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The upcoming Chevrolet Cruze will use a turbocharged 1.4-liter four-cylinder gasoline engine.

The Pontiac Solstice GXP uses a turbocharged, direct injection 2.0-liter four-cylinder engine.

Chevrolet Malibu Hybrid
GM goes high-tech to improve fuel efficiency

General Motors has seen the writing on the walls when it comes to efficient vehicles. Although gas prices have dropped more than 15 cents in the past few weeks, Americans are still gravitating towards smaller vehicles that are easier on the wallet when the times comes to fill up the tank.

GM has spent the past few years working on a number of technologies to bring lightweight, advanced, and fuel efficient powertrains to its vehicles and a number of them are already available or will soon be hitting the general populous.

GM's reinvigorated powertrain efforts revolve around traditional gasoline engines, diesels, hybrids, and Homogeneous Charge Compression Ignition (HCCI) engines according to Automotive News. GM is also looking to replace nearly all of its existing four and five-speed automatic transmissions with more efficient six-speed units.

For its gasoline engines -- much like Ford's efforts with its EcoBoost lineup -- GM is looking towards direct injection (DI) and turbocharging to extract V6 performance from four-cylinder engines and V8 performance from six-cylinder engines. GM's current turbocharged DI 2.0-liter four-cylinder engine can be found in the Pontiac Solstice GXP, Saturn Sky Red Line, Chevrolet HHR SS, and the Chevrolet Cobalt SS. In its current form, the engine delivers an impressive 260 HP and 260 lb-ft of torque.

In the near future, GM will apply turbocharging to its existing DI 3.6-liter six-cylinder engine to boost output from roughly 300 HP to around 400 HP. On the lower end of the spectrum, a new 1.4-liter turbocharged four-cylinder engine will finds its way into the Chevrolet Cruz -- the replacement for the Chevrolet Cobalt -- in place of the existing 2.2-liter normally aspirated (NA) four-cylinder engine.

On the diesel front, GM points to its upcoming 4.5-liter V8 diesel engine which will be used in its light-duty pickups and full-size SUVs. According to GM, the engine itself is 75 pounds lighter than traditional diesel engines and will allow its hefty trucks to achieve 26 MPG on the highway.

When it comes to hybrids, GM is already making ground with its mild hybrid system in the Chevrolet Malibu Hybrid and Saturn Aura Green Line. Eventually, the company's more efficient two-mode hybrid system -- currently used in full-size pickups and SUVs -- will find its way into the Saturn Vue Green Line and GM's other mid-size cars and SUVs.

Finally, GM is also banking on HCCI technology to extract diesel-like fuel economy from a gasoline engine. DailyTech first brought you news of this technology when Mercedes unveiled its F700 research vehicle. According to GM, adding HCCI to a gasoline engine boost fuel economy by 15 percent and significantly reduced harmful tailpipe emissions.

GM hopes to stay a step ahead of its competitors with its upcoming powertrain advances; however, its competitors likely aren't sitting still when it comes to their own efforts in striving for greater performance and engine efficiency.



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RE: Good to see
By mdogs444 on 8/26/2008 12:32:42 PM , Rating: 3
quote:
Yet it's fuel mileage is 19/27, or a bit better than the 430 HP Chevrolet V8 at 16/26. Hmmm, V6 power at V8 mileage, I would say that was, ummm, well, NOT fuel efficient.

I have an 07 Honda Accord coupe V6, which is 244hp and gets 21/29. Not much better than the 260HP 4cyl turbo in the Solstice.

So whats your point? Is nothing "efficient" unless its a crappy 60mpg golf cart with doors?


RE: Good to see
By HinderedHindsight on 8/26/2008 1:40:59 PM , Rating: 2
I think the point he's making is that when it comes to cars, American manufacturers seem to make questionable decisions when it comes to equipping engines. I'll use Ford as an alternate example to GM cars

For the longest time Ford had a solid 200 HP V6 3.0 24 Valve DOHC Yamaha based engine (since the mid 90's). They still use it today in a variety of vehicles (Fusion, Taurus, Escape) and it has been can reach 240 HP without a turbo.

Yet, their cash pony, the Mustang, they continue to equip a noisy 4.0 liter SOHC (bored out from a 3.8 liter they used to use in older Mustangs which only made 150 HP) which does 210 HP.

By all accounts, the 4 liter is less fuel efficient and more costly to produce, and is slower than the 3 liter depending on the vehicle you're sitting in.

This seems to be a staple of American car manufacturing: lots of different engines, instead of fine tuning one platform and using it in a variety of applications. They even have a very powerful and fairly efficient/cheap to produce 3.5 liter, yet they continue to invest almost every year in improving the underpinnings (suspension, gearing ratios, etc) and redesigning the exterior of the vehicle rather than upgrading the platform and giving it a more competitive edge.

And this comes from a person who loves the Mustang as a car and a staple of American history.


RE: Good to see
By Brandon Hill (blog) on 8/26/2008 1:46:19 PM , Rating: 2
I wasn't aware that the Duratec 30 was a Yamaha design. As far as I know, the Duratec 30 was developed by Ford.

Now, the 3.0 liter 220HP V6 used in the first and second generation Taurus SHO was indeed Yamaha designed as was the 3.4 liter V8 used in the third generation SHO.


RE: Good to see
By HinderedHindsight on 8/26/2008 2:03:24 PM , Rating: 2
My understanding is that the Duratec wasn't directly developed by Yamaha, but it was based off of the same design from those original SHO's. I was just as surprised to find that out the Duratec in my old 2001 Taurus.

Yet another sad mistake on the part of Ford. Because the 3.4 liter V8 was much heavier than the 3.0 V6 used in the first two SHO's, the third gen was a few tenths of a second slower to 60.


