More Power, Less Fuel, Fewer Emissions - A Direct Injection Trifecta

[Right Lane Cruiser]

"Direct injection is going to play a huge role in our fuel-savings and emissions-reducing efforts."

Chris Meagher - FastLane Blog - Mar. 9, 2009

This tech is quite promising! --Ed.

We talk quite a bit about future technology on Fastlane, but today I want to take a little time to discuss a fuel-saving engine technology that’s available now and offered on many of our 2009 models - direct fuel injection. It’s the technology that helps a 260 hp vehicle like the Chevy Cobalt SS go from 0-60 mph in 5.7 seconds and still get 30 mpg on the highway. Basically, direct injection allows us to make gasoline engines that are more powerful and more efficient with fewer emissions.

With direct injection, highly pressurized fuel is sprayed directly into the combustion chamber, instead of through the cylinder ports, to create a more complete burn of the fuel-air mixture. Less fuel is required to produce the equivalent horsepower of a conventional port-injection combustion system and the mixture is more precise, which also helps the engine save fuel and start quicker with fewer hydrocarbon emissions. All of this makes for a more complete combustion of the gasoline, providing more power with less fuel.

That’s a pretty technical description, but let me see if I can make it a little easier to understand. Basically, direct injection is one of the advanced internal combustion engine technologies that allows us to downsize from a V8 to a V6, or a V6 to a four-cylinder without sacrificing power, but still improve fuel efficiency with fewer... [Read More]

[southerncannuck]

GM is still thinking high horsepower. 260 HP in a Cobalt, are they nuts?

[MaxxMPG]

Originally Posted by southerncannuck

GM is still thinking high horsepower. 260 HP in a Cobalt, are they nuts?

That would be 260hp and a 5300 rpm. That number would be important for the Fast-n-Furious driver. For the hypermiler, look at the torque: 260 peak at 2000rpm (where most of us upshift). The Cobalt powerplant has a turbo, and so will behave like a regular 2.0L four when driven properly. When you mash the pedal, the blender goes from "mix" to "frappe" and onto "puree" and can ultimately cram enough air through the intake to in effect turn the engine into a 4.0L - which is where the horsepower comes from. Double the air means double the fuel, which explains why we can get 40mpg out of it while the "I hate my life and I hate my wife and I am full of strife" road rager will get the corresponding 20mpg.

According to my Cobalt printbook, the SS (2.0L DI) has a 3.84 final drive, while the XFE has a 3.63 final drive. The performance gearing means slightly higher highway rpm, but not enough to offset the 9% reduction in engine displacement, not to mention the lower torque peak that moves the car without as much throttle.

[philmcneal]

well explained maxxmpg! thank you

[Radio_tec]

Originally Posted by southerncannuck

GM is still thinking high horsepower. 260 HP in a Cobalt, are they nuts?

Exactly. GM is playing to more horse power and not efficiency. Oh sure, they hyped up efficiency in the video but what they are showing are more of the same compact muscle cars or SUVs. So in the end they'll have SUV's getting maybe 20 mpg city. That's still pretty pathetic. So who's gonna' drive these things when gas prices rise again?

[hobbit]

Okay, that's one of the funnier descriptions I've seen in a while.
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_H*