Classic Mini - BMW K Head Conversion - Head Modifications

A look over the head modifications I’ve done to the BMW K1200 head in order to fit it to the A-series block. Also a look at how I’m going to be doing the head drains, water and breathers.

[@philtucker1224]

Very nicely explained and presented. I’m now going to find the next episode on KZbin….

[@chrishenniker5944]

I wonder if you can adapt the head to the Triumph or Reliant engines too? They have similar dimensions and are basically a similar design, from the look of it. I’d love to see one of these in an Austin 7, running side draft Webers or ITBs.

[@NickThornhill]

It would be an interesting day at a cylinder head gasket shop comparing notes wouldn’t it. So few engines are designed from a blank sheet of paper, there’s direct lineage from the a-series to the bmw k and a couple of other engines hence why it works. I’d love to find another conversion though, imaging an MGB with a Honda vtec head.

[@jamesconnors4297]

is this possible on an automatic gearbox ? and use a k00 8 valve head ?

[@NickThornhill]

That would be a good question for someone with more experience with the auto gearbox. Try speaking to John Guess of Guessworks. The auto block could obviously be converted to run a K head but whether the torque converter or the gear bands could hold the extra torque, I don’t know I’m afraid.

[@bernardwarr4187]

I am not sure what’s best for a street hot rod Mini, the K BMW head or the B series Vtec. Great video, thanks for the information

[@NickThornhill]

It’s a tricky decision to make. I went with the a-series and a better breathing cylinder head obvs. A Rover k engine swap or a Nissan micra engine swap were also on the cards and they’re all equally complex. Driveshafts are the hardest part to get right from an engine swap perspective as well as fitting the cooling in somewhere. I’d love to have a drive in an engine swap car and see how the handling feels. For me though I get a nice 16v throttle body burble but with the character of the Mini gearbox and the original weight distribution, plus everything from the head downwards is a known quantity.

[@sjc75vs]

If you want lots of power and not to keep blowing cogs out of the box then the B series box is happy upto about 600bhp or so in stock form, the A series one isnt especially reliable when you venture much over 100bhp.

[@NickThornhill]

Yeh I hear you. I considered all the options. I’ve now been out in a Honda B18 mini and I’ve driven a red top Vauxhall one too. They were great for power but were missing something for me. I think Chris Harris got the sentiment in lockdown when he said “with classic cars, it’s not all about speed, you’ve got to celebrate the shitness too” For me a fast mini is all about a whining gearbox, lightweight and fun. The Honda and Vauxhall both put extra weight over the front wheels and that, for me, changed the driving experience. Plus the k head swap means the historic element of a 1979 mini is still valid.

[@yamahajog04]

Nice wrk

[@ReubenVanGraan-fp8md]

Hi nick its Reuben here what head gasket do you use for the BMW cylinder head on the mini block thanks

[@NickThornhill]

You can just punch out the holes to modify the standard mini head gasket, a lot of people have done that but also both specialist components and med sell one for it. I’ve gone for the med/cometic one. It’s not always listed on their website but call them.

[@Sternhammer89]

Nice - I'd heard of the K Series Mini's but didn't actually know what they were, a BMW Bike Engine, cool. In the video, what have you got connected to the Gearbox where the Oil Pick Up Pipe bolts to the gearbox case, it's normally a metal plate, but you appear to have something black there? Is this particular to a K Series?

[@NickThornhill]

Hi bill. Good spot. That’s a specialist components neodymium magnetic pickup, I’ve got another one in the regular sump plug but this offers extra protection. The theory is it picks up anything that’s makes it through the strainer before it gets to the oil pump. It’s removable like the sump plug so you can keep a check on what’s gone up the pipe. Hit me up on Instagram and I’ll send you the link.

[@BasEerdenKeuning]

What engine and head combination would you think is the eseayest to do? When doing a dry deck

[@NickThornhill]

Easiest would be a standard mini block and head. Dry deck is only really needed for race cars, it stops you losing the water when you have a head gasket failure and adds water flow to the far side of the a series block. I’m doing it because I plan to do some track work in it, so covering all bases.

[@BasEerdenKeuning]

@@NickThornhill and if you would convert it to a k head? A k1000, k1100 or k1200. And paired with what motor? 1000cc or 1300cc or anything else?

[@freman007]

@@BasEerdenKeuning The K1100 is regarded as the most flexible fitment for a roadgoing Mini by Specialist Components, and with a 1293 (0.020" over 1275) they should give about 120 to 130 bhp while still being completely streetable.

[@BasEerdenKeuning]

​@freman007 is there any reason for using a k1200 head? Does it flow better for example or?

[@NickThornhill]

@rens3325 yes it does. The port shape and valve size, even the castings are the same but the K1200RS runs a thinner 5mm stem valve to aid airflow. The k1100 heads run 6mm valve stems. Every little helps and if bmw decided it was worth doing, they must have seen an improvement in airflow.