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MG Midget and Sprite Technical - midget engine swaps

I'm a midget fan and have some experience with them, but I've never done anything unique with them, always put midget parts back in. have always fancied putting a different engine in one. All the talk on here is about the k series, but surely it is simpler to take the engine and gearbox from something rear wheel drive, then it's just a case of adapting the prop to go into existing diff.

Am I being too simplistic, is k series the easiest way forward? There must be other engines that can be used?
matthew stubbings

The reason most people go for the K is

1. plenty of people have done it.
2. you can buy bits off the shelf to make it fit if you want.
3. Looks like it was designed to fit with little encouragement to make fit.

Other engine options include vauxhall, toyota and of course V8 if your able to do serious bodywork mods. I have also seen a spaceframe midget with a bmw m3 engine and rear axle, just depends on how much time and effort your willing to put in.

Oh another option is to put a BMW 'K' head on a 1275, turbocharge, supercharge.

Hell you could make anything fit if you had the time and money but the K is the easiest.

Shaun

Shaun

Or Ford Zetec....
Dean Smith ('73 RWA)

So I guess if you take a k series out of a rover 200 or what-have-you then you use the rover engine and gearbox? I can't get my head around how that will put power through the rear wheels of the mg
matthew stubbings

no Matthew

you use a Ford Sierra type9 five speed gearbox, adapter bellhousing, adapter spigot bearing, adapter engine mounts and adapter "allsorts"...

for more better info go to the "twin cam 16v" section on this BBS

Lots of advice and expertise there for you
Bill sdgpm

The Kseries engine is used in RWD cars too, incl Rover (Freelander??) Or at least MGF, and Lotus Elise. Please also remember the likes of Caterham.

I use Caterham bellhousing/internals.

The Rover fwd box/transaxle is discarded.

There are over 50 Kseries conversion in UK (plus Holland and New Zealand), as recorded in the KSeries register.

As Shaun says, the K looks very at-home under a Midget (and even Sprite) bonnet.

(I can see from pic the ally bonnet was off for spraying.)

A


Anthony Cutler

Ant, your forgetting brother Knut from Norway. ;)
Arie de Best

Apologies to Knut in Norway, and thanks to the Nut in Holland for pointing out my error ;)

BTW Matt - take a look at KMidget projected performance on my website, bottom of the page (that should decide it for you):

http://www.btinternet.com/~anthony.cutler/AldonRR.htm

Whether you choose 1.4, 1.6, 1.8 (MPi, VVC, turbo) - standard or tuned, the K is the engine BMC should have used in the first place.

A
Anthony Cutler

No Ant, dont bore him with numbers or graphics but show a picture of a hot chick in bikini on the bonnet of a Kspridget while the car is doing a burn-out!
That will defenetly pull Matthew over to the darkside! :)
Arie de Best

The K-series is a lot lighter than the Zetec - 20Kg springs to mind.

The K-series is well supported with tuning parts if you want to tune it for a lot more power.

You can use the Ford type 9 gearbox.

Just about every other engine swap will be heavier.
Daniel Thirteen-Twelve

I have always admired Bugzuki:
http://www.ado13.com/dohczuke/dohc.htm

If you have the skills, it is amazing what can be achieved.
Guy Weller

And Bugzuki is pretty awesome in person as well. Of course, when the exhaust cam breaks, it can be a bit of a pain to repair...
David "yes, Bugzuki was at the US Spridget 50th" Lieb
David Lieb

Arie

Quite right! What WAS I thinking?

I'll take such a pic over the weekend and post.

A
Anthony Cutler

I definitely fancy a rotary. Preferably turbocharged. Light and very revvy. If the V8 is not to my liking, there is loads of room for a turbo'd rotary. The engines aren't cheap tho.
Tarquin

Tarqs, that would be cool and very fast i guess.
I have no clue what a v8 performancewise will do in a midget but to be honest, nothing can compete with the sound of a V8.
That sound will give you a st1ffy everytime you drive it. LOL
Arie de Best

There are several alternatives to the K series shown in the British V8 Newsletter photo section. Most would be available in GB as well as other parts of the world. http://www.britishv8.org/Photos-MG-Conversions.htm or http://www.britishv8.org/Photos-Austin-Healey-Conversions.htm
You might also like to consider these including information on the famous "Bugzuki" http://www.ado13.com/dohczuke/dohc.htm
http://home.earthlink.net/~roethler/engine.html
Bill Young

OK capacity apart is there any one engine that is a easier fit, I know Caterham used the 1400cc (plus1800) the Elise and MGF have them transverse not inline, so no really advantage there … if you don’t change the rear diff then I guess the 1400 is a good and very cheap solution;

What’s needed from the donor car ? off to the K series side of the site :-)

Kind regards
Matt

Matthew Mason

This may be obvious to everyone else, but what about putting a "B" engine in a Midget? That would give you about a 33% increase in displacement, and engines and parts are easy to come by. Is there a reason this is not done, besides its not very sexy?

