2 stroke thread (with occasional F1 relevance!)

[manolis]

Hello Henry.

You write:
“What are he advantages of the tapered valve?
An earlier poster, who seemed quite Cross, remarked on the awkward shape of the inlet tract involving two right angled turns into the cylinder. Does this tapered design improve that and so improve volumetric efficiency?
It looks to me that it does but try as I may I cannot make stereoscopic imaging work. Perhaps I need to return to childhood.”


Basically, the tapered version makes clearer the gas flow in a PatRoVa cylinder head:.



a primary tumble (as in the Cross-Bishop), and two symmetrical secondary tumbles; the symmetry of the design eliminates the interference between the left and right halves of the cylinder.

It gives some more freedom in the design of the intake and exhaust “manifolds”.

It allows a “lower” engine (the lower “side” of the two oppositely arranged fronts – i.e. the two flat sealing surfaces of the spool – “get” into the piston crown, if desirable) and a higher compression ratio:



Thanks
Manolis Pattakos

[J.A.W.]

Yes Manolis, the Canadian tri-star 3 engine is rather lightly stressed in piston speed/BMEP terms..
It is difficult to tell from the site views - which do not show the assembled crankshaft - the exact arrangement.
Certainly it does not seem to use either 'knife & fork', or 'master & slaves' for conrod setup...

As for your revised overhead rotary valve, is it capable of the the speed/breathing capacity, to run as a 2T?
Or would you only use it for exhaust purposes on a 2T, with a ring of inlet ports let into the sleeve?

[manolis]

Hello J.A.W.

In case of a port-less 2-stroke, in the cylinder head they are required two “ports” (one for exhaust, one for intake) away from each other. Like, say:



With the one PatRoVa rotary valve dedicated to the exhaust and the other to the intake (or transfer), the tapered disk design is just an option (that fits better with the intake).

The bigger the bore to stroke ratio, the better: because this way it is enabled some kind of (cross) through scavenging: the fresh charge entering from the other end of the cylinder scavenges the exhaust gas without being too much contaminated from it.



An oval piston would be an interesting choice: the form of the combustion chamber gets oblong with the intake and exhaust ports at its “ends”, which is good for an efficient “through” scavenging.

By the way, the wrist pin of the oval piston can be arranged either as in the Honda NR 750:



wherein a pair of connecting rods is required, and wherein the thrust loads are taken by the flat side of the piston skirt,

or,

the wrist pin can be arranged normal to the flat surfaces, allowing the use of a single connecting rod and of a single crank pin per piston, allowing also the receiving of the thrust loads by the round (and not the flat) part of the piston skirt.



With the PatRoVa rotary valves the cylinder head has not rev-limit and its air-flow capacity can be extreme.

During compression most of the residual gas is concentrated into / near the exhaust cavity, with the cold intake cavity being the preferable choice for the combustion to take place.



If desirable, the crankcase can be used as the scavenging pump of the engine.


A tuned exhaust can be used to exploit the energy of the exhaust gas for a more efficient scavenging and a higher volumetric efficiency.

Thanks
Manolis Pattakos

[J.A.W.]

Good reply, ta Manolis..
Would it be practicably feasible to rotate your rotary valve seating within the cyl-head, to sit horizontally?
This could save space, even if it complicates the drive train, by adding the needed 180`directional drive gears...
.. but it might be worthwhile for an individual head set-up, 'Panigale-wise'..

[mikaelj]

Since the Rotor engine has come up here previously I'm hoping this is still sort-of on-topic:

http://www.motorcyclenews.com/news/2017 ... race-bike/

Comments/thoughts on how they've solved(?) cooling, oil consumption, etc?

[J.A.W.]

Since the Rotor engine has come up here previously I'm hoping this is still sort-of on-topic:

http://www.motorcyclenews.com/news/2017 ... race-bike/

Comments/thoughts on how they've solved(?) cooling, oil consumption, etc?

