Official GM Info: 2.9L/3.7L Engines

[Perian]

Link: http://media.gm.com/servlet/GatewayS...=2&docid=26823


Larger-Displacement 2.9L - 3.7L Vortec Inline Engines Deliver More Power


PONTIAC, Mich. - For the 2007 model year, GM's popular midsize trucks - Chevrolet Colorado and GMC Canyon - as well as the HUMMER H3 SUV, feature new, larger-displacement inline four- and five-cylinder engines. The new Vortec 2.9L I-4 and Vortec 3.7L I-5 deliver more horsepower and torque than the engines they replace, giving the vehicles increased performance.

The Vortec 2.9L DOHC four-cylinder with variable valve timing (VVT) replaces the previous 2.8L four-cylinder and delivers 185 horsepower (138 kW) and 190 lb.-ft. of torque (258 Nm).* The Vortec 3.7L DOHC five-cylinder with VVT replaces the previous 3.5L engine and is rated at 242 horsepower (180 kW) and 242 lb.-ft. of torque (328 Nm).*

The 2.9L engine produces approximately 6 percent more horsepower and 3 percent more torque than the previous four-cylinder, while the 3.7L offers a substantial 22-horsepower increase and 17 lb.-ft. more torque than the previous five-cylinder engine. The 2.9L is standard in all 2007 Colorado and Canyon models except 4WD Crew Cab; the 3.7L engine is standard in 4WD Crew Cab models and available on all others. The 3.7L engine is the only engine offered on the '07 HUMMER H3 and H3X.

GM's inline engines meet the diverse demands of midsize pickup and SUV customers. The I-4 engine delivers more power than many other comparable four-cylinders, while the more powerful I-5 offers comparable power and torque to many competitors' six-cylinders.

Increased bore diameter

Both new engines are based on GM's modular inline engine design, which also serves as the foundation for the award-winning 4.2L I-6 in the Chevy TrailBlazer, GMC Envoy and Saab 9-7X. They feature dual overhead camshafts, variable valve timing, electronic throttle control and other features that contribute to high levels of operating efficiency and fuel economy. Balance shafts help ensure smooth operation and reduced vibration of the engines, providing a higher level of refinement.

In addition to their larger displacement - delivered through larger, 3.76-inch (95.5 mm) bores - the 2.9L and 3.7L engines feature improved airflow in and out of the combustion chambers, which helps boost power. They also share additional upgrades and changes, compared to the previous engines:

* Larger, 1.52-inch (38.7 mm) intake valves, vs. previous 1.45-inch (37 mm) intake valves
* Larger, 1.32-inch (33.5 mm) exhaust valves, vs. previous 1.18-inch (30 mm) exhaust valves
* Revised camshaft profile optimizes valve lift and duration in accordance with larger valves
* Cylinder head airflow increased to match capabilities enabled by larger valves and revised camshaft
* New, noise-reducing oiling system uses cylinder wall squirter system enabled by a hole in each connecting rod that delivers a precise oil stream onto the cylinder wall beneath the piston
* New aluminum camshaft cover helps reduce noise
* Tighter-clearance balance shaft bushings promote quieter operation
* New, 2-megabyte powertrain control module houses new diagnostic information storage
* New cartridge-type engine block heater, which fits neatly into a specially machined block orifice; for use with available engine block heater.

Additionally, the 3.7L five-cylinder engine has several features that help it meet new BIN 5 emissions requirements, including a larger, close-coupled catalytic converter and A.I.R. system.

VVT-enhanced performance

The new inline engines employ state-of-the-art air-fuel and spark management, including a dual-overhead cam valvetrain, four-valves-per-cylinder, variable valve timing and coil-on-plug ignition. Like the common-design engine blocks, the aluminum cylinder heads for the 2.9L and 3.7L are modified four- and five-cylinder versions of the 4.2L I-6 head. The cylinder head design includes chain-driven camshafts with large sprockets to ease the load carried by the timing chain. Also, a roller follower valvetrain reduces friction to improve engine performance and fuel economy, while reducing noise.

VVT enhances performance and improves emissions by regulating the timing of the opening and closing of the exhaust valves. With VVT, camshaft lobe profiles are selected to enhance power, torque and engine smoothness, and the valve timing is optimized for the camshaft at different rpm levels by the PCM. VVT also eliminates the need for external exhaust gas recirculation (EGR) and contributes to improved emissions. With VVT, the exhaust valves' timing can be adjusted to "retard" the exhaust cam, thereby creating internal EGR. These leftover gases are recycled into the next burn cycle, improving emissions and engine performance.

