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A New Lease On Internal Combustion
Somnus suggests we check out the latest issue of MIT's Technology Review, where researchers describe how they can dramatically boost engine output and efficiency by preventing pre-ignition, or "knock." How they do it: "Both turbocharging and direct injection are preexisting technologies, and neither looks particularly impressive... by combining them, and augmenting them with a novel way to use a small amount of ethanol, Cohn and his colleagues have created a design that they believe could triple the power of a test engine."
...become simpler with the addition of a small amount of ethanol.
In a large glass.
Congratulations You've discovered the same thing as Rudolph Diesel except that you don't quite have it right. You don't need to use ethanol or port injection ditch both of those and use good ol fashioned vegetable oil. 0 preignition and you can turn the boost way up on a tiny engine.
I suppose my first question is, when the owner inevitably lets the ethanol run out, what happens? Can the engine computer dial down the boost enough to prevent detonation? Or does the engine just have to shut down?
That aside, it's always great to improve internal-combustion efficiency, but the real solutions will have a more dramatic effect than this. My own view is that the solution should be a plug-in series hybrid with about 60 miles of electric-only range and the ability to run maybe 400 more with the engine providing generator power. This would not seriously compromise the essential attributes of modern cars, while *dramatically* (think 80% or more) improving their fuel economy in many real-world usage patterns.
Then we should have nuclear power behind all those 220v outlets... and 90% of cars should be much smaller, with people able to obtain bigger trucks for big jobs on demand from time-share or rental companies... a guy can dream, can't he...
This sounds an awful lot like a modern diesel engine. Modern diesels are turbocharged and use common-rail injection to achieve insane pressures at the injector heads (for really fine atomisation of the fuel), which directly inject into the cylinder. I believe the newer engines even stagger the injection during the compression and combustion cycles too to achieve more power and cleaner burning.
(NB: I'm not a revhead so I might be talking shit)
Even still, water and alcohol injection used to cool the charge is not new, and has been around since the 30's.
# Turbo_Jetfire
Whoever wrote the article doesnt understand why SUVs and trucks have big engines. Its not because they are powerful, its because they need lots of torque. You can pull a trailor up a hill in an S2000 just like you can a road tractor, but the tractor will use much less fuel and less wearing of the engine doing it.B enignes arent going anywhere in SUVs any time soon, despite this seemingly "revolutionary" new technology.
I predict this will end up as a failure just like the last time an engine manufacturer tried this: http://en.wikipedia.org/wiki/Oldsmobile_V8_engine
No matter how novel the technology, when the product's life depends solely on the customer, your product wont usually stay on the shelves for very long.
How do we go from this:
...Cohn and his colleagues have created a design that they believe could triple the power of a test engine, an advance that could allow automakers to convert small engines designed for economy cars into muscular engines with more than enough power for SUVs or sports cars.
A vehicle that used this approach would operate around 25 percent more efficiently than a vehicle with a conventional engine.
to this:
does a 25% increase in efficiency translate into tripling the power output?
You can't handle the truth.
This should be a lot more accurate than the original summary.
Blah blah sig blah blah blah irony blah blah
"People in the tuning industry have been controlling "knock" in various ways for a long time."
Exactly. This sounds a lot like water injection, which has been around forever and does increase mpg by about 10% in turbo cars and allows lower octane fuel.
Here's what's going to kill the technology from TFA:
"Ethanol would be stored in its own tank or compartment and would be introduced by a separate direct-injection system. The ethanol would have to be replenished only once every few months, roughly as often as the oil is changed. A vehicle that used this approach would operate around 25 percent more efficiently than a vehicle with a conventional engine."
This is exactly like water-injection and it's why we don't see water-injection in vehicles. No one wants to have a separate tank that we need to remember to fill-up, and the 10% increase provided by water just isn't enough. This is the same story except it's ethanol, not as easy to find as water, and it's 25% better mpg instead of 10%.
We will never see a production ethanol injection vehicle. Vaporware with a capital V
my karma will be here long after I'm gone
From TFA (and this goes for the reply above mine as well as the parent):
"Similar approaches, some of which used water to cool the cylinder, had been tried before. But the combination of direct injection and ethanol, Cohn says, had much more dramatic results."
Show me someone in the tuning industry using directly injected ethanol along with a turbocharger and regular gas. I've never heard of this approach.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
It might be a while. They're still busy relocating Jimmy Hoffa's body, plotting out new wars in the Middle East, and assassinating more people connected to the moon landing hoax.
Assuming ethanol comes from murdered children and the hydrogen from magic, hydrogen saves 132% more lives than ethanol.
I was thinking the same thing when I started reading the article. A quick search at any of the major car enthusiast websites will lead you to dozens of threads on direct injection and forced induction (turbocharging). This isn't news. There are already direct injection, turboed factory motors out there. The 2007 Saturn Sky Red Line, for example, is powered by a 2.0-liter direct injection turbo engine. You may have heard of another auto manufacturer using this same technology in it's diesel engines... VW's TDI (Turbo Direct Injection).
i nes)
The "new" part comes where they are using ethanol direct injection. It's a new twist on an old idea. See also water-methanol injection:
http://en.wikipedia.org/wiki/Water_injection_(eng
Sure, it's not anything evolutionary. And the article might read like 1st Grade literature for anyone who is familiar with cars and tuning... but it's still interesting stuff.
