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GM Powertrain Unveils More Engines with Direct-Injection, Active Fuel Management and E85
18 May 2006
GM Powertrain today introduced three new versions of existing engine models: a 3.6-liter V-6 gasoline engine with direct injection and variable valve timing (VVT); its first V-6 application of Active Fuel Management (cylinder deactivation) on the 3.9-liter V-6 for 2007 Chevy Impala; and E85 ethanol fuel capability on the 3.9-liter V-6 offered in 2007 Chevy Uplander fleet models.
The 3.6L VVT DI engine reduces fuel consumption by up to 3% while increasing power by 15%. The 3.9-liter AFM application improves fuel economy by an estimated 5.5% (from 22 mpg EPA combined to a projected 23.2 mpg combined).
This brings the total of new or significantly revised engines for model year 2007 to 19.
The 3.6-liter VVT DI. GM will apply a version of its 3.6-liter V-6 gasoline engine with direct injection and variable valve timing (VVT) technologies in the 2008 model year. The company will announce a specific vehicle target later this year.
The application of direct injection technology to the 3.6-liter VVT engine contributes greatly to a 15% increase in horsepower over the current levels that range from 240 hp to 267 hp; an 8% increase in torque, and up to a 3% improvement in brake-specific fuel consumption (BSFC). An approximate 25% reduction in cold-start hydrocarbon emissions is also achieved.
GM projects that by 2010 one out of every six GM vehicles in North America will be equipped with a direct injection engine.
Direct injection delivers precisely metered fuel directly to the combustion chamber, producing a cooling effect in the chamber. Cooling the incoming air charge enables a higher compression ratio (greater than 11.0:1 in the case of the 3.6), which also improves engine efficiency. Less fuel is required to produce the equivalent horsepower of a conventional port injection combustion system.
The 3.6-liter VVT with direct injection will be our highest specific output non-turbocharged V-6 engine, as well as one of the most fuel-efficient offerings in our high-feature family.
—Tim Cyrus, chief engineer for high feature V-6 and Northstar V-8 engines
The 3.6-liter is GM’s third engine with gasoline direct injection. The announcement of the 3.6L VVT V-6 with direct injection comes after the introduction of GM Powertrain’s Ecotec 2.0-liter four-cylinder Turbo engine with direct injection on the 2007 Saturn Sky Red Line and Pontiac Solstice GXP roadsters. GM has been delivering a naturally-aspirated Ecotec 2.2-liter direct injection engine on Opel models in Europe since 2004.
The fuel injectors in the gasoline direct injection system are located beneath the intake ports. The intake ports only transfer air, unlike port fuel injection, which flows air and fuel, thus increasing efficiency.
Direct injection requires higher fuel pressure than conventional fuel injected engines and an engine-driven high-pressure fuel pump is used to supply up to 1,740 psi (120 bar) of pressure.
The system regulates lower fuel pressure at idle—approximately 508 psi (35 bar) and higher pressure at wide-open throttle. The exhaust cam-driven high-pressure pump works in conjunction with a conventional fuel tank-mounted supply pump.
The 3.6-liter VVT DI is based on GM Powertrain’s 60-degree dual-overhead cam (DOHC) V-6 engine. The 3.6-liter V-6 VVT DI employs four-cam phasing to change the timing of valve operation as operating conditions such as rpm and engine load vary.
The result is linear delivery of torque, with near-peak levels over a broad rpm range, and high specific output (maximum horsepower per liter of displacement) without sacrificing overall engine response and driveability.
Cam phasing also reduces exhaust emissions by optimizing exhaust valve overlap and eliminating the need for a separate exhaust gas recirculation (EGR) system.
By closing the exhaust valves late at appropriate times, the cam phasers allow the engine to draw the desired amount of exhaust gas back into the combustion chamber, reducing unburned hydrocarbon emissions.
