ESE's works engine tuner

[lohring]

As I've posted before, supercharging a two stroke requires raising the exhaust pressure along with the intake pressure. Unlike in a four stroke, this doesn't produce negative work on the piston since it all happens at BDC, not during a full upstroke of the piston. Tuned pipes supercharge the cylinder in this way as do turbochargers. Mechanical superchargers alone without some exhaust restriction will blow everything out the exhaust without raising the cylinder pressure. The blowers in most two strokes are just a more efficient substitute for crankcase pumping. Snowmobile engines are the most noted for taking advantage of all this, see below. I think there are small enough turbochargers today for this system to work on engines as small as 50cc.

Lohring Miller

[TZ350]

More brilliance from 2Stroke Stuffing.

[wobbly]

The problem is the Devil is in the detail.
Alex has given up on the 100% exhaust concept because he never got the detail correct regarding the trapping of the reverse L ring.
The concept has been proven , and patented , so it can be done .
Now we have a new concept - just because the old one was " too hard ".
Currently we have carbon fibre rorary valve discs , with a ton of lubrication being applied with cold intake fuel/air and even with lots of development , this system
has wear issues.
What is going to happen to a stainless ( I assume ) rotary valve subject to 650* C and virtually no lubrication at all - yea sure , plastering ceramics all over the place may help.
Hate to be negative , but read again the first line.

[SwePatrick]

Why invent the wheel twice?

There are already twostroke supercharged engines out there with more efficient scavenging.

Twostroke diesels!

The same design is ofcourse usable with petrol, just lower the compression and change the glowplug with a sparkplug.



Problem is that a small 50cc twostroke probably doesn´t have power enough to turn it on idle.
This complicates it all, magnetic clutch might be an answer.
And, no you don´t need any reedvalve.
Lastly, it also need an oilpump to lubricate the bearings in crankhouse and lubricate the bearings in the supercharger.

[ceci]

The only thing I agree with is his suspenders.
Simplicity in mechanism, complexity in materials.
Renault has been researching this type of engine for many years, supercharged and with valve-controlled non-asymmetric exhaust.

[husaberg]

Why invent the wheel twice?

There are already twostroke supercharged engines out there with more efficient scavenging.

Twostroke diesels!

The same design is ofcourse usable with petrol, just lower the compression and change the glowplug with a sparkplug.



Problem is that a small 50cc twostroke probably doesn´t have power enough to turn it on idle.
This complicates it all, magnetic clutch might be an answer.
And, no you don´t need any reedvalve.
Lastly, it also need an oilpump to lubricate the bearings in crankhouse and lubricate the bearings in the supercharger.

I could be wrong but i am not so sure the detroits are operated above the pressures of what a conventional 2 stroke is unless it's supercharged and turbocharged.
The roots blower just makes up for the lack of crankcase.

[ceci]

As I've posted before, supercharging a two stroke requires raising the exhaust pressure along with the intake pressure. Unlike in a four stroke, this doesn't produce negative work on the piston since it all happens at BDC, not during a full upstroke of the piston. Tuned pipes supercharge the cylinder in this way as do turbochargers. Mechanical superchargers alone without some exhaust restriction will blow everything out the exhaust without raising the cylinder pressure. The blowers in most two strokes are just a more efficient substitute for crankcase pumping. Snowmobile engines are the most noted for taking advantage of all this, see below.
Lohring Miller

I return to expound, the concept that to increase the power of a 2S parallel twin, a turbocharger is not necessary.
I accompany it with enlightening images.
From my point of view, the brake for the crankcase feeding is the pressure in the crankcase and the later it starts, it is the more favorable for the use of a 24/7 valve.

[SwePatrick]

I could be wrong but i am not so sure the detroits are operated above the pressures of what a conventional 2 stroke is unless it's supercharged and turbocharged.
The roots blower just makes up for the lack of crankcase.

That´s why you add a turbo on top of everything.

Alex setup is no different that an old diesel as for trapping air.

[Peter1962]

More brilliance from 2Stroke Stuffing.

Will a rotary valve by this design be able to cope with the extreme pressure and heat that is coming from an exhaust chamber ? Maybe a solution like RCV designed, would be more suitable ? (not for intake, but possibly for exhaust it could work ?
https://www.rcvengines.com/technology/

[Norman]

Regarding turbocharging of two stroke engines.

Lennarth Zanders work.

Power up to ~70 hp was seen on dyno (125cc) as I understand reading the paper.

https://www.sae.org/publications/tec...-0642/preview/

[lodgernz]

Will a rotary valve by this design be able to cope with the extreme pressure and heat that is coming from an exhaust chamber ? Maybe a solution like RCV designed, would be more suitable ? (not for intake, but possibly for exhaust it could work ?
https://www.rcvengines.com/technology/

Alex drew a disc valve, but he mentioned it could be a drum valve, which would handle the pressure much better.

[F5 Dave]

Didn't Lotus piss around with barrel valve 2 stroke in, erm. . . 2000ish?

[ken seeber]

Didn't Lotus piss around with barrel valve 2 stroke in, erm. . . 2000ish?

Dave they certainly did, in the late 90s. Called the Lotus Omnivore. Orbital made some of the pistons for their first prototypes.

Such a simple mechanism: https://www.youtube.com/watch?v=fIG9pWldO8U

[TZ350]

Didn't Lotus piss around with barrel valve 2 stroke in, erm. . . 2000ish?

Lotus sleeve or rotary valve two stroke development. https://www.jstor.org/stable/44611314?seq=1

[lodgernz]

Back in the 1950s, when I was about 12, I tried to make a 4-stroke engine. This is the head:


Would never have worked.