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MG Midget and Sprite Technical - Twincam conversions?

Hi

In response to the lack of technical threads, here is a classic Christmas armchair question before I head into the garage tomorrow!

Anyone had experience of A series twincam engine conversions in Spridgets, either the BMW K100 head or the KAD head?

http://twinkam.co.uk/

http://www.force-racing.co.uk/bmw-k-100-conversion-kits/

http://www.kentautodevelopments.com/shop/category/16v-cylinder-head-kits-and-installation-parts/

Guess these require a bonnet bulge and a strong gearbox.

Cheers
Mike

M Wood

Here are some earlier thoughts, including go K series.

http://www.mg-cars.net/mg-midget-sprite-technical-bbs/bmw-motor-bike-cylinder-head-for-a-series-2011101107050031472.htm

http://www.mgexp.com/phorum/read.php?3,1898713

http://www.mmoc.org.uk/viewtopic.php?f=4&t=23068

Any other thoughts?

Thanks
Mike
M Wood

Toby, who used to be a regular contributor on the BBS, was well on the way with this conversion. It was looking really good when he last posted here. Its a great pity he left just as it was getting interesting!

http://www2.mg-cars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=97&subjectar=97&thread=2008100616522226720

and more photos here:
http://tinyurl.com/5xz9do
Guy W

At the Bo'ness Revival Hill Climb last September there was a classic Mini with an A-series twin-cam. I had never seen such a motor before - it really surprised me that such a thing was possible. I believe it was a BMW head.
Mike Howlett

I'll confirm what mike saw at Bo'ness was indeed a k100 BMW head on a 1275 block.
I had a chance to speak to the owner and was really surprised to find it bolted to a standard block and gearbox!
Should be possible to fit in a midget without a lot of chopping around.
Kits are not cheap if buying as a full bolt on upgrade but I guess you can shave a bit by picking up second hand units and refurb'ing at home.

Best of....
MGmike
M McAndrew

I have only dynoed one KAD headed Mini and was eagerly anticipating stunning performance which was not forthcoming. I was told I had set it wrong, wheels not contacting rollers giving low reading etc etc. I was running the rollers as inertia which would mean a daft high reading (good for pubs) if the wheels were not in contact with both rollers! I was shown an engine dyno graph but, unfortunately it was not dated and didn't have customers name on it so I could not help but think it may have been generic, it certainly bore no resemblance to what we found! We saw around 120 bhp flywheel when it was supposed to be 150+ flywheel and it was very expensive!

Contacting those with far more A series experience than I have told me the same about power output!

I have been told the BMW conversion is good but never dynoed one.

Peter
Peter Burgess Tuning

There are 2 differant heads for bmw motor cycle... 2 vlave versus 4 valve

My understanding is you want a 2 valve head as its alittle more torquy and better suited to the More vintage A series

I think the 2 valve head is known as the bmw k1100 or bmw k1200

Its a great enginering challenge to say look what I did, but for what all is involved the BIG negitive is the lower end is still a leaky 3 bearing block

Personally id invest the time, effort, and money into a more modern suzuki swift 1600, duratec, ecotec, + (varients) , honda S2000, kseries, ect. ect.

The distributor doctor in michigan built one a few years back, it was a nice build, but not for the 1st time wanna be for sure

Tobys engine was a work of art... sadly towards the end of his build he got infected with a nasty little sexually transmitted virus called "Fatherhood" and im not sure if he ever did get the engine built.

