F1 Cylinder Head Design and Pneumatics, a closer look

[riff_raff]

Thanks Brian. BeCu valve seats are a good match for aluminum heads and titanium valves. The BeCu seats have better thermal conductivity than nickel alloy seat materials. And BeCu alloy seats have a CTE that more closely matches aluminum head materials so it is easier to produce a secure interference fit. The BeCu alloys used for valve seats also respond to the work hardening effect produced on the surface that repeatedly contacts the valve face.

But as for Tommy Cookers comment about big interference fits between large diameter, thin radial section BeCu valve seats and aluminum heads being no problem, I would disagree a bit. Elastic modulus of the BeCu seat material versus aluminum is only one factor. There is also the relative section thicknesses of the seat versus that locally at the head to consider. If you look at some of the photos showing a section cut through the port, you'll note there is substantial head material surrounding the seat OD. So I would imagine the thick aluminum head is far stiffer radially than the thin BeCu seat at this interface.

[Tommy Cookers]

maintaining 'a secure interference fit' fundamentally means maintaining a certain contact load between the seat and the head
with BeCu contact load will vary less with temperature in use, due to both its CTE and E being closer to the head materials CTE and E
yes the head is stiffer than the seat
and this effect is greater with BeCu (E 1.3 x 10etc) than with eg a conventional seat (E 2.1 x 10 etc)
this helps - the notional maximum contact load on fitting is lower with BeCu (while maintaining in use the required contact load)

a given contact load (stress) implies 40-50% more strain with a BeCu seat than with a steel seat
but BeCu will stand the stress (because it's strong ) and so will hold elastically the corresponding strain and maintain the contact load
there are grades that have an elastic limit equivalent around 9000 microstrain (remarkably high, equal to a super-strong steel)
cold-drawn tube properties or similar properties through round hollow bar on special request to the mill

in reality the contact load developable will for any seat material be limited by yielding of the head material around the seat
(even with the counterbore improved by rolling)
so the greater strength of the strongest steel is unuseable anyway
BeCu has a far greater thermal conductivity, this is the game changer
yes the actual dimensional interference required is a bit more, but it's not a problem to the BeCu seat
because the stress can never be greater than the stress at which the head material commences to yield
(this is even lower than the official yield stress values that are yield stress corresponding to 2000 microstrain of yield)

afaik BeCu is what we British called Beryllium Bronze
when detachable heads had been made possible by the development of head gaskets that worked .....
but Aluminium alloys were not strong enough to use for making heads (because of inadequate strength when hot)
(non-Beryllium) Bronze cylinder heads appeared in racing (motorcycles mostly) around 1927-35 - very heavy though

[riff_raff]

TC- interesting discussion. I recall a while back when I was involved with the design of a turbo race engine where we used 32mm Judd BeCu intake valve seats shrunk into an aluminum head head with Del West titanium valves. We had to play around a bit with the interference fit of the intake seats to get things right. But the BeCu intake valve seats were not as thin as the ones shown in the pictures. One other consideration was that the bridge material between both the intake valve and exhaust valve seats was more generous than what an F1 engine would use.

The exhaust valve seats were stellite and the exhaust valves were 718 Inconel made by Del West. I think I still have one of the Judd BeCu intake valve seats and one of the stellite exhaust valve seats somewhere. If i can find them I'll post some pictures and dimensions.

[Brian Coat]

http://www.flightglobal.com/news/articl ... ed-409207/

I remember some discussion of 3D printing with full metallurgical properties on this thread.

This recently broke cover.

[gruntguru]

Some parts e.g. single crystal turbine blades, will probably never be 3D printed but this http://www.training.com.au/ed/monash-un ... et-engine/ indicates that short-life prototype parts will be increasingly made that way. The short lead times can cut development time dramatically.

[Brian Coat]

The significance of this part is Spec+Size

I agree lots of parts will remain cast/forged.

GE is already putting 3D blades in the LPT of the GE9X?
Lower temp parts, though (TiAl).

GE says Single crystal may get replaced by CMCs: also not printable?

[riff_raff]

There are a few commercial turbofan engine components that can currently be produced economically, such as fuel nozzles with small, complex internal passages that were being made from several pieces welded together. DMLS can make the base component in a single piece that only requires a bit of finish machining.

I agree with gruntguru that hot section components like HP turbine nozzles that are currently made from single crystal castings will not be made using DMLS, due to the metallurgy involved.

