MIT experiments with turbocharged, direct injected, ethanol and gasoline powered engine
This information will not come as a shock to our readers, but I thought that I would go ahead and share the story with you anyway. As you are well aware, turbocharging an internal combustion engine can lead to higher power output by adding additional oxygen into the engine. This has been used to great effect on street and race cars for a long time now. I'm sure you are also aware that raising the compression of an engine also has the effect of raising the engine's power output. One hardship to overcome with turbocharging an engine that already has a high compression is the octane level of the gasoline. As the power output of the engine increases, and additional gasoline and air (fuel) are burned, the heat generated raises as well. In extreme cases, the fuel will ignite before intended, causing what many refer to as knocking. Pretty normal stuff here, I know. Anyway, by using what is known as direct injection, the chances of knocking are reduced. Audi and Volkswagen have been doing this as of late on their gasoline engines. Diesel engines have also been making use of this technology.
Here is where the information gets a bit more interesting. Regular readers may remember some of our past articles related to the performance potential of ethanol. Because ethanol burns cooler than gasoline, the compression of an engine designed to run solely on ethanol can be raised. By combining this characteristic with direct injection and turbocharging, researchers at MIT have been able to vastly increase the power output of small engines. The engines use gasoline through standard fuel injection, with a separate direct injection system for the ethanol. The benefits include saved weight over a comparably powerful, less advanced engine, and possibly lower cost. Check the article out here for more information.
Overall, the concepts introduced in this article are not new. Combining them into a single working engine may be, however. I can't specifically recall the use of direct ethanol injection into an engine running on normal gasoline. If you are aware of anything similar, why not let us know about it in the comments?
[Source: Technology Review via Edmunds Inside Line]
Reader Comments (Page 1 of 1)
rgseidl 4:49PM (3/18/2007)
BMW combines second-gen direct fuel injection and turbocharging in its production 335i. Saab combines turbocharging and E85/E100 capability in its BioPower variants.
The MIT claim of a 3x improvement in power seems awfully far-fetched, unless the comparison is based on something designed in the stone age.
In terms of the architecture, spray-guided direct injection of an E10 or E20 blend should achieve much the same effect, i.e. permit higher boost pressures. By avoiding port injection altogether, you can permit greater negative valve overlap without increasing engine-out HC emissions. In a turbocharged engine, that means you increase the air mass at IVC and hence engine power at virtually no cost.
Btw, your image shows a variable geometry turbo (VGT) without a water jacket. These becoming common in lean-burn engines (e.g. diesels) whose exhaust temperatures at rated power are manageable with premium but still regular alloys. So far, Porsche is the only company that offers a VGT in a production vehicle with a spark ignition engine. It features a water jacket and extremely expensive high-temperature alloys.
I strongly suspect any turbo-DI-ethanol combo that may be announced in the next 2-3 years will still feature one or more fixed-geometry turbos.
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spdracerut 10:42PM (3/18/2007)
Aftermarket tuners have been using water injection, alcohol injection, and methanol injection for quite a while on turbocharged gasoline cars. I believe the diesel guys like to use propane injection.
All three allow the use of more boost and more timing for significantly increased power.
Recently, some tuners have been running turbocharged cars on straight E85. It allows for more power with a gas mileage penalty (lower energy content than unleaded gas). But hey, more power and you can feel 'PC' by not using foreign oil, haha.
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