- Variable-Valve-Tech -
- Variable-Valve-Tech -
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Breathing Smart[/align][align=center][:-]
Variable-valve technologies breathe new life into internal combustion.
By Dennis Simanaitis•Illustrations by Alan Daniels
August 2007
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Images: [/align][ul][*][align=center]Smart Valve Drawings[/align][/ul][align=center]
Downloads: [/align][ul][*][align=center]Chart: Smart-Valves — A selection of Technologies [/align][*][align=center]Graph: Otto Cycle [/align][/ul][align=center]
Overhead-valve V-8
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Honda VTEC
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Cam-phasing using hydraulic pressure
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Continuous cam-shifting
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Mechadyne cam-in-cam
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The Valeo system
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Maybe you remember “suck, squeeze, pop, pooey”? Or, in a more learned context, intake, compression, expansion, exhaust. A lot of attention has been paid to engine breathing, the first and last of Otto's four strokes. And no wonder, as characteristics of intake and exhaust are crucial in an engine's production of power, its consumption of fuel and its emission of pollutants.
[b]I originally intended this to be a survey of those cars exploiting variable-valve technology, only to realize that just about everyone has some scheme or other to optimize intake and exhaust valve operation under changing conditions. What's more, I've just re
Breathing Smart[/align][align=center][:-]
Variable-valve technologies breathe new life into internal combustion.
By Dennis Simanaitis•Illustrations by Alan Daniels
August 2007
[/align][align=center]
[/align][align=center]Images: [/align][ul][*][align=center]Smart Valve Drawings[/align][/ul][align=center]
Downloads: [/align][ul][*][align=center]Chart: Smart-Valves — A selection of Technologies [/align][*][align=center]Graph: Otto Cycle [/align][/ul][align=center]
Overhead-valve V-8
Enlarge image[/align][align=center]
Honda VTEC
Enlarge image[/align][align=center]
Cam-phasing using hydraulic pressure
Enlarge image[/align][align=center]
Continuous cam-shifting
Enlarge image[/align][align=center]
Mechadyne cam-in-cam
Enlarge image[/align][align=center]
The Valeo system
Enlarge image
Maybe you remember “suck, squeeze, pop, pooey”? Or, in a more learned context, intake, compression, expansion, exhaust. A lot of attention has been paid to engine breathing, the first and last of Otto's four strokes. And no wonder, as characteristics of intake and exhaust are crucial in an engine's production of power, its consumption of fuel and its emission of pollutants.
[b]I originally intended this to be a survey of those cars exploiting variable-valve technology, only to realize that just about everyone has some scheme or other to optimize intake and exhaust valve operation under changing conditions. What's more, I've just re
RE: - Variable-Valve-Tech -
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[/align]General Motors' all-new 3.9L V6 has been honored with a Breakthrough Technology award by Popular Mechanics for its innovative use of variable valve timing in an overhead valve engine. For ages GM has continually developed its line of overhead valve engines and the addition of VVT is an industry first, adding a dose of sophistication to an old school architecture. The powerplant develops a healthy 242 horsepower and can be had in the 2006 Impala, Monte Carlo, Malibu SS, Malibu Maxx SS and Uplander; Pontiac G6 GTP and SV6; Buick Terraza; and Saturn Relay. And hey, if you're going to be honored by a group of mechanics, it's better they be the popular kind, right?
Full press release after the jump…
Popular Mechanics Awards Gm 3.9 V-6 For Breakthrough Technology
POPULAR MECHANICS AWARDS GM 3.9 V-6 FOR BREAKTHROUGH TECHNOLOGY
New York - General Motors? new 3.9-liter V-6 has been recognized for ground-breaking technology by the editors of POPULAR MECHANICS in the publication?s first ?POPULAR MECHANICS Breakthrough Awards.? The announcement was made today at the American Museum of Natural History and will be featured in the October issue of POPULAR MECHANICS, on newsstands nationwide October 11, 2005.
The POPULAR MECHANICS Breakthrough Awards recognize ten individuals and teams, including one winner of the Breakthrough Leadership Award, that are helping to improve lives and expand possibilities in the realms of science, technology and exploration. Additionally, POPULAR MECHANICS highlighted a separate group of ten consumer products that represent milestones in design and engineering.
