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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 mmcdonalataocdotgov on 8/26/2008 12:24:46 PM , Rating: 2
So let me get this straight. The Pontiac Solstice puts out 260 HP, essentially the output of a V6 engine. 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.

BTW, the Solstice weighs less than the Corvette by 300#, so the mileage figures are even more dismal.


RE: Good to see
By Brandon Hill (blog) 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.

http://www.ajdesigner.com/phphorsepower/horsepower...
as well as
http://www.solusinc.com/horsepower.html
don't forget
http://www.rbracing-rsr.com/aerohpcalc.html
and also why not this
http://www.autopedia.com/stuttgart-west/Physics/St...

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.


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?


RE: Good to see
By Chaser on 8/26/2008 12:47:44 PM , Rating: 2
As a C6 Corvette owner the Corvette is a car of extremes. Driving on the highway with very little traffic to help maintain 65 miles per hour in top 6th gear over a period of time will gain you 26MPH -with a tail wind. :) Under all other circumstances the Vette gets 16. ALL other circumstances. The Solstice on the other hand will get 19 when driving it hard, but maintain a noticably higher average in "everyday" city driving and get 27MPH when on the highway in almost all circumstances.


RE: Good to see
By theapparition on 8/26/2008 2:03:33 PM , Rating: 3
Have to disagree. My wife's stock 08 C6 is getting an average of 24mpg. That's a combined average, made up of mostly city driving.

I'd suggest your foot is just a little bit too heavy. I also fall into that catagory, so don't be offended. Both my C5 and C6 get an average of closer to 20mpg.

My two vettes don't count since they are "slightly" modified.
:P

Climate, driving conditions and tuning all make a huge difference. With a good tune, you should really be able to gain performance and increase gas milage, signifigantly. The cars come pig rich from the factory.


RE: Good to see
By FITCamaro on 8/26/2008 2:12:19 PM , Rating: 1
Exactly. I mean hell my dad's Trans Am gets 27 mpg at 75-80 mph and its a hell of a lot less aerodynamic than a Vette.

What I'm really wondering with the Vettes is why they haven't introduced the 3-valve heads on them yet. They demoed them like 3 years ago.


RE: Good to see
By Spuke on 8/26/2008 3:23:22 PM , Rating: 2
Well, if we're going to use real world driving. My Solstice gets 28 mpg on commutes with a lead foot. 30 mpg on 80 mph freeway jaunts (with some point and squirt driving) and 33 mpg on that same freeway drive if I manage to keep my foot off the floor.

Other drivers report much higher freeway figures but they're also driving at 60-65 mph. A place I don't go.


RE: Good to see
By FITCamaro on 8/26/2008 5:00:03 PM , Rating: 1
Ok and? I think that turbo-Ecotec is a great engine. I know it gets good fuel economy and makes great power.


RE: Good to see
By fxnick on 8/29/2008 2:41:13 AM , Rating: 2
3 valves on a pushrod motor? ive never heard of such a thing. they must have been using a different engine.


RE: Good to see
By FITCamaro on 8/26/2008 2:05:53 PM , Rating: 2
Don't know what options or whatnot you've got. But all the C6 6-speed owners I've talked to are getting 28-29+ MPG on the highway at 75 mph. At 65 it should be even better.


RE: Good to see
By lightfoot on 8/26/2008 2:45:34 PM , Rating: 2
As a Saturn Sky Redline (the solstice's twin) owner I have to say that you're exactly right. For me it's almost impossible to get less than 25 MPG in the Sky regardless of driving style, but on the highway I can regularly get 30-32. The 27 MPG quote is for the non-turbo charged 2.4L V4, not the 2.0L turbo-V4. The EPA highway of the Solstice/Sky is 29MPG. In any case it is wrong to say that 16 vs. 19 city mileage is a minimal difference - It's HUGE the Corvette uses 18.75% more fuel in city driving, and 11.5% more fuel on the highway. Not to mention the fact that the Corvette is going to cost you double the amount up front. Is the ‘Vette a more efficient engine? Yes it is, but large engines typically are.

