2 stroke thread (with occasional F1 relevance!)

[manolis]

Hello Tommy Cookers

From “your” link:

DKW supercharged engine layouts:



1. URe 250
2. ULd
3. SS 350 and URe 350
4. SS 250
5. US
6. Kurt Bang's opposed-piston prototype
image source:

The Twingles (1 to 5) have a not-compact combustion chamber with bad shape and large surface to volume ratio (say like the side valve 4-stroke enignes).

The opposed piston (6) combustion chamber is compact, an external scavenge pump is used, while 9 gearwheels do the synchronization between the two crankshafts.



Hello Issy

Quote from your link https://www.motorsportmagazine.com/news ... -formula-e wherein F1



Pat Symonds, chief technical officer of Formula 1, at the Motorsport Industry Association’s energy-efficient motorsport conference:

"The opposed piston engine is very much coming back and already in road car form at around 50 per cent efficiency.”

Does anybody knows which car he means?



Hello J.A.W.

You write:
“Pat Symonds may've been a follower of this thread, perhaps...”



Hello Saviour Stivala

Here is an animation of the TS-3:



From the beginning the (blue) rocker arms were a problem. They oversize and oversize them until to be reliable.



Hello Pinger

You write:
“There's a fundamental difference that an engine driving a generator does not have to restrain any torque reaction via its mountings. Thus, they can be very compliant and very possibly sufficiently compliant to absorb the rocking couple of a 180 deg twin cylinder engine. A task made easier still if the engine only has to operate over a narrow rpm band. (A rubber mounted RG250 engine is beautifully smooth at high rpm and at lower rpm the mounts soak up the vibes).”

A Wankel REM (Range Extender Module):



or an OPRE REM (more at https://www.pattakon.com/opre1_files/pattakonOPRE.pps ) :



or a PatOP REM:



are, among others, rid of unbalanced inertia forces, too.

Thanks
Manolis Pattakos

[J.A.W.]

Hi Manolis.

I do not know for sure - which such development - Pat Symonds is being inspired by...

Could it perhaps be this fairly recent Achates program?

http://achatespower.com/wp-content/uplo ... I_2017.pdf

Or has Honda been checking out member here - Uniflow, & his work on 2T HCCI - thus decided to
rescind their 'No 2T!' zeitgeist, (as they've done before, both in the early 1970s & 1980s)
for similar reasons (ludicrous costs for wins @ MX/MotoGP/F1 4T racing), to go 2T racing again?

[gruntguru]

"The opposed piston engine is very much coming back and already in road car form at around 50 per cent efficiency.”

Does anybody knows which car he means?

I know Achates have installed their OP diesel https://www.youtube.com/watch?v=UxON-HIlz5E (modernised Junkers) in a Ford utility truck but don't know of anything in production.

[J.A.W.]

"The opposed piston engine is very much coming back and already in road car form at around 50 per cent efficiency.”

Does anybody knows which car he means?

I know Achates have installed their OP diesel https://www.youtube.com/watch?v=UxON-HIlz5E (modernised Junkers) in a Ford utility truck but don't know of anything in production.

Somehow gg, I'd think going 'diesel' is def' a step too far for F1, so the same 'multi-fuel' function
aspect designed in, as a NATO military requirement (& which goes back to the Leyland L60 tank-mill
of ~55 years ago), as well as being a feature of the hi-tech/efficiency Napier Nomad turbo-compound
aero-engine 2T (cancelled ~65 y/o) which allows for an advanced 'petrol/liquid fuel' response, is more
likely of interest, esp' given the ability of 2T to provide an 'exciting sounding' exhaust, even at fairly
placid RPM levels, due to its firing urgency/pulse-blowdown fundamentals...

[saviour stivala]

The Commer TS3 2-stroke diesel was the only production opposed piston road transport engine made in any volume that I know of.

[Pinger]

"The opposed piston engine is very much coming back and already in road car form at around 50 per cent efficiency.”

Does anybody knows which car he means?

I know Achates have installed their OP diesel https://www.youtube.com/watch?v=UxON-HIlz5E (modernised Junkers) in a Ford utility truck but don't know of anything in production.

The last I heard of the Achates was a it was being trialled for USA military duties. On reading that, I kind of assumed if successful there, chances are it will disappear from the market (as we know it).

[J.A.W.]

US Milspec regs are not bound by civilian emissions standards, which is how the
venerable old Detriot Diesel 2T continues in use by US forces, but likely the Pentagon
would prefer to eventually replace them with a higher-efficiency program.