The 3.9 V-6 has been awarded for the innovative adaptation of variable valve timing, an industry first for overhead valve engines.
?General Motors keeps finding ways to advance overhead valve engines and the 3.9-liter V-6 used in the Impala reaches new levels,? said James Meigs, editor-in-chief, POPULAR MECHANICS. ?For their continued success and innovation, we?re proud to recognize GM with a 2006 Breakthrough Award.?
The 3.9 is part of an all-new family of advanced overhead valve, 60-degree V-6 engines. The engine is designed new from the block up and in addition to variable valve timing, incorporates a host of advanced, premium features, including a variable intake manifold, piston-cooling oil squirters, and an advanced 32-bit engine controller.
?The breakthrough development of variable valve timing for the 3.9 demonstrates the continued relevance of the elegant overhead valve engine design,? said Dr. Gary Horvat, assistant chief engineer, V-6 engines. ?We?re honored that the editorial team at POPULAR MECHANICS recognize the significance of this technology.?
The variable valve timing 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 helping lower emissions. Within its range of operation, 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 award-winning, 242-horsepower 3.9 V-6 is available in the 2006 Chevrolet Impala, Monte Carlo, Malibu SS, Malibu Maxx SS and Uplander; Pontiac G6 GTP and SV6; Buick Terraza; and Saturn Relay
[/align]Popular Mechanics honors GM's 3.9L V6
[/align]General Motors' all-new 3.9L V6 has been honored with a Breakthrough Technology award by Popular Mechanics for its innovative use of variable valve timing in an overhead valve engine. For ages GM has continually developed its line of overhead valve engines and the addition of VVT is an industry first, adding a dose of sophistication to an old school architecture. The powerplant develops a healthy 242 horsepower and can be had in the 2006 Impala, Monte Carlo, Malibu SS, Malibu Maxx SS and Uplander; Pontiac G6 GTP and SV6; Buick Terraza; and Saturn Relay. And hey, if you're going to be honored by a group of mechanics, it's better they be the popular kind, right?
Full press release after the jump…
Popular Mechanics Awards Gm 3.9 V-6 For Breakthrough Technology
POPULAR MECHANICS AWARDS GM 3.9 V-6 FOR BREAKTHROUGH TECHNOLOGY
New York - General Motors? new 3.9-liter V-6 has been recognized for ground-breaking technology by the editors of POPULAR MECHANICS in the publication?s first ?POPULAR MECHANICS Breakthrough Awards.? The announcement was made today at the American Museum of Natural History and will be featured in the October issue of POPULAR MECHANICS, on newsstands nationwide October 11, 2005.
The POPULAR MECHANICS Breakthrough Awards recognize ten individuals and teams, including one winner of the Breakthrough Leadership Award, that are helping to improve lives and expand possibilities in the realms of science, technology and exploration. Additionally, POPULAR MECHANICS highlighted a separate group of ten consumer products that represent milestones in design and engineering.
The 3.9 V-6 has been awarded for the innovative adaptation of variable valve timing, an industry first for overhead valve engines.
?General Motors keeps finding ways to advance overhead valve engines and the 3.9-liter V-6 used in the Impala reaches new levels,? said James Meigs, editor-in-chief, POPULAR MECHANICS. ?For their continued success and innovation, we?re proud to recognize GM with a 2006 Breakthrough Award.?
The 3.9 is part of an all-new family of advanced overhead valve, 60-degree V-6 engines. The engine is designed new from the block up and in addition to variable valve timing, incorporates a host of advanced, premium features, including a variable intake manifold, piston-cooling oil squirters, and an advanced 32-bit engine controller.
?The breakthrough development of variable valve timing for the 3.9 demonstrates the continued relevance of the elegant overhead valve engine design,? said Dr. Gary Horvat, assistant chief engineer, V-6 engines. ?We?re honored that the editorial team at POPULAR MECHANICS recognize the significance of this technology.?
