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6/25/2003
17:52:40
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 Subject: The Hemi
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Hemi: (HEM -e) adj. Mopar in type, V8, hot tempered, native to the United States, carnivorous, eats primarily Mustangs, Camaros, and Corvettes. Also enjoys smoking a good import now and then to relax. - David Charles Gedraitis
The new Hemi Magnum (as though the Hemi name couldn't stand on its own!) produces 345 horsepower (5,600 rpm) and 375 lb-ft of torque (4,400 rpm) from 5.7 liters (345 cid*) - one horsepower per cubic inch, and it is still the engine's first year. In addition to truck duty, it will be used in the new LX series, in front of a Mercedes five-speed automatic. The Hemi is smaller, faster, and more economical (we hear also cheaper to build) than the 360 it is replacing. What's more, a 6.1 liter version is being developed for even more power, to replace the current V-10.
John Veatch wrote: "Seeing all the hoopla surrounding the new Hemi and the previous speculation on whether its displacement was going to be either the nostalgic 354 or 383, I am amazed no one has made mention of what is probably the coolest coincidence of all. The actual production engine came in at 345 c.i.d. @ 345 hp, the exact same specs as the '57 DeSoto Adventurer 345/345 Hemi, the first standard engine to make the 1hp/ci mark (albeit the '56 300 optional HP engine had earlier accomplished the feat). Both preceded the much ballyhooed optional 283/283 hp '57 Corvette engine."
The Hemi's first vehicle was the 2500 and 3500 Rams, where it is the base engine. It moved next into the Ram 1500 (calendar year 2002), then eventually to the Grand Cherokee and LX cars, and possibly Durango and Dakota.
In January 2003, the public saw the first supercharged Hemi engine ever officially produced by Chrysler. It produces 430 horsepower and 480 lb-ft of torque, using the 5.7 Hemi engine and a Whipple supercharger, and was first shown in the Dodge Magnum SRT-8 concept. The 300C version had "over 400 horsepower" and 350 lb-ft of torque.
Hemi production began in June 2002 at the Salitillo plant in Mexico, with a projected production of 440,000 engines a year. Only about a quarter of those engines will be used in heavy duty pickups, with the rest expected to end up in Grand Cherokees, large cars, Dakotas, Durangos, and light duty pickups.
The original Hemi was smaller, but the most famous, the unbeatable 426 Hemi, was considerably larger - and produced quite a bit more power, albeit before emissions standards. That engine took first, second and third place at the 1964 Daytona 500 and became the de facto drag racing standard, not to mention the killer street engine - one which added about a third again to the price of a new car. It re-entered production for racing in the late 1990s. Click here for more "old" Hemi details.
The engine's unique two-valve hemispherical combustion chamber within an aluminum head provides impressive air flow, torque and power (hallmarks of the original), and gives the engine its throaty rumble. Fifty-six pounds lighter than the 5.9-liter V-8, the 5.7-liter Hemi produces 41% more power and 12% more peak torque.
An electronic throttle control system, Chrysler's first drive-by-wire gasoline engine, moves the throttle in response to accelerator pedal position. The throttle system is based on engine torque control, and compensates for changes in the engine load needed by the air conditioning system, compressor, alternator, power steering pump and automatic speed control.
Dual spark plugs per cylinder ensure consistent, complete and rapid combustion, without knock, that increases peak power and torque, reduces exhaust emissions and increases fuel efficiency. It even smoothes the engine's idle. The 5.7 delivers an 8-10 percent better fuel efficiency than the less-powerful 5.9.
Testing included 11 million customer equivalent miles, with stronger durability testing than any previous Chrysler engine. The 7 year/70,000-mile powertrain warranty is backed by 11 million customer equivalent miles (CEMs) of testing, including more than 200,000 CEMs of durability testing for the average consumer - more than any other Chrysler engine. The battery of reliability tests closely represents real-world driving conditions, in some cases exposing the engine to more severe abuses than drivers can dish out. For example, during a 260-hour period, the 5.7-liter HEMI was repeatedly heated to 240°F and then slammed with coolant that was -25°F.
"The engine was exposed to some of the harshest testing conditions and abuses imaginable," said Donald Dees, Vice President of Quality for the Chrysler Group (and formerly of Toyota, so you know that means something).
Cylinder deactivation, which shuts off fuel to some cylinders under idle and low demand situations, is expected in 2004. That will increase fuel economy.
Every person we've contacted who has driven a Hemi has been impressed by its power - and the economy beats the much less powerful 360 it replaces. However, the proportion of regulated pollutants is a problem for Chrysler. Bob Sheaves noted:
The HEMI design combustion chamber is one of the poorest designs for emissions-why do you think it took so long to get it into production? It almost did NOT make emissions test requirements even with the modifications. NOx is the problem due to the cool temp flame front inherent in the design (also why it builds so much torque). There is also a little problem called "flame quench" (which causes additional NOx) with a true HEMI design, as was used on the v16 aircraft engine and the automotive engines produced in the 1950s. Today's HEMI is that (a "Hemi") in name only.
Power (SAE net): 345 bhp (257 kW) @ 5,400 rpm
Torque (SAE Net): 375 lb.-ft. (508 Nom) @ 4,200 rpm
Displacement 345 or 353 cu. in* (5,654 cu. cm)
Bore x stroke 3.92 x 3.58 (99.5 x 90.9)
Valve system Pushrod-operated overhead valves, 16 valves, hydraulic lifters with roller followers
Fuel injection Sequential, multi-port, electronic, returnless
Construction Deep-skirt cast iron block with cross-bolted main bearing caps. Aluminum alloy heads with hemispherical combustion chambers
Max. engine speed 5,800 rpm
Fuel requirement Unleaded mid-grade, 89 octane (R+M)/2 - recommended, Unleaded regular, 87 octane (R+M)/2 - acceptable
Oil capacity 7 qt. (6.6L)
Coolant capacity 18.7 qt. (17.7L)
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