Jack
Jack Orkin

The weight of the engine and the work to get it fitted.
A 1.8 ltr cast iron block or a 1.8ltr alloy fuel injected high torque k series ?

If i already didnt have a K in mine i would consider the toyota engine 4pag? 4age? cant come up with the right typename at the moment but you probably already know what i mean.
Arie de Best

Toyota has been my latest brain toy too Arie (4age innit)
Bill sdgpm

Jack,
One of the lovely things about fitting the Buick/Rover aluminum V8 into an MGB is that the curb weight when you are done, even with the extra water and bigger radiator, is virtually the same as with the cast-iron 4. You do NOT want that kind of weight in the front of a Spridget or you will be dealing with terminal understeer. You simply do not want to upset the handling of a Spridget with extra weight. Even the 1500 was almost too much, especially with the rubber baby buggy bumpers. The Mazda rotary engines are nice and light. So is the K-Series (why oh why did they never ship any of those to us???). Weight and power are the criteria you are looking for.

David "how much is a K-Series kit again?" Lieb
David Lieb

I see. I always knew size was important, at least that's what I've always heard! But I forgot about that little item known as weight! But, we can't get the "K" over here, right? What about the Honda vtec that is being put in Minis? I wonder how hard is it to get them to work going front to back?
Jack Orkin

Well I'm glad I started such a healthy debate.

Can anyone tell me what is wrong with this simple plan:

Buy a battered / rusty / damaged 2.8 capri. Install the engine, gearbox, diff, rear wheels, brakes and everything into the midget. Seems very simple, all it needs is the shafts cutting down a bit to fit where I guess they'll be too long.

Simple. Easy. Cheap
matthew stubbings

Alternatively could do the same thing with a Rover SD1 or P6 V8
matthew stubbings

Mathew,

The 2.8 is a heavy lump although more compact than a V8 and narrower as it's 60 degree V. By diff do you mean the whole axle or the final drive unit. The axle will be much heavier then the spridget one but can be narrowed as was commonly done for rally Escorts. Also IIRC the final drive/diff assembly can't be removed from that axle in the same way as it can from the sprite axle and swapped as the final drive casing is integral with the axle.
David Billington

The Ford 2.8 V6 I think you will find is a bit long for the Spridget engine compartment, you'll have to trim a significant portion of the battery support and foot wells to get it in behind the steering rack. As far as weight, it can be handled. I used a GM 2.8 V6 with T5 five speed and a narrowed GM rear axle and the car weights in at 2010 pounds with a full tanke of fuel and spares in the boot. Original front springs with about a 1/2" spacer underneath and 1500 Midget rear springs. I think that I'd probably go with a modern DOHC 4 such as the K series or a Toyota if I had to do it again though.
Bill Young

Bill,

Is the GM engine an iron or aluminium block?. The Ford V6 is iron. An aluminium engine would be much nicer from the handling point of view.
David Billington

David - I meant take all the running gear from engine back, including axle, the whole thing.

There are two major problems I have with using a modern engine

1 I don't want to be collecting different parts from different cars all over the place. I ideally want to take everything from one car and graft it into the MG.

2 It's just not right. Classic car, classic appearance, with a smooth little Japanese engine under the bonnet. I know some people like the two generations to be together, I always prefer to keep a classic engine in a classic car.

Oh and a third one, I'm not made of money! Fitting different parts together from different marques appears to be a major and expensive challenge.
matthew stubbings

Or what about a triumph 2000 or GT6, surely that would work?
matthew stubbings

i wouldn't have a clue to go about it... but since I've started doing some work for the local Honda Dealership I keep looking at the S2000.

That engine would certainly fit in the B, I saw a MGA at Silverstone a couple of years ago with one fitted, but I wonder if it's possible to shoehorn one into a Midget :-)

A.
A I McGee

Lotus 907 engine ! I bought a complete running but rotten Jensen Healey (for £250 !) and that became the basis for my Sprite. OK its now got a Lotus Eclat engine and 5speed box, but its lightweight, powerful (should be 160 bhp) and it pulls the light weight of the Sprite easily from 1000rpm. It DID take a lot of cutting/fabricating to fit tho
na munn

Or the smaller engined SD1, 2600 or 2300
matthew stubbings

Alfa V6 anybody? It would be realy nice maybe even a trans axle! now that would be differant!