The variable valve timing 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 helping lower emissions. Within its range of operation, 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 award-winning, 242-horsepower 3.9 V-6 is available in the 2006 Chevrolet Impala, Monte Carlo, Malibu SS, Malibu Maxx SS and Uplander; Pontiac G6 GTP and SV6; Buick Terraza; and Saturn Relay
Joined: Jun 2007
Posts: 736
From: CFB Petawawa, Ontario, Canada
RE: - Variable-Valve-Tech -
GM’s new overhead-valve V6 engines define the concept of high value in powertrain development. They apply and refine time-tested design principles, yet they are new from the cylinder block up. The deliver advanced, industry exclusive technologies with real benefit for customers, yet they keep both the cost of production and the cost of ownership low. By any measure, the 3.5L V6 delivers a top-notch balance of good specific output, low-end response, even torque delivery, low maintenance and value, with vehicle packaging flexibility in a wide range of applications.
This new generation V6 allows a high level of flexibility, with common castings over a range of displacements. The 3.5L V6 shares its block, pistons and cylinder heads with Powertrain’s new 3.9L (RPOs LGD, LZ8 and LZ9). A common bore measures 99 mm; displacement is increased in the 3.9L with a longer stroke (84 mm, compared to 76 mm for the 3.5L). The two engines share 80 percent of their parts.
Thanks to its relatively narrow 60-degree block angle, the 3.5L V6 is compact, giving vehicles teams more latitude with platform design and styling. More importantly, the 60-degree V is inherently balanced, ensuring powertrain smoothness without the additional cost of balance shafts. The new 3.5L V6 differs from previous GM 60-degree designs in its offset cylinder bores. The centerlines through the bores on each bank do not intersect at the crank axis; rather, they intersect 3 mm below the crank axis. The offset bores present a number of advantages, including room for larger cam journals and flexibility to stroke the engine for more displacement. The 3.5L block also features a unique “U-flow” coolant path. The coolant passages flow coolant in a specific, predetermined path, starting at the front of block, then rearward toward the transmission, up through the cylinder heads and back to the front. The thermostat is placed near the inlet from the radiator, decreasing warm-up time. The fill point is at the highest point of the cooling system to prevent air pockets in the hoses or passages.
New cylinder heads apply design features developed for the high-output LS1 and LS6 Corvette small-block V8s. The 3.5L V6’s valves are similar to those in the LS1, as is its combustion chamber design. Low-friction hydraulic roller lifters work the valves, improving the engine’s efficiency and reducing vibration. The 3.5L also applies the latest electronic throttle control (ETC) technology, streamlining the system by eliminating a separate throttle actuator control (TAC) module. The ECM controls the throttle motor directly. The direct link improves throttle response time (albeit in millisecond increments that are not apparent to the driver) and improves system security by removing a device (the TAC) the must be monitored for malfunction.
The 3.5L V6’s “returnless” fuel injection system is the new standard at GM. It eliminates fuel return lines between the engine and the gasoline tank, essentially eliminating heat transfer from the engine to the tank and reducing the amount of vapor emissions substantially. New generation fuel injectors with shrouded nozzles are designed to minimize clogging and maintain optimal performance in extreme heat. The 3.5Ls flex-fuel technology (LZE) is simpler and more robust than that used on previous flex-fuel engines. The standard valves and valve seats are durable enough to withstand the long-term corrosive effect of E85 ethanol, so no upgrade is necessary. Nor do flex-fuel 3.5Ls require a separate fuel sensor. The advanced E38 ECM uses data from the oxygen sensors to determine fuel composition, and within miles of a fill up adjusts fuel and spark timing for optimal performance with whatever fuel is used.
For all the advanced systems in the 3.5L V6, perhaps the most significant—certainly the one that has garnered the most attention—is variable valve timing (VVT). GM’s new generation V6s were the first ca
This new generation V6 allows a high level of flexibility, with common castings over a range of displacements. The 3.5L V6 shares its block, pistons and cylinder heads with Powertrain’s new 3.9L (RPOs LGD, LZ8 and LZ9). A common bore measures 99 mm; displacement is increased in the 3.9L with a longer stroke (84 mm, compared to 76 mm for the 3.5L). The two engines share 80 percent of their parts.
