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Any disadvantages to a 2 piece cylinder head like this?

Any disadvantages to a 2 piece cylinder head like this?

(OP)
saw this at SEMA a few weeks ago and was really entertained by it. For some reason though the 2 piece design really bothers me... Any major disadvantages to this design that could be problematic in the future?

Link

RE: Any disadvantages to a 2 piece cylinder head like this?

Expense of manufacture would be the major disadvantage. Are you worried about sealing? If you skip the BMW error of using nitrile seals for everything you can have long lasting seals that will easily make it to the end of life of the engine.

RE: Any disadvantages to a 2 piece cylinder head like this?

He specifically says the two-piece design is due to CNC limitations while pointing at the water passages. In production, I imagine he might start with an aluminum casting having integral water passages.

RE: Any disadvantages to a 2 piece cylinder head like this?

Modern CNC is fast as inexpensive, if he is only making these in the hundreds or thousands then machining everything makes sense.
And since it is all the same material the clamping and sealing shouldn't be a big issue. Not like Al heads to a CI block.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Any disadvantages to a 2 piece cylinder head like this?

The entire Electro Motive Diesel engine is fabricated by welding including the cylinders. The heads are a single casting, though.

RE: Any disadvantages to a 2 piece cylinder head like this?

Took a picture of the very same head at the NEC this year. Was chatting to the guys - nothing special, machine away as much as you can, I think in some areas they used beryllium copper pins into very hot spots and these extended up into the top deck. It all gets bolted together with small bolts, and then the head bolts clamp all. They use thermal paste as well as some other goop in important seal areas to join both.

To me it seems a crime to do it that way given that you can now get a head printed(sand) and poured in 7days for about 1400euro.

Heres a shot I took,



Mechanically, I guess its fine. But, in terms of mass and it raising the center of gravity, not so fine.

I think they said they have a short life and run alcohol as fuel so it provides extra cooling - I could be totally wrong here, but I think alcohol and short sprints was mentioned - I was very tired visiting said show.

Heres another totally non related picture taken at same show,



Brian,

RE: Any disadvantages to a 2 piece cylinder head like this?

Must not have worked very well if they're willing to show such a detailed cross section.

RE: Any disadvantages to a 2 piece cylinder head like this?

In engine development multi-piece heads like this on test engines are rather common when you need something different in terms of valvetrain mounting. Since those upper surfaces typically see low stress levels and are unimportant for head joint sealing, you just mill them off on a production head and bolt on whatever valvetrain structure is needed as a starting point. There's also quite a few similar slab heads used successfully on production diesels, nothing wrong or unusual about it.

RE: Any disadvantages to a 2 piece cylinder head like this?

BMW used a two piece cylinder head split along the axis of the cam shafts on their first Euro S50 M3 engine (286 bhp version not the US anaemic joke 240 bhp version) and this was in production.As far as I know the structure presented no problems but the later evolutions (the B32 S50 and S54) got rid of this arrangement

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