Two Stroke Challenge

[roadster]

Has it occurred to anyone that a direct injection blown petrol engine could be ideal for running as a two stroke?

You would need a different camshaft and some sort of low rpm blower ( maybe electric ?)

Then a different electronics package. Perhaps a tuning company would like to take this on? Not with my car though.

Is that what the TS stand for?

[horkin]

Has it occurred to anyone that a direct injection blown petrol engine could be ideal for running as a two stroke?

You would need a different camshaft and some sort of low rpm blower ( maybe electric ?)

Then a different electronics package. Perhaps a tuning company would like to take this on? Not with my car though.

Is that what the TS stand for?

Then you really WOULD start the "ticking" thread off all over again with a vengeance

[GeneralPurpose]

Not sure this thread is posted in the right place...but it's interesting all the same. It has been tried and was totally impractical. Lubricating the engine under high duress was the problem along with very very poor fuel consumption and emissions. The engines broke all the time, especially the pistons and rings followed by the big end rollers. Although two stroke diesels worked fine and were fitted into trucks and buses for years. I've even rebuilt one for an enthusiast some years ago. Essentially though, there isn't a way round the appalling fuel consumption and emissions problem of two strokes, blown or not. The closest thing today would be a 'Rotary' engine with a blower, they aint that good either and still have problems with the rotor seals after quite moderate mileages if you actually drive it with gusto! Very smooth though...

Edited 24 January, 2011 by Estate Man

[roadster]

Not sure this thread is posted in the right place...but it's interesting all the same. It has been tried and was totally impractical. Lubricating the engine under high duress was the problem along with very very poor fuel consumption and emissions. The engines broke all the time, especially the pistons and rings followed by the big end rollers. Although two stroke diesels worked fine and were fitted into trucks and buses for years. I've even rebuilt one for an enthusiast some years ago. Essentially though, there isn't a way round the appalling fuel consumption and emissions problem of two strokes, blown or not. The closest thing today would be a 'Rotary' engine with a blower, they aint that good either and still have problems with the rotor seals after quite moderate mileages if you actually drive it with gusto! Very smooth though...

Isn't direct injection the answer to poor fuel consumption though? If you only blow fresh air out of the closing exhaust valve no fuel is wasted and the extra air cleans up the exhaust.

Regards Roadster

[Fatbloke]

Research into 2-stroke technologies continues though as a way of getting greater thermal efficiency from future synthetic and bio-fuels. Direct injection is part of it and variable compression systems from managed forced air charging, interesting stuff

[duffman502]

Not sure this thread is posted in the right place...but it's interesting all the same. It has been tried and was totally impractical. Lubricating the engine under high duress was the problem along with very very poor fuel consumption and emissions. The engines broke all the time, especially the pistons and rings followed by the big end rollers. Although two stroke diesels worked fine and were fitted into trucks and buses for years. I've even rebuilt one for an enthusiast some years ago. Essentially though, there isn't a way round the appalling fuel consumption and emissions problem of two strokes, blown or not. The closest thing today would be a 'Rotary' engine with a blower, they aint that good either and still have problems with the rotor seals after quite moderate mileages if you actually drive it with gusto! Very smooth though...

Im assuming you mean detriot deisels I regularly build these engines at work there ok, just very dirty emmisions wise and generally having said that the design is aincent (sherman tanks had detriots in them) and would love to see a new take on the two stroke

[Jim H]

I was going to mention the new FIAT 'TwinAir' engine in the 500. However I think that's 2 cylinder, but 4 stoke (with a turbo).

What I would be interested in is a supercharged diesel engine in a car. I've seen a marine 2-stoke diesel with 2 or 3 supercharges, and a massive turbo, but never one in a diesel car.

[GeneralPurpose]

Isn't direct injection the answer to poor fuel consumption though? If you only blow fresh air out of the closing exhaust valve no fuel is wasted and the extra air cleans up the exhaust.

