"Axial" engine design

[PapaSmurf2k3]

What do you guys think about this design?
http://www.carthrottle.com/could-this-c ... ombustion/

It seems to me it has a lot of the problems of a rotary, but isn't quite as simple and doesn't offer all the benefits.

[NolimitZ32]

I imagine that as you said it will have some of the rotary's seal problems, I'd love to see more development and long term tests, if nothing else it would allow for smaller engine bays and a lower center of gravity (the same basic advantages of the rotary).

[MinisterofDOOM]

They make a paint if criticizing the weight of a crankshaft and block in a normal piston engine, but it she seems to me that the big, broad, large diameter reciprocator and rotating cylinder housing would not only be heavier (or at least AS heavy), but a greater source of rotational mass and inertia as well. Rev matching seems like it'd be a nightmare.

Also, I don't quite understand why these guys (and rotary proponents) still talk about the inherent valve-in-block design of those engines as though it's a benefit. Yes, sparing the added complexity of the valvetrain (NOT the valves themselves) is beneficial. But most of the significant improvements in internal combustion engine design in recent years have been due to advanced valvetrain tech allowing for more efficient combustion (and thus energy extraction). Locking the engine to set aspiration timing is anything but boastworthy, even in light of resulting simplicity.

So, yes, I agree: all the same problems as a rotary and apparently none of the benefits. It looks like the worst of both worlds.

[frapjap]

That rotating cone/disc piece really bothers me. It reminds me of a shoddy carnival ride at the country fair.

[elwesso]

I guess fundamentally if you're after efficiency, there's only so much that an internal combustion engine can do, regardless if it's an otto cycle, diesel cycle, or something else. To me, it doesn't make a whole lot of difference, there's many different ways to skin a cat...

Of course everyone knows the best way to increase the thermal efficiency of a combustion engine is to increase the compression ratio... Right now the limiting factor is the fuel we can get easily...

[lne937s]

Kind of fun to think about. But, despite a claimed 30% reduction in overall mass versus a V6 engine (250lb?), that's a lot of rotating mass with the engine block spinning. Maybe for stationary applications or an onboard generator, but it would take a while to get up to speed. Think about an engine with a 150 lb+ flywheel. And a 14:1 compression ratio on 91 octane compares to the same compression ratio from the 2.0 Mazda Skyactiv in the CX5 on regular fuel. The sealing issues and potential difficulty in machining would make this a tough sell.

I think something like the ZEOD's engine (10hp/kg), with unitized block and head and separate crankcase (like an Offy), offers greater weight savings (80% versus a comparable output V8), without all that rotating mass or sealing issues. But it is fun to think about alternatives.

[Nicodomeus]

I am sure this guy is excited.....

[float_6969]

I think any advancement in the reciprocating piston engine is a waste of time. I'm sure there are lots of different engine designs out there that would increase efficiency, but the design of a reciprocating piston is inherently flawed IMHO. Even today's most efficient IC engines are only in the 20% range IIRC. How much more can that really be improved?