Lotus Teases With a Fuel-Agnostic Two-Stroke Engine 269
JohnnyBGod writes "Lotus claim to have invented a new, more efficient engine design. The two-stroke, flex-fuel engine can achieve, according to the surprisingly technical press release, 'approximately 10% better [fuel consumption] than current spray-guided direct injection, spark ignition engines.' The engine has a sliding puck arrangement to control its compression ratio, and has direct injection and a wet sump, to eliminate fuel leakage to the exhaust and the need to mix oil with the fuel, two common problems with two-stroke engines. Lotus engineering have released a video explaining the engine's operation."
Re:What took it all so long?? (Score:4, Informative)
Various theories hint at the interests of the oil lobby to continue four-stroke dominance (just look at the low mpg of most american manufacturers in general) and perceived customer comfort being the most widely used trump. High fuel efficiency does not usually provide sporty acceleration, low engine noise, and high torque at low revs.
That being said, no doubt many consumers don't care as much about that as the marketing departments of the automotive industry. In reality, noisy diesels have sold well in Europe (thanks in part to diesel fuel subsidies) and customers have bought poor performing, smaller cars for everyday use. They just don't make big margins on cars that sell for less than €8000 new. So once again striking a balance between shareholder interest (increasing profits) and global economic / ecological interest (decreasing emissions and oil reliance both by better fuel efficiency and better combustion of cleaner, more varied fuel) is an impossible mission.
Until oil prices go up, don't expect any good technology to prevail. The four stroke petrol engine will die, but not before oil costs increase.
Re:What took it all so long?? (Score:1, Informative)
Diesel fuel subsidies in Europe!
Wow, that's impressively wrong, almost a slashdot record.
Re:What took it all so long?? (Score:2, Informative)
Not to mention the fact that modern diesels are most definitely not "noisy". Americans in general are painfully ignorant of modern diesel technology, which is a shame.
Toyota has a 2.2 turbo diesel engine so smooth that they are able to balance an upright coin on the engine cover with the engine running at idle, without knocking the coin over. Impressive.
Re:What took it all so long?? (Score:5, Informative)
Don't forget one of the big 2-stroke killers in the USA was the as usual the EPA. Because they set at the emissions requirements as ratios; rather than say an absolute value per horsepower hour. A 2 stroke looks dirty compared to a four stroke if you compare the various amounts of controlled gases in a sample but they are often allot better in absolute terms; because they can do more work per unit of displacement and revolution.
Re:What took it all so long?? (Score:4, Informative)
Something like 50-60% of new cars sold in Europe for the last few years are diesel. Nobody seems to see a problem with them.
nb. This figure applies to luxury cars (Mercedes, BMW, etc) as well. The rich people aren't seeing a problem either (in fact diesels are very good for long-haul highway driving).
Diesel engines would be a far better match than gasoline for American tastes (ie. lots of torque at low revs), I can't imagine why they don't use them.
Re:What took it all so long?? (Score:5, Informative)
"In reality, noisy diesels have sold well in Europe "
Speaking as an Englishman and part time car nut: noisy diesels would sell rubbish,
My GF's diesel Ford is quieter above 30mph than my petrol Honda, once you get above about 2000rpm when the turbo starts to kick in the diesel has more torque and the difference in noise is impossible to tell, but the extra torque means that you can rev the diesel lower. At idle my petrol Honda is slightly quieter but the idea of noisy/dirty diesels is old.
Now at peak revs the petrol produces more power and I don't see me putting a diesel engine in my motorbike anytime soon, but for me the competition in none race cars has already been won by the diesel.
Except of course that the last Monte Carlo 24 hour race was won by a diesel...
Re:What took it all so long?? (Score:4, Informative)
I don't know what technical marvels they implemented to get 168mpg.
From my understanding, it'd be set up like the huge ship based two stroke diesels. You utilize a turbocharger and direct injection into the cylinder. That way you're not blowing gas/oil out with the exhaust. You can control precisely how much and when fuel is introduced into the chambers.