Carl
C Bintcliffe

The GM 60 degree V6 is an iron block with iron heads in the RWD configuration. GM does offer an aluminum block for racing, but it's pretty expensive and you still have to use the iron heads in the configuration I chose. Still the iron engine is not that much heavier than the original 1275 considering how well the stock front springs support it. I did take quite a bit of time looking at different engines before I selected the GM unit. I looked carefully at the Nissan V6, but concluded that with the SOHC heads it was too wide to fit the Spridget engine compartment without major work on the steering. I didn't find any RWD configuration V6 other than the GM unit that was close to the dimensions available and many 4s were a bit on the long side as I didn't want to disturb the heater or battery tray if possible. The links I posted above show about all the combinations that I've seen that seem to fit well and offer reasonable performance. When considering an engine swap there are some basic measurments that I recommend following for best results and I've listed them along with drawings here. http://www.mgexperience.net/phorum/read.php?40,1092270
Bill Young

Mathew,

The Triumph engines are straight 6 as is the SD1 2600 and 2300. I could be done as a couple of cars have been done like this, a US one having a Jaguar XK engine in it, but all heavy lumps and quite long, and in the UK would require substantial modifications to the chassis and one would have to wonder about the SVA implications.
David Billington

Carl,

I had wondered that before also, at least using the Alfa transaxle, but it is quite long and the clutch fits on the front end of the box and might be a tad close to ones hips in between the seats. An alternative could be the Volvo transaxle as that is much more compact and doesn't include the clutch assembly on the front of the box, might not have the best of ratios though but is used with a DeDion axle and the PCD is 100mm IIRC so very close to 4".
David Billington

David

Is the spitfire engine bay larger than a midget? My thinking is if it fits in a GT6 it 'must' fit in the MG. Although this is not really based on any knowledge, just my assumption
matthew stubbings

Mathew,

IIRC much more space in the Spitfire engine bay at least lengthwise.
David Billington

For a compact engine with lots of power potential I always liked the FIAT/Lancia twin cam. The engine is quite compact as it has 4 siamesed bores so is short and could fit without engine bay modifications. Used to be very common but not so these days and so not a cheap option. A mate and I started to collect the bits for a 4x4 powered by a FIAT twin cam in the early 1990s, but life moves on. That was using largely Sierra running gear, with a type 9 4x4 box fitted with a FIAT bellhousing, which I still have, along with some of the running gear. Many spridgets have been fitted with the FIAT engine in the past IIRC including turbo examples.
David Billington

Jack Orkin mentioned the Honda Vtec , problems if its a B16 lump is lack of a suitable gearbox as this engine runs in a reverse direction to all normal engines . Many years ago my friend put a midget engine and box in a Honda S800. Didnt make a good conversion as it had 4 reverse gears and one forward , ended up in scrapyard ..Seen a S2000 engine and box in a few cars , that would make a good conversion .
R Mcknight

Very funny - 4 reverse gears and 1 forward!! Yes, a Honda S2000 sounds like a great swap, but I guess if you use a modern engine you have to hassle with all the computerized stuff that goes with it. But, back to the statement about vtec's running backwards - this may be quite oversimplified, but if the starter gets it turning in the right direction, and the plugs fire at the right time, why wouldn't it run in the other direction? Oil pump, water pump, alternator, etc. turning the wrong way?
Jack Orkin

Matthew, don't trust your eyes when it comes to judging the fit and size of engine bays, it can be very decieving. The Spitfire/GT6 bay is quite large and it also benefits from having the steering rack mounted very low so that the engine can run up over it. The engines also have a very shallow front oil pan to clear the crossmember and rack. Doesn't translate well into the Spridget chassis. As for the Honda S2000, I haven't checked one with the tape measure, but again looks can be quite decieving. There is a Spitfire in the British V8 Newsletter with a S2000 installed and it is neat, but don't know if it would fit in a Midget chassis or not, it's larger than it looks at first glance. http://www.britishv8.org/Triumph/JoeCurry.htm
Bill Young

Matthew

I know what you mean about retaining some sense of classic if doing an engine swap. However, the Midget's balance & handling are also key to its classic-ness, so fitting a heavier engine which disrupts these is also something to avoid. I wrestled with all this at length and eventually was happy to settle on the K series. OK, it is a modern engine, but
1. (most importantly to me) it was a family member, in fact ours was an MGF engine, even better.
2. Not only that, it was designed as the successor to the A series (first used to replace the A series in the Metro). That's also one of the reasons it fits so well, not to mention .....
3. The weight (or lack of it) is compatible, so it wouldn't stuff up the car's behaviour.

Not being an engine swap person for largely the same reasons as you, these comsiderations got me over the line. OK, you have do do something about the gearbox, but you guys have the type 9 and bits off the shelf so that's easy - much easier than getting a foreigner to fit as we had to (no type 9's here).
For the rear axle, we retined the standard unit and fitted an LSD and bullet-proof halfshafts. This was all in 2001. We set up the engine with 185BHP and bags of torque. Since that time we have done a lot of serious competing, including lots of autotests (including FTD's in the California Cup and the NZ championship) which are hardest of the lot on the rear end. And it's held together.

If retaining a classic engine is a priority above all, and it proves (as I suspect) hard to get one which doesn't stuff up the balance and handling, why not supercharge the A series for the extra torque and power? Period engine (and original!) and period modification, all that's non-period is the grunt!
Paul Walbran

This thread was discussed between 17/06/2009 and 19/06/2009

MG Midget and Sprite Technical index

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