Coil-on-plug ignition delivers a high-energy spark, contributing to a cleaner, more consistent burn of the air-fuel mixture. The system uses a separate ignition coil for each cylinder, mounted above the spark plug. An electronic engine-sensing spark control system sends energy to the coils, eliminating the need for timing adjustments.

The engines also benefit from numerous quality-enhancing characteristics:

* Electronic throttle control allows the tailoring of throttle position to optimize driveability, fuel economy and emissions control
* Accessories - including a new, 125-amp alternator featuring Regulated Voltage Control - are mounted directly to the engine block to reduce vibrations
* The air intake plenum is constructed with sound-absorbing foam to reduce noise heard in the passenger compartment
* High-mounted starter is shielded from road splash
* GM Oil Life System permits oil-change intervals of 5,000-15,000 miles

The engines also feature an exhaust manifold-mounted, three-way catalytic converter design. Constructed as part of the manifold, the close-coupled converter provides optimum light off (quickly reaches high temperature) to oxidize, primarily, hydrocarbon and carbon monoxide emissions.

Shared traits

The inline engines share much of their design and technology, including dual-overhead cams, four valves per cylinder, variable valve timing (VVT), sequential fuel injection and a coil-on-plug ignition system. Approximately 75 percent of the I-4 and I-5 engines' components are shared with the larger Vortec 4.2L I-6, and about 90 percent of the four- and five-cylinder engines' parts are common. This permits increased assembly efficiency that affords GM greater flexibility in adjusting the production of each engine to meet consumer demand.

The foundations of the engines' design are deep skirt, cast aluminum engine blocks. They are produced with a lost foam process that allows more precise dimensional control, while reducing necessary finish machining in oil galleries, coolant passages and other internal passages. The deep-skirt design places block material below the crankshaft centerline to enhance rigidity of the block, while the lightweight aluminum offers better control of oil temperature, eliminating the need for auxiliary oil cooling. The lighter-weight engine block enhances fuel economy, too, by reducing overall mass.

In addition to superior dimensional accuracy and less need for finish machining, lost foam casting also allows the blocks to be produced with fewer pieces and more complex shapes. Overall, fewer pieces are needed to assemble the engines, and the accuracy of the casting process results in less scrap. And because the dry sand used in the casting process requires no bonding agent, it does not have to be discarded as solid waste. In fact, the sand is re-used for future castings.

At the assembly stage, the I-4 and I-5 engine blocks are fitted with balanced crankshafts and main bearing caps that are designed to add strength and reduce noise and vibration. Also, the engines' oil pans are structural members, contributing to overall stiffness. Both the four- and five-cylinder engines' crankshafts are specially counterweighted for their unique cylinder configuration.

The 2.9L and 3.7L engines are built at GM's Tonawanda, N.Y., engine assembly plant.

[Perian]

I guess the lack of MPG number inclusion means no improvement(s) in that category.

Remember the GMT900 press releases had the (estimated) MPG numbers in the headline...

[Buick61]

I still don't understand GM needs to have the 2.2L Ecotec, 2.4L Ecotec and the 2.9L Atlas.

As the 2.2L gets the same mpg rating as the 2.4L, I'd say the smaller motor is a good candidate for being eliminated. And the 2.9L doesn't make that much more power than the 2.4L--185 vs. 177. If the fuel economy rating for the Atlas is good enough, then get rid of the 2.4L too.

What GM really needs is a n/a 2.0L ecotec equipped Cobalt that can do battle with the 41mpg Corolla.

[Perian]

Originally Posted by Buick61

What GM really needs is a n/a 2.0L ecotec equipped Cobalt that can do battle with the 41mpg Corolla.

Or at least a change in the Cobalt gearing and tire selection - like GM is doing with the 07 Cadillac SRX to increase MPGs.

[ponchoman49]

This will surely do nothing for mileage. I'll bet it drops in some cases. It's amazing that some models with the 4 cylinder automatic get about the same mileage as the 5 cylinder automatic. There is no reason a basic 2WD regular cab 4 cylinder stick Colorado shouldn't have a 30 mpg highway rating! And there is no reason why GM can't offer a V6 in this truck like they do the Australian version!

[Randle2I]

How many I4's does GM have? Theres the 2.0, 2.2, 2.4, 2.9 and the 1.8 found in the Vibe (although that's technically not theirs). The 2.0 is a rather impressive engine so no reason to get rid of that, but as Buick61 said there certainly seems to be a strong case for getting rid of at least 2 of the other ones.