Well M-J, the Wankel rotary piston design does have some 2-stroke-like features, but
their design fundamentals tend to predicate against practicable every-day use..

I understand that military contract money* has been used to improve certain aspects
of efficiency/durability for UAV/drone use by Roton, which is spinning off into 'racing potential'..

Separating the promises of 'spin/hype' from series production success is quite another matter..
So what class they'd race it in, other than the I.o.M. TT prototype/'run-what-you-brung', is moot..


* Eerily - also very like the situation with 'The Vincent' motorcycle, ~60 years ago, which while
gaining sporting kudos to add to the 'legend', did actually not convert into commercial success..

[manolis]

Hello J.A.W.

You write:
“Would it be practicably feasible to rotate your rotary valve seating within the cyl-head, to sit horizontally?”


Yes but in expense, among others, of air flow capacity.

In case wherein the “lower” cylinder head together with the cylinder liner comprise a single piece part, the arrangement of the PatRoVa with its rotation axis parallel to the crankshaft strengthens the engine structure and provides freedom and space for the intake and exhaust ducts.



You also write:
“This could save space, even if it complicates the drive train, by adding the needed 180`directional drive gears...
.. but it might be worthwhile for an individual head set-up, 'Panigale-wise'..”


The Desmo cylinder heads of the Ducati Panigale are big;



a lot of space will be empty after their replacement by PatRoVa cylinder heads of substantially higher flow capacity and of unlimited revving capacity.



By the way, with the following I was explaining in another forum how the architecture of the PatRoVa reduces the spark advance and the duration of the combustion:


QUOTE from http://home.people.net.au/~mrbdesign...utoTechBRV.pdf about the Bishop rotary valve engine:

“This oblique flow through the window is responsible for one of the rotary valves most useful attributes - its strong in-cylinder tumble flow. The tumble ratio on engines with near square bore/stroke ratios is typically twice that reported for similar 4 valve engines. Unlike the poppet valve this high tumble flow is generated without any loss of volumetric efficiency (VE) and is responsible for very fast burn rates observed. Production based engines built in the early 1990’s had ignition timing of 15°, or less than half that of the best four valve engines.”

End of QUOTE


In the PatRoVa the combustion chamber (i.e. the cavity at the “top” of the cylinder head) is substantially more compact and more fatty and more concentrated around the spark plug than the combustion chamber of the Bishop rotary valve.

The high tumble flow in the PatRoVa remains strong even at the end of the compression (piston at the TDC) because of the shape of the cavity.

These characteristics make the required spark advance substantially shorter than in a Cross-Bishop rotary valve engine (and a few times shorter than in the best 4-valve engines), and the combustion ends shortly after the TDC.


For comparison with a high-tech poppet valve engine:

Think of the combustion chamber of the Ducati Panigale 1299 (116mm bore, 60.8mm stroke, 12.6:1 compression ratio (i.e. mean “height” of the combustion chamber when the piston is at the TDC: 4.5mm)) which is like a coin with abnormal top and bottom surfaces (valves, valve pockets etc).

The flame in the Panigale 1299 propagates in two only dimensions, while in the PatRoVa the flame propagates in all three dimensions.

The flame in the Panigale has to travel twice the distance it travels in the PatRoVa.

The stronger tumble, swirl and turbulence in the PatRoVa force a substantially faster flame propagation.


With the combustion completed substantially earlier in the PatRoVa Panigale, the actual expansion ratio is substantially bigger, the fuel efficiency is better, the exhaust gas temperature is lower and the power output is higher.

Thanks
Manolis Pattakos

[manolis]

Hello MikaelJ

You write:
“http://www.motorcyclenews.com/news/2017 ... race-bike/
Comments/thoughts on how they've solved(?) cooling, oil consumption, etc?”


Thanks for the interesting link.