This D-D powered Maritimo C1 raceboat gives a vivid impression of 2T 'energetics':

https://www.youtube.com/watch?v=wqntIr2cKk4

[izzy]

or a PatOP REM:

https://www.pattakon.com/patop/PatOPbw.gif

are, among others, rid of unbalanced inertia forces, too.

oh great, i was trying to imagine how they could have only 1 crankshaft!

[toraabe]

Normally they are around 20 degree offset due to porting times..

[Tommy Cookers]

Somehow gg, I'd think going 'diesel' is def' a step too far for F1, so the same 'multi-fuel' function
aspect designed in, as a NATO military requirement (& which goes back to the Leyland L60 tank-mill
of ~55 years ago), as well as being a feature of the hi-tech/efficiency Napier Nomad turbo-compound
aero-engine 2T (cancelled ~65 y/o) which allows for an advanced 'petrol/liquid fuel' response, is more
likely of interest, esp' given the ability of 2T to provide an 'exciting sounding' exhaust, even at fairly
placid RPM levels, due to its firing urgency/pulse-blowdown fundamentals...

Mr F1 Pat Symonds sees 'synthetic fuel made using surplus green energy' - (I wonder where is this surplus green energy ?)

re the post quoted above ........
and http://archive.commercialmotor.com/arti ... on-engines
and http://archive.commercialmotor.com/arti ... at-chobham
Commer TS3 and even 5 litre BMC and 2.5 litre Land Rover engine multi-fuelled !

though from these links we wouldn't know how multi-fuel running was achieved (anyway just a gimmick in the L60) ....
MF seems to mean running a 'diesel' engine using another liquid fuel - probably needing raised CR, maybe lower boost
no change ??? to the Nomad III using JP-4 'wide-cut' jet fuel (regardable as kerosene/heavier gasoline fractions blend)
NB not dual-fuel - this means a diesel run on pilot diesel injection (the minor fuel) 'carefully' igniting gas (the main fuel)

the Nomad of course used all or almost all the turbine energy to compress the large amounts of air
(its exhaust energy state could be raised by adding further fuel (to the exhaust) but of course the efficiency then plummeted)
the Nomad was about using diesel or jet fuel costing 62% of Avgas 100/130 and c. 50% of Avgas 115/145 costs
posterity seems required to count the Nomad's (low) exhaust thrust as contributing to equivalent horsepower ehp
but ignore the Wright Turbo-Compound's exhaust thrust (ehp didn't exist when Wright sold their first 10000 TCs)

a former co-worker witnessed the shooting-down of a Ju 86P that unwisely tried to land at Manston
its high-boosted high altitude engines transmitted little power from crankshaft to crankshaft via the gears ...
because the supercharger took so much power from the crankshaft driving it

[hollus]

Mr F1 Pat Symonds sees 'synthetic fuel made using surplus green energy' - (I wonder where is this surplus green energy ?)

Wind (or anything else) to methanol and wind (or...) to Hydrogen are likely coming. Pat is a few years ahead of his time, but it would be a nice coup to run F1 on methanol, a proven racing fuel, 100% from wind. Pointing out that all fuel used by F1 cars comes from this, this and this wind turbines in particular would be a nice thing. Wishful thinking for now, though.
Spain is asking for huge EU money to fund a huge renewable to H2 network, including transport. The wind turbines would be made explicitly for that project.

https://www.energy.dtu.dk/english/news/ ... a31d0ad478
https://static1.squarespace.com/static/ ... roject.pdf

[J.A.W.]

I see BRP/Rotax is now offering a Ski-Doo 850 2T snowmobile - factory equipped with a turbo.

https://www.ski-doo.com/2020-whats-new-ski-doo.html

At a modest +4lb max-boost, this installation is fully intended to simply maintain power over
the altitude* climbs typical in mountainous terrain - & yet retain its lower weight/handling
cost advantages over the heavier, more complex/expensive 4T turbos - on the market.

*Just as the US 2-stage turbo-supercharged aircraft of WW II were, being designed to
be functionally capable of 'sea-level rated power' up to ~25/30,000 feet ( ~7.5-9.5 km).

[Bandit1216]

I guess it's time to remove "with occasional F1 relevance" from the topic

[michl420]

Since a few years I think the vehicle manufacturers do a lot of nonsense in the last 100 years (of Course not for their profit).

[Bandit1216]

I agree. 2-stoke with it's disadvantages, has been discarded except for ships, were those disadvantages are not too big. Stationary engines (whatever stroke) can make a comeback in hybrid street cars. Stirling even, why not.

I don't think 2-stoke, high-ratio-turbo compound, direct injection, (relative) low rpm, otto/diesel Frankenstein engines is a step forward for F1 though.