Date: Mon, 24 Apr 2000 15:58:32 -0700
Reply-To: Stuart MacMillan <stuart@COBALTGROUP.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stuart MacMillan <stuart@COBALTGROUP.COM>
Organization: The Cobalt Group
Subject: Re: New High Power Subaru Boxer Engines
Content-Type: text/plain; charset=us-ascii
There are some interesting tweaks on this engine: Dual stage intake and
exhaust!
As far as an all gear cam driving system goes it would be more
expensive, complicated to make, and heavier on an opposed four with four
cams than an in-line engine. LOTS of gears would be needed, all fitting
together to close tolerances.
More info from the Subaru Web site (how many years before Kennedy makes
a kit?!! This mod would be worth the trouble.)
All-New High-Ouput Engine
The horizontally opposed layout gives the Subaru H6-3.0
powerplant inherent smoothness without the need for
power-robbing balance shafts used in some V-6 engines.
Liquid-filled engine mounts contribute to the smooth, quiet
ride. The horizontally opposed design also provides a
lower center of gravity which enhances handling and
performance.
The new Subaru high-output H6-3.0 features an
aluminum crankcase, double-overhead camshafts and
four valves per cylinder. A direct ignition system uses an
individual ignition coil for each cylinder, eliminating the
need for a distributor and sparkplug wires. The engine
displaces 2,999 cubic centimeters (183 cubic inches) and
produces 212 horsepower at 6,000 rpm and 210 lb.-ft. of
peak torque at 4,400 rpm. By 2,200 rpm, the Subaru
H6-3.0 engine is already producing a substantial 174 lb.-ft.
of torque, providing quick response at lower speeds.
The H6-3.0 produces nearly 30 percent more horsepower
and torque than the 165-horsepower 2.5-liter H-4 in the
Outback Limited model, yet is only 20 millimeters
(0.8-inch) longer than that four-cylinder engine. Like all
Subaru models the new Outback H6-3.0 models run on
regular fuel, but 91 octane is recommended for maximum
performance.
Dual-Stage Intake And Exhaust
The new Subaru H6-3.0 uses a variable intake manifold
and a dual-stage muffler to optimize power delivery
throughout the engine speed range. Low-speed and
mid-range power have not been compromised for
high-rpm power, and vice versa. The variable intake
manifold features an induction control valve that provides
two intake characteristics. Below 3,700 rpm the valve
remains closed to create a long intake runner length,
helping to boost low-end and mid-range power. When the
valve opens above 3,700 rpm, the manifold creates a
"scavenging" or light supercharging effect, allowing each
cylinder to catch high-pressure waves of intake air
bouncing off the opposite side of the manifold.
A mechanical valve in the rear muffler varies muffler
volume to help enhance engine power in different speed
ranges. At lower engine speeds (around-town driving, for
example), the valve remains closed to provide a
smaller-volume muffler chamber. The resulting level of
exhaust back-pressure enhances power at these speeds.
When exhaust pressure reaches about 22 psi -- which
occurs at about 2,400 rpm -- the valve opens to allow
exhaust gas through an additional chamber. The resulting
increased muffler volume reduces exhaust
back-pressure, enhancing power at higher speeds.
Muffler valve operation does not affect the noise level.
--
Stuart MacMillan
Manager, Case Program
800-909-8244 ext. 8208
Fax: 206-269-6360
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