According the specifications of the Rotron Wankel engines:

their Rotron RT300LCR (300cc, single rotor Wankel) :



provides 30HP max. continues and has a specific fuel consumption of 0.527lb/hp/hr at 6,000rpm / cruise:



while

their Rotron RT600LCR (600cc, twin rotor Wankel, reasonably two RT300LCR sharing the same eccentric (or power) shaft) :



provides only 54 HP max. continues and has a specific fuel consumption of 0.61lb/hp/hr at 6,000rpm / cruise:



which means a BTE of only 21.5% at cruise (and 22.5% at its optimum point of operation).


It is strange that Rothron gives the single rotor 300cc as being 15% more fuel efficient than the double rotor 600cc version.
If this is not a mistake, a pair of independent RT300LCR seems preferable (provided their cost is comparable to the cost of the double rotor version) than an RT600LCR: more safe (two independent engines) and more fuel efficient.



QUOTE from a previous post of this discussion:

At medium-high speed the Evinrude E-TEC G2 250 H.O. operates at 30% Break Thermal Efficiency (268gr/kWh), and at high speed it operates at 28.5%BTE.
At its worst mode (low speed) the E-TEC runs at 24%BTE.

End of QUOTE


The 2-stroke E-TEC Evinrude at its worst point operates at 10% higher Brake Thermal Efficiency (BTE) than the optimum Brake Thermal Efficiency of the “4-stroke” Wankel rotary engine, and at its best point it runs at an almost 50% higher BTE than the Rotron Wankel!


Even if Rotron / Crighton really achieved to make long lasting seals for their Wankel Rotary engines (their seals, as they claim, can operate without lubricant), they obviously did nothing on the “sealing” efficiency of the Wankel and on the poor fuel efficiency of the Wankel.

Think of a small airplane having a lightweight Rotron Wankel rotary engine and a heavyweight fuel tank carrying the additional required fuel for a specific range.


A direct injection Diesel like the PatTop at http://www.pattakon.com/pattakonPatOP.htm :





Youtube video at: https://www.youtube.com/watch?v=2ByEgfTTq1I

(Opposed Piston, 636cc (850cc built-in scavenge pump), 20Kg (45lb) total weight, aircooled, fully balanced etc)

is some 10% more lightweight than the 600cc Rotron RT600LCR Wankel and requires, for a specific range, less than half of the fuel the Rotron Wankel requires.



Regarding the 700cc racing version with the 200bhp/11,000rpm, does anybody know where the 700cc refers to?

Is the capacity of each chamber of each rotor 700/2=350cc?
If so, the specific torque (93mN/lt at 11,000rpm) they milk from their 700cc racing Wankel rotary is 15% higher than the peak specific torque (81mN/lt) Mazda achieves with their RX8 Wankel.

Thanks
Manolis Pattakos

[mikaelj]

...... that military contract money* has been used to improve certain aspects
of efficiency/durability for UAV/drone use by Roton, which is spinning off into 'racing potential'..

Separating the promises of 'spin/hype' from series production success is quite another matter....

What I found interesting was the blurb about being able to achieve Euro4 levels... but I guess only time will tell!

[J.A.W.]

Hi Manolis,
Re: the "700cc" nominal capacity of the racing wankel-type rotary-piston motorcycle engine,
this refers to the FIM's fictional 'equivalence' factor, deemed needful to provide a balance of
performance, in restricted cubic capacity competition class engines..

However, since Moto GP bans all but 4 cylinder 4Ts, & World Superbike demands a regular production basis,
the supposed 'nominal capacity' issue is, these days, moot..

In race tune, I would expect the power output to be significantly higher than a road-legal emissions
compliant Mazda RX-8, but you'd have to check what the last competition-homologation for sports
car racing RX-8, with triple rotor type-20B engines were rated at, for a more realistic comparison..

