MX5 engine in B

[69MGC]

Has anyone run across someone who has put a Mazda MX5 engine and trans into a B?

If it fits I was thinking of dropping one into my project car.

 

[aeronca65t]

Just a comment: most swaps take an enormous amount of dedication.

And often, they do not add to the value or fun of the car.

That said, the Miata swap into an MGB makes more sense than most engine swaps.


Carl Heideman did one for Grassroots magazine. He did it correctly and with a skilled worker, an excellent shop and proper tools, it turned out to be a big job.

Anyway, here's a link to Carl's job:

https://www.eclecticmotorworks.com/miatab.html

https://www.eclecticmotorworks.com/miatab2.html

You can find more at this link (lower left side of page)

https://www.eclecticmotorworks.com/previousbritish.html

 

[jhorton3]

The Eclectic B GT is the only one that I know of. Someone else has a MGA with a MX-5 engine and transmission fitted. I think there was a good bit of modification and fabrication needed for the swap. To my knowledge there aren't any prefab conversion kits.

If you're wanting to fit a completely different drivetrain in perhaps you could look into some V6 or V8 conversions. There are at least kits that help with fitting them in.

 

[rick_ingram]

You might also want to take a look at https://www.britishv8.org

There is a lot of information to be found there on many different types of conversions.

 

[aeronca65t]

I meant to say this before: if you really want to have a modern Miata engine, why not just leave it in a Miata! And keep your MGB as well.

There are plenty of Miatas cheap and still decent. I've seen them in the $2500 range and even some "runners" in the $1000 range.

Just a thought....

<span style="font-size: 8pt">(I have an MGB and a Miata.....a nice combo actually)</span>

 

[69MGC]

All good info. Thanks guys. Can't say that I am all that keen on the looks of the Miata, but I hear the engine is a screamer. I had thought about putting in a V6 or V8 but both of my B's are early models and I don't relish the thought of doing extensive engine compartment mods to make one fit.

Perhaps some day I will get a later model and drop in a V8.

I had my 72 B engine completely rebuilt so maybe I should just put that back in the car and do an engine swap on some future car.

Thanks for all your advice.

kev

 

[MGZT260]

If it's power you are looking for - beyond what a back to factory spec B engine will do then some thoughts:

*cross-flow head with appropriate weber carb
*super charger
*"C" six-cylinder engine - you know that will fit will minimal parts which are probably all available form Moss or VB, coming up wit hthe engine is trickier

 

[gblawson]

One of our club members put a 'rotary' in his B.... little thing screams and looks pretty tiny in the B's engine bay....

 

[billspohn]

If it's power you are looking for - beyond what a back to factory spec B engine will do then some thoughts:

*cross-flow head with appropriate weber carb
*super charger
*"C" six-cylinder engine - you know that will fit will minimal parts which are probably all available form Moss or VB, coming up wit hthe engine is trickier

"You know that will fit" ???? Are you serious? The factory couldn't put the C series engine in there without changing evey internal body panel forward of the firewall, AND changing the whole front suspension to a completely new torsion bar set up. I think the old saw "Don't try this at home" surely applies here.

Couple of other things. If you fit a crossflow head with 4 intake ports no one but an idiot (they are out there) would fit 'a 'Weber carb', which indicates a single downdraft, although many have fitted two sidedraft Webers (even though a pair of SUs is the better choice for street with that head).

The supercharger, however, is an excellent bolt on performance improver!

The Miata engines are an excellent option, but with a lot of do it yourself skill and time. A friend has done one MGC and at least a couple of MGBs - here's a pic of his MGA:

The OP shouldn't be put off the V6 route if that's what he wants to do. The kits are available for reasonable money to fit one with T5 trans to an MGB, and there isn't that much extra that needs to be done to relieve a couple of spots in the tighter tunnel on the early cars. Get in touch with one of the vendors to get details.


The minimal mods needed to put the V6 in an early MGB pale in comparison to the major work needed with the Miata transplant.

 

[rick_ingram]

<snp> "C" six-cylinder engine - you know that will fit will minimal parts which are probably all available form Moss or VB, coming up wit hthe engine is trickier

Sure...you can fit a C block into the MGB...but you're going to need to change the front crossmember, take a look at the front suspension (the MGC uses a torsion bar suspension and tube shocks up front), a new slam panel, alter the firewall, find a C bonnet....etc, etc, etc....almost easier to do a V6 or V8 conversion!

