Print 103 comment(s) - last by randomly.. on Aug 29 at 12:13 PM

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.

Comments     Threshold

This article is over a month old, voting and posting comments is disabled

RE: Good to see
By Brandon Hill on 8/26/2008 12:27:25 PM , Rating: 2
Gearing, it's all about gearing.

RE: Good to see
By Shark Tek on 8/26/2008 1:20:07 PM , Rating: 3
I second that, the gearing on Corvette Specially the 6th is the one that helps it do that MPG. Drive it without it and you will see how thirsty are those horses.

RE: Good to see
By Jimbo1234 on 8/26/2008 1:35:17 PM , Rating: 1
Wrong. Gearing mates the engine's specific torque versus fuel consumption to a particular speed. If too low or too high, you get not ideal MPG results, but may get better performance.

Areodynamic drag is what it's about. It's Cd*Frontal Area.
2008 Z06: Drag area = Cd (0.34) x frontal area (22.3 sq ft)= 7.6 sq ft

Solstice Drage area = 24.8 sq ft.

HP (or torque, take your pick) vaies with the weight and rolling resistence linearly and with the square of aero drag. Overall that makes HP increase to the 3rd power with speed.

RE: Good to see
By Spuke on 8/26/2008 3:10:42 PM , Rating: 3
Thanks Jimbo, I was just about to post that.

RE: Good to see
By randomly on 8/26/2008 6:55:15 PM , Rating: 2
Gearing does directly affect the engine rpm and thus the pumping losses and friction losses. The pumping losses can be substantial.

Rolling resistance varying linearly with velocity and air drag varying by the square of the velocity does not mean HP requirements increase to the 3rd power of speed. That's just bad math.

RE: Good to see
By Jimbo1234 on 8/26/2008 8:04:44 PM , Rating: 2
Look it up yourself in any engineering handbook and you will see that is does relate to the 3rd power. While I agree frictional and volumetric efficiency does make a difference as to how much fuel is consumed at a given torque load and throttle position per RPM, both cars should be designed to operate at the optimum in the final gear. Also difference engines have different characteristics. But drag will kill you your MPG and aero drag is the largest component of it.
as well as
don't forget
and also why not this

So you do the math. I'll buy you a beer if it's not to the 3rd power. As a mechanical engineer, I have done the calculations, run the dyno tests, etc. I do not spew BS.

RE: Good to see
By randomly on 8/29/2008 10:56:44 AM , Rating: 2
Power requirements for air drag do go up as the 3rd power of velocity, but not rolling resistance and engine friction losses etc. The total power requirements are the power required for air drag AND the power required for the frictional/pumping losses. Unless the other losses are negligible with respect to the air drag the total power requirements do not increase with the 3rd power of velocity but at a lower rate.

It will asymptotically approach 3rd power at very high speeds where the air drag losses are much larger than the other losses but that's not a region where cars normally operate unless you're on the Autobahn or racing, which is the situation most of the links you posted are addressing.

Rolling resistance, pumping losses, and frictional losses are a substantial percentage of the total power demands on a normal car on the freeway.

btw thanks for the links, some nice information there. You can drink the beer for me ;-)

RE: Good to see
By Alexvrb on 8/26/2008 11:05:27 PM , Rating: 2
The 2.0L TC Solstice coupled to a 5-speed MT gets 19/28 (as tested by the EPA). The 2.4L NA coupled to a 5-speed MT gets 19/25 (again as tested by the EPA). This is on the same car, with the same drag characteristics. It IS about gearing when manufacturers DO NOT always gear a car for maximum fuel economy.

RE: Good to see
By Spuke on 8/27/2008 12:02:33 AM , Rating: 2
There's too many variables for you to make that conclusion. The 2.0L turbo'd Solstice also has direct injection and less displacement than the 2.4L.

"When an individual makes a copy of a song for himself, I suppose we can say he stole a song." -- Sony BMG attorney Jennifer Pariser

Most Popular Articles5 Cases for iPhone 7 and 7 iPhone Plus
September 18, 2016, 10:08 AM
Automaker Porsche may expand range of Panamera Coupe design.
September 18, 2016, 11:00 AM
Walmart may get "Robot Shopping Carts?"
September 17, 2016, 6:01 AM
No More Turtlenecks - Try Snakables
September 19, 2016, 7:44 AM
ADHD Diagnosis and Treatment in Children: Problem or Paranoia?
September 19, 2016, 5:30 AM

Copyright 2016 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki