A view from inside the gallery, the flow is split by the central divider/head face support section,
Another point to note in the image below is to consider the head mounted in its working position, in this case rotating the parts below to the left - the position of the vertical drilling in the gallery ensures no trapped air at the internal gallery roof area,
Coolant flow through head-gasket area is given priority via two drillings beneath the exhaust ports, only one smaller drilling exists between the intakes.
Moving onto the oil system now. The oil is pumped from the block up into the head and from there into the hollow camshafts. Unlike some cylinder heads where hydrodynamic oil films are formed by supplying pressurized oil to the journals via internal drillings within the casting, this case is different.
Here oil is supplied to each journal via drillings in the camshaft itself. This has several advantages in that it ensures a constant supply to each journal, it does away with complex drillings within the head which take up room and it also provides excellent cooling throughout the camshafts length.
The head features oil squirters also which take their supply from a groove in the lower cam journal. These take a small amount of pressured oil from the cam via a small drilling - the spray is directed at the tappet face where the cam lobe presses on it.
These squirters are fitted and bonded into a drilling which runs the full length of the head. A full drilling is the easiest to drill as access is extremely limited for chuck/collet holder clearance should they have drilled each hole individually with a right angle head assembly.
The entry and exit locations of this drilling are simply closed with adhesive either end.
Below are a collection of pictures displaying what is described above. The first picture the shape made by the oil way up to the cross drilling that connects both cam supplies,
The cross drilling is just inside this section,
The oil enters the cam here through an orifice. Im guessing the sizing of this orifice is done in the r+d phase as it is a separate part and threaded + staked in after.
Here is the bearing that controls endfloat of the cams. Its important to note here that the main large groove in the middle is just for axial positioning and does not supply the oil squirters. These are fed from the smaller grooves and holes in the actual journal surface. The squirter rears are not open to this large central groove.
A shot of the cam showing axial endfloat ring, as well as the main supply hole at the end(hard to see) and also the angled lobes required to activate the splayed valves.
An overhead shot showing other journals and general layout,
With regards oil drain from the head, and its flow back to the sump, two holes at either end of the head look after this. They are placed on the exhaust side of head which is the lowest side when the head is in service. Two very slightly ramped drains with their highest points in the centre of the head directs oil to both these drain holes. The ramp down to the holes is very slight and not much more than 2-3 degrees from horizontal.
Here you can see the outline of the drain path from the outside and its protrusion outwards at the far end which translates to a downwards slope once head is in service and angled on the block,
The drain hole on one end,
An inner shot along the drain, notice too the cast pillar which is directly under the camcover bolt - tying the cast structure together and sharing loads,
The cam cover locates onto head casting with a solid steel dowel either end - Same in the cast of the heads onto the block itself,
A Quick mention of the head studs and securing nuts. These are normally a major problem in terms of room required for acess to them in order to remove the head. In this case everything has to come out in order to undo the huts and remove the head. Once the cams and pneumatic valves have been removed a crows foot spanner is used to undo nuts as they are not directly accessible with a straight socket. It is similar to some Ferrari production engines in this way necessitating the use of a special tool.
This image gives a good Idea how access is gained through the tappet bore with the crows foot spanner,
Onto the pneumatic valve train, this head uses a barrel and piston type pneumatic arrangement. The barrels are pressurized via two main drillings parallel with the crankshaft. These main drillings can be seen below exiting at the tub end of the head,
And again mid way through the head, if you look closely you can also see the vertical drilling leading from the barrel counter-bore into the main drilling,
Here is a closeup of the counter-bore itself, showing the three tapped holes for fixing the barrel as well as the air supply hole/drilling,
Here it is with the valve guide pressed in, notice the small groove in the guide with the O ring above. Oil enters this groove via cuts in the base of the barrel where it flows around the guide groove and exits out another drain cut in the barrel base pictured below,
There is a small entry point drilling in this groove needed to supply oil to the stem for added cooling/lubrication,
Below are the grooves mentioned in the base of the barrel, one directs splash/run off oil to the stem, the other is the drain. When installed one groove faces up hill and collects the oil directing it in towards the guide,
Notice too the orange seals (x4) required to seal the barrel to the counter-bore, three for the screws, one for the air hole,
Internally, the barrel base has been pocket milled out in order to lighten between the screw positions,
The screws do not lie equally (120 degrees)about the centre meaning the barrels cannot be installed/indexed wrong blocking off the air entry hole.
With the guide removed and installed in the barrel you can see how the grooves in the base feed the groove in the guide,
The hole in the bottom of the barrel is angled at the corners to allow the barrel to be installed down on the guide compressing the O ring as it is eased down therefore avoiding damage to seal and doing away with any special tools.
The tappets are pretty much 'standard items as far as it goes,
The body of the barrel is turned down to allow the tappet to slide down over it without crash when the valve is in the full open position,
Here you can see just how little clearance there is between the tappet bore, and the barrel wall when installed - the tappet slides in this gap,
Installed, with the squirter aimed at the centre,
Here is a shot of the top of the valve guide seal, I took it before everything had been stripped and polished before the analysis started,
Here is the same valve guide with the seal removed and the entire thing media blasted and polished for easy insertion in and out of valve guide drilling to port,
The stem of valve, complete with low friction texture surface coating for improved oil retention - remember, a hydrodynamic film is not easy sustain on a reciprocating valve stem and it is relying more-so on boundary lubrication. On close inspection it does look more like PVD coating but further testing required to be certain, the 'roughness' certainly does aid oil retention,
The barrel interior bore is of extremely high surface finish, almost mirror like. One of the most critical features with such dry sliding seal design we see here is surface finish on the bore walls. It must resist corrosion during periods while the engine is being built, being stored, or is in transit. The cylinder features hardcoat anodic coating internally and externally on the base. The anodic coating also benefits in terms of lessening sliding friction when impregnated with PTFE.
As mentioned at the start of this thread Im choosing not to show pictures of some of the pneumatic parts, in this case the piston. It is nothing special and has just two seals, one in the centre where stem passes through it, its located on the underside of the piston below the collets and is that same type seal we have seen above in the top of the guide except no sliding exists at this seal since the stem and piston/collet keeper are an item.
The other seal is located in the edge of the piston and is the main gas seal between the barrel and the piston. Again, it is nothing special and dare I say a 'common' seal/arrangement.
So in total there are eight seals needed in each pneumatic valve spring assembly - two of which are sliding seals, the other four being static o-ring seal arrangements. The first of the sliding seals is situated in the piston itself where it seals against cylinder bore, the second sliding seal resides in the top of the valve stem where it provides a seal with the valve stem. The other four seals are used around cylinder fixing holes, air feed hole, and valve stem hole through piston. This amounts to a total of eighty seals just in the pneumatic spring assemblies alone.
No air control valve/reg or valving items are present within the head itself.
Ill finish with two shots of the combustion chamber itself,
With all of the above in mind I hope the thread and information here has helped everyone from Casual Viewers, Enthusiasts, F1 fans, Engineers, Designers, Students, and Teachers Worldwide.
All pictures are backed up and on 20yr prepay hosting so they are not going to vanish anytime soon.
Taken from here> F1 Cylinder Head Design and Pneumatics, a closer look - Forum - F1technical.net