The first vehicle to receive the 4.7 is the newly redesigned 1999 Jeep Grand
Cherokee, which will carry that engine across the world.
International buyers will also have the option of a new turbocharged Diesel
engine, and both American and international buyers can get an
updated version of the 4.0 straight-six currently in use.
As the first member of Chrysler's first new V-8 family since the 1960s, the
4.7 will have more power, less weight, increased fuel efficiency,
and lower emissions than the LA series 318 - a member of sole remaining V-8
family from the 1960s. A new V-6 and V-10 are also
planned, both to be based on the 4.7, in much the same way as the current
3.9 V-6 and V-10 are based on the LA 318 and 360.
On the Jeep, it will be mated with an all-new, electronically-controlled
transmission with five forward ratios. An alternate second gear ratio
will provide improved performance.
The 4.7 has, on the Jeep, 235 horsepower (over 172 kW) and 295 lb.-ft. (400
Nm) of torque, slightly more power than the 318. It
produces 30% less pollution, noise, vibration, and harshness. Fuel economy
is 7% better with the new four-speed automatic. The engine has
more pulling power, faster initial acceleration, and three miles per gallon
better economy.
Buddy Revell pointed out that the new engine is "almost" a Hemi - "the only
reason it isn't called a hemi is because the combustion chambers
have a wall on one side that makes it look kind of like a flat tire. Other
than that everything is in the same arrangement. The valve springs are
across from each other and the spark plug goes right down the middle."
The 4.7 has a cast iron block and two cast aluminum cylinder heads with a
single overhead camshaft per bank and two valves per cylinder.
It displaces 4701 cm3 (287 cu in.). A relatively small bore of 3.66 inches
(93 mm) helped reduce overall length of the engine, packaging it
for the compact engine bay of the Grand Cherokee. The stroke is 3.4 inches
(86.5 mm).
A natural-gas version for the Charger concept car produces 300 hp.
Breathing features include a new tuned-length runner intake manifold,
free-flowing intake and exhaust ports and fast-burn combustion
chambers. Operating with a high 9.3:1 compression ratio, the engine still
only requires regular-grade fuel.
Lightweight material applications and more efficient engine accessories such
as the alternator, power steering pump and air conditioning
compressor further bolster performance and economy. Aluminum cylinder heads,
a hollow camshaft with sintered steel lobes, magnesium
valve covers and a molded composite intake manifold contribute to an overall
weight reduction of 54 pounds (24 kg) compared to the
previous 5.2-liter engine.
Drivability is enhanced by variable fuel injection timing, sequential
multi-port injection, a quick-sensing inlet-side positioned thermostat and
coil-on-plug ignition, in which each individual spark plug has its own
secondary ignition coil.
In order to improve fuel economy, the new engine features a patented hybrid
cooling fan system that combines in-line electric and
engine-driven fans. This system allows the engine fan to idle at a very low
speed (250-300 rpm. vs. the typical 650-700 rpm.), decreasing
noise and vibration at idle and low speeds. The newly designed cooling
system, with a high efficiency water pump and a secondary
thermostat control, reduces power consumption by 12 percent (6 bhp/4.5 kW).
The new coil-on-plug ignition system, two-stage chain cam drive with
automatic tensioners, premium gaskets and cylinder head mounted
fuel injectors are a few of the basic design features that provide for a
greatly increased engine life. The engine is designed to operate
150,000 miles (240,000 km) under normal conditions without part replacement
other than normal maintenance items. A new automatic
serpentine belt tensioners increases the average accessory belt life to
100,000 miles (160,000 km).
-----------------------------------------------------------------
Steven St.Laurent
2000 Dodge Dakota 4.7 (V-8) SLT 4x2
2000 Ford Roush Mustang Stage 1
1999 Astro LS 4.3 HO V-6
1993 Chevy Tracker 1.6 (gutless)
mailto:stlaurents@mctssa.usmc.mil (work)
mailto:Saint1958@home.com (home)
Office: (760) 725-2296
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