New engine design: cheap and efficient.
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A group
of MIT professors have invented a new type of ethanol-boosted, turbocharged, gasoline engine that promises to be almost
as efficient as a gas-electric hybrid, but at a much lower cost. The main idea behind the concept is to reduce fuel
consumption by reducing engine size, adding turbo charging, and increasing the engine compression ratio. I’m sure
many of you are thinking this doesn’t sound like anything you haven’t heard before, and I would have to
agree with you so far.The novelty of the idea comes in the form of a separate injection of ethanol to avoid combustion knock. Combustion knock happens when gasoline spontaneously combusts, as opposed to the combustion initiated by the spark plug, and can cause significant engine damage. This spontaneous combustion happens most frequently when the engine is operating at a high output or running at high speeds. Turbo charging and increased compression ratios increase engine efficiency, but also contribute to increased risk of engine knock. In addition, when the engine is downsized substantially, it will be operating at high output and at higher engine speeds more frequently, again increasing the changes of engine knock. To avoid engine knock, the MIT professors propose to inject small quantities of ethanol into the combustion chamber when the engine is operating at conditions that are prone to knocking. An increase in fuel consumption of 30% is predicted. The main problem would be related to logistics, since consumers would have to fill up an ethanol tank, but the interval might be as infrequent as an oil change.
[Source: The Technology Review]
Reader Comments (Page 1 of 1)
Glenn A. 2:54PM (4/24/2006)
This idea was put into production by General Motors in 1962, as the 1962 and 1963 Oldsmobile F-85 Jetfire.
It had Buick's alloy V8 (with specific Oldsmobile alloy heads), a turbocharger and alcohol injection (you had to buy the alcohol fluid at the Oldsmobile dealers and refill a tank under the hood).
The Jetfire weighed in at 2740 pounds due to a modern (for the time) unit-body, and had 215 HP.
So what did Oldsmobile do for 1964? They built a LARGER body-on-frame car which weighed in at 3380 pounds, and was powered (in F-85 4-4-2 form) with a 330 cubic inch cast-iron lump of a V8 with 310 HP.
In those days, nobody bought light, small and fast. They wanted heavy, big and faster. So, within 40 years, nobody bought any Oldsmobiles at all, right?
I'm hoping humanity will be smarter "this time around" but forgive me for being cynical as I sit in my Prius with my wife (we carpool) and see the road filled with solo drivers in SUVs and 4 door full-sized pickup trucks.
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Charles S 4:36PM (4/24/2006)
I often thought about what will happen 10 years from now.
If gas prices stay the same, would people get used to the prices and go back to buying slightly-less-gas-guzzling gas-guzzlers?
If prices continue to spike, can people afford to drive, especially if the economy slowed to a crawl? Would the have-nots crave for the gas-guzzlers because that is the status symbol for the rich?
If prices do fall, which is just as likely, even if it's temporary, then perhaps there would be a sharp decline in the value of alt. fuels and fuel-efficient vehicles. All the investments would end up to be a loss for investors, and the general public are once again disillusioned.
I am also pessimistic about it all. Even if fuel-efficiency is considered an advancement in automotive technology, people will not view it as goal, but rather a necessity.
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St?ane Dumas 5:11PM (4/24/2006)
for turbocharged ethanol-powered car Glenn A. there the Saab 9-3 BioPower, there an article from Popular Science http://www.popsci.com/popsci/automotivetech/564c1196aeb84010vgnvcm1000004eecbccdrcrd.html
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Bruno Vanzieleghem 5:21PM (4/24/2006)
While this concept does resemble some existing engines, the proposed engine would actually have two injectors, injecting directly in to the cylinder of the engine. One injector would provide gasoline, while the second injector would provide small amounts of ethanol, to reduce the chance of knock.
The engines mentioned above either use pure ethanol (Saab 9-3 Biopower), or have a carburator where gasoline is mixed with alcohol (GM-Oldsmobile 1962-63, actually a mixture of water & alcohol). The Oldsmobile engine had a compression ratio of 10:1 and ran 5psi of boost. With precise control over knock, the approach suggested by the MIT professors will likely allow significantly higher compression ratios and boost pressures.
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Glenn A. 8:40AM (4/25/2006)
I'm pretty sure Oldsmobile engineers got the idea from World War II engines where water/alcohol injection and supercharging (sometimes with a two-speed planetary set to increase boost) was adopted towards the end of the war on some aircraft engines.
My father had a friend who was a bomber pilot in
WW II and if German fighters came for them, they had a brass wire "gate" across the throttle quadrant on the bomber - this meant their lives were at stake when they used it - it also mandated a complete engine rebuild on all four engines, plus the supercharger would max out and water/alcohol injection would kick in. He told my father that the exhaust pipes on the engines would glow red-hot in this emergency mode.
"Nothing new under the sun" (?)
This is, of course, not to take away from the efforts of the engineers on the current projects, nor does it mean the ideas are invalid. Anything but, in fact.
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Arpad 10:37AM (4/25/2006)
Actually, this is still used today in performance modified cars. It's really been catching on in the last few years... the turbo buick guys have been big into it for about 10 years, and the 3000gt and DSM crowd about 8. Today, the Evolution, WRX STI, and SRT4 crowd (to name a few) has been really pushing the market.
Water has almost the same effect as alcohol but most people agree that the most efficient is a 50/50 mixture. The liquid is sprayed directly into the intake air preferrably some distance before the intake manifold so that it has a chance to cool the air and for the liquid to vaporize as much as possible. Water and alcohol by themselves each present some challenges that a 50/50 mixture alleviates: pure water will have problems with biofilms, and pure alcohol is flammable.
Unfortunately, the comment about not having to fill up often is simply not true... You need quite a bit of liquid to produce the anti-knock effect. When driving hard, you will go through a 2-gallon tank within a few laps around a medium-length roadcoarse. Also unfortunately, water is heavy.
It's interesting to note that propane injection has the same anti-knock effect as water/alcohol but achieves this through a different mechanism. Water/alcohol basically cools the in-cylinder temps down to eliminate knocking(although alcohol has a slight octane boosting effect), while propane mostly increases the octane (although it also has a slight cooling effect as well).
Propane is also lighter and a 10-lb tank will last 3-6 months depending on driving habits. A BBQ-sized one will last much longer...
Water/alcohol is also much harder to design maintenance-free because of the inherent difficulties that it presents. Even the best water pumps will fail, and you have to worry about galvanic currents, plugged nozzles, mold, contact electrification and such. Propane injection is as simple to set up and maintenance-free as nitrous and actually makes the perfect companion to nitrous.
If you're thinking that having a propane tank in your car is dangerous, it's actually not... They're over-engineered. A normal gas tank is much more dangerous than a propane tank.
Anyway, I hope that propane injection catches on more... right now it's not common unfortunately, since water/alcohol injection has stolen the limelight.
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Lars Boelman 4:08PM (4/25/2006)
Is it me or does "A predicted increase in fuel consumption of 30% is predicted." not like a good thing?
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carl kadlec 4:25PM (2/25/2007)
And a good day to you all.
I have a 1966 440 dodge in a 1967 250 ford truck.
The engine is out of a highway patrol car stock headers, mild cam etc.
Pings terrible. Used to have water injection.
Woud like to find information on how to set up the propain system.
Any help woud be much appreciated.
Carl
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