Technical Strange engine description

I have been around and worked on all types of engine , new and old for most of my life.
But when I read this description of a 2 stroke Australian race car engine, it had me scratching my head.
The car was built in 1934.
I'm not certain if one set of pistons runs inside of the other like a sleeve valve or if it is a system where on set of larger cylinders feeds a smaller set as a two stage.
Give it a read and let me know what you think.

 

it sounds like there is a crank on top, and a crank on the bottom, so maybe the pistons face each other?
it sounds to me like they are opening ports for the exhaust and intake as they move.
interesting.

 

google: opposed piston engine, see what you find

 

I agree with tb33anda3rd above. Apparently, both pistons move toward each other and compress the mixture and both are moved away as the mixture burns/expands and provide power output, though the lower set, being much larger and longer stroke, are the primary power output.

I have seen references and drawings of 'opposed' engines before, with a crank and pistons on each end of a common cylinder, but never, to my knowledge, with different bores sizes on either end. As I recall, they were large marine and locomotive diesels.

Very interesting information.......thanks for posting.

 

Thanks for the input guys
I think i will do some googling and see if I can come up with some more information on it.

 

Look up "Napier Deltic", it's a good read.

 

In Australia in about the 50,s or 60,s there was a English Commer truck with a simular set-up ,it was nicknamed a Commer knocker..

 

The Gordon - Brielle had this type engine back in 1906, a Google search should turn up some info. Bob

 

We've had opposed-piston engines on the Wildest automotive engine concept thread, e.g. http://www.jalopyjournal.com/forum/...ive-engine-concept.643785/page-4#post-9261996

 

I think the builder of this car was called Robert (Bob) Chamberlain. I saw this car at a vintage race meeting about 7 years ago in unrestored condition. It still drove and sounded incredible. From memory it is basically a two stroke and was completely hand built. I'm sure google will give a better answer.

 

Google "Chamberlain vintage racing car Australia" Plenty of info.

 

An image search turns up only this:

 

Ok , you guys are going to have to forgive the amatuer drawing.
(Years ago my art teacher said I maxed out at stick men)
But I think this is the basic idea some of you are trying to explain to me.
The top piston real function is to act like a valve to open and close the intake port and at the same time form a combustion chamber.
While the bottom crank and pistons act pretty much like a normal 2 cycle and make most of the power.

 

That's my take on it. The separate piston allows better control of intake timing, and can allow for supercharging by closing the intake after the exhaust.

On a conventional piston port 2-stroke, the exhaust opens first and closes last, so the cylinder pressure is limited by the exhaust port pressure, and remaining stroke after the exhaust closes. They depend a lot on exhaust pulse tuning for maximum power. There tends to be a narrow power band when the engine is "on the pipe", when timed exhaust reflection creates negative port pressure when the intake is open, and positive port pressure after the intake closes until the exhaust closes.

 

Thanks relic , now it makes sense why the went to this trouble to control the intake port, thats the only way you could have positive cylinder pressure with a supercharger on a two stroke.

 

Ha theres that car! I asked about 2 stroke engines a few months ago, specifically looking for info that you posted... My post got deleted for being ot...

 

Back in the olden days when I was in the USCG on the ice breaker Westwind we had 10 Fairbanks Morse opposed piston engines, 6 for propulsion and 4 for generators. As design they had 2 crankshafts with a vertical shafts connecting the 2. Pistons were opposed and were port fed. Blowers were hug and provided scavenging air to blow out exhaust and a fresh charge of air for the next cycle. They were 2 stroke and the mains were rated at over 1000Hp. They were very noisy, that's one of the reasons I can't hear shit, LOL.

 

There is another small paragraph about the car in the same book.I will try to remember to post it when I get home

 

Either that or poppet exhaust valves, like on a Detroit Diesel. That's why some Detroits have turbochargers on top of the scavenge blower.

Apparently someone has turbocharged a Vespa 200 2-stroke. I haven't quite thought that one through.

 

Some bird in England built a V4 2 stroke motorcycle using Villiers twin parts. He had to add a Judson supercharger to fill the cylinders a la GMC diesel because he couldn't use crankshaft pressure. The writer of the magazine article was impressed with the blower, not realizing you can't supercharge a 2 stroke because the pressure blows out the exhaust port.

 

I have worked on OP 2 strokes for years. They are pretty simple. The liner is ported for air and exhaust. The crankshafts mechanically connected, crank lead dgs starts out at about 9 dgs before IDC. The turbo charged ones approach 17 dgs before IDC.

 

IDC= inner dead center
ODC= outer dead center

 

One crank typically drives the blower, and they other drives the accessories. Scav air is a must.

 

I am assuming these are large industrial?
IDC when pistons are closest together?

 

My Dad a WWII submariner was telling me about the Fairbanks-Morse engines today.
The ones he worked on were the 8 cylinder opposed piston, it was his favorite engine.
Mike

 

Found this vid of the little beast actually running

 

now thats something you dont see everyday