But the story is different because the system will know what to do when it runs out of ethanol, which is to say retard timing and reduce mileage and power output until you add more ethanol. Water injection is aftermarket and usually not compensated for automatically.
The mileage improvement is pretty compelling and I think we'll see it implemented if fuel prices rise much more.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
The '07 MINI Cooper'S has a 4 cylinder 1.6 liter direct-injected twin-turbocharged engine - and since most fuel in the US now contains 10% ethanol, I'd say the "experimental" technology these guys are pushing is already out there in at least one production car. The problem with knocking has been nailed a bazillion years ago - just about all modern cars have an anti-knock sensor that can richen the mixture if it detects signs of knocking - but with high octane gasoline - it only very rarely has to actually do that - so the "problem" of knocking isn't really there. The only time the MINI actually does something like that is when the dumb user filled the thing with regular low-octane gas instead of 'the good stuff'.
Add to that that the MINI has goodies like electric oil, power steering and water pumps that can actually be turned off (rather than merely bypassed) when not needed - so the engine reaches it's most efficient temperature faster and you aren't burning fuel circulating fluids that don't need to be circulated yet. It has computer controlled inlet and exhaust valves - so the timing is infinitely variable - and can be varied separately for each cylinder. For short bursts of accelleration, the car has an 'overboost' feature from the turbo - which won't help you much for prolonged hard accelleration - but is great for a rapid burst of speed for overtaking, blasting out of a corner (FUN!) or blowing away those bloody ugly Scion xB's at traffic lights (a personal mission of mine, I might add).
www.sjbaker.org
the beauty of a diesel is it runs on any oil, used cooking oil, cod liver oil, diesel fuel oil, motor oil. Properly setup itl'l run on used motor oil, used transmission fluid, used any oil.
I'm intrigued to imagine what they could do if this ethanol based charge cooling works out. I'm already forced to put 15% ethanol in my Audi V8 (sadly NOT an RS4), living in NYC, but if this works out maybe I can support the farmers AND have a powerful car for the weekends (I commute on the subway).
You either need to read the article or, if you have, brush up on your reading comprehension skills. The technique used in the article is supposed to allow them to push the turbo pressure much higher than any modern car can handle, even when using high octane fuel. They're talking about using a separate direct injection system to pump a small amount of pure ethanol into the cylinder out of phase with the gasoline. It would cool the cylinder enough to stop knock when the gas is injected at extreme pressures. Supposedly, you would have to replace the ethanol about as often as you have to replace the oil (every few months).
Next time, please try reading the article instead of seeing "ethanol" and "turbocharger" in the summary and shooting your mouth off.
-GameMaster
Rules of Conduct:
#1 - The DM is always right.
#2 - If the DM is wrong, see rule #1
People have long known that ethanol fuels have high octane ratings (the measure of how knock resistant a fuel is).
People have also long known that turbo charging an engine is a great way to extract more power out of a small engine.
People have also known that direct injection allows you to reduce the tendency to knock since it lets you inject fuel into the hot engine at the very last second - reducing the amount of time the air/fuel mixture has to heat up.
And guess what? Mazda produces cars today that has both direct injection and is turbo charged. For example, the MazdaSpeed 3.
It's 2.3 liter engine produces 263hp and 280lb/ft of torque and has an EPA fuel economy rating of 20/28mpg. So yes, while it does provide good power and decent gas mileage, it's nothing earth shattering compared to turbocharged cars without direct injection.
The engine has a very high compression ratio for a turbo charged gasoline engine (9.5:1), especially one that pushes over 15psi of boost into the cylinders. That is direct injection working for you.
For example, the slightly bigger turbo charged 2.5 liter Subaru WRX engine has a compression ratio of 8.4:1 and maximum boost of 11.6psi is rated at 230hp/235lb/ft of torque (though it is admittedly underrated) with similar fuel economy as the Mazdaspeed 3 considering that it is all-wheel-drive (20/26mpg EPA). The more powerful WRX STi has the same 2.5l displacement, 8.2:1 compression ratio and a bigger turbo pushing 14.5 psi is rated at 293hp/290lb/ft of torque but less fuel economy, 18/24mpg.
Unless there is a lot of potential still to be found by combining these 2 technologies, I see it as more of an evolution rather than a revolution. Perhaps a 1.0 liter engine would be able to muster 120+ hp/torque but I find it hard to believe that it could achieve mileage ratings significantly higher than a hybrid. And you still can't turn the engine off when idling or coasting down hill.
So how about a direct-injection, turbo-charged, atkinson cycle hybrid and combine the best of all technologies?
Both turbocharging and direct injection are preexisting technologies, and neither looks particularly impressive. Indeed, used separately, they would lead to only marginal improvements in the performance of an internal-combustion engine. Really? So there aren't people slapping large turbochargers on little 3 liter supra engines and increasing the engine output 5-fold? Or is that only marginal?