Then you end up with an engine that's almost half the weight for the power. Cooling needs can even be reduced because you can use the air during the flush phase to help cool the engine.
Re:What took it all so long?? (Score:4, Informative)
Cars, choosing them is one of the areas where decisions of people are being extremely influenced by perceptions and urban myths.
You know your extremely visible purchase will be witnessed by many people, you might want them to look at it in particular (depending on the area) way. Also, since it's a non-trivial expense, you rationalize your choices excessively. All this creates quite complex behaviors.
Re:What took it all so long?? (Score:2, Informative)
According to Wikipedia [wikipedia.org], Diesel has the highest energy density of all the more popular fuels and as anyone who has ever driven a new diesel will know, torque, noise, etc. are non-issues.
Would we even be having this silly discussion if not for those blasted average Americans? =P
Re:10% improvement isn't that much (Score:5, Informative)
Specifically because retarded people weren't able to make the distinction between rape and rapeseed, they call the plant Canola on this side of the pond.
Re:What took it all so long?? (Score:4, Informative)
FYI, soot is not the only emission to look out for, NOx emissions of a diesel are the other headache. The Issue is that you can directly trade NOx emissions for Soot emissions visa/versa simply by changing the injection timing, while making the same power. Soot I don't believe is a green house gas, and is more of a local air quality item. So any manufacture can make a very clean diesel engine that makes no soot, NOx be dammed, IE European standard. So that is what you saw, starting after 2000 manufactures eliminated the soot. Then in 2008 NOx was the driving regulation in USA, so they brought back the soot, and added in Soot filters to capture that out of the exhaust and burn it later.
Also The amount you refine petroleum the reduced energy content, but also the cleaner burning. So diesel is less refined, and thus has more energy content, but wasn't as clean of burning. So now we refine it more, make it cleaner burning at a cost.
Re:What took it all so long?? (Score:3, Informative)
I've got a 2002 Jetta TDI myself, but I like to be able to hear my engines. In fact I've advanced the injection timing at idle 5 from stock (which on mine was 0.6 BTDC at idle). This gives me much better fuel economy and a bit more power too. All you need is a Ross-Tech VAG-COM or equivalent $20 Ebay knockoff and it takes about 2 minutes to do, all on the computer. The motor will immediately sound different, better in my opinion, but it is louder and actually sounds like a diesel afterwards. It's also completely reversible if you don't like it, but I suspect the few extra MPG you'll get will more than make up for it.
The quick and dirty howto is: With the car running, plug in the VAG-COM to the computer and the OBD2 port, open up the VAG-COM software, click Engine, login with 12233, click Adaptation, pick Channel 3, 4 or 5 (can't remember off the top of my head) and you will see the injection timing BTDC and a couple other measurements. Add 100 to the default of 32768 for each degree of advance you want. The maximum is 5 degrees in software, any more and you have to rotate the injection pump under the hood (not for beginners!). It's fine grained so you could go 1.25 degrees if you want by adding 125. I just added 500 (33268) and tested and saved. That's it. Your fuel economy instantly improves. If you don't like it, set it back to 32768 and save it, and your motor will go back to sounding like it did before.
NB: You can only do this on the injection pump style motor, the venerable ALH, which was installed from 1999.5 to 2003. The PD style motors (BRM, BEW, BHW) were installed from 2004-2006.5 and you can't do this adaptation. On the newer common rail motors (CBEA) it's also not possible (2009+). I'm talking North American engines and model years here, I'm not well versed on the European models.
Either way, check out the TDIClub if you're not already a member on the forums. Tons of little tricks and tips to make your TDI'ing much more pleasant. That's where I learned everything I know about them.
As for the newer motors being quieter, yes they are. My mom drives a 2009 TDI and you can barely hear the engine at all from inside the car. Standing outside next to it, it's barely noticeable that it's even a diesel. Tons of power and can VERY easily get you into trouble with radar-wielding cops.
Re:10% improvement isn't that much (Score:4, Informative)
Canola isn't actually rapeseed, it's a crossbreed. Its name comes from Canadian Oil Low Acid. It was developed to have an edible form of rapeseed and now is grown across the world. The Brassica genus includes everything from mustard to rutabega.