The return of exhaust gases also decreases peak temperatures, which contributes to the reduction of oxides of nitrogen (NOx) emissions. In tandem with the 25% reduction in cold-start hydrocarbon emissions brought on by direct injection, the 3.6-liter VVT DI V-6 surpasses all emissions mandates, and does so without complex, weight-increasing emissions control systems such as EGR and air injection reaction (AIR).
3.9-liter Active Fuel Management. The new 3.9-liter engine with AFM is GM’s first V-6 application of its cylinder deactivation technology. (GM had pushed back the introduction of the V-6 AFM engine back to the 2007 model year to do additional fine-tuning on noise and vibration.) (Earlier post.)
Preliminary testing of the 2007 Chevy Impala equipped with the 3.9-liter V-6 with AFM indicates an estimated 20 mpg in the city and 29 mpg on the highway—improvements of approximately 5.5% and 7.5%, respectively.
Active Fuel Management enables the engine to automatically operate on half of the engine’s cylinders under light load conditions, improving efficiency by reducing fuel consumption when the cylinders are deactivated.
GM offers this technology in 11 vehicles for 2007, including trucks and SUVs – more than any other automaker. The Impala is GM’s first V-6 application of AFM in North America. GM also is launching a 3.0L V-6 with AFM in China that will debut in the Buick LaCrosse this summer.
A new engine controller determines when to deactivate cylinders, allowing the engine to maintain vehicle speed in lighter-load conditions such as highway cruising. When the cylinders are deactivated, the engine effectively operates as an inline three-cylinder engine, with cylinders 1, 3 and 5 deactivated on the left cylinder bank. The engine returns to V-6 mode the instant the controller determines the vehicle speed or load requires additional power.
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| The special hydraulically-activated de-ac lifters that enable GM’s Displacement on Demand. |
GM uses two-stage hydraulic valve lifters which allow the lifters of deactivated cylinders to operate without actuating the valves. The lifters have inner and outer bodies, which normally operate as a single unit. When the engine controller determines cylinder deactivation conditions are optimal, the outer body moves independently of the inner body on the disabled cylinders’ lifters.
The outer body moves in conjunction with camshaft actuation, but the inner body does not move, holding the pushrod in place. This prevents the pushrod from actuating the valve, thereby halting the combustion process. Also, fuel supply to the fuel injectors is halted while the cylinders are deactivated.
Solenoids in the Lifter Oil Manifold Assembly (LOMA) operate to deliver high-pressure oil to the switching lifters, activating a release pin to separate the inner and outer bodies. Oil circulation and pressure do not vary regardless of the engine’s operational mode. Lifter design and pushrod length are the same for every cylinder, but camshaft lobe profiles differ for cylinders designated to be deactivated.
Because the noise and vibration characteristics are different between a V-6 and the effective inline three-cylinder operation when the 3.9L is in fuel-saving mode, engineers tuned the engine and exhaust system to maintain consistent operational sound and feel. For example, the alternator features a unique decoupling clutch that instantly adjusts tension on the accessory drive belt when the engine switches from six- to three-cylinder operation.
The 3.9-liter’s cam-in-block variable valve timing technology also works synergistically with Active Fuel Management, as the cam phaser enables the engine to produce maximum torque during three-cylinder operation. This allows the engine to remains in fuel-saving mode longer.
The VVT system incorporates a vane-type camshaft phaser that changes the angular orientation of the camshaft, thereby adjusting the timing of the intake and exhaust valves to optimize performance and economy, and help lower emissions. It offers infinitely variable valve timing in relation to the crankshaft.
The cam phasing creates “dual equal” valve timing adjustments. In other words, the intake valves and exhaust valves are varied at the same time and at the same rate. The cam phaser vane is attached to the camshaft on the front journal—a technique made easier by the assembled-camshaft design developed by General Motors.
With this design, separate camshaft lobes are installed on a hollow camshaft tube rather than the traditional method of grinding a camshaft from a single piece of stock.