About the provision of a horizontal rotary valve, I was more interested in 2T applications*, whereby its
full flow capacity could be directed for sole use as an exhaust valve..
& thus purposely form the most efficaciously shaped combustion chamber..
- with swirl as per: http://www.Sonexresearch.com/technologies/3743046

* Whether as a CI mill, ( no spark plug) or as a spark ignition unit, with the plug central mounted,
projecting through the hub of the rotary valve.. ( & the valve might well feature electronic drive, too)..

[Muniix]

By the way, with the following I was explaining in another forum how the architecture of the PatRoVa reduces the spark advance and the duration of the combustion:


QUOTE from http://home.people.net.au/~mrbdesign...utoTechBRV.pdf about the Bishop rotary valve engine:

“This oblique flow through the window is responsible for one of the rotary valves most useful attributes - its strong in-cylinder tumble flow. The tumble ratio on engines with near square bore/stroke ratios is typically twice that reported for similar 4 valve engines. Unlike the poppet valve this high tumble flow is generated without any loss of volumetric efficiency (VE) and is responsible for very fast burn rates observed. Production based engines built in the early 1990’s had ignition timing of 15°, or less than half that of the best four valve engines.”

End of QUOTE

In the PatRoVa the combustion chamber (i.e. the cavity at the “top” of the cylinder head) is substantially more compact and more fatty and more concentrated around the spark plug than the combustion chamber of the Bishop rotary valve.

This compact area creates a flow choke point limiting cylinder filling, increasing pumping losses and adding to cylinder surface area increasing heat loss.

The high tumble flow in the PatRoVa remains strong even at the end of the compression (piston at the TDC) because of the shape of the cavity.

I don't know how you are going to create tumble or dual tumble flows from this geometry.

These characteristics make the required spark advance substantially shorter than in a Cross-Bishop rotary valve engine (and a few times shorter than in the best 4-valve engines), and the combustion ends shortly after the TDC.

You keep repeating opinions​ with no evidence, whereas Bishop had a dedicated CFD expert (the first to sucessfully model the turbulence generation mechanism during compression in a CFD simulation)
optimising flows, turbulence and combustion, this work was published in his dr. thesis which provides​ the facts based on CFD data and is matched with experimental measurements, the best correlation at that time. Including data from Kistler pressure sensors that cost $4k each, and known to die during detonation, they never experienced knock, ever saving them some money!

Bishop was supported by a major engine manufacturor and their $40 million a year in licensing income in 2000 with $15m RnD budget company wide. Bishop are a reference for how to write patents to protect and get income from.

Your diagrams clearely show that the air flows through a small flow area by comparison to the Bishop valve so it will be at 2-5 times the velocity without valve geometry to assist in turning the flow into the cylinder, requiring the inertial energy of the flow to be opposed if it is not to continue flowing inside the valve as it rotates. Flow velocities above mach 0.5 have various issues and this flow velocity is where peak torque rpm is achieved, so your peak torque rpm will be significantly lower and with far higher pumping losses required to negate flow inertia. Until you show some CFD flow streams it is just opinion that doesn''t agree with known fluid flow theory.

What is the flow coefficient through your small windows and are they sized equivelently larger to not restrict flow? What is the torque potential, you can work it out from the dimensions and flow coefficient.

The very first bishop valve where the flow at the roof was turned 90 degrees and then flowed straight down into the cylinder, the flow at the floor would seperate from the surface as it tried to turn into the cylinder reducing flow coefficient to just over 0.5.
Without that nice flow provided by the roof your flow coefficient will be lower, likly around 0.33.

What flow does get through the window will now be increasingly turbulent and the opposiing flows flowing into one another.

It took Bishop a lot of CFD effort to improve the flow coefficient through the window, by using a throat section at the bottom of the valve just before the window a hump causing flow velocity and pressure to increase resulting in the flow followig this curved surface avoiding flow seperations and turning it up to 60 degrees before entering the cylinder with long narrow windows so the flow was laminar as possible the coefficient rises to 0.8 and above as the flow angle varies from 60 degrees to 90 across the long window, it is the length that improves coefficient in turning flows. The window is sized accordinly to maintain velocity and pressure, remember that energy must be conserved.

Your flow structure from this point on is now guess work with high turbulence a given. You have many issue to address, opinions are like ... Simulation is the best method to keep people honest, vendors who don't like comments on their equipment from load and simulation testing are best to be avoided if you want success.

Remember that the bishop engineers are at the top of their industry, one went on to create the 2016 automotive innovation of the year, TJI turbulent jet ignition used by Mercedes and Ferrari in F1. Others are all dong world leading engineering, at Memjet, M&W Ignitions etc. The 2021 F1 engine rules should allow them again, and Mercedes will likely dominate again, Australia breeds some clever people.

It was the bans and then Hondas decision not to use a Bishop valve engine in Moto2 that denied them the opportunity to demonstrate how good it was. Then in July 2006 Arthur Bishop died. Now with no support from Mercedes Ilmor and Arthur no longer funding development it was over, the opportunity/timeframe to get multi million income from it was now unknown, a business decision then effectively shelved it. There being no commercial incentive or funding to continue the high investment and operating costs to continue. There being no way to demonstrate it as it was "Banned as a matter of urgency" to "Avoid competition".

So a Lighter, smaller, faster combustion, less heat loss leading to 6% less fuel needed for same power. Incorporating squish and dual cross tumble created large oval shaped Central flame kernel with area equivalent to a 30 mm round kernel, twice the size a single central plug produces.


Here is the link to the EU investigating the ban of the Bishop valve in MotoGP and F1.

http://ec.europa.eu/competition/antitru ... _250_3.pdf

[manolis]

Hello Muniix

A few months ago, in our private communication (via e-mails), you made, among others, some estimations / prediction / rough calculations about the poor flow characteristics of the PatRoVa.

You insisted.

After 25 replying e-mails to you, and being tired / exhausted to repeat the same “simpleminded” things, I proposed you to bet on your predictions.

Please, do publish the e-mail of January 13, 2017 (and the rest ones, if you like so).
I am sure the members of this forum discussion will enjoy it.



I have spent several hours reading the patents granted (or filed but not granted) to the guys of the multi-million Bishop team.

I admit I failed to understand the way the sealing means of the Bishop rotary valve are lubricated: just like the piston rings of the conventional 2-strokes they pass over big holes (the intake and exhaust ports on the Cross-Bishop rotary valve), yet they don’t leave any lubricant to get into the combustion chamber or to be lost towards the exhaust.
As explained in previous posts, the theories about the “dry lubrication with the carbon particles of the combustion” are not persuasive.

I also admit that I still do not get the real difference between the Bishop rotary valve and the original Cross rotary valve (or the rotary valve of Ralph Watson).
If anybody in this forum can explain, in simple words, their main difference, it would be great.



Your repeat writing the millions of dollars invested on (and lost by) the Bishop rotary valve project.


Here is a similar sad story:

For almost two decades EcoMotors was presenting in the press, in thousands of articles in paper magazines and in the web, their miraculous OPOC engine.

The founder of EcoMotors is Peter Hofbauer, a reputable auto industry engineer; his name can be found in some rotary engine (Wankel like) patents filed by the VW half a century ago.

Some of the investors of EcoMotors are regarded among the smartest guys in the world (Bill Gates, of Microsoft, invested 23.5 million dollars on the OPOC), not less smart than the investors of the Bishop rotary valve project.

The OPOC had the same basic problem with the Bishop rotary valve: they never address the lubrication issue.
The OPOC is based on the “total loss” lubrication of the conventional old 2-strokes.

The magazines around the world were publishing, again and again and again, the misleading promises of the EcoMotors board team (comprising big / known / reputable / successful names of the auto industry).


