No Connecting Rods!
 

Opposed (Conjoined) piston engine with no connecting rods

I always liked the Scuderi Split Cycle engine but I thought it should be a boxer. What's popular with the cool kids these days in three cylinder/six piston opposed engines.

So maybe an opposed piston split cycle engine?

Here is a four cylinder version. A flat eight?

Conjoined Piston Engine with Eccentric Connecting Rods

It appears the stroke is ~.68 the bore in this instantiation.

no connecting rods
 

If they can achieve a BSFC of 0.135 lbs / bhp, and zero carbon, they'll win all the marbles.:)

Youtube also recommended this video to me. I thought it was interesting.

Compare the Achates Power solution. Two crankshafts, one combustion chamber vs one crankshaft, two combustion chambers.

I do wonder how much friction or how quickly those gear mechanisms will wear. Seems like a lot of force with very little movement distance.

Seems quite unpractical. Any increase to stroke would also be dependent on an increase to the bore too.

Even though the Achates Power design requires conrods and two crankshafts, it doesn't require a valvetrain which adds complexity. Not to mention the Achates Power doesn't require head gaskets, and the absence of actual cylinder heads is also claimed to decrease thermal losses.

Thanks. I think that's what I was looking for.

Is it just me, or does anybody else sees some resemblance of its crankshaft with the one of a Wankel?

Not sure why this is us in the unicorn gallery. I don't see any ridiculous claims being made, but it seems like a novel and compact arrangement.

Fair enough. If the thread isn't over I can have the mods move it. Which subforum?

Is this one more unicornish?

https://www.youtube.com/watch?v=FgP85F2ZE_c

If there's no crank throw, why wrist pins in the pistons. Do three points of sliding friction and two planetary gear sets have less friction than one main bearing?

Definitely more unicornish, as it seems even more expensive to manufacture.


Even considering the piston pin as another point of sliding friction just like the main bearings, it would still sound more convincing than having to deal with 3 points of sliding friction and 2 planetary gearsets. Not to mention once again the need for more head gaskets and valvetrain parts as the engine would look more similar to a boxer on the outside. And even though this specific design doesn't seem to be so much more optimized for an oversquare bore-to-stroke ratio as the other, it would still make more sense to have fewer cylinders with a longer stroke from an efficiency standpoint.

Change of venue at 4:12?

It's like an OK Go video with placeholder music.

I am enjoying this thread.
 

It isn't really Unicorn material, though practicality is in question.

I've always admired the Commer Diesel engines and remember them puttering around our barrio as a kid.

https://youtu.be/q3TTE469f58

The Youtube algorithm has decided I need to see more of these.

https://www.youtube.com/watch?v=3eqBRSK35-A

Only a gentle nudge from an infinite force needed to change direction in an instant. :rolleyes:

All that's needed is a three cylinder variant with 120° spacing.

Make it a radial and shorten the length of the crank- cam- shaft thingy.

I like how if you stall your engine or something at all out of the normal happens, your timing is shot?

¯\_(ツ)_/¯

You should install a Youtube recommendations blocker add-on, on your browser.

How does that work? I'm talking about the main page.

If I could block their channels like Black Lie Smatter and Free With Ads, that would be great.

OK Here was an engine that still had some kind of connecting rods but not the same as standard engines: THE Bourke Engine.

I have a large report on the engine, it WAS built and run.

Here are some excerpts from this article: Bourke-Engine : Bourke 30

And this from the article: Bourke Engine Documentary - Bourke Cycle Edition

"The Bourke Engine Ran With A 50:1 Air/Fuel Ratio And Produced More Horsepower & Torque Per Pound Than Any Other Engine In History. It Had Only 2 Moving Parts, The Oil Never Had To Be Changed, It Was Very Quiet, And It Ran Very Cool. At nearly 70% thermal efficiency, it's the most efficient gasoline engine ever made!"
REVEALED: The most important gasoline engine ever made, where it came from, how it works and how to build one.

Sadly this page is also SELLING info on this engine so be warned.
None the less there is a ton of info in these pages…this could be very worthwhile looking deeply into these claims.

Rich

Free info at en.wikipedia.org/wiki/Bourke_engine
https://upload.wikimedia.org/wikiped...nder-Color.png

en.wikipedia.org/wiki/Bourke_engine#Engineering_critique_of_the_Bourke_e ngine lists 12 points. The Scotch Yoke is a deal-killer for me.

"The Scotch Yoke is a deal-killer for me."

Why??

I can see the write up is not accurate, the 4 cylinder version of this engine was a 4 cylinder boxer engine like the VW.

As far as I have read it ran up to 50:1 A/F radio, and it fires on each compression stroke which is each time the piston compresses, plus the power stroke of a firing piston helps compress the other side piston.

Anyway this is a very interesting design and should be researched more.

Rich

Sliding friction vs rotating friction.

Which is why I liked the example at Permalink #1.

Which is why he invented a skipper bearing...


Rich

I had never seen most of these designs ... fascinating! That's why I like this forum - no matter how much you think you know (or are aware of), somebody always manages to come by with new and interesting stuff! ;-)

racprops — I opened both links and Cmd-F 'skipper' gets 0/0 on both. DDG 'bourke skipper bearing' yields sail boating links. :confused:

Sorry faulty memory, It was called a Slipper Bearing: https://www.bourkeengineprojectllc.com/crankcase/

Rich

Check it out...

I am renewing knowledge of this very interesting engine...

Guys your really need to look into all the information here:

https://www.bourkeengineprojectllc.com/

I ran into a guy with photo copies of the scraped together book by Mr. Bourke about the engine... it was a bit of a mess.

It has been cleaned up and is much better form now.

Now if I was struck rich I have a second dream to build, and this engine just might be number one ahead of Gasoline vapor.

Rich

I can see the slipper bearing. Now I have to figure out what the transfer port does.

My favorite interesting engine is the Scuderi split-cycle engine, and it has a transfer port. But it's 4-cycle so probably not much likelihood of combining the two, although the Scotch Yoke might carry over.

https://upload.wikimedia.org/wikiped...ne_-_Cycle.gif

I guess the 15° crank offset is a problem.

Scuderi split-cycle still sounds more down-to-earth compared to other breakthrough designs.

Seems silly, to use a whole piston to do a pre-compression, when a simple super charger, or turbo charger is so much better at cramming in air.

Rich

As in a 2-stroke Diesel?

The magic is that the transfer port can be a compressed air tank. So it can run as a compressed air engine. Engine compression is ~150psi, SCUBA tanks hold 1500psi.

Had it been combined with an electric compressor or other auxiliary air supply, could qualify as some sort of hybrid. Makes me wonder to which extent DFCO and engine-braking could be compared to the regenerative braking of a hybrid.