The whole argument is silly - these are both performance cars - mileage is not a major concern. What really matters to owners of these cars is this: the Corvette will do in 3.7 seconds what the Sky/Solstice takes 5.5 seconds to do. That's the 0-60 time, and that is why people buy these cars. And they both get incredible mileage while having the ability to do so.

If you really want mileage, then buy a Smart car. It will cost you 1/6th the 'Vette, and 1/3 the Solstice and it will beat the socks off both of them in MPG - you just have to settle for a 12+ second 0-60 time.


RE: Good to see
By FITCamaro on 8/26/2008 5:02:22 PM , Rating: 2
Buying a SMART car is the dumbest thing you can do. Other far larger cars can nearly match its MPG and don't involve driving a gift box for a car (not even a shoe box).


RE: Good to see
By Spuke on 8/26/2008 6:15:26 PM , Rating: 2
quote:
don't involve driving a gift box for a car (not even a shoe box)
LOL! Kinda looks like my Logitech mouse.


RE: Good to see
By lightfoot on 8/26/2008 10:01:11 PM , Rating: 2
I don't disagree, but econo-boxes aren't performance cars and they shouldn't be compared. The Smart car is only slightly smaller than the Sky/Solstice and thus was a good parallel. If you don't need to haul cargo, and only need a single passenger they will both do the job. However, if all you care about is fuel economy, the Smart is the better choice.


RE: Good to see
By walk2k on 8/26/08, Rating: 0
RE: Good to see
By FITCamaro on 8/26/2008 2:16:38 PM , Rating: 2
Yeah and they were beaten by GM by more than that. Just not on 4 cylinders. GM and Ford have had a host of turbo-charged and super-charged vehicles throughout the past 60 years.

Your arguement = epic fail.


RE: Good to see
By Jimbo1234 on 8/26/2008 8:16:02 PM , Rating: 2
Read the latest Car and Driver and you will see that turbo's of the 80's were a failure. Manufacturers tried them at the time for fuel efficiency, but soon returned to N/A engines. Less cost, more reliable, and eventually more efficient but advances in control systems. Today's turbo engines are much, much better than those of the 80's.


RE: Good to see
By Jimbo1234 on 8/26/2008 8:17:04 PM , Rating: 2
...because of advances... typo


RE: Good to see
By Spuke on 8/26/2008 9:39:39 PM , Rating: 2
Wasn't there a turbo Corvair?


RE: Good to see
By Alexvrb on 8/26/2008 11:15:54 PM , Rating: 2
19/28 (22 combined) for the 5 speed MT, actually. 16/26 (19 combined) for the vette IS pretty good. I think that is more a testament to how efficient LS-series engines are. Pushrods can be powerful and efficient. :P Anyway. Yeah, the Solstice weighs 270 lbs less. But the vette has less drag, and has an extra gear. Remember, 5th and 6th are overdrive gears for the current LS3-equipped vettes.

If you want a more fair comparison, look at the weaker (especially in torque) 2.4L NA engine in the base Solstice. Slower AND less fuel efficient (19/25 for the 5MT). Compared to the 2.4L ecotec, the 2.0L DI TC ecotec produces more power and is more efficient. So using DI and TC engine combinations in their engine lineup all the way from 1.4L on up could be used to boost power or fuel economy - depending on the model, sometimes both.


RE: Good to see
By Spuke on 8/27/2008 12:11:34 AM , Rating: 2
In real world driving, the 2.0L gets 2-3 mpg better than the 2.4L on average. PLUS the added benefit of NOT having to drive like a grandma to get good gas mileage. I got 30 mpg on a 170 mile mountain road and country road drive with spirited driving on the mountain parts. The 2.4L cars in the group got 26 mpg.


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