Somebody had to say “The king is necked”; the following comment of mine was published in “The knee slider” a few years ago:

“In EcoMotors they have the funds, they have the publicity (every time a guy in EcoMotors “coughs”, every magazine in the world publishes -or reproduces- an article for OPOC), they have the support (only the name of Bill Gates “opens” every door). What they don’t have is a good engine design.
Unless I am wrong, after several years there is not yet an OPOC in a car or truck for tests by an independent third party.
Get in the place of the independent inventors / researchers / makers and think how they feel seeing in the press, again and again and again, about the OPOC of EcoMotors, about how many parts less than the other engines it comprises (which is a false claim), about how many less fuel it will consume (which is also a false claim), about how “green” it will be (which is also a false claim), and so on.”

and predicts, more or less, the sad end of the story.


And what is the end of the story?

A few days ago I tried to visit the web site of the EcoMotors to see if they had some news.
And there is no web site, any longer.

The wikipedia has a complete page dedicated to the EcoMotors / OPOC and gives as “Official EcoMotors website” the: http://www.ecomotors.com/ Try it.

It is sad.

100 million dollars, or so, were lost on the OPOC.
And now, nobody of all those famous / smart guys involved in the “great, promising, game-changing, etc, etc, OPOC engine project”, paid the required a hundred, or so, dollars (not thousands, just dollars) to keep the web site of EcoMotors alive / active.


In comparison, the PatOP engine project of pattakon has a total cost, so far, around 10,000 dollars (including the patenting, the manufacturing of the prototype etc), i.e. some 10,000 times lower than the cost of the EcoMotors OPOC project.


The PatOP engine solves several crucial problems not addressed by the famous EcoMotors OPOC engine.

The Wikipedia does not mention the PatOP engine, at all.

A few years ago I added, at the “External links” section, at the bottom of the EcoMotors OPOC web page in the wikipedia, a link to the PatOP engine; a few weeks later they deleted it (congratulations to the wikipedia for their censorship).

Today, anyone who needs information about the PatOP can look at http://www.pattakon.com/pattakonPatOP.htm , or can communicate with the pattakon by e-mail, while nothing is now officially available in the web about the “promising” EcoMotors OPOC engine (nor it is possible to communicate with EcoMotors to ask anything).



Despite the many millions of dollars (as you like to write / repeat) invested in the Bishop rotary valve project (and the many famous and smart guys involved in the Bishop project), nothing is left.

Nothing at all.

Not one (just one) motorcycle having the Bishop rotary valve on the cylinder head for normal use or for road tests.



The PatRoVa rotary valve changes the game because it brings new and important characteristics not existing before.

The total force on the bearings of the PatRoVa rotary valve is zero.
Just zero.
No matter how high is the pressure in the combustion chamber.

And it needs no oil to lubricate heavily loaded sliding surfaces and sliding seals (the Achilles’ heel of the Bishop rotary valve for mass production / emission complied engines). Because there are not heavily loaded surfaces or seals in the PatRoVa.

As for its flow capacity, you should think “out of the box” to see how good it can be.

It becomes more obvious in the PatRoVa with the “tapered disks”:



two symmetrical tangential air streams (entering into the cylinder by the two symmetrically arranged chamber ports) move without affecting each other (each at its own half of the cylinder).
Like having “a ideal curtain” dividing the cylinder in two halves.


So, take another different look at the PatRoVa rotary valve.

And talking for “a different look”, did you achieve to look at the above animation stereoscopically?

Many people cannot look the proper way and instead of insisting, they think it cannot be done.

Thanks
Manolis Pattakos

[manolis]

Hello J.A.W.

The following drawings show a 2-stroke Flat-Head PatRoVa:












The piston is shown in the BDC (bore 116mm, stroke 60.8mm, i.e. as in the 4-stroke Desmo Ducati Panigale 1299)

The blue rotary valve spins at half crankshaft speed.

There are two exhaust ports on the ceiling of the combustion chamber, and two “cuts” on the rotary valve.