Hydraulic roller lifters with low-friction followers complement the camshaft, and the engine controller enables the engine’s cam phasing. The system’s demand for precise camshaft position information is met with a unique, cam target ring with four equally spaced segments that communicate the camshaft’s position quickly and accurately. Also, a leaf spring-type tensioner is used on the timing chain to ensure precise tension.
The 3.9L V-6’s camshaft is unique and matched to the engine’s bore-and-stroke characteristics. It is different, for example, than the camshaft in the 3.5L V-6.
May 18, 2006 in Engines, Fuel Efficiency, Vehicle Systems | Permalink | Comments (52) | TrackBack (0)
Comments
Posted by: Angelo | May 18, 2006 at 01:53 PM
Are we suppose to go from ' My car/VUS is larger than yours' to 'My car/Vus is more powerful than yours' or are we going to grow up soon?
Posted by: Harvey D. | May 18, 2006 at 02:10 PM
Um clueless peoples the reason they needed an engine at 3.6l that got 15% more power while using 3% less fuel is because its replacing a 4l engine.
In short they are downsizing the engines This engine gets the power of a bigger ebngine while using less fuel then the old engine OF ITS SIZE. Combined thats prolly a 20% fuel eff improvement.
Posted by: wintermane | May 18, 2006 at 02:16 PM
"That should be a very telling statement, that GM has many articles on this website, with this website being GCC, or GREEN---CAR---CONGRESS Maybe they are closer to being green than they are yellow?"
It certainly means that there's news to report; that they talk about it and do some stuff, but it doesn't mean that they are green. Being mentioned on GCC doesn't equate being green. You have to look at real-world results..
Posted by: Michael G. Richard | May 18, 2006 at 03:30 PM
I commend GM on their work. Minimal engine modifications for extra power, fatter and broader powerband, and better gas mileage to boot. I'm hoping they add direct injection to the 3.9L pushrod too, for the same net gain. I love pushrods, and you efficiency nuts should too. Simplicity and Economy = efficieny.
I remember reading somewhere, I believe Grass Roots Motorsports, that GM was actively researching AFM/DoD for their 6.0L LS2. Corvettes running the prototype engines averaged 'well over 30mpg' - real world, 70mph+ testing according to an engineer. I bet it's released for a mid-model update to the C6. How will GM look when it's ICONIC SPORTSCAR gets an EPA rating far better than the family 4 door?
Also, I can't believe no one noted the hollow camshaft part! Awesome. Shaves pounds, more efficient, and probably cheaper in this age of expensive commodities.
Joseph,
You're absolutely wrong on the 300C. First of all, the 'C' designation goes to Hemi equipped 300's only. The 300 2.7L w/ 190hp 4A is rated at 21/28. The 250hp 5A 3.5L is rated at 19/27 and 17/24 w/ AWD. The 5.7L Hemi is rated at 17/25 5A RWD, and 17/24 AWD. Those are by no means Corvette numbers on the highway.
A quick check at the 300C forums reveals real world highway mileage about 10% less than the EPA posted for the RWD Hemi, although 425hp SRT8 versions apparently routinely meet or exceed EPA ratings of 12/20. ;]
Posted by: Adam H | May 18, 2006 at 04:20 PM
I hate to make this petty, but for the author of the following,
"Um clueless peoples the reason they needed an engine at 3.6l that got 15% more power while using 3% less fuel is because its replacing a 4l engine.
In short they are downsizing the engines This engine gets the power of a bigger ebngine while using less fuel then the old engine OF ITS SIZE. Combined thats prolly a 20% fuel eff improvement."
If you are going to call someone out like this, know your facts. First of all, they aren't disclosing what the application of the 3.6L is going to be, so how do you know it's replacing a 4.0L? Second of all, I challenge you to find the last GM car that had a 4.0L engine. Lastly, where the hell does that, "20% fuel eff improvement" come from???
Please, stick to the facts, especially if you are to call others clueless!
