ESE's works engine tuner

[husaberg]

Ken, my proposal is no better than the BMEP-approach. I only left out the constants, so everybody should be able to do the math.
Speaking of which, I translated the Crecy's 5.1" bore x 6.5" stroke into 129,54 x 165,1 mm, giving 2175,93 cc per cylinder and 26.111 cc altogether.
I could not discover at what rpm the Crecy produced its maximum of 2729 hp, so I assumed it to be at the 2500 rpm that was quoted for its fuel consumption.
This would give 0,0418 hp per cc per 1000 rpm, 26% better than the 0,0332 hp/cc/1000rpm of the (unblown) RSA.
Makes me wonder what the RSA would do at the 100 kPa supercharger boost of the Crecy....
https://ww2aircraft.net/forum/thread...e-crecy.50534/
Attachment 348990

The last version based on a single slave engine produced an estimated 5000HP from its 26 liters.

Only six complete examples were built when the research was terminated in December 1945. An additional eight vee twins were built. Serial numbers were even, Rolls-Royce practice being to have even numbers for clock-wise rotating engines when viewed from the front. Crecy number 10 achieved 2500 hp on 21 December 1944. Subsequently single cylinder tests achieved the equivalent of 5000 bhp for the complete engine.

no idea re the revs

but

The thrust produced by the two-stroke exhaust was estimated as being equivalent to an additional 30% increase in power at the propeller on top of the rated power of the engine, and was exceptionally loud.

[Flettner]

However, if it was going to seize, I’d take it in a tractor rather than 25,000 feet in the air…just a simple pain avoidance preference though…[/QUOTE]

😁 I soon learnt to test the uniflow jet boat upstreem in the river.

[wobbly]

So , apart from ignoring all the hideous cubic inches and ft/lbs etc , it would appear that even running the 50cc at 17000 , using sleeve valve and other of the planet
ancient technologies has no advantages , power density wise , over SOTA done properly.
If only NoLuc was 1/2 way right , sigh.

[andreas]

325psi/22.4 bar x 17000 rpm x 50cc = 42 hp

[Flettner]

325 BMEP , supercharged.
Actually last versions of Crecy were compound turbo / supercharged. Exhaust turbine added to crank power.
Im guessing that was more than 325 BMEP. However that is calulated?

[sniemisto]

Why do you want steps or fins on the back side of the combustion chamber.
This is one of those old Monkey see Monkey do scenarios.
Cooling the chamber , does nothing but pull heat out of the combustion process.
The more heat in the chamber , the greater the gas expansion , the greater the power.
Throwing away heat into the water , is throwing away horsepower.
The better thing to spend time or money on is to arrange water to get close to the plug threads , and ceramic coat just the chamber , not the squish band , to retard heat loss into the water.

Thanks Wobbly!
New head is now almost ready. I followed advice and focused getting water closer to the plug. Original plug hole o-ring was changed from axial to radial style and is now smaller diameter.

[Flettner]

Id still tend to run a uniflow OP setup. One advantage, (and there are many), even though its got two pistons, its still a single cylinder. One combustion chamber. Good for where you are allowed only one cylinder. Or for that matter twin cylinder racing. Four pistons.

[husaberg]

Okay, i found some RPM data.

[lohring]

The single cylinder test I referenced was run at 3750 rpm. The speed was increased to 4000 rpm but some sleeve damage resulted, shutting down the program. The Bosh style fuel injection pump was a limiting factor at its maximum pumping volume. This is an engine with a 5.5 inch stroke.

Lohring Miller

[Peter1962]

I found this historic overview of the sleeve valve engine, interesting reading i think.
The engineers who build engines like that were ahead of their time.
file:///C:/Users/peter/AppData/Local...s-14-00616.pdf


It is so sad, that after the war, the company destroyed the existing crecy prototypes...

[Peter1962]

And this looks like a modern incarnation of the incredible Junkers Jumo from WW II : the Achetes 3 cylinder opposed piston engine. https://www.youtube.com/watch?v=UF5j1DvC954

[Peter1962]

This is interesting from start to end, but the real message is in the last 30 seconds of the video.
https://www.youtube.com/watch?v=zf6OH4iVUkY

[koenich]

Thanks Wobbly!
New head is now almost ready. I followed advice and focused getting water closer to the plug. Original plug hole o-ring was changed from axial to radial style and is now smaller diameter.

I changed the water flow through the MHR cylinder by closing the holes above the exhaust and opening a passage in the back of the cylinder in the insert. this requires relocating the water outlet to the front and a vent in the cover. helped quite dramatically with power stability over time...

[Flettner]

This is interesting from start to end, but the real message is in the last 30 seconds of the video.
https://www.youtube.com/watch?v=zf6OH4iVUkY

All diesels though. Completely different to a petrol OP uniflow.

[lohring]

I love that engine. I plan to learn CFD to help refine my design for a 60cc opposed piston engine. I wish someone had "discovered" opposed piston engines in my youth. Then the GM two stroke was the most advanced two stroke diesel. There would definitely have been a place then for a better design. Today, I'm afraid it's too late for new IC engines. Most of the work is toward electrics with battery and/or fuel cell power. A similar opposed piston engine by Eco Motors has died. They considered a gasoline small version. See below for their engine and ignition solution. That company is dead, and my friend who worked there has moved on. Achates does have some significant government contracts. I hope it works out.

Lohring Miller