Re:What took it all so long?? (Score:2, Informative)
Diesel emissions are awful if there are no emissions controls, true. However, there are many technologies out there that can capture or incinerate diesel soot on the exhaust. The problem has been that the EPA would not approve diesels in passenger vehicles with consumable emissions control systems (such as urea) and the sulfur content of diesel fuel was (until recently) too high to simply use particulate filters and catalytic converters.
With modern emissions control systems, light-duty ultra-low sulfur diesel engines are both more efficient and cleaner than gasoline.
Old 2-strokes are NOT "better in absolute terms" (Score:5, Informative)
I learned to drive in a 2-stroke car -- a 1968 Saab, AFAIK the last 2-stroke car that could legally be sold in the US (50CID was the limit for that year, it was at or a hair under). They are not better in absolute terms, old style 2-strokes are just plain filthy. Their rear mufflers would not rust, instead they would become plugged with a mixture of soot and partially-burned gunk. If you left one of those cars idling for too long next to another car, you would leave an sooty oily spot from the exhaust. You could rejuvenate a muffler, if you had access to a trash fire or bonfire, by cooking it to bake/burn off the gunk.
Using synthetic oil for lubrication helps a little bit, because it is formulated to burn better, but in general, there is no way that these cars were cleaner.
So -- I actually drove one for years, actually worked on their exhaust system, actually left one idling next to another car for too long, and have seen all this with my own eyes. Where did you get your information? I'm curious to know what would cause someone to spout such obvious nonsense with such self-assured authority.
Re:What took it all so long?? (Score:4, Informative)
What? I guess it depends how you define efficiency but for equivalent rotations of the output shaft a Wankel engine sweeps twice it's measured volume compared to 4 stroke 4 pot, that's why they have appalling mpg, they're small but they definitely not efficient.
Re:What took it all so long?? (Score:5, Informative)
That's only true because they have one ignition event per revolution per cylinder. When you burn gas every revolution rather than every other revolution, you're going to perform more work per unit of displacement, per revolution yes.
But you aren't necessarily going to perform more work per volume of fuel consumed, or more work per volume of pollutants released.
The common 2 stroke engine blows a lot of gasoline (unburned hydrocarbons) out the exhaust, because the exhaust port must, by the nature of the common 2 stroke, be open long after air and fuel is sucked into the engine.
Likewise, they produce foul smelling fumes, because oil must be mixed into the fuel. The common 2 stroke uses the crankcase as a pressure chamber to force air into the cylinder. Because the crankcase cannot be filled with oil, the fuel it's self must lubricate the engine, requiring a mix of oil to be introduced to the gasoline. The result is an engine that smells like a 4 stroke with badly worn out rings and valve guides.
Now, there are a few designs that work around these issues:
Diesel 2 stroke engines use exhaust valves, superchargers, and fuel injection. Because fuel is not injected into the cylinder until long after the intake port and exhaust valves have closed, the engine does not blow unburnt fuel out the exhaust. And because a supercharger is used for exhaust scavenging (removal) the crank case can be filled with oil, eliminating the need for premix. Anyone who's been near a diesel locomotive can attest that it doesn't smell or smoke like your typical 2 stroke.
The same technology can be employed with 2 stroke gasoline engines. Gasoline Direct Injection with supercharging has some clear advantages over traditional 2-strokes... Never-mind the fact that the supercharger could be used to produce some pretty insane power output out of a small displacement engine.
2 strokes also have the advantage that they are quieter than your typical 4 stroke. The only reason people tend to think of them as loud is because they don't require much in the way of silencing.
Anyway... Long rambling post. Short version: no, traditional 2 strokes are not clean. Modern 2 strokes show a lot of promise.
Re:What took it all so long?? (Score:5, Informative)
Because diesel is a lot more expensive than gasoline here. Diesel used to be way cheaper tan gas, I don't know what changed to make diesel more expensive. Taxes, maybe?
