According to GM, the new Vortec 3900 V-6 is a close relative of the 3500 V-6 launched in the 2004 Chevrolet Malibu. The 3900 is the first GM overhead-valve (OHV) engine to utilize variable valve timing (VVT) and displacement on demand (DOD).
Engine size was increased 400 cc with DOD in mind. GM engineers felt that the larger displacement was needed to get optimal performance in the three cylinder mode.
To keep from having to cast a new block the larger bores in the 3900 are created by lowering the bore center on the block.
DOD works the same on the 3900 V-6 as it does on the 5300 V-8, though rather than alternating cylinders on each bank, the 3900 drops the left ban when in DOD mode.
The variable valve timing system uses and electronically-controlled, hydraulic gear-driven cam phaser that can alter the relationship of the camshaft from 15 degrees retard to 25 degrees advance (40 degrees overall) relative to the crankshaft.
By using VVT, GM engineers were able to eliminate the EGR valve and also found that maximum exhaust-valve opening helped to warm the exhaust catalyst quicker, improving cold start emissions.
The VVT also works in conjunction with an active manifold GM says that the variable intake manifold serves as a low speed torque enhancer giving the engine a broader torque curve.
A valve in the manifold creates a longer path for intake air at low speeds, enhancing combustion efficiency and torque output. At higher speed the valve opens creating a shorter air path for maximum power production.
The 3900 has GM's latest ECM currently available. The Motorola-based E67 has 32-bit processing power and 32 megabytes of Burst Flash memory, 32 kilobytes of external RAM and 36 kilobytes of internal RAM plus a high speed CAN bus to deliver the necessary power to run VVT and the active manifold.
The 3900 also has electronic throttle control that enhances the engines interface with DOD.
The 3900 will be built at GM's Tonawanda, N.Y., assembly plant.
http://www.findarticles.com/p/articles/mi_m3012/is_12_183/ai_111617012
http://www.auto-report.net/index.html?gmpt05.html
General MotorsThe largest of GM's expanding family of 60° V-6 engines, the 3900 achieves larger displacement via an increase in bore size to 99 mm from the 3500 V-6’s 94 mm — requiring the bore centers to be ofset by 1.5 mm. Michalski said the 3900’s increased displacement fits glove-in-hand with Displacement on Demand: "A bigger engine is better when you want to maximize the amount of time the engine spends in three-cylinder operation," he explained.
The LZ8 3900 will be the first GM overhead valve engine to use variable valve timing, and it will be GM’s first V-6 to use DOD. The 3900's variable valve timing is coupled with another important new feature: a dual-path, active intake manifold.
"The variable intake manifold is a significant low-speed torque 'enhancer' for the 3900. It gives the 3900 a broader torque curve that retains higher specific torque output across the engine speed range."
Dick Michalski, chief engineer for 60-degree OHV V-6 engines.
The new 3900 V-6 (LZ8) is a 3.9 liter, two-valves-per-cylinder OHV V-6 that is most closely related to the 3500 V-6 (LX9) launched for the 2004 model year Chevrolet Malibu. Its first application without DOD will be on the 2005 Pontiac G6 in late 2004. A version of the 3900 V6 featuring the DOD system will debut in 2005.
The 3900 is estimated to develop 240 hp at 5900 rpm and 245 lb-ft of torque at just 2800 rpm. Moreover, thanks to the 3900's torque-enhancing technologies, 90% of peak torque is available from 1800 rpm to 5800 rpm, enhancing the engine's driveability and performance "feel." According to Alan Hayman, manager-advanced concept group in GM Powertrain's Advanced Powertrain unit, a new 3-valve cylinder-head developed for GM's OHV engines could boost output to 270 hp.
he LH6 isn't the only engine that will receive the benefits of displacement-on-demand. We've already mentioned that Daimler-Chrysler's Hemi will be getting some form of DOD in the near future--but we don't have exact details of that yet. What we do know is that GM is coming out with a 3.9L V-6 (RPO code LZ8) which is scheduled to first appear in the 2005 Pontiac G6.
The "high value" 60-degree OHV V-6 will become the staple engine in vehicles which typically had the old 3100-, 3400- and more recent 3500-series engines (on which the LZ8 is based). Rated at 240hp at 5900 rpm and 245 lb.-ft. of torque at 2800 rpm, the 9.8:1 compression LZ8 will make 90 percent of its peak torque between 1800 and 5800 rpm. That compares very favorably with the venerable supercharged 3800 (RPO L67) which, in most iterations, makes 240hp at 5,200 rpm. What's more, the LZ8 does it with only 100cc more displacement, two valves per cylinder, pushrods and no supercharger.
Like the LH6, the LZ8 will have electronic throttle control and cylinder deactivation (running on three cylinders to the LH6's four), but will also throw into the mix variable valve timing and a variable intake manifold for dynamic runner tuning. Variable valve timing will be accomplished electronically by a gear-driven camshaft phaser capable of altering timing by as much as 40 degrees. As a happy coincidence, this feature will also allow the elimination of EGR control.
For the time being, the LZ8 will only be available in non-DOD form, but we've been assured that it will eventually appear. What's more, the LZ8 is designed to work in a rear-wheel drive configuration, which would pave the way for its use in a future base-model Camaro. If that occurs, the LZ8 would trump the '05 Mustang's base V-6 by nearly 40 horsepower while returning the same fuel economy.
http://www.popularhotrodding.com/features/0405phr_gmdod/
very bottom.
**borrowed from SappySE107 from 60degreev6.com**
Same power and performance as a 3.8SC but without a power adder and with lighter aluminum heads and a torque curve that puts a 4.9 to shame.
Whos first!?
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Calgary - August 1, 2004 Fiero Fiesta
1984 Indy Fiero 3.4/3100 Hybrid NA and...
*ALL THROTTLE AND NO BOTTLE*
http://www.gmpcm.com/ Killer ECM/ PCM tuning software and information
[This message has been edited by donk316 (edited 07-15-2004).]
