Vortec I-6 for 2005

["Brien Tourville" <hh7x@xxxxxxxxxxx>]

[quote'
Then Chevy came out with the "
Vortec I-6 as their new truck engine. It has variable timing, and the
"
I-6 is a cost saving package for that. With a V engine four cam
adjust "
mechanisms are needed, with the in-line only two (or one if only
intake "
or exhaust is variable).

btw only one cam is variable on the 4200 vortec - cost and complexity
issues, i suppose.
[end quote]



             Vortec 4200 4.2L I-6 (LL8)

2005 Model Year Summary

·???????? Application in 2005 Saab 9-7X
·???????? Improved cam phaser
·???????? Returnless fuel injection
·???????? Improved compression rings
·???????? Improved intake manifold and throttle body gaskets
·???????? Improved ORVR purge valve
·???????? Vented starter solenoid
·???????? Improved throttle mapping
·???????? NVH enhancements
·???????? GF-4 engine oil


IMPROVED CAM PHASER
"The Vortec 4200 is now equipped with a vane-type cam phaser,
replacing the helical spline and piston phaser used since the
engine?s launch. The vane phaser represents the current state-of-the-
art in cam phaser and it delivers several benefits."

The cam phaser changes exhaust cam lobe timing relative to the cam-
drive sprocket, which in turn varies exhaust valve timing on the fly,
maximizing engine performance for given demands and conditions.

At idle, for example, the exhaust cam is at the full advanced
position for minimum intake-valve overlap.

That allows exceptionally smooth idling.

Under other operating demands, the phaser adjusts to deliver optimal
exhaust-valve timing for performance, drivability and fuel economy.

The result is linear delivery of torque, with near-peak levels over a
broad rpm range, and high specific output (horsepower per liter of
displacement) without sacrificing overall engine response, or
drivability.

Because it manages valve overlap at optimum levels, cam phasing also
eliminates the need for an Exhaust Gas Recirculation (EGR) system."


"As it was with the spline-piston phaser, the new vane phaser is
actuated by hydraulic pressure from engine oil, and managed by a
solenoid that is set to a specified duty-cycle and controls oil
pressure on the phaser.

Yet the operating mechanism is different.

Instead of helical spline and piston, the vane phaser uses a wheel
with four vanes (like a propeller) to turn the camshaft relative to
the cam-sprocket.

The solenoid directs oil to pressure points on either side of the
four vanes; the vanes, and camshaft, turn in the direction of the oil
flow.

The more pressure, the more the phaser and camshaft turn. Like the
previous phaser, the vane phaser turns the Vortec 4200?s camshaft a
maximum 24 degrees relative to the sprocket."

"The vane phaser is a much simpler device than the spline-piston
phaser, with fewer parts.

The vane wheel is made of extruded aluminum; it requires less
machining and it?s less expensive to manufacture.

Moreover, the vane phaser is more robust. It?s validated to ten years
or 150,000 miles of operation. It is less sensitive to disruption
from excessive debris in the oil."

"Most important, the vane phaser performs more quickly and
efficiently than the spline-piston phaser.

Because it generates less friction, in turns the camshaft faster?in
some conditions, as when the engine is warm and operating at low rpm,
nearly four times faster.

This improved response time will be transparent to the driver, but it
improves the Vortec 4200?s overall efficiency and reduces compromises
when balancing performance, drivability, fuel efficiency and
emissions reduction.

More precise control gives engineers more options in calibrating the
cam phaser to maximize its benefits. "

RETURNLESS FUEL INJECTION
"All Vortec 4200s are equipped with a new ""returnless"" fuel
injection system that eliminates fuel return lines between the engine
and the gasoline tank. The new fuel system is also known as a demand
system."

"Before model year 2005, the Vortec 4200?s Sequential Fuel Injection
(SFI) used a return line to manage fuel pressure by bleeding off
excess fuel at the fuel rail and returning the excess to the fuel
tank.

The new system eliminates the return lines and moves the fuel-
pressure regulator from the fuel rail on the engine to the fuel tank.


But because the returnless system delivers only the amount of fuel
needed by the injectors, and returns no fuel to the fuel tank, it
eliminates heat transfer from the engine to the fuel tank. This
reduces the amount of vapor generated in the tank, and captured by
the evaporative emissions control system, or Onboard Refueling Vapor
Recovery (ORVR). "

IMPROVED COMPRESSION RINGS
"The Vortec 4200's second piston ring has been redesigned. This new,
improved Napier-type compression ring increases in thickness from 1.2
to 1.5 mm, and it has a step in its edge. The new compression ring is
more durable and ensures consistent performance over the engine's
life. It also improves oil consumption at higher mileage.  "


IMPROVED INTAKE MANIFOLD AND THROTTLE BODY GASKETS
"The Vortec 4200 has new intake manifold sealing gaskets manufactured
from a fluorocarbon material.. They are common with those used on the
Vortec 3500 and Vortec 2800 inline engine, increasing assembly plant
efficiency. "

IMPROVED ORVR PURGE VALVE
Improvements to the Vortec 4200?s evaporative emissions system (ORVR)
include a new purge valve. The purge valve empties the collection
canister into the engine?s intake stream. The new valve also operates
more quietly.

