Fitting a BMW K1200 engine....

[Hal Mercier]

I've been thinking about this recently. The K1200 (BMW bike) engine is a 4 cylinder inline, with all aluminium construction, water cooled, twin overhead cam, 16 valve, fuel injected, and has a sigle dry plate type clutch, so it's got a lot of similarities to a car unit.

It weighs 76 kg, so not far off the 60kg of the Imp, when weighed with its Webers and exhaust.

It rotates in the opposite direction to the Imp, BUT has a contra rotating flywheel, so the flywheel rotates in the same direction as the Imp, giving 4 forward speeds when attached to the Imp or JK box.

I think the BMW block, which has 5 main bearings, must be slightly longer than the 3 bearing Imp, and I'm pretty sure fitting it to an Imp box will be far from straightforward as i seem to remember the K doesn't have a normal flywheel arrangement, but I'm going to see an engineer buddy to see what he thinks.

The K1200 gives a reliable, economic, lead-free 135bhp, and can be tuned for MUCH more.

A friend had a RBRacing turbo installation on one, that gave 300bhp.

This will, if I do it at all, be fitted on the Mk 7, so much easier as the rear body lifts off and it has the cantilever engine support.

Loadsaroom in Mk 7 tail...



Needs respray too....

[Hal Mercier]

It seems there was a singleseater race series that used the BMW K1200RS engine with a Quaife 6 speed sequential box.....Google "BMW 1200 singleseat race series"

[dickdixon1]

Nice idea, be interested in result or it might have to be http://theamazoeffect.blogspot.co.uk/20 ... e-you.html

[Dave6091]

With many bike engines finding their way into small kit cars i wondered if you have to alter cam timing or such to pull the torque curve lower down the rev range due to gearing and extra weight?.

D.

[Hal Mercier]

Good question. I've not calculated what the final drive ratio would look like on the car with this engine, compared to the bike. Bike has larger diameter wheels, but geared for them, so I have no idea how it'd work.

I've just had to do exactly this on the GL1000 Honda engined rig, as the 1976 spec engine in it is, as I discovered, not right for pulling a heavyish sidecar. It has its torque peak at 6500rpm. The 1978 spec has more torque, and it peaks at 5500rpm and comes in stronger throughout the mid range.

To do this, I had to change the cams, the carbs, and the cam-driven automatic timing device.

BMW bits should be easier to come by though...

[Hal Mercier]

Nice idea, be interested in result or it might have to be http://theamazoeffect.blogspot.co.uk/20 ... e-you.html

That Suby lump looks to fit very nicely. I wonder what it weighs, complete with the VW box? I hope he worked out which way it turns.......or maybe that's why it's for sale?

[Hal Mercier]

Just noticed on the Imp club forum....this conversion has now been done successfully, in an Imp and a Clan!

Fantastic!

http://forum.theimpclub.co.uk/viewtopic ... &start=200

[Hal Mercier]

I think I'll have to go for this.

I've found a lowish mileage year 2000 K1200RS with a gearbox problem but otherwise very good, with many new parts.
At the price, it should be possible to recover the lot by breaking it, so it's a free engine once the bits are sold on.

The only problem (apart from a slight financial crisis) is it's about 650km from me!

[Stakhanovite]

Hi Hal
this is from one of the BMW single seaters you noted above- going in my car over the winter..

[Hal Mercier]

Very nice! What did that cost? What bhp? PM me if you like. I've been researching these in and out of bikes.


I imagine that one's been rebuilt after a few season's racing?

I bought a Caterham engine which had been used in endurance racing for 2 seasons, then "rebuilt completely using all new parts,"(quote) by John Wilcox Competition Engines a few years ago.

Put it in my Caterham, and it sounded really noisy at the top end.

Removed the head after checking the valve tappet clearances (shimmed 16 valve twin cam) and found many shims were badly hollowed out, gaps all over the place, and worn guides. It would surely have dropped a valve pretty soon. Seriously unimpressed with Wilcox...

So....whatever you were told, I'd be inclined to check it!

I ended spending over £700 getting this head put right, after tracing the guy who built it originally, in 2000, at Janspeed.

Roger Fabry, now independent, operating as Sabre Heads, Wisbech....he fitted special extra length Colsibro guides all round, relieved the head for future fit of a second high-lift cam and did some slight finessing on the ports and inlet tracts.

Very nice guy, Roger.