RE: Good to see
By Spuke on 8/26/2008 3:13:37 PM , Rating: 2
quote:
I think the point he's making is that when it comes to cars, American manufacturers seem to make questionable decisions when it comes to equipping engines.
See Jimbo's post on CD's and frontal area. The Solstice's frontal area is why it gets worse mileage compared to say a Corvette. When you drop the same engine into the Cobalt, the mileage improves to 22/30.


RE: Good to see
By Alexvrb on 8/26/2008 11:23:03 PM , Rating: 2
Cobalt gains 3 MPG in city and 2 on highway, and its because the cobalt SS has so much less drag than the Solstice? Gee, and here I was thinking about how the FWD Cobalt is geared less aggressively and is slower than its RWD Pontiac comrade.


RE: Good to see
By Solandri on 8/26/2008 2:13:59 PM , Rating: 2
It's important to remember that peak horsepower is only achieved at one RPM, and fuel efficiency is most definitely not measured at that RPM. Most of the time the engine is only going to be putting out ~15-30 HP to maintain the vehicle's speed. Fuel efficiency is more a measure of how well the manufacturer can tune the engine's performance at that low power output. It can have very little or nothing to do with the engine's peak horsepower, especially now that they're doing tricks like shutting off fuel to cylinders at low power.


RE: Good to see
By FITCamaro on 8/26/08, Rating: 0
RE: Good to see
By ziggo on 8/26/2008 6:40:52 PM , Rating: 4
Nobody I know has a car that cruises on the interstate at full throttle. A dyno chart only tells you whjat the engine is capable of producing at a given RPM at WOT.

The most fuel efficient platform would be a NA engine geared so that it would operate at full throttle near the torque peak on level ground at the desired cruising speed. Such a car would accelerate painfully slow though which is why it is not done.


RE: Good to see
By randomly on 8/26/2008 7:06:20 PM , Rating: 2
a properly turbocharged engine at full throttle will be more efficient than a NA engine because of the improved thermodynamic efficiency.


RE: Good to see
By ziggo on 8/26/2008 10:23:05 PM , Rating: 2
False. Turbocharged engines are a wonderful thing. But from a thermodynamic efficiency standpoint they do not help. The energy used to compress the incoming air is essentially captured from the exhaust stroke, causing the exhaust pressure to be higher than for a NA engine.

At full throttle turbo engines have to run pretty rich to keep cylinder temps down. Also turbocharged engines generally have lower compression ratios, which is the only factor for the thermodynamic efficiency of a pure otto cycle.

The major benefits are size and weight. They also allow a smaller displacement engine to act like a larger one when necessary. Thus you can act like a small engine when cruising at low loads and still have the power on demand like a larger engine.


RE: Good to see
By Spuke on 8/26/2008 10:38:30 PM , Rating: 2
quote:
At full throttle turbo engines have to run pretty rich to keep cylinder temps down
Not with Direct Injection you don't. DI, boosted engines are run lean as hell. You also don't have to run as low of a compression ratio either as VW's run 10:1 and GM runs 9.2:1. I wouldn't be surprised if these new DI, turbo engines coming from Ford and GM run even higher than 10:1.


RE: Good to see
By ziggo on 8/27/2008 10:52:36 AM , Rating: 2
I have a DI turbo engine. My target afrs are still around 12 under full boost. The compression ratio isn't stellar either.

It could be designed to help, but the engine I have uses the DI cushion to up the boost to 16lbs. In any case, from a thermodynamic efficiency standpoint, NA cars are the way to go.


RE: Good to see
By Spuke on 8/27/2008 11:20:13 AM , Rating: 2
quote:
I have a DI turbo engine. My target afrs are still around 12 under full boost. The compression ratio isn't stellar either.
Ours are WAY leaner. Different tuning I suppose. What kind of turbo are you guys using? We have a K04 variant and it is capped to 20 psi in stock form.


RE: Good to see
By randomly on 8/29/2008 12:13:48 PM , Rating: 2
It's not necessarily true that the energy the turbo uses to compress the incoming air is captured from the exhaust stroke because of critical or choked flow. The mass flux of air becomes independent of the downstream pressure and so the turbo does not change the back pressure on the exhausting piston. The energy is drawn by the turbo results in a lowering of the exhaust temperature, and thus you are extracting more thermodynamic energy than you were before. This increases the engine efficiency.
This is particularly effective on Diesel engines.

If you are forced to lower the compression ratio because you running near the predetonation limits of the engine with a particular fuel you of course lower the efficiency of the engine which may chew up most of the added gain from the turbo.

The drawback to turbos are the added expensive, complexity, maintenance, and response lag. But properly used they CAN improve the thermodynamic efficiency of an ICE.


RE: Good to see
By Jimbo1234 on 8/26/2008 8:11:38 PM , Rating: 3
Exactly. Although dyno tests are performed at WOT as well as partial throttle. At the partial throttle is where you will be cruising and the car's gearing will be adjusted to run at the optimal specific torque per fuel mass at highway speed. The torque requirement is calculated from the Cd, frontal area, mass, and rolling resistance (see my post above).

I'm glad there are a few here that actually know what they are talking about when it comes to speed, torque, HP, MPG, the first and second laws of thermo, etc.


RE: Good to see
By mmcdonalataocdotgov on 8/27/2008 12:51:40 PM , Rating: 1
The point is: "GM goes high-tech to improve fuel efficiency" is a crap assertion.


RE: Good to see
By Spuke on 8/27/2008 1:11:35 PM , Rating: 2
quote:
The point is: "GM goes high-tech to improve fuel efficiency" is a crap assertion.
Er. They are. What's crap about it?


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