi
May I ask which MX5 engine, and gearbox you are fitting in your mgb.
Regards John

[Not_Anumber]

Mine is from a facelift NB type MX5 which is generally referred to as a Mk 2.5. This has a similar 1.8 Mazda engine as the NA / Mk1 and the early NB / Mk2. A family of engines which are regarded as relatively easy to transplant into a B with minimal modifications required to the car. The variant in the Mk2.5 has the addition of variable valve timing which produces 147bhp. I was lucky enough to buy a complete Mk2.5 'Icon' donor car with service history from the last year of production 2005.

The other MX5 engine swap route is with the Mk3 /NC type donor. This was a significantly different car with a Ford Duratec derived engine. It has a large following as it is a bit more powerful and has more after market tuning parts available as is often the case with engines associated with the blue oval. It is a rather more awkward engine to fit in a B though, needing a special inlet manifold to clear the steering pinion shaft to name but one obstacle. Most who go this route seem to spend more on their conversions and are less inclined to reuse donor parts such as the standard injection system and ECU. An enthusiast turned fabricator has done a splendid job of producing a range of conversion components that simplifies fitting this into a B.

After weighing the two options I went for the earlier, Mazda engine route as a personal choice and to control costs. So far the cost of the donor has already been offset by selling my original engine and gearbox. There will be a whole host of saleable parts left over from the MX5 donor when I eventually finish too.

[MGB281]

Chris, the simplest way to document this and at the same time help many others is to start a Project Journal on British V8, here is a link to mine;
https://www.britishv8.org/smf20/index.p ... 669.0.html The best part is that you can link the journal from this register and keep everyone updated. I see that you have looked at Ved's MX5 swap so at least there is one good build to follow.
I had no intentions of starting a journal but Carl asked me to start one, I had deleted a good many of my photos so there is a big gap with nothing to show.

[Not_Anumber]

Thanks Philip. I am nearly ready to begin something there.

I have got as far as chopping away the original engine bearer brackets from the B's engine bay rails and just want to get to the point of making up new mount brackets for welding to the sides of the crossmember then i can kick off my build thread.