 

[billspohn]

<snp> "C" six-cylinder engine - you know that will fit will minimal parts which are probably all available form Moss or VB, coming up wit hthe engine is trickier

Sure...you can fit a C block into the MGB...but you're going to need to change the front crossmember, take a look at the front suspension (the MGC uses a torsion bar suspension and tube shocks up front), a new slam panel, alter the firewall, find a C bonnet....etc, etc, etc....almost easier to do a V6 or V8 conversion!

<span style="font-weight: bold">Almost</span> easier?

Hmm - cut off all the car in front of the windscreen and come up with something else that works, including torsion bar mounts under the seats, or bolt in a V6 mount kit in less than a day......... :lol:

 

[rick_ingram]

<snp> "C" six-cylinder engine - you know that will fit will minimal parts which are probably all available form Moss or VB, coming up wit hthe engine is trickier

Sure...you can fit a C block into the MGB...but you're going to need to change the front crossmember, take a look at the front suspension (the MGC uses a torsion bar suspension and tube shocks up front), a new slam panel, alter the firewall, find a C bonnet....etc, etc, etc....almost easier to do a V6 or V8 conversion!

<span style="font-weight: bold">Almost</span> easier?

Hmm - cut off all the car in front of the windscreen and come up with something else that works, including torsion bar mounts under the seats, or bolt in a V6 mount kit in less than a day......... :lol:

You knew what I was implying. :angel:

 

[MGZT260]

Okay, okay, it would be easier to score a C that had been rearended and mate it up to a B from the firewall back - and even then that is not a bolt-on application but a job for super-welder because of full unibody construction. But even until the end challenging engineering concepts never stopped the factory from converting V6 fwd Rover-based sedan into rwd ZT260 with Mustang 5.0 V8's up front.

I have a V8 project myself in the wings, deciding on whether to follow through or save it for something else. The Maxda twin-cam somehow looks exactly right in that A. Maybe...

 

[glemon]

Waren't both the original miata and original MGA twin cam motors 1.6 liters, I see some symmetry there....an MGA twin cam with a modern trouble free motor, best of both, know swaps are a lot of work, have looked pretty deep into it, been scared off, it is not so much the blacksmiths work of fitting the motor, but making the rest of it work right and not look and drive like a chop job. Instruments suspension and brake balance.

I have seen some very well done conversion but probably a few more not so well done.

 

[tony barnhill]

The old MG World magazine (before it went out of circulation) had an article about an early B into which had been transplanted a modern twin cam engine.

 

[jmc948]

Another option would be to boost the power of what you have, which would probably be cheaper and less hassle than a transplant. And it wouldn't be very hard to match the output of the 1600 Miata with good reliability.

Dave Headley at https://www.fast-mg.com/ does good work. Full disclosure: I'm a friend of his.

Jim

 

[JPSmit]

This month's Classic Motorsports has the outcome of their MG Midget restore/ update project. It beat the Miata around the track by about 3 seconds

 

[tony barnhill]

Redoing the original engine with some performaqnce items is always less expensive that fancy transplants...not to say fancy transplants aren't fun.

 

[billspohn]

Okay, okay, it would be easier to score a C that had been rearended and mate it up to a B from the firewall back

I don't know how to break this to you, but an MGC from the firewall back <span style="text-decoration: underline"><span style="font-weight: bold">IS</span></span> an MGB.

So like I said, just use an MGC and forget about the MGB.

 

[tony barnhill]

Okay, okay, it would be easier to score a C that had been rearended and mate it up to a B from the firewall back

I don't know how to break this to you, but an MGC from the firewall back <span style="text-decoration: underline"><span style="font-weight: bold">IS</span></span> an MGB.

So like I said, just use an MGC and forget about the MGB.

Actually, an MGC from the firewall back isn't an MGB....the torsion bars go beyond the firewall, the front floorboards are different, etc.

I don't know why the desire to convert an MGC specifically when there's so many reasons not to....later MGB's are almost a "drop-in".