Posted by: Angelo | May 18, 2006 at 04:26 PM
I think he's referring to the fact that a smaller engine is inherently more efficient - be it from weighing less and having less moving parts. I don't know where that 4.0L number came from.
Here's a good example of engine downsizing, although more like 5% city/10% highway, rather than 20% all around.
The new ford explorer runs a 4.6L engine with 292hp, and is EPA rated for 15/21 in RWD. The old explorer, with a 5.0L engine and I believe, 245hp, was rated 14/19 by the EPA. This despite the new Explorer weighing a few hundred more pounds. The numbers speak for themselves.
Perhaps if the downsized engine was rated at the same HP of the previous larger displacement engine (not increased) and the engine was placed in the exact same vehicle (not a newer, heavier model), a 20% improvement would be realized. Which is not too far fetched.
The engineers should say that the efficiency of the engine relative to its weight and displacement has been increased 20%.
Posted by: Adam H | May 18, 2006 at 04:46 PM
All of these improvements from GM are a good thing. GM still sells alot of cars and 5% better is not bad. I restate my opinion that GM in 2007 will be the greenest US brand. In 2007 GM will have more hybrid models and save more gas then Ford and Chrysler. If you want to bash an American brand bash Chysler. They have no publicly available hybrid, GM will have three hybrids before they have one.
Posted by: hampden wireless | May 18, 2006 at 06:15 PM
"If you want to bash an American brand bash Chysler"
...errr, you mean, "German brand", right? Ha, Ha....oh, how things have changed.
Posted by: Angelo | May 18, 2006 at 06:31 PM
Um dear clueless who just proved themsevles such... the 20% comes from the fact that its using less fuel then its displacement engine did and its extra power is making it replace a bigger engine that would indded use up more fuel again.
As for engine sizes.. your realy clueless as they in fact go all the way up into the 5 liter mark.
Gm has been trying to make smaller engines with more power for years now because any of thier prime sellers need full time power yet also need far better fuel econ. This engine will get that.
Posted by: wintermane | May 18, 2006 at 06:38 PM
Joseph, You're absolutely wrong on the 300C.... The 5.7L Hemi is rated at 17/25 5A RWD, and 17/24 AWD. Those are by no means Corvette numbers on the highway.
They have the same combined fuel economy. Quoting highway fuel economy is meaningless, since hardly anyone drives highway only. That's why we have combined ratings. The 300C with AWD has a combined rating of 20 MPG. The 7 liter Vette has the same numbers, and the 6 liter gets 21 MPG.
They're both gas hogs, and rightly so.
Posted by: Joseph Willemssen | May 18, 2006 at 06:49 PM
Geez...more V6s?...hope planD is a couple of 4&5 cylinder turbodiesels, maybe made in Tonawanda?
Posted by: fred@dzlsabe.com | May 18, 2006 at 07:35 PM
3.6 liter with GDI and VVT, and still 267 hp? How do they manage to have such low output? And uncooled EGR? Looking for additional troubles and emissions?
3.9 liter engine for front wheel drive Impala? Almost permanently driving on unbalanced 3 cylinders with another 3 permanently overcooled? VVT on pushrod? Addition of another reciprocating mass (hydraulic actuator) to pushrod?
Looks like GM engineers still have half of their brains deactivated.
Posted by: Andrey | May 19, 2006 at 02:49 AM
"Um dear clueless who just proved themsevles such... the 20% comes from the fact that its using less fuel then its displacement engine did and its extra power is making it replace a bigger engine that would indded use up more fuel again.
As for engine sizes.. your realy clueless as they in fact go all the way up into the 5 liter mark."
I realize this could go back and forth infinitely, but seriously, you have no idea what you are talking about. Now you are saying this 3.6 is going to replace the 5.3 or something larger? Do you even remember what you initially proposed?
