M50 + M50 = 48v custom V12!

[keri-WMS]

A friend of mine built this years ago as a prototype power plant for a Lambo kit car company, but before BMW went and made their own OEM 48v V12 in 2003 - the N73!

It had billet custom cams machined up in the states ($12,000 from memory) plus loads of other strangeness....plus the custom inlet manifolds which are the only remaining parts, all the rest was scrapped.

Are the inlet manifolds any use for a normal M50? Sad to see them sitting about, knowing him he'll have a bad day and scrap them as well!

[DanThe]

WTF

That is a bit mad to say the least! What was the score with the block?

[keri-WMS]

Again not 100% sure, was the 2v/cyl type though. I think he reversed the coolant flow in the heads or something as well - not sure!

[keri-WMS]

I found the old email I got about it - looks like it's M50 heads?

Here's the blurb, a bit garbled as I pulled it out of the email:

"...this had huge potential, and well capable of excess of 500hp @ 8500 rpm and spent much time working on the design and analysis of the engine characteristics, especially flow and piston design.

The standard 2v heads were designed for smoothness of running, combustion characteristics and emissions, and simply didn't meet my then 'customers' expectation.

So I had embarked on a full development initially out of curiosity and blind enthusiasm than much else. The initial idea being that I would launch a business from it etc etc - but it was abandoned by the customer....

I finished the build just to prove to myself it would hold together and then mothballed it. I had no application for it, and the cost simply didn't make it economical on a one off basis, or something people would be interested in buying, everything was custom as you imagine, and similar power could be had cheaper with the ubiquitous American V8s”¦ although the V12 had a sound to behold.

Two straight six heads, one reversed then machined appropriately, special cams were made for it at a cost of about 10k USD ”“ 300 degree profile similar to the Cosworth A1 profile, then dry belt conversion.... so it went on...

Sadly I guess for someone such as you, I scrapped it at the metal salvage end of last year as I had got feed up seeing it - this project was finished over a year ago I guess now, and I had toiled over it for 2 years in build and longer in design.

I didn't have machining capability at the time, and hence everything came at a premium price, now I do, but on reflection I think it was still over ambitious. The engine unfortunately didn't get up onto an engine dyno as I had run out of funds, and would have dropped it into a kit car chassis to run on a rolling road, but I had nothing large enough to take it.

The project died at that stage and I tried very hard to forget it. The engine was based on the M70 block and M50 heads, if I remember the numbers correctly: 2 versions of the head available with different valve sizes, I choose the smaller version as it had a more compact combustion chamber (needed for the higher compression ratio) but would need larger inlet valves, as this was going to be expensive outsourcing the work, so the original inlets were used in what was going to be the initial and resulted in only build.

The water passages were modified, copper gaskets made to drawing, and the oil circuit was brought out separately to each head from the block. The oil pan was shortened, and the original oil pump and drive modified. The front cover and cam chain drive was ditched, and blanking plates with oil seals were used and dry belt drive to the quad cams.

The cams were machined from billet with extended key shafts so the pulley positions could be sorted on build.

I didn't like the extended shaft arrangement, but they were supported by additional ball race bearings to take the end thrust and bending moment, but again not ideal ”“ these were supported in blocks that were positioned and dowelled in place on build again all rather one-off style.

The cam-pullies were pinto adjustable mated to bored out pinto crank pullies - these were the cheapest. The water flow was changed in direction to balance block and head temperatures front to rear, so treated as two parallel banks, through the block front to back, and then up and down the heads the other way.

The water pump never got sorted; the excuse being it would have some external arrangement. A main bearing to block skirt cradle plate was made, but needed shimming to prevent block twist (may have been too stiff but sat packed and shimmed off the bearing caps so this added a couple), as it was possible to get the crank to bind on torque One area I had real concerns, and never got to find out, was the relative block support offered by the aluminium M50 heads as apposed the original M70 head. This never got tested or analysed, and felt this may be the Achilles heel, but, as the engine was never loaded to full power I will never know.

The point being that the original 2v head was much more substantial in terms of adding stiffness to what was otherwise a relatively open block

I didn't have information available and nobody was prepared to tell me. I asked KS who were casting the blocks for BMW but no answer. If anything was going to fail technically in a race application with the conversion I think it lay here. True, I hadn't performed harmonic analysis on the cam drive and mechanical system properties - damping and fatigue, but the system and the shafts were kept stiff to hopefully put any resonant frequencies higher than any excitation

The down draught inlet runners, were connected to a large plenum chamber, as I had decided to use two large throttle bodies, than separates. Space with the production 4v heads was a premium i.e. there was so little room between the heads, and given previous experience with Lambo V12s I decided separate TBs wasn't worth it. I used a Sach racing clutch matched to a modified Cosworth flywheel and an uprated Renault UN1 gearbox... The clutch and gearbox are happily being used in my Renault Alpine now So all wasn't lost.

As you have no doubt already seen and realised, the two ends of the original heads were milled off and then handed with front and rear plates welded on. The front plate machined to take the additional cam support bearings, and remove the bending load on the first cam lobe and the resultant positional error: on the head that was reversed. Thus no longer provided support for the first valve position etc etc

It did look rather heavy and ugly to be honest from certain directions, and had I done it again would have added a little finesse!"

[Cook318IS]

That would be an absolute weapon if it works. If anybody can do it, you can dan

[keri-WMS]

Probably won't ever happen again - the bill came to £25k or something at the point it all got melted down, really sad.

So might the manifolds be any use for an M50/M52, or as the base for a plenum or something?

[rancido64]

That is awesome!

[DanThe]

The manifold from the 'proper' intake side would only be any use as a flange, the angle of the runners would be useless

[keri-WMS]

Bummer! They'll remain as paperweights then, I was hoping they could have a use somehow...

[E30BeemerLad]

Are they not symetrical? if you spun the inlet around would they not sit at an angle good enough to be fabbing a stainless inlet plenum to for a forced induction type? Mind you then where do injectors go?

[glenn]

i've seen these pics and read about this before....somewhere??

cant think where though?!?

[keri-WMS]

Probably me, might have brought it up in the distant past?

[DanThe]

You cant turn it upside down Lee, the bolt holes are all off centre

[Royalratch]

Crazy stuff.

How can anyone seriously say it costs 10K to machine a set of cams?

[keri-WMS]

Yeah, makes sense to me - each of the four is different (as far as I can tell) and full CNC machined from a hard steel, so that's only $2,500 each - £1,000-1,500 each isn't hard to reach on one-offs...?

[gareth]

As a development cost, that's entirely reasonable. These things only get cheap when mass produced.

[dips346]

i've seen these pics and read about this before....somewhere??

cant think where though?!?

its from when we done mine


http://www.boggbros.co.uk/gallery2.html

[glenn]

i've seen these pics and read about this before....somewhere??

cant think where though?!?

its from when we done mine


http://www.boggbros.co.uk/gallery2.html

i knew i had seen them somewhere before dips,
you must have pm'd me with a link when we were doing your v12

[ross_jsy]

And he melted it down after 25k investment? Madness!

[keri-WMS]

I think it kept reminding him of the nightmare poject (where the customer pulled a fast one) so he didn't want to have to look at it kicking about!

[ross_jsy]

Ah that sucks! Thought someone would take it off his hands.

Keep on forgetting to tell you how happy I am with the brakes btw. Yet to fit them but if they stop the car half as well as they look I am sure I will be chuffed!

[keri-WMS]

Cool!