That aside, the problem with this is that a turbocharged engine at full output is very inefficient. A larger naturally aspirated engine will always be more efficient than the small turbocharged engine of the same maximum output. That's because a lot of energy is wasted compressing the intake charge, more than can be made up for with the displacement decrease, even with the newest fanciest garrett turbos. The only merit efficiency-wise of turbo engines is engine efficiency at low loads (when the engine is not under boost) relative to the maximum output. There is obviously a balance to be struck here, and that's why 18 wheelers have big v8's with turbo chargers, rather than even bigger engines or smaller engines running under high pressure. Designing a motor vehicle is always a balancing act, and in most cases a turbo is not helpful because of the cost, reliability and other shortcomings versus the benefits.
Recently, car makers have started using direct injection to combat preignition that can damage an engine. It allows them to run leaner fuel mixtures, higher compression and more aggressive spark timing, improving the power/efficiency of engines. Direct injection has the exact same benefit with turbocharging. There are no compounded benefits from mixing the two technologies.
The '07 MINI Cooper'S has a 4 cylinder 1.6 liter direct-injected twin-turbocharged engine - and since most fuel in the US now contains 10% ethanol, I'd say the "experimental" technology these guys are pushing is already out there in at least one production car
As the article notes, direct injection has been around for a while (since the '50s). Turbochargers are older than that. The idea here uses direct injection in a novel way.
. . . just about all modern cars have an anti-knock sensor that can richen the mixture if it detects signs of knocking - but with high octane gasoline - it only very rarely has to actually do that - so the "problem" of knocking isn't really there.
The problem isn't stopping current engines from knocking. The problem is to increase compression ratios or boost of an engine without introducing knocking. Increasing the amount of gas in the mixture only makes your fuel efficiency worse.
The key to this new idea is that the ethanol is injected separately from the regular gas (specifically, during the compression phase). Naturally, you'll need a separate tank of ethanol, which the article claims would need to be replenished about as often as a oil change.
As we know from thermodynamics, matter going through a phase change from liquid to vapor will suck away a lot energy. Ethanol has the nice quality that it will go through a phase change at a lower temperature compared to water.
Thermodynamics also tells us that as pressure increases, so does temperature. In a normal engine, the piston will compress the fuel/air mixture, thus increasing the temperature of the mixture. If the temperature gets too high, the mixture will ignite on its own. This is more likely if your engine has too high of a compression ratio or you're using some kind of boost system (turbo or superchargers). This is why cars with turbos often have intercoolers.
What they're doing here is increasing the compression ratio and/or adding a turbo. You can choose to slap on an intercooler if you wish. As the piston goes through the compression stroke, the fuel/air mixture gets hotter as before, but then some ethanol is injected, which vaporizes, thus cooling the mixture. The mixture is then ignited by a spark plug normally. Brilliant.
Not a typewriter
Preignition is when the fuel/air charge ignites at the point of lowest compression, and then the engine has to compress this hot, expanded gas. This is how holes get burned in pistons. Knock is detonation, where the fuel/air charge does not burn in a controlled flame front, i.e. it suddenly detonates. It requires that timing advance be backed down a bit.
There are only 10 kinds of people in this world... those who understand binary and those who don't
Other people have different things to say about Cobasys:
And this, which killed the electric RAV4:There's plenty more, just perform the search suggested at the first link.
It appears likely that the advances in Li-ion and carbon-backed lead-acid will make it far more difficult to keep the next round of batteries out of vehicles. Regardless, the delay in availability of mass-market PHEV's and EV's has meant many billions or tens of billions of dollars in additional revenue for the oil companies and oil exporting nations. (The current administration shares responsibility for e.g. terminating the Partnership for a New Generation of Vehicles, which would have delivered 80-MPG sedans about.... now.)
The take-home lesson? Don't believe everything you read.
Sustainability and energy independence essay
"...limiting their power"
Harsh. Apparently someone hasn't been keeping up on Diesel Technology lately. You know it was an Audi Diesel that one the last LeMans right?
I dirve a little VW Golf TDI. 115hp is nothing special, but 175 lbs/ft of torque is enough to get the car moving in a hurry. The car is almost as quick stock as my '88 Fiero with a 3.4l V6 (about 180 hp and 175lbs/ft).
When you have an engine that can (lightly/medium modded) put out 250 lbs/ft or torque from 1800rpm to 3500rpm, the concern is less about RPM and more about Gearing and shifting. Have you seen the new VW/Audi dual clutch manual automatic trannys? Their 6 speed DSG auto transmissions can upshift in 8ms. With that wide of gear range, and that fast of shifting, having a somewhat* limited rpm band is not an issue.
*I say somewhat because the vast, vast majority of drivers will never spin their engine over 3500 rpm. Hondas, Subarus, what have you, they are all designed (stock) as commuter vehicles. And if you have to turn 7k rpms to get your car off the line, it's not going to hold up to daily driving.
-Rick
"Most people in the U.S. wouldn't know they live in a tyrannical state if it walked up and grabbed their junk." - MyFirs