Thanks to its relatively narrow 60-degree block angle, the 3.5L V6 is compact, giving vehicles teams more latitude with platform design and styling. More importantly, the 60-degree V is inherently balanced, ensuring powertrain smoothness without the additional cost of balance shafts. The new 3.5L V6 differs from previous GM 60-degree designs in its offset cylinder bores. The centerlines through the bores on each bank do not intersect at the crank axis; rather, they intersect 3 mm below the crank axis. The offset bores present a number of advantages, including room for larger cam journals and flexibility to stroke the engine for more displacement. The 3.5L block also features a unique “U-flow” coolant path. The coolant passages flow coolant in a specific, predetermined path, starting at the front of block, then rearward toward the transmission, up through the cylinder heads and back to the front. The thermostat is placed near the inlet from the radiator, decreasing warm-up time. The fill point is at the highest point of the cooling system to prevent air pockets in the hoses or passages.
New cylinder heads apply design features developed for the high-output LS1 and LS6 Corvette small-block V8s. The 3.5L V6’s valves are similar to those in the LS1, as is its combustion chamber design. Low-friction hydraulic roller lifters work the valves, improving the engine’s efficiency and reducing vibration. The 3.5L also applies the latest electronic throttle control (ETC) technology, streamlining the system by eliminating a separate throttle actuator control (TAC) module. The ECM controls the throttle motor directly. The direct link improves throttle response time (albeit in millisecond increments that are not apparent to the driver) and improves system security by removing a device (the TAC) the must be monitored for malfunction.
The 3.5L V6’s “returnless” fuel injection system is the new standard at GM. It eliminates fuel return lines between the engine and the gasoline tank, essentially eliminating heat transfer from the engine to the tank and reducing the amount of vapor emissions substantially. New generation fuel injectors with shrouded nozzles are designed to minimize clogging and maintain optimal performance in extreme heat. The 3.5Ls flex-fuel technology (LZE) is simpler and more robust than that used on previous flex-fuel engines. The standard valves and valve seats are durable enough to withstand the long-term corrosive effect of E85 ethanol, so no upgrade is necessary. Nor do flex-fuel 3.5Ls require a separate fuel sensor. The advanced E38 ECM uses data from the oxygen sensors to determine fuel composition, and within miles of a fill up adjusts fuel and spark timing for optimal performance with whatever fuel is used.
For all the advanced systems in the 3.5L V6, perhaps the most significant—certainly the one that has garnered the most attention—is variable valve timing (VVT). GM’s new generation V6s were the first ca
Monte Of The Month -- February 2008
Joined: Aug 2006
Posts: 4,286
From: Born in East LA
RE: - Variable-Valve-Tech -
You go guys, Space & Fox.I am loving my dual intake manifold and roller engine more and more as you guys dole out the information.
I just blew away one of those stupid Lincoln pickup trucks with a catback and CAI. Even though it was an eight cylinder the thing was stupidly slow compared to my 3.9 rolller vvt.
I just blew away one of those stupid Lincoln pickup trucks with a catback and CAI. Even though it was an eight cylinder the thing was stupidly slow compared to my 3.9 rolller vvt.
Joined: Jun 2007
Posts: 736
From: CFB Petawawa, Ontario, Canada
RE: - Variable-Valve-Tech -
Roller rockers are highly engineered levers designed to overcome the many faults of low cost factory rocker arms which in performance applications are prone to failure which can result in an expensive engine rebuild.
The standard non roller rocker type of rocker arm pushes and pulls the valve stem sideways every time the valve is opened. This causes the guides to wear prematurely, which in turn causes the valve seat to deteriorate. With a roller rocker, the roller rocker tip prevents this side loading, giving the guide and stem the best chance of survival, making them ideal for not only performance engines, but standard engines as well.
In laymans terms, roller rockers are more efficient, and a tuners dream, as you can remove/upgrade them as you need. Some high end ones are adjustable, but you need severe caution, too high of a ratio, and you will strike the surface of the piston on the intake/exhaust cycle..
The standard non roller rocker type of rocker arm pushes and pulls the valve stem sideways every time the valve is opened. This causes the guides to wear prematurely, which in turn causes the valve seat to deteriorate. With a roller rocker, the roller rocker tip prevents this side loading, giving the guide and stem the best chance of survival, making them ideal for not only performance engines, but standard engines as well.
In laymans terms, roller rockers are more efficient, and a tuners dream, as you can remove/upgrade them as you need. Some high end ones are adjustable, but you need severe caution, too high of a ratio, and you will strike the surface of the piston on the intake/exhaust cycle..