A Heftier HEMI

15 June 2004

Chrysler is developing a 6.1 liter version of its powerful new 5.7 liter HEMI V8 engine.

Casting aside fears that rising gas prices will steer consumers away from gas-guzzlers, Chrysler is developing an even larger version of its popular V-8 Hemi engine...

Though the larger HEMI will likely get lower gas mileage than its predecessor, it may not be enough to deter interested buyers, [Anthony] Pratt [senior manager for global powertrain at J.D. Power and Associates] said.

“All things said and done, I think power is more important to the typical American car buyer than fuel efficiency, ” he said.

It seems like the 50s all over again. The original HEMI -- named such for the hemispherical combustion chambers it used as a tool to boost power -- was one of the quintessential muscle car engines of the pre oil-crisis era. (For background, go here.) Chrylser uses the HEMI V8 as an option in its new 300C, and the 300 series cars have been zooming off the lots: 13,079 in May, some 40% with the HEMI engine. The last time Chrysler sold more than 10,000 passenger cars in a month was 1986.

There is some good news for those who bang their heads on the wall in despair at the prospects of yet another gas guzzler lumbering off the assembly lines: the Hemi 5.7L now features Chrysler’s Multi-Displacement System (MDS).

MDS and similar cylinder deactivation systems being deployed by other manufacturers are one of the types of tools being used to increase fuel efficiency. The MDS seamlessly alternates between smooth, high-fuel-economy 4-cylinder mode and V8 mode when more power is demanded. The result, Chrysler claims, is an estimated fuel economy gain of up to 20% under various driving conditions, and a projected 10% overall improvement.

Enabling the MDS are the speed of electronic controls, the sophistication of the algorithms controlling the systems and the use of Electronic Throttle Control. The HEMI will be able to transition from eight cylinders to four in 40 milliseconds (0.040 seconds).

That’s great, and it’s an example of using technology innovation to improve fuel efficiency. But in the 300C we are still looking at a two-ton car that gets 17 mpg city, 25 mpg highway. That is undeniably a big improvement on what it MIGHT be without MDS, assuming that the buyers that buy the HEMIs would buy some variant of a big, powerful, fast car. The larger 6.1L version will consume more gas.

Let’s see the manufacturers take that technology and apply it to smaller vehicles. Honda, for example, is implementing Variable Cylinder Management (same concept as MDS) in its upcoming 2005 Honda Accord Hybrid, due out this fall.