I'm going to quote a very insightful post I once read. But first, the cliff notes:
1. Diesel is more in-demand in this country than most people think, because there is a very high demand for heating oil [wikipedia.org] in the winter. Heating Oil ~= Diesel with a different dye added.
2. Given a barrel of oil, you can only extract about half as much Diesel fuel as you can regular gasoline [yahoo.com]. This limits the amount we can supply in-relation to regular gasoline, which is why Diesel (already im high demand) is more expensive.
3. Diesel is more heavily taxed than heating oil or regular gasoline, so in-addition to the fact that diesel is already heavily in-demand, it is the most highly taxed fuel on the road.
So really, the diesel revolution everyone wants to happen in this country is not going to happen. If we had as many Diesel cars as Europe, the fuel prices would go through the roof, because our demand for Diesel/Fuel Oil is already very high.
And now, the quote:
Because the price is set, like all prices in a capitalist economy, by what the market will bear rather than by absolute cost of production. They call this process "market forces," as if they exist outside of themselves, when talking to consumers, but refer to "record profits" when talking to stockholders.
Diesel used to be much cheaper than gasoline, until it became popular to put it into consumer vehicles, but several things have happened to change the production cost of the fuel at the pump.
First is the transition to ultra-low sulfur diesel, which adds perhaps five to eight cents per gallon, counting both direct costs -- the purchase price of low sulfur oil is higher than oil o lesser quality -- and investment costs required to further refine ordinary oil.
The second is taxes. Diesel fuel is essentially the same stuff as heating oil, but is taxed at a higher rate. 18% of the average price at the pump, according to the DOE, is taxes, 54% is the cost of the oil itself, 22% is the cost of refining, and 18% is distribution, marketing, and profit.
Of course many companies sell themselves their own oil, so there may be substantial profit on that transaction as well.
For gasoline, again according to the ODE, 15% of the price is taxes, 55% the cost of the oil, 15% the cost of the refining process, and 14% distribution, marketing, and profit.
In 1990, the average price of gasoline was $1.16 per gallon, the average cost of diesel fuel was $0.73 per gallon, and the average cost of heating fuel was $1.06.
In 2002, the average cost of gasoline was $1.36 per gallon, the average cost of diesel fuel was $0.76 per gallon, and the average cost of heating fuel was $1.13.
1in 2005, the average cost of gasoline was $1.87 per gallon, the average cost of diesel fuel was $1.95 per gallon, and the average cost of heating fuel was $2.05.
As you can easily see, the relative prices have varied all over the map.
The obvious inference is that, despite the higher taxes on diesel fuel in comparison to heating oil, and very similar costs of production, people are more driven to heat their homes than they are to drive their diesel cars, so the companies can charge more.
Likewise, in 1990, diesel cars were uncommon, and the primary users of diesel fuel were commercial, driving large trucks or tractors.
Presumably, a fellow filling up a truck with 300 gallons of diesel fuel every day or two is in a better position to drive a hard bargain than is a fellow filling his VW diesel with 16 gallons one a week or so.
Cheers,
Lee Anne
Re:What took it all so long?? (Score:3, Informative)
Eh, the power-to-weight ratio is good on a two-stroke, because they often can just skip the whole oil-sump design element altogether (total loss lubrication). You can't do that in a four-stroke without wrecking the cylinder walls on the non-induction strokes.
If you take a two-stroke with an oil circulation system, say a Detroit Diesel Series 71 or Series 92 engine, you just wind-up with an exceptionally dirty (from a pollution standpoint) engine that gets mediocre fuel mileage and has an odd power curve, all else being roughly equal in the application you're using the engine in.
The ONLY advantage most two-stroke engine have are the way they have fewer moving parts to adjust or break, since they use ports (passive fenestra in the cylinder walls which the elongated piston blocks) instead of valves (the diesels usually have intake ports and exhaust valves), which makes them slightly more reliable and inexpensive to produce. Some applications also thrive on the power curve you get from the two-strokes, mostly all-or-none type of things where the engine is either idling or at full-throttle (from chain saws to locomotive generators). They typically start to fall flat in applications that require massive low-end torque.