Achates engine

[tr7v8]

This has just come up on my FB feed. Any comments from anyone about why it isn't a more mainstream design. I know the really big ship engines use opposed pistons. I thought it might be friction & manufacturing costs.

https://youtu.be/JoQkTIfAB2U

[PositronicRay]

Cooling that top set of pistons looks nightmarish. (I'm not an engineer though)

[anonymous-user]

It's simply too complicated and expensive! (and a nightmare to package too)


two cranks require joining to one output shaft, lots of heat to oil, can't do variable cam timing, bulky, heavy.

The big economy benefit comes from the gasoline compression ignition technique, not the opposed piston tech, and you can apply GDICI to a conventional engine.

[tapkaJohnD]

"No valve train, which reduces friction" but TWO crankshafts!

This is a three cylinder, direct injection engine, just like a Ford EcoBoost.
But with more reciprocating parts.
The vibration without countershafts would be ... a lot.

John

[Mignon]

Crazy. Piston friction is the largest parasitic loss in an an engine and this has just been doubled. Engine height and weight would seem to be impractical for smaller vehicles. Poppet valves may not be perfect but sticking an entire second bottom end on an engine to replace a relatively light and compact cylinder head is nuts.

[PaulKemp]

These engines have been used in lorrys years ago but laid flat so keep center of gravity down
As for 2 crankshafts the Arial square four used 2 side by side in an early motor bike

[GreenV8S]

These would be even less controllable than a conventional cam operated poppet valve as well as bigger and heavier and relying on the extra complexity of forced induction. I think the Freevalve camless poppet valve approach is far more likely to succeed, since it's simpler as well as more flexible than using a cam.

[kimducati]

Take it a stage further - look up Napier Deltic.
https://en.wikipedia.org/wiki/Napier_Deltic
Now there is a complicated engine.
Kim

[lufbramatt]

If you like that, check out this page:

http://douglas-self.com/MUSEUM/POWER/unusualICeng/...

[Gojira]

That whole site is proof that you don't -need- to be sane to be an engineer

I've spent many happy hours wading theough the weird and wonderful stuff there...

[Allan L]

Yes the Oechselhauser two-stroke system (Patented 8. July 1892) is best known from Junkers Jumo diesel aero engines, also made by Napier under licence as the Culverin - and the Deltic mentioned above was a direct consequence of that.

As said above the exhaust pistons have a hard life and the flame ring technology may be the 21st century advance which make it work well enough to be sensible.

[YankeePorker]

In fairness the man behind the company gives credit to the original inventor from the 1930s. Will maybe have applications for trucks, but what a bh to develop the more efficient diesel just as they get kicked out of the car market for stinking up our cities!

https://youtu.be/zf6OH4iVUkY