The passageway around the hole for the spark plug (at the centre of the cylinder head) provides “pressure” at the top of the rotary valve, so that the rotary valve can spin without friction (the flow of the exhaust gas happens only through the bottom side of the rotary valve).


If the exhaust ports at the top of the combustion chamber seem not big enough, then a different version can be used wherein the rotary valve rotates at crankshaft speed and serves two neighboring cylinders (twin even firing 2-stroke), with the rotation axis (or the shaft) of the unique big-diameter rotary valve being between the two cylinders; in such a case, the area of the exhaust port on the ceiling of the combustion chamber can be as big as the piston area.

Thanks
Manolis Pattakos

[J.A.W.]

Most excellent visualisation of what I had in mind, Manolis, & very much appreciated, ta..

[Pinger]

Cracking thread (yes, I read all 93 pages)with some real knowledge and endeavour on display. A couple of points (and questions) on some of what has been discussed. Re sleeve valves (I saw no mention of). Did Ricardo not experience severe scoring of sleeves when the motion was vertical only? No mention either of him ‘knife-edging’ the sleeves’ upper edges (the sealing breakthough IIRC). The ‘knife-edging’ reputedly made the sleeves very vulnerable to damage up to and during assembly.

Re FOS cylinders. Hardly new (if I’ve understood correctly – a belt of exhaust ports utilising the cylinders full circumference with the same below for transfer?) it is a feature of at least one model aero engine (DC Spitfire) – its conical piston crown is a notable feature apparently missing in the larger current versions. Is this a design that requires or would benefit from high crankcase compression to propel the transfer streams high into the cylinder? Is the Ryger concept (which looks suspiciously similar to Bernard Hooper’s stepped piston design crossed with cross-head to my eyes) the best suited bottom end for FOS? Was FOS porting imagined to be part of the Ryger (high crankcase compression) concept (prior to the detail becoming available)?

Uniflow (if you are still looking in), thanks for the insights on injector positioning re fuel injection. Can I ask, when you say a reed motor ‘on the pipe’ has its reeds open all the time, is that even on the pistons downward stroke? If so, is that due to the momentum of incoming charge (courtesy of the extreme pressure differentials created by the ‘pipe’)?

Two-strokes in F1? Yes!!!! But on what equivalence basis, as the thread has discussed, is harder to know. Personally I’d look to the 2T’s other virtues and tinker with the minimum vehicle weights/fuel allowance. However, 440hp/litre 2T isn’t necessarily where I think the 2T needs to be pitched.

Re road transport. The 4T CI engine is near the end of its development path. The 4T SI is heading in the same direction (the downsized pressurised units have only been a partial success). The 2T however can deliver without the NOx inducing pressures the 4Ts are dependent on. The obvious bugbears – prejudice, and charge loss (important even on DI motors – crucial for non DI motors) are not insurmountable.
The FAST concept >> http://www.pit-lane.biz/t5235-2-stroke- ... tim-hickox and the work done by Primavis >> http://www.primavis.eu/about point to direction which hasn’t been exploited within the more conventional 2T architecture (though blower scavenged engines have to a degree (unkowingly!) utilised it) which I believe to be essential to win over an auto industry heavily resistant to change and fearful of technologies new to it (the first prejudice). Has anyone got more information re the above and/or blower scavenge comparisons? Also, if anyone has info on the Thornhill(?) V6 that Jaguar(and/or Ford) played with before abandoning it – I’d love to see it.

Another topic of interest I’m keen to hear you views on (and it’s relevant to the thread title!) is recovering energy from the exhaust via a turbine. This applied to a simple 2-stroke (power 70 – 120hp) which provides its main output at its crank, the exhaust half of a turbo is the obvious candidate for turbine duty, but how the hell to ‘gear’ it to the drive train? Any thoughts?

Enough, I think for an opening post. Looking forward to reading your views – especially regarding the future of 2T for road transportation. Don’t hold back (as if!)