This is an absurd argument - of course a smaller engine should consume less fuel, and I'll bet you could get to your 20% mark by comparing this to a large enough engine. However, you based it on a "4.0L" engine. Now, I can only guess you are estimating, and mean something like the 3.9L that is used in many applications. If that is the case, there is no way the 3.6L uses 20% less fuel.
The MOST IMPORTANT point is that how the hell do you know the 3.6 is going to replace a larger engine?? It could very easily be the case that the 3.6 is replacing.....a 3.6! IF that is the case, baring any other changes to the vehicle (maybe their new 6spd auto will be applied), it is a relatively miniscule 3% improvement that we are left with. Not going to help too much.
Posted by: Angelo | May 19, 2006 at 04:19 AM
How will GM look when it's ICONIC SPORTSCAR gets an EPA rating far better than the family 4 door?
How many people buy iconic sportscars vs. family four-doors?
If GM really cared about fuel economy, they'd be able to make one car that gets over 40mpg, and have all their passenger cars get at least 30mpg in the city.
But if all they care about is their image, they'll improve the gas mileage in their SUVs and "iconic sportscars" to make themselves look good.
Posted by: Icelander | May 19, 2006 at 05:22 AM
I think the important thing to remember here is that GM is improving, efficiency wise.
The whole GM vs Chrysler debate started because of the public image that Chrysler is trying to sell. Put "Hemi" on anything and it will sell. Doesnt matter if its fuel efficient. The Dodge truck commercials are a perfect example. The guy pulls off a tarp and sees "Hemi" says ("sweeeeeeeet'), while the other guy in the car drives off the cliff ("that cant be good"). Dodge is pushing "Hemi" power, and horsepower. Amusing commercials, but do nothing for me. GM's latest commercials at least have been leaning toward fuel economy or towards ethanol, of which I am not much of a proponent of, but thats a different story and should be on a different thread.
GM is trying, give them that. It takes a while to turn around an "aircraft carrier", as opposed to a "rowboat", to use another analogy. Of course everyone can voice their opinion with their wallet. Oh, my household has a Jeep Liberty and a Nissan Altima, so I am no GM lover (at the moment).
Posted by: Mark A | May 19, 2006 at 06:24 AM
Another problem is that increased engine efficiency doesn't mean real world efficiency gains.
If they put a 5% more efficiency engine in a vehicle that is 300 pounds (or whatever) heavier than the previous generation (bloat has been the plague of the whole industry for decades), it doesn't help much.
Posted by: Michael G. Richard | May 19, 2006 at 09:02 AM
Although GM is draging it's heels some, most of the blame should be put on the American buying public. GM builds about a dozen models that get 35+ mpg. Until recently US buyers had absolutely no interest in fuel efficiant cars. If you want to see what GM can do when there is legitimate demand for high MPG, try Holden, Opel or Vauxhall.
Posted by: Joseph | May 19, 2006 at 10:04 AM
(a) Overhauling an engine design takes 30-40 months from concept to series production. The main reason GM (and to a lesser extent, Ford and Chrysler) are so heaviliy criticized on this website is that they have been caught out by a double whammy of high oil prices and competitors' advances in technology. To some extent, this is crying about milk spilt many years ago.
GM's CEOs, including Rick Wagoner, have long been drafted from its finance rather than its engineering divisions. That works very well as long as market conditions change slowly but exposes the company to serious risk during periods of rapid innovation in the industry. Bob Lutz was give a prominent role to beef up IP generation as well as the quality and emotional appeal of the product line. Unfortunately, it takes time to revamp an ingrained corporate culture of beancounting and consumers are impatient.
(b) GM has indicated it will be relying more heavily on its international divisions' R&D competence to plug some holes in its North American product lineup. In particular, the staid Saturn brand will supposedly leverage Opel vehicles far more aggressively than in the past, starting with the Saturn Sky/Opel GT roadster. The more "sensible" Opel Astra and Vectra models may follow later.