VENTED STARTER SOLENOID
"The Vortec 4200 is fitted with a new vented starter solenoid. The
solenoid case has a micromesh-covered vent that protects the solenoid
from debris particles but prevents moisture buildup. When the engine
is warm, any moisture on the solenoid evaporates through the vent. "


IMPROVED THROTTLE MAPPING
The Vortec 4200?s Electronic Throttle Control (ETC) system is
programmed with a new throttle progression intended to deliver more
immediate engine response at part throttle.

"The Vortec 4200 was one of the first truck engines with electronic
?drive-by-wire? throttle.

There is no mechanical link between the accelerator pedal and the
throttle.

A potentiometer at the pedal measures pedal angle and sends a signal
to the Powertrain Control Module (PCM); the PCM ? via the Throttle
Actuator Control (TAC) module ? then directs an electric motor to
open the throttle at the appropriate rate and angle.

Besides the accelerator pedal?s angle, the PCM measures other data,
including the transmission?s shift patterns and traction at the drive
wheels, in determining how far to open the throttle. "

"The refinements in the throttle mapping focus on part-throttle
application.

At full throttle the Vortec 4200?s performance does not change. Yet
at part throttle, the response is more immediate to the driver.

With a 25-percent application of the gas pedal, for example, the
throttle might open 10 percent farther than it did with the previous
map, and the vehicle will accelerate more quickly. "

NVH ENHANCEMENTS
"The Vortec 4200 gets several subtle improvements that make one of
the smoothest, quietest six-cylinder truck engines in production even
quieter.

These include a new, denser insulating pad on the engine side of the
dashboard and thicker downpipe that reduces the transmission of
exhaust noise.

The stainless steel down pipe connects the exhaust manifold with the
catalytic converter. "

GF-4 ENGINE OIL
"All Vortec 4200s will be shipped to the customers with new engine
oil that reduces engine deposits, extends oil change intervals,
improves fuel economy and improves the life of emissions control
systems. GM Powertrain has taken a leading role in developing and
introducing the new oil, designated GF-4 (for ?Gasoline Fueled,
Standard 4??) by the American Petroleum Institute."

This new oil improves fuel economy by lowering engine friction. It
uses an ash-free anti-oxidant that prolongs the life of the emissions
control system and it also resists oil breakdown caused by high-
temperature oxidation. 5W30 oil is recommended for low friction and
good cold-weather starts.


"The Vortec 4200 4.2L I6 (LL8) was introduced in the 2002 GM mid-size
SUVs, including the Chevrolet Trailblazer and GMC Envoy, and was the
first inline six-cylinder engine in GM Powertrain?s lineup in nearly
20 years.

While the industry largely had turned away from the inline six, GM
recognized that, given careful design and development, the inherent
advantages of inline six-cylinder architecture were perfect for the
new millennium.


"An exceptionally light, rigid engine block and cylinder head
combination, cast with the GM's patented lost foam process, provide
the foundation for the Vortec 4200?s success.

All-aluminum construction means less weight than conventional cast-
iron truck engines, and less weight means improved fuel economy. The
bottom end of the engine derives strength through many features,
starting with a bearing beam, or ladder, that connects the seven main
bearing caps to further stiffen the engine?s structure.

The oil pan bolts to the transmission bell housing as well as the
engine block, eliminating points of vibration and making the complete
engine more like a single casting.

The oil pan also gives ?pan-axle? all-wheel-drive capability to
trucks equipped with the Vortec 4200.

A passage cast through the width of the oil pan allows a drive axle
to pass through it rather than under it, allowing the engine to be
placed lower in the vehicle for a more compact package that improves
the vehicle?s handling dynamics and gives designers greater styling
flexibility."

"The Vortec 4200's feature list reads like those for premium
luxury/performance car engines: dual-overhead cam cylinder head, four
valves per cylinder, roller-follower valve actuation and exhaust-cam
phasing; a 10:1 compression ratio that delivers the seemingly
incompatible benefits of high compression and regular-grade fuel;
Electronic Throttle Control (ETC); direct accessory mounting."

In 2003, the Vortec 4200 was fitted with polymer coated pistons that
reduce engine noise and enhance durability.

The oil-pump was refined to limit noise; and the cam-chain tensioner
was improved for quieter operation.

The oil filter is easily accessible from underneath Vortec 4200-
equipped vehicles and is mounted pointing straight down, reducing the
potential for spilling oil during removal. "

Vortec 4200 delivers more peak horsepower and comparable torque (275
hp, 275 lb-ft)




Brien.

NEW YORK