2 stroke thread (with occasional F1 relevance!)

[FW17]

its just pure inefficient. you "dirty" up your fuel or send more fuel out the outlet valve. Its probably going to cool the outlet gasses which is all well and good if you worried about Nox emissions but not good if you want to burn away as much Co2 as possiable. Besides how you going to lubricate it? have a sump in a two stroke? or you going to let it run dry when its a 4 stroke? theres no NEED for this engine. especialy with VVTI, turbo charging, DPF filters, ERG valves, catalistic converters.

The Ricardo engine is a direct injection

Lubricant cycle can be made as a dry sump as you would see today with a turbo charger

[Edis]

its just pure inefficient. you "dirty" up your fuel or send more fuel out the outlet valve. Its probably going to cool the outlet gasses which is all well and good if you worried about Nox emissions but not good if you want to burn away as much Co2 as possiable. Besides how you going to lubricate it? have a sump in a two stroke? or you going to let it run dry when its a 4 stroke? theres no NEED for this engine. especialy with VVTI, turbo charging, DPF filters, ERG valves, catalistic converters.

All things that were made to allow a 4 stroke engine to provide more power and produce less harmfull emissions. oh and the last 2 sroke car engine i remember was a small car producer from austria who produced a 2 seater 1.2ltr L4 two stroke...untill it was banned for being dirty..onto of being loud and guttless

All larger two stroke engines use separate spool pumps (not the crankcase), direct injection and regular pressurized lubrication to avoid the problems normally associated with two strokes. That you blow some air out through the exhaust is of no concern since the fuel injection doesn't begin until after the exhaust port has closed.

Turbocharged two stroke engines like these are capable to exceed 50% efficiency

[piast9]

I think there would be some packaging issues with that kind of engine in a F1 car.

[Federico]

I think these huge diesel engines uses overhead poppet valve with scavenge ports. I don't think this design is applicable in a race petrol engine

[Ian P.]

While it may not appear to be important, but the key factors for 2-stroke marine engines like this are packaging, weight and total power. Sound familiar.???
The engines also need to last "forever", be fuel efficient and run on literally crap. They usually have clean fuel for port and cheaper bunker for sustained running.
In many ways a more restrictive design basis than an F1 engine.
Maybe some CG issues in an F1 car.
Not often you see an engine where you can climb inside the cylinder to check it out.

[autogyro]

http://en.wikipedia.org/wiki/Rolls-Royce_Crecy

http://www.sa.hillman.org.au/TS3.htm

Havnt we been here before?

[Edis]

I think these huge diesel engines uses overhead poppet valve with scavenge ports. I don't think this design is applicable in a race petrol engine

These engines usually use uniflow scavenging



I can't think of a reason why they can't be used in F1, but I also can't think of a reason why they should be used instead of four stroke engines. Just because something can be used, it doesn't mean it should be used.

The Deltic is also way cooler than the Crecy
http://en.wikipedia.org/wiki/Napier_Deltic

[autogyro]

The Deltic is cool.
We have a company named after it Deltic Engineering and usethe engine on the logo.

The Crecy was an aero engine.
We are discusing a modern version on another site forum.

Both these engines IMO surpass anything used in F1.

F1 is a four stroke poppet valve over regulated old boys network.
2014 will see it pull up its knickers or go down.

[Edis]

The Deltic is cool.
We have a company named after it Deltic Engineering and usethe engine on the logo.

The Crecy was an aero engine.
We are discusing a modern version on another site forum.

Both these engines IMO surpass anything used in F1.

F1 is a four stroke poppet valve over regulated old boys network.
2014 will see it pull up its knickers or go down.

No, they don't surpass anything used in F1 really, what they are is different. But different does not mean better.

At the time of the development of these engines there was a lot of interrest in sleve valves due to the problems encountered with poppet valves. Not to mention personal belief of some engine designers. But rather than a switch to sleve valves, those problems were resolved by better detail design of the poppet valves.

[autogyro]

The Deltic is cool.
We have a company named after it Deltic Engineering and usethe engine on the logo.

The Crecy was an aero engine.
We are discusing a modern version on another site forum.

Both these engines IMO surpass anything used in F1.

F1 is a four stroke poppet valve over regulated old boys network.
2014 will see it pull up its knickers or go down.

No, they don't surpass anything used in F1 really, what they are is different. But different does not mean better.

At the time of the development of these engines there was a lot of interrest in sleve valves due to the problems encountered with poppet valves. Not to mention personal belief of some engine designers. But rather than a switch to sleve valves, those problems were resolved by better detail design of the poppet valves.

I do not believe the interest in sleeve valves was motivated by the problems with poppet valves. Sleeve valves give a far higher potential for better gas flow.
Loop scavenged two strokes are probably unbeatable in this respect.

[Nowhereman]

For F1 applications, a 2 stroke derrivative would dominate in the HP / weight catagory.
2 strokes can be much lighter than 4 stroke designs.
I also believe that do to the common pratice of the engine being a stressed member of the chassis, a 2 stroke design could be developed to promote better chassis stiffening than it's 4 stroke counterpart.
The F1 should allow 2 stroke designs to compete with 4 stroke designs if F1 is truly the pinnacle of motorsport.