(c) any large company forced to downsize its unionized workforce by (tens of) thousands is going to be constrained in its ability to excel financially or even just technologically. Porsche and Nissan have gone through this. Citroen/PSA and Renault have won concessions from their unions. DaimlerChrysler, Ford and GM are also at different points on the trajectory. VW and Fiat have yet to get started in earnest.
(d) As a voter/taxpayer, you don't really want these big companies to fail because of the negative social and macroeconomic impacts. Instead, you want them to become competitive again. I'm not certain that GM will pull it off, but I wish them well.
Posted by: Rafael Seidl | May 19, 2006 at 12:03 PM
Anyone who is trying to knock GM for adding Direct Injection to the 3.6 and "only" gettting 267hp from it should wake up and take note that GM has recently announced that the 3.6L DI will actually have 305 HP. This engine will be available in the 2008 model years. This was shown in Motortrend July 2005 Page 22. Looks like GM will be able to compete in the horsepower wars after all.
Posted by: Patrick | June 20, 2006 at 07:58 PM
7 years ago the Camaro Z-28 and Trans Am with 6 speeds were getting 28MPG on the highway while having 305HP engines. Imagine what they could get with DI & AFM with a 5.3L engine and some tweaking. Add E85 to the mix and you can have your cake and eat it too. My wife drives 50 miles a day for work and 45 of it is highway so she would benefit from it greatly.
Posted by: Travis | July 06, 2006 at 04:34 PM
I refuse to buy a car with cylinder deactivation until GM and Chrysler prove that their designs are fail safe i.e. that valves will not hit pistons if the deactivation pin breaks. I'll never forget my 1981 Cadillac which had the infamous 4-6-8 engine. It ran unbalanced in the 6-cylinder mode and I finally disconnected the high pressure switch on the transmission to fool the computer into thinking that the car never reached third gear. This kept the car on 8 cylinders all the time and I was happy.
Posted by: Enn Norak | August 02, 2006 at 11:59 AM
Saab Ecotech 2.0 has EPA 23/34 and still does 0-100mph in around 17 seconds (Car & Driver). That's an Opel/GM/Saab design, and is particularly smooth and quiet. Mine runs with my A6 twin turbo (not so good mileage) and on my 40 minute test route gets 25% better mileage day to day. No contest at a steady 80: Audi 21 saab 34. Lamda chassis, Opel engine. Saab tranny (6 speed on my 03)= GM. Great seats, too.
Posted by: mark trail | January 29, 2007 at 12:36 AM
"The 3.6L VVT DI engine reduces fuel consumption by up to 3% while increasing power by 15%."
That's the problem right there. Instead of putting efficiency gains into downsizing and fuel economy, they put them into yet more useless power.
---> when efficiency is increased, power will increase as well. LOOK IT UP
Posted by: Daniel | May 20, 2008 at 06:33 PM
Name one GM car that gets over 40mpg. Just one. (Hint: There aren't any.)
Really? Umm... Going down the list in the 09 lineup I have here : Allure39, Lucerne39, CTS38, STS38, Aveo49, Cobalt48, HHR43, Impala40, Malibu46, G5(48, G6(43, Solstice40, Vibe46, Wave49, Saab9-3(41, 9-5(39, Astra46, Aura46, Sky40, Vue46, Vette37<--... In don't see one here under 23mpg highway (Express Cargo Van)
Posted by: syx3s | August 10, 2008 at 09:43 AM
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Adding to an earlier point I made, there are a few different types of Direct Injection as well:
1. Wall guided: First generation DI, limited fuel efficiency gains. Is this what GM is using, giving the minimal fuel efficiency gains?
2. Charge Motion/Air Guided: Current generation, modest fuel efficiency gains - I believe this is the type Audi and Mazda are using?
3. Spray guided: the future "micro-piezo" versions that spray with such a fine mist that there are significant gains in efficiency [15%] due to the ability to run a very lean mixture. Both BMW and Benz will be buying this type from Bosch and implementing in the near future.