As for CMCs, I don't see how the laser sintering process used could be made to work with a powder mixture of metal and ceramic fibers. The most difficult part of producing some CMCs is getting the liquid metal to wet out properly on the surface of the ceramic fibers. It requires the use of something like a metal coating on the ceramic fiber surface, and this coating must have a melting temperature above that of the base metal being used.

[Brian Coat]

I agree, hence giving CMC as an 'unprintable' example. But they don't contain metal ...

Still not likely to see in F1 soon!

[riff_raff]

I agree, hence giving CMC as an 'unprintable' example. But they don't contain metal ...Still not likely to see in F1 soon!

Sorry, meant MMCs and not CMCs.

MMCs are mostly produced using permanent mold or investment casting techniques. But they do not lend themselves to laser sintering processes due to the need for even distribution of the ceramic fiber reinforcements. It is also very difficult to machine MMC materials due to the extreme hardness of the ceramic fiber reinforcements used, such as SiC.

TiAl is an intermetallic material, and I don't know if it can be fabricated using laser sintering while achieving the quality required for applications like HP compressor blades.

[Brian Coat]

TiAl is certainly used in Motorsports turbine wheels.

It is used in GT LPT and could as you suggest, be used in HPC.

I am not aware of succesful laser sintering of TiAl (I think residual stresses may be an issue) but EBM method of printing has been demonstrated for turbocharger and GT LPT applications.

Other methods include centrifugal casting and Isothermal forging + ECM.

I believe this latter method was used to make engine valves for one of the F1 teams during the Atmo era.

A team with a big budget ...

[Light-tuner]

I've been reading this thread for almost a year and it never seize to amaze. I really appreciate the effort and time given to gave such detailed posts. Thanks Brian for posting this and I apologize if I wasn't able to thank you the first time I saw this. I just registered earlier to give thanks

[Brian.G]

I've been reading this thread for almost a year and it never seize to amaze. I really appreciate the effort and time given to gave such detailed posts. Thanks Brian for posting this and I apologize if I wasn't able to thank you the first time I saw this. I just registered earlier to give thanks

Thanks for taking the time to sign up! Its posts like this that make these sort of efforts all the more worth while.

Brian,

[Light-tuner]

I've been reading this thread for almost a year and it never seize to amaze. I really appreciate the effort and time given to gave such detailed posts. Thanks Brian for posting this and I apologize if I wasn't able to thank you the first time I saw this. I just registered earlier to give thanks

Thanks for taking the time to sign up! Its posts like this that make these sort of efforts all the more worth while.

Brian,

To be honest Brian, I am planning to cast my own cylinder head for my scooter when I saw this post. This one gave me an idea on what the design will be. The measurements and the internal layout allowed me to reverse engineered it for my project. Right now, I am still on the designing stage as I only do my research on my spare time.

But moving forward, do you know of any online materials out there that is worth reading? Perhaps sand casting techniques, etc.

[riff_raff]

TiAl is certainly used in Motorsports turbine wheels.

It is used in GT LPT and could as you suggest, be used in HPC.

I am not aware of succesful laser sintering of TiAl (I think residual stresses may be an issue) but EBM method of printing has been demonstrated for turbocharger and GT LPT applications.

Other methods include centrifugal casting and Isothermal forging + ECM.

I believe this latter method was used to make engine valves for one of the F1 teams during the Atmo era.

A team with a big budget ...

I recall a few years back the lightly loaded turbos used in Champ Car racing had magnesium compressor wheels and titanium turbines. These turbo designs were all about throttle response.

[Punch]

I've been reading this thread for almost a year and it never seize to amaze. I really appreciate the effort and time given to gave such detailed posts. Thanks Brian for posting this and I apologize if I wasn't able to thank you the first time I saw this. I just registered earlier to give thanks

Thanks for taking the time to sign up! Its posts like this that make these sort of efforts all the more worth while.

Brian,

To be honest Brian, I am planning to cast my own cylinder head for my scooter when I saw this post. This one gave me an idea on what the design will be. The measurements and the internal layout allowed me to reverse engineered it for my project. Right now, I am still on the designing stage as I only do my research on my spare time.

But moving forward, do you know of any online materials out there that is worth reading? Perhaps sand casting techniques, etc.

Channel " mrpete222 " on youtube has alot of sandcasting videos with aluminium, post machining, assembly +++. Ive certainly learnt alot from him. I think he uses alumium from discarded cylinder heads in his hommemade furnace
Also you can find alot of books online. Try find "Automotive engineering books collection" or "Elsevier engineering collection"