Regards Roadster

Unfortunately, I've not seen a turbo'ed or charged petrol two stroke, I suspect because they would self destruct due to poor lubrication. But I stand to be corrected if anyone has seen one...do tell, I'm interested! I have seen charged diesel two strokes (detroit diesels) but poor consumption and emissions nailed the coffin lid. There isn't direct injection with a petrol two stroke, just indirect injection (although almost non are injected due to all sorts of difficulties with design and reliability) and this would be 'fired' into the crankcase under the piston ready to be transferred to the upper cylinder as the piston goes down on the power stroke. The crankcase pressure forces the new charge into a transfer port in the side of the cylinder bore and then into the cylinder bore above the piston ready for compression. However, as it does so it forces the old gas that has just been spent on the power stroke out of the exhaust port into the exhaust system. There isn't an exhaust valve on most two strokes but in some instances there is a rotary gate valve of sorts sitting in an exhaust port. However, nearly always regardless of design, some of that new fresh charge of fuel, being used to push out the old gases before compression, also goes out with those spent gases and is lost making emissions deadly and accounting for poor fuel economy. Porche carried out some work on two stroke engine design in the late nineties and early noughties, with some good performance results but failed to come up with any workable, efficient, and reliable engine design and thus it was largely abandoned. I suspect we won't ever see a large scale future for the two stroke. It is banned in many states in the USA and Europe frowns on even the cleanest of two strokes...because they are very dirty, and again have been virtually banned in all but tiny motorcycles and scooters for road use. However, maybe new materials might change things in the near future, but this won't over come the inefficient design and fuel usage compared to a four stroke.

I apologise for the above largely incoherent ramblings!

[raisbeck]

Not really a Fabia thread but its an interesting read all the same.

There does exist a 4 mix engine that uses 2 stroke premix fuel in a 4 cycle engine......clever stuff. Stihl make it for small engines

Click here

It would negate the need for a sump making the engine lighter with less resistance.

As a self confessed fan of 2 stroke motorcycles in the past......RD350 RG500 I for one will inhale a lungful of gloriously burnt 2 stroke oil as the Fabia 2 stroke goes past

[GeneralPurpose]

Not really a Fabia thread but its an interesting read all the same.

There does exist a 4 mix engine that uses 2 stroke premix fuel in a 4 cycle engine......clever stuff. Stihl make it for small engines

Click here

It would negate the need for a sump making the engine lighter with less resistance.

As a self confessed fan of 2 stroke motorcycles in the past......RD350 RG500 I for one will inhale a lungful of gloriously burnt 2 stroke oil as the Fabia 2 stroke goes past

Thanks for that link Raisbeck. Very very interesting. This type of design was tried a number of years ago in the aviation industry to save weight on Ultarlights and microlights. I even held a group 'A' licence at the time and was looking forward to a flight in the test bed in my capacity as a ppl and engineer. It would have made a nice change from my 150. It didn't get past the initial testing stage unfortunately and my flight never took place. Lubrication was still an issue as it turned out with the destruction of several test engines on the ground. Looks like it may be a goer now but 50.1 is still messy by todays standards so surely wont' go anywhere in a road based vehicle I wouldn't have thought. Interesting thought though...about the two stroke Fabia. After all, remember the Saab 3 pot two strokes.

[lol-lol]

Actually the most powerful internal combustion engines evert biult are two stroke (diesel but they could make petrol ones now we have perfected firect injerction of petrol).

These engines are in several types of scavenge ie ported like a 2 stoke motorbike engine, or axial flow ie ports at the bottom uncovered by the piston and a single valve or second piston at the top.

These engine can be up to 40,000 hp or so, 12 cylinders and directly drive the propellor ie at around 100 rpm. Several turbochargers the size of cars, the engines can weight up to 1000 tons and are about 4 storeys high.

They have the highest thermal effeciency of any internal combustion engine ie approaching 50% compared to only 25% for most high speed diesel.

The bores are up to a metre or so and stroke about 2 metres.

Emmissions may be a problem I guess as the scavenge part of the cylce is much shorter of course.

Two strokes will probably have their day again soon now we have perfected direct injection petrol engines, better emission contol etc. Like Dr Felix ****el's (one cannot write his name) engines they can be much more powerful than 4 strokes for the same size

Edited 26 January, 2011 by lol

[Can]

If your referring to shipping engines then yes they have power but they also don't see the same RPM as you'd expect out of a "modern consumer engine" They also are mainly viable due to the filth they will run on it's more like tar than fuel. And they are being overshaddowed by gas turbines these days as fuel efficency comes more and more into importantce. They also are not very suitable for high speed applications

[GeneralPurpose]

sorry could not delete this

Edited 27 January, 2011 by Estate Man