New 4.7 engine thoughts...

From: William T. Goldbach (goldbach@tellink.net)
Date: Wed Dec 09 1998 - 18:24:04 EST


>
>The first vehicle to receive the 4.7 will be 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.
>
>The all-new 4.7-liter V-8 engine, Chrysler's first new V-8 family since
>the 1960s, will have more power, less weight, increased fuel efficiency,
>and lower emissions than the LA series 318 - a member of the current
youngest,
>and sole remaining, V-8 family.
>
>It will be mated with an all-new, electronically-controlled transmission
>with five forward ratios. An alternate second gear ratio will provide
>improved performance.
>

Interesting, no mention of a STANDARD transmission. One of the big reasons I
bought a Dakota was the availability of a decent V8 and a stick. This
"automatics only" trend really bothers me.

>The V-8 engine will have 230-horsepower (172 kW) and 295 lb.-ft. (400 Nm)
>of torque,
>roughly comparable to the 318. It produces 30% less pollution, noise,
>vibration,

Too bad they didn't leave it at 5.2 liters. Probably would have been about
260 HP!

>and harshness. Fuel economy is 7% better (all compared with the current
>318/5.2)
>- - with the new four-speed automatic, the engine has more pulling power,
>faster initial
>acceleration, and three miles per gallon better economy.

Now they say "four-speed" automatic. Well, Chrysler, is it "4" or "5"?

>The new engine 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).
>
>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.

Lots of cheap, lightweight parts. Hmmmm. Sounds like what GM has been doing
for years. "Composite intake manifold"? That's scary! On a truck?

>Driveability 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.

I think my '97 Dak drives just fine. Didn't need any improvement.

>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).

More high-tech stuff that will just break.

>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 tensioner increases the average accessory
>belt life to
>100,000 miles (160,000 km).

I guess those are all "good" things. If this engine ends up in the Dakota
(which is quite likely), I'll have to think twice about buying another one
in a couple years. Especially without the 5-speed stick option.

Just my opinions.

-Bill

Bob
Burlington, Ontario



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