[Tommy Cookers]

I do not believe the interest in sleeve valves was motivated by the problems with poppet valves. Sleeve valves give a far higher potential for better gas flow.
Loop scavenged two strokes are probably unbeatable in this respect.

The interest in sleeve valves was based on Ricardo's finding that sleeve valves ran cooler than poppet valves, this improvement wrt detonation enabled much higher mep (supercharged) with the low compression ratios envisaged with 1920s fuel (a skewed comparison, like so many). That apparent advantage largely disappeared with the sudden improvement in fuel quality that followed.
Once Heron's internally cooled exhaust valves were fully developed (in the USA, handily before WW2), the sleeve valve was redundant. The huge US sleeve valve engine programs were abandoned early in WW2

If RR had known to silver-plate the bigend faces of the Vulture (like Wright etc) the Sabre would not have appeared in numbers. The Sabre was a reserve engine, resulting from a policy of having technical reserves.

C.F.Taylor said that the usual (eg Sabre) type of sleeve valve was lacking in port area. I think this was why Ricardo's interest turned to the 2 stroke open sleeve as realised in the Crecy.

All cylinder ported engines are relatively starved of port area as larger bore:stroke ratios are used (for higher power via higher revs). This is broadly a historical trend, associated with broad historical progress in fuel quality.

Poppet valves are advantageously aligned wrt gas flow and size, and to use overlap. Crucially, poppet valves areas are relatively larger at larger bore:stroke ratios. F1 uses this to great advantage, now that valve action is so improved via pneumatic springs. F1 b:s ratios are now around 2.4:1 (this is startlingly large)

Poppet valves are used in some 2 strokes ?


Would the 2 stroke prevail in current F1 ?

GP motorcycle 2 strokes always had relatively low bore:stroke ratios to allow sufficient port depths (a fraction of stroke). Shortening the stroke for more revs and power wouldn't work because the port areas would not increase. All these engines had b:s ratios close to 1

GP motorcycle noise limits introduced about 35 years ago were very hard on the 4 stroke, the last ever (flat 4, never raced) MV Agusta failed the noise test at full rpm when producing no power (driven electrically) ! The last MVs that actually raced made as much noise as a grid full of 2 strokes. They were competitive, having a stroke short enough to rev about 40% higher than the 2 strokes


Would 2 strokes work in 2014 style F1 ? ...... good question !

The Ford Ka was designed for a 2 stroke (that's why the engine bay could only take the pushrod engines as substitutes).
Don't modern 2 stroke outboards meet exactly the same environmental rules as 4 strokes ? ............

but F1 is pretending to be 'road relevant', and has been forcing the conventional for 30 years.

[ESPImperium]

Cooper once made a 2 pot engine specifically for Monaco sometime in the 50s i remember Peter Windsor saying. It had enough torqure that it could pull a building appart. The engines horsepower wasnt that much, something like 80 or 90 but it had something like 8 times that figure in lbs/ft of torque. The engine was all about acceleration, it could pull out a lead from a corner in a heart beat, however by the time the more powerful engines in terms of horsepower and pots had cought up with it it was time for breaking.

Id like to see what the engine guys could come up with for a small 2 pot like a V-Twin ot Inline-3 that weighed somewhere in the 45 to 50 kilo mark for F1 that revved high enough to get a great sound and didnt cost the earth to build or run for a team that also had a good shelf life on it. However in todays F1 there would be Turbo and Superchargers added somewhere with KERS, HERS, VERS and SERS. Id just want a good driveable I-3 that had a massive and driveable torque band with a high volume supercharger on it with a fuel flow limit of 1.5L per 5Km. Maybes some KERS as well, posibly about 15 seconds a lap as well would do well with battery changes evert 4 races and engine changes every 5 and gearboxes every 5 as well. I think something like this, something that was cheap enough would be a massive plus point for an affordable engine formula not just for F1 but maybes for another formula.

[Tommy Cookers]

This was the 1100cc J.A.P. engine in the usually 500cc Cooper ? Total dry weight 530 lb

Raced at Monaco GP by Harry Schell ?

Stirling Moss finished 3rd in one at Lake Garda F2 race in 1951 ? (then Ferrari offered a drive)

Aurelio Lampredi took Ferrari away from F2 V12 to 4 cyl, then he designed a 4valve 2.5 litre TWIN for 1954 F1 (184 bhp ?)

Fiat make twin cylinder engines now, don't they !


An early Marcos was 1500cc for a record attempt, a Jaguar 6 cut down into a compact 3 cyl

[PlatinumZealot]

Apart from the fact that there will be a brand new four stroke turbo formula from 2014 you also find a lot of environmental concerns against two stroke engines. Unless something fundamental changes I see practically no chance in the next decade. Two stroke engines are not fuel efficient and they have no closed lubrication circuit. The FiA will be dead against the technology.

you might want to educate your self a little the new two strokes are cleaner and more efficient than there 4 stroke counter parts for the same power.

Have a source? Or example? Other than politics, There must be a reason why they are not common on the roads now.
Imagine two cylinder two stroke turbo city cars, dream come true? Looking at the way a 2 stroke works the window of intake is so small that you have to run really high boost to clear the exhaust air out (depending on the degree of EGR that you want of course). but yes, 18000 rpms would sound like 36000 rpms with a two stroke. Power would be nasty!