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MG MGB GT V8 Factory Originals Technical - 95 Miata Engine

Hey everyone I have a 68 B roadster with a blown up engine and my 95 mazda miata was recently stolen. the miata was recovered by the cops complete but totaled. the engine is still very strong has anyone ever converted this engine? what would it take to do and where/how would you get the computer system out of the miata to run the fuel injection and all that?

thanks everyone


The guys at Eclectic Motor Works have done one, photos and info here:
Not much information about interfacing the computer, but I think Carl would pass along what information he has.
Bill Young

cool thanks bill i just dont know if it will be the same because thats a 74 rubber bumper and mine is a 68 chrome if anyone has any more advise id greatly appreciate it

Scot Hamm

Well I'm not expert on this, but thought it would be a very cool conversion so I did some research a while back.

My conclusion was that it would be a bit more difficult to do compared to V6 conversions because there would be so much more custom fabrication and trial and error. There are at least 3 v6 vendors experienced in conversions, but 0 miata conversion vendors. Over at MGB Experience a few weeks ago, someone from Eclectic posted their conclusions about the conversion. You should try searching for that - I think they said they had planned to make a conversion kit, but decided against it since the Moss supercharger would be much less money and effort for the about the same HP.

Unless you are really good with a welder and want something fairly uncommon, you'd probably save time and money by selling the Miata engine and buying a 2.8-3.4 GM v6 or just rebuilding your engine. But, there is little logic in classic cars, so go for it if you want!

regards, Mike
Mike Wiser

yeah thanks it soiunds like a lot oif fun lol yeah i actually im pretty good with a welder and im thinking about giving it a shot i wish i could find a running mg engine i blew a hole in the number 2 cylinder but no one in the area has even an old mgb that doesnt run sitting around for sale that and i dont have the od trans so i figured that the 5speed from the miata would run great
Scot Hamm

Scott, I installed a Chevy V6 in my midget and was able to interface the stock computer to the new car, but it is a hassle getting all the required inputs for the computer incorporated into the MG. One if the problems was figuring out a speed sensor which was originally incorporated into the Chevy speedometer. I was able to modify the Midget speedo a bit, but I wouldn't recomend that route to anyone. New instruments or a special aftermarket computer system might be better. If you are happy with the performance from the original 1800 then I think you'd be far ahead to find another engine even if you have to pay shipping and convert to a 5 speed trans. You could probably be on the road for under 3K and I'd bet if you figured out your time and all the headaches in setting up the MG to work with the Miata electronics you'll even be cheaper to stay with the stock engine. You really have to want the improved performance to make such swaps worthwhile. I've seen far too many projects abandoned when the problems mount and the builder lacks the determination to see it through to the end. You wind up with a car that no one wants and not worth it's original value, not to mention the additional money spent on the conversion.
Bill Young

Bill's words are worth re-reading:
You really have to want the improved performance to make such swaps worthwhile. I've seen far too many projects abandoned when the problems mount and the builder lacks the determination to see it through to the end. You wind up with a car that no one wants and not worth it's original value, not to mention the additional money spent on the conversion.

As far as cost: average conversions are running between $3 and $5K for V6 and more for V8 and unique conversions for parts alone.

I like the idea of a four cylinder conversion in an MGB but i dont think its worth it unless like Bill says, you just want something different. Carl has a Miata vs. supercharged MGB vs. a V8 MGB on the second chart here:

That said, a V6 and V8 can be pushed further. All motors can be pushed, but there is always a point of reliability that needs to be addressed before starting a conversion. The worst thing i hear is that someone is going to use a certain motor because they already have it. Even though you already have the motor, gearbox, wiring and so on, you will still spend a few thousand in cash and a few hundred hours converting your car. Check both was before starting your conversion.

BTW: I am one of the three V6 vendors, but there are also BOP/R vendors as well as Ford V8 vendors now as I understand as well... Lot of options.
BMC Brian McCullough

I think it would be worth it. The Miata was always designed with the 'B in mind (legend has it the CEO of Mazda drove his 'B into the workshop (he was a big fan) while they were building the exhaust system, and said "make it sound like that"). It's an 1800 I4 just like the B engine, although with more power and much better reliability, and the 5-speed will make things much nicer on the freeway.

And of course the upgrades are available for the Miata, superchargers and the like, which will give you more power if you want it. Plus the engine and gearbox are free to you, which is always a powerful incentive.

I'm not familiar with the genesis of the Miata engine, but many engines in use these days had earlier versions based on the same block which used non-computer controlled ignitions and carburation. Many of these early parts still fit the newer designs and make swaps a lot easier for the electrically challanged. If there are earlier style parts available for this engine then that would make the swap far easier.
Bill Young

I know a few people who have converted thier race Miatas to weber sidedraft, so the stuff is out there. With carb, you generally loose torque but can gain hp. With OHC (Miata is DOHC) you can gain top end performance which is another reason why they have power after the B series stop producing power.

BMC Brian McCullough

Heck we put a 454/turbo400 in a Hillman station wagon. All it takes i$ a torch and $ome imagination and you can do almost anything.
R J Brown

even if you got rid of the fuel injectors wouldnt you still need the computer system for the timing advancement to properly adjust while running?
Scot Hamm

Exactly Scott. That's the reason to check for earlier versions of the engine that use a conventional advance distributor. Like I said, I'm not familiar with the Mazda engine history, but engines like the GM V6 and 2.5 inline 4 have been around long enough to have conventional distributors and intake systems available. Of course the engine will perform best with the proper computer controls and fuel injection, but the setup of these can be a real challenge. There are aftermarket systems available, but then these add to the cost of the conversion. Bolting in a Chevy or Ford V8 is a snap, but use a late model motor and try to adapt the computer is another story all together. RJ is right, $ can overcome almost any obsticle.
Bill Young

I raced an early 90 Miata (lighter) for several years.
The engine did not have a decent botton end torque with the FI and worse with Webers. In stock form it produce power above 3000 rpm. in race form from 4500-5000 rpm that is when the power output started to a red line of 8500 rpm.

The engine is a replica of the Alfa engine right down to the valve cover. The early engines that were used in the sedans in Japan had turbos and the miata engine kept the piston oilers which help cool the engine. With carbs you used the same computer to fire the coils, not a problem at all.

The early Miatas have the same dimemsions in the interior as the B.

The engine 1600 1990-1993 or 1800 1993 and up can produce 200 + hp but the torque is high in the rpm's Turbo is the solution for the Miata they respond much better due to the head design 4 valves per cylinder. The experts in the field is Flying Miata They are the only ones who can make a Miata fly. Keep in mind that reliability goes down. Flying Miata has the computer (pigy back) that can be tune as needed.
Bill Guzman

thanks for all the imput guys i think u all answered most of my questions i think imma give it a shot

This thread was discussed between 10/04/2006 and 21/04/2006

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