How Chrysler's Hellcat engine almost died

One of the year’s hottest new engines almost never happened.

In early 2011, as Fiat was developing a strategy for Chrysler and deciding where to spend scarce product development funds, the 707-hp Hellcat Hemi V-8 debuting in the 2015 Dodge Challenger and Charger didn’t make the cut.

The project was shelved and engineers scattered to work on other projects, said Chris Cowland, Chrysler’s director of advanced and SRT powertrain.

Still, the idea for a new and superpowerful Hemi engine wouldn’t die among the SRT team, which continued to lobby for the engine. Four months later, Chrysler’s product development committee reversed its decision.

Even though the first Hellcat-powered Challengers and Chargers have yet to be sold, the payback already has been enormous. The Hellcat Challenger arrives at dealerships in a few weeks, and the Charger version is scheduled for the first quarter of 2015.

Never mind the engine’s incredible power ratings, the highest ever for a regular production engine in a Detroit car. The Hellcat has probably already paid for itself by helping recast the Dodge division as Fiat Chrysler’s performance brand. You can’t buy the kind of publicity the Hellcat has generated.

Chrysler’s PR maestros have played the Hellcat for all it is worth. The engine has been an Internet sensation. Nearly every word, tire-shredding photo and sound bite of the snarling exhaust has been gobbled up by octane junkies.

Cowland recently explained how Chrysler engineers coaxed the 707 hp and 650 pounds-feet of torque out of the Hemi V-8.

It took a lot more, he said, than just dropping a beefy supercharger between the cylinder heads. “Ninety-one percent of the content in the Hellcat is new,” Cowland said. And some of the engine’s new parts are intriguing.

To reach the 700-hp target, Cowland said, Chrysler engineers knew they had to optimize every part and every system in the engine.

Because of the engine’s extremely high power output, Chrysler engineers’ knowledge of metallurgy was put to the test. They had to find the strongest but lightest components for such items as pistons, valves and rods. And more than that, they had to make sure that parts won’t fail under the extreme punishment the Hellcat engine is likely to receive.

“It came down to micron levels of changes in the crank to be able to withstand the pressures of the engine,” Cowland said.

For example, the washer used on the front pulley on the nose of the crankshaft, which drives the supercharger, has steel washers embedded with industrial diamonds.

Yup. Diamonds. They prevent the pulley from slipping on the crankshaft under hard acceleration. It takes about 80 hp to drive the supercharger.

Chrysler also had to invent entire systems, such as a separate cooling circuit for the supercharger. The engine uses an electric water pump, piston cooling jets, a variable oil pump and bronze bushings in the connecting rods.

You might think an engine as powerful as the Hellcat would be thirsty enough to a drain a fuel tanker. Despite its massive thrust, the engine can deliver as much as 22 mpg on the highway -- if driven with a light right foot.

“We’re proud of the fact that even though we have this huge power output, we haven’t been socially irresponsible and put out a gas guzzler,” Cowland said.

The 707 hp is 57 more than the most powerful Corvette, while the closest 2015 Ford is the Mustang GT at 435. To get more horsepower than a $60,000 Hellcat Challenger or Charger, you’d be looking at some megabuck Ferrari or Porsche.

To build something as audacious as a 707-hp V-8 in the middle of a fuel economy race took guts.

Under Fiat control, Chrysler engineers are having fun again.