"Collectors" kits: To build or not?

Jon
No oil pump as such but it uses the cyclic variation in crank case pressure with two one way ball valves in the back plate. When the crankcase is below atmospheric oil is drawn in through a oil passage an fed via rotary valve and hollow crankpin the the big end. When the crankcase is above atmospheric any excess oil in the crank case is blown through the opposite one way valve and piped back into the oil tank. The volume of oil moved per stroke is very small but at 150 pulses per second it is a case of 'little and often'. Only the big and little ends are plain bearings everything else including the cam shaft use ball bearing so only needed an oil mist from the crankcase.
This cut away drawing he did shows the rear rotating valve & oil passage to the big end.
 
Note the "hemi" head and 45 degree inclined valves with the exhaust at the front following full size air cooled aero engine practise.
Why did he do all this?
In 1956? the model plane endurance record (limited to 10lb all up) had just been broken at 12 hours using a 10cc two stroke. He deduced that a powerful 5cc petrol 4 stroke would be little heavier but have a much better fuel economy particularly at the reduced throttle settings as the fuel was burnt off. He wanted to prove the point so built the engine! This was some time before there were any small commercial 4 stroke model plane engines let alone petrol ones.
Unfortunately by the time it was complete and tested the 10lb weight limit was scrapped and not much later as was the endurance category for safety reasons.
The fact that the 5cc worked so well set him off making a 1/4 scale model of BRM's 1.5 litre V8 (not the V16!) Grand Prix engine!
At 1/4 scale it would have a capacity of 23 cc but to ease the manufactures what were already very thin cylinder liners the cylinder bore was reduced a bit to give a 'recognised' total capacity of 15cc.
He obtained the original drawings from Rubery Owen and after 10 years it was structurally complete but minus inlet manifolds and carburettor so was never run before his death.
I later made this display case with one head "exploded" for a Model Engineer Exhibition.
 
His intention was to run it at least initially on methanol +10% nitro using glow plugs. He expected 1hp at over 20,000 rpm.
Long stroke diesels?
I have an original Mills 0.75 (my first IC engine) and later a Mills 1.3.           
 

My dad took me to see that BRM at Folkingham airfield and we stood next to it as it came round and drifted off the concrete onto the gravel and stones, flung very big cobbles way high into the air, word was it was Fangio driving it

The BRM 1.5 litre V16 was indeed a technical marvel but with a two stage mechanical centrifugal super charger (like a late mark Merlin) its engine torque was nothing, nothing and then suddenly everything between 10,000 & 12,000 rpm with so much power it could induce wheel spin in any gear! If you got caught off guard and let it rev too high it blew up at 13.000 rpm. Very few drivers could master it and still drive fast. At  the time F1 rules were 3 litre un super charged or 1.5 supercharged.
Here it is at Shelsey -Walsh hill climb. 600hp on skinny tires!
www.goodwood.com/grr/race/historic/video...o%2Dvisual%20delight.  
In comparison their earlier un super charged 1.5 litre V8 was successful so when the 3 litre un super charged only class was introduced they created a 3 litre H16 by basically "flattening" two of their V8s one on top of the other with two crankshafts. I did prove to be as powerful as any 3 litre V8 but it was heavy. In addition its complexity and reliability were against it.
After both of these 16 cylinder failures BRM withdrew permanently from Formula 1.
 It was the Ford Cosworth 3 litre DFV (double 4 valve) with its roots in the humble Ford Cortina "Kent" engine that went on to dominate F1 and sports car racing for the next two decades.