[Ultra Magnus]

What GM really needs for these trucks is the small Vortec V8 (4.8L) with DoD/AFM and as many gears as they can cram into the package. Then they will really have something that people can get behind.

[Co27sskid]

don't forget about the 1.8 in the Aveo The E-Tec II

[nadepalma]

Originally Posted by Co27sskid

don't forget about the 1.8 in the Aveo The E-Tec II

I thought that was 1.6 liters...no?

[JVal14]

Originally Posted by ponchoman49

This will surely do nothing for mileage. I'll bet it drops in some cases. It's amazing that some models with the 4 cylinder automatic get about the same mileage as the 5 cylinder automatic. There is no reason a basic 2WD regular cab 4 cylinder stick Colorado shouldn't have a 30 mpg highway rating! And there is no reason why GM can't offer a V6 in this truck like they do the Australian version!

30mpg is a lot to ask for, even in a I-4 midsized truck. There are some cars that have comprable power numbers and barely get 30 mpg on the hwy. Never-the-less, without the addition of a 6-spd. AT, the mileage would probably be worse than before; so GM has traded one complaint for another. Engine power was only one shortcoming for these trucks; unless they are all addressed, I don't think there's much hope for improved sales with the 360s.

[BullyDog]

The 3.7L engine is the only engine offered on the '07 HUMMER H3 and H3X.


Have they announced the wrangler fighter on accident? H3X?

[b4z]

I drove a Vauxhall Astra in England last week that was 1.6L and 104 hp.
0-60 was 12 seconds!

[jomo]

Originally Posted by Buick61

I still don't understand GM needs to have the 2.2L Ecotec, 2.4L Ecotec and the 2.9L Atlas.

As the 2.2L gets the same mpg rating as the 2.4L, I'd say the smaller motor is a good candidate for being eliminated. And the 2.9L doesn't make that much more power than the 2.4L--185 vs. 177. If the fuel economy rating for the Atlas is good enough, then get rid of the 2.4L too.

What GM really needs is a n/a 2.0L ecotec equipped Cobalt that can do battle with the 41mpg Corolla.

What you don't understand is that the 2.9L Atlas is a very TALL engine. It won't FIT in a car. I don't know how many times people have proposed that the Atlas replace X.XL Ecotec while neglecting that basic fact. I didn't realize it until I bought a truck, but truck engine's are HUGE compared to the comparable car engine. So if one would have to displace the other, that would mean the 2.4 would displace the 2.9 since it can fit inside the lowest common denominator (cars). Since the 2.4 is only 177 HP, that would put the Colorado and Canyon back where they started. "Underpowered". So, no, the 2.4L Ecotec can't go. I don't have a beef with snatching out the 2.2L Ecotec if it's economy really is that poor, but I must point out that the average American buys fuel economy LAST. A N/A 2.0L just doesn't have enough horsepower for the average American buyer. I know people who were soured on American cars more because of the perceived "under-powered" nature of some of the eights/nineties econoboxes than any perceived quality short-coming. Should GM have a high-efficiency 4? Yes. Working it into the line-up, though, is another question entirely.

I've said this in another thread, but what GM really needs is to have user-tunable economy. Just a simple range of economies that the user can select. On one end of the scale, give me the maximum SAFE horsepower (ie won't blow the engine). On the other end of the scale, give me best economy (again, won't do engine damage). You'd see a lot more benefit to the Displacement On Demand V8s if users could dial in how quickly the V8 mode kicked in instead of it being an on/off thing. You could have the engine stay in 4-cylinder mode longer to maximize fuel economy.

[CADILLACSIXTEEN]

WHAT is the Hummer H3X???????????????

[Al465]

[quote=Buick61]I still don't understand GM needs to have the 2.2L Ecotec, 2.4L Ecotec and the 2.9L Atlas.

As the 2.2L gets the same mpg rating as the 2.4L, I'd say the smaller motor is a good candidate for being eliminated. And the 2.9L doesn't make that much more power than the 2.4L--185 vs. 177. If the fuel economy rating for the Atlas is good enough, then get rid of the 2.4L too.

What GM really needs is a n/a 2.0L ecotec equipped Cobalt that can do battle with the 41mpg Corolla.[/quote

Yes, I agree with your assessment, GM should take the Cobalt and make it the milage champion of it's class. This would greatly help in changing the image that GM has.