Prop
Prop and the Blackhole Midget

http://m.ebay.com/itm/BMW-K1100LT-K1100RS-K1100-K-1100-1993-ENGINE-CYLINDER-HEAD-VALVES-Low-Miles-/252199163903?nav=SEARCH

Wow... only $75 buy it now for the 4 valve bmw K1100 cyl head

Sadly... head gaskets appear to be almost like hens teeth... ebay shows ONLY 2 full pages ... 50, maybe 60 HG in all... luckly all at the same price
Prop and the Blackhole Midget

Toby's engine is fine,dandy and in the car


----------------------------------------------------






But as Prop has succinctly put it, he had other things thrust upon him

It needs a bit more plumbing and setting up the ECU I think

I hope this gives the lad a reminder, c'mon Toby
You know we need to see it in that French field in June
Bill sdgpM

http://m.ebay.com/itm/BMW-K100-K100LT-K100RS-K100RT-cylinder-head-valves-cams-camshafts-/321943787181?nav=SEARCH

Here is the 2 valve bmw k100 ... apperantly bolt on ready complete for a buy it now of only $200

Prop
Prop and the Blackhole Midget

Using a used Zetec , both power and economy would be much better than the bike headed A series.
I know of 2 customers with these engines, which did nothing but give trouble with head gaskets and over heating. Its not a simple bolt on job either.
Here's our Zetec Midget 170bhp easy fit and Type 9 box. Not cheap if using everything brand new, but savings can be made with some ingenuity


J L HEAP

Better yet Bill,

Toby should stop in and say hello with some photos of his master piece of spidget art...

It is new years eve... bill if you got his number by chance can you give him a ring and let him know the water is fine, comfortable and shark free

Im sure all would love to see some of his pics

Prop
Prop and the Blackhole Midget

"Nasty little sexually transmitted virus called "Fatherhood"."
LOL Prop!
Bernie Higginson

Happy new year JL,

You should see Robs set up, its a zetec / variation but he has combined it with a freaky little fast shifter transmission... im not sure what it is, i want to say it a 6 speeder

Personally im still a big fan of the Suzuki Swift engine dohc engine .. I saw it on Buguzki in 2005 ... great project and alot of work, id still love to do it with a spridget only do a ford isde crank trigger ignition and a 4 bank of SU HS1 carbs one on each intake port... probably leaving alot of power in the trash, but wow, total bling cool factor looking at it under the bonnet

Prop
Prop and the Blackhole Midget

Another engine alt we never talk about is the mazda rotory12b engine... its been done several times as well as the toyota 4age

Prop
Prop and the Blackhole Midget

Happy New Year to you too Prop.

We are just about to start a 400bhp turbo zetec mgb roadster with possibly a Lexus or Mazda 6 speeder. Think I have seen Robs Midget.
J L HEAP

The turbo mini boys have got BMW heads working well - mostly 16 v. However they need the A block to sit over the gearbox. We don't have that restriction so a different engine makes sense for ultimate power. I like the challenge of wringing the neck of the original block and head, so turbo and some nitrous for the strip. Looking for about 280 bhp at the flywheel this year, but it does give the (Ford) transmission a hard time. However it is still very tractable on the street unless provoked.
steve cowling

You should see Robs set up, its a zetec / variation but he has combined it with a freaky little fast shifter transmission... im not sure what it is, i want to say it a 6 speeder


Prop, I think that's Darren's beast youre describing.
With the sequential gearbox
Arie

Thanks Arie,

You may well be correct... I havent had my turmaric suppliment this morning.

Thanks for the heads up

Prop
Prop and the Blackhole Midget

yep, Darren's is the one with the sequential box.

Mine's the little 1400 that gives 121 bhp at the flywheel.

For what I spent on it, I'm fairly sure there's no cheaper way to get that output reliably.

Mine's done around 30K now. Only issues have been down to a poorly made oil take off plate and some funky wiring. Both totally under my control, and both fixed now. Does weekends away followed by Track Days followed by MASC meetings in all weathers with the only adjustment being the front dampers.

I costed up a 100bhp A series. A 105bhp K series was cheaper, and considerably cheaper for the same engine longevity.


Rob Armstrong

I quite often get tempted by the idea of a different engine - K series, Zetec etc, especially after seeing pics like the JL Heap engine bay!

But I love the good old A series and there is something very satisfying in having a tuned up version of the original engine that came in the car.

Maybe I'll do the maths like Rob and go down the transplant route when mine eventually explodes as I'm sure it must do one day!
john payne

This thread was discussed between 31/12/2015 and 05/01/2016

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