2/4SIGHT: This Engine can Switch Between 2-Stroke and 4-Stroke, Fuel Savings of up to 27%
by Michael Graham Richard, Gatineau, Canada on 04. 2.08
Researchers in the UK have developed a new kind of engine. It could be called a hybrid, but what it combines is not two power sources but rather two mode of operation: 2-stroke and 4-stroke. The goal is to be able to significantly downsize the engine and get the fuel economy benefits of smaller displacement, but to be able to switch seamlessly to 2-stroke mode when more power is required at high loads and low speeds.
The prototype (seen above) is a modified 2.1-liter V6. After tests at the University of Brighton, it has been found to produced performances similar to a 3 to 4-liter engine, with fuel savings of 27% and emissions reduced by about the same amount.
The next goal of the researchers is to incorporate the prototype engine in a vehicle.
It isn't the first time that this kind of hybrid 2/4-stroke engine design has been looked at, but in the 80s and 90s the technology simply wasn't advanced enough. "According to Ricardo, the only reason the company is able to make a viable system now is because of the software that controls the gas exchange and engine modes."
If all goes well and nothing major holds back the adoption of such a technology, it could make a big difference in the next few years. Of course, the goal is to move away from fossil fuels, but realistically, that will take a while and in the meantime a 30% improvement in efficiency would be welcome (trucks with 2-liter engines, cars with 1-liter engines). No reason why these couldn't run on cellulosic ethanol...
::Nonelectric Hybrid Engines, ::Ricardo and Partners Complete 2/4SIGHT Prototype Program; Projected 27% Fuel Savings,
See also: ::Honda Looks Into Recycling Engine Waste Heat, ::Citroën C2, Now With Stop & Start Technology
As the attached article indicates, existing 2-cycle technology is relatively polluting.
"As the attached article indicates, existing 2-cycle technology is relatively polluting. "
The article also says that this will be Euro 4 compliant, and be able to meet future requirements too.
To all my knowledge a 2 stroke engine needs lubricant in the fuel, which is added oil. Thats why they stink.
Well ... for the 1-liter car part, quite a few cars in europe use 1 liter gasoline engines, like my personal Peugeot 106, and for light trucks, Turbodiesel engines, which are quite torquey are in the 2-liter class.
Every engine consumes oil to lubricate himself, 4-stroke engine just use a little, whereas 2-stroke engines have the oil mixed with gasoline. I have heard of 2-stroke engines lubricated like 4-strokes a while ago. seeing the operating mode in "2-stroke like", it still uses a 4-stroke lubricating part. 2-strokes engines do not have valves, and have the air/gasoline mixture incoming by a hole on the side of the combustion chamber. I believe that's part of their high power-vs-displacement ratio.
Two strokes make more power because there is combustion on EACH revolution of the crankshaft rather that EVERY OTHER revolution of the crankshaft as in a four stroke.
The is also a split piston engine that fires on each revolution
of the crankshaft but where four strokes are divided between two pistons performing two of the strokes simultaneously and combustion only happening in one of the cylinders.
Treehugger covered a version of this this engine from a company named Scuderi.
With such an engine, the 2-stroke mode would probably only be used rarely (when climbing a hill or towing). That's the beauty of it. You can downsize because you know that when you really need it, you can switch to a more powerful mode.
By the way, there are two stroke engines that don't mix oil and gas, that carry oil in the crankcase just like a 4 stroke.
Do a web search on "Orbital engines".
They utilize direct fuel injection rather than the intake port in the side of the cylinder.
Aprilia makes a scooter that does something like this.
There is much lower hanging fruit than ICE tech at this point:
1. Mass reduction
2. Aerodynamics
3. Hybridization
4. Increased electrification
I’m also skeptical that the 2/4 strokes will meet California emission standards
Bottom line is that you are still burrning fuels, but at a much less amount. Another thing in order for you to compleately get rid of the hydrocarbons that are expended into the atmosphere you have to invent a new exhast system.
Two strokes have enormous potential. I see one with intake valves and a super charger. BUT, can you please stop saying: "two cycle". It's just not right!