Small cars (like most of those we mentioned above), in addition to offering many of the tech and convenience features of larger and more expensive cars, are becoming increasingly refined. The Neon, which was loved for its perky driving feel and impressive handling, was disliked for its lack of refinement and a body structure that left lots to be desired. Likewise, the Caliber was sold short with subpar interior materials and unnecessarily noisy and coarse powertrains.
Based on what we see in the cabin of the Dart models shown at Detroit, cabin appointments appear to overcompensate for the Caliber’s woes. But with the new Tigershark engines that are standard under the hood of all Dart models (2.0-liter, or 2.4-liter in the R/T, although a Fiat 1.4T is optional) what of noise, vibration, and harshness? That’s what we asked Dart chief engineer Mike Merlo at the show this week. And if the revised Charger and Journey aren’t evidence enough, it sounds like much has changed in the way that Chrysler engineers vehicles.
Here are six reasons why the Dart will be much more refined than former Chrysler small cars—as well as, possibly, many other cars in its class:
1) A Better World (Engine). The new 2.0-liter and 2.4-liter Tigershark in-line four-cylinder engines are derived from what was formerly called the World Engine. And while they share some block architecture and other pieces, there are actually few carry-over parts, the automaker insists. “The displacement is still basically the same, but we've changed bore and stroke a bit, in an effort to improve the overall noise and vibration characteristics,” said Merlo. That also includes an all-new forged crankshaft, said Menlo, and they’ve changed the bearing locations for better stability (and less vibration).
2) Moving Exhaust Noise Away From The Driver. The most important change, perhaps, is that engineers changed the way the engine is installed and mounted; it's been rotated 180 degrees, with the intake manifold in back and exhaust in front. “By positioning the exhaust in the front side of the engine, we're really moving most of the noise away from the passenger compartment,” explained Merlo.
3) More Noise Treatment Everywhere Else. “And we’ve changed the head around dramatically, obviously, because of the front exhaust and rear intake,” said Merlo. To match the new orientation, Chrysler designed a new, long-runner intake manifolds for these engines, with various noise treatments and a bi-metal noise and heat shields for both intake and exhaust.
4) Better, Smoother Breathing. The 2.0-liter version that the 2013 Dodge Dart SE, SXT, Rallye, and Limited models will come with standard maintains the same basic DOHC arrangement that the World Engine had, but with some improvements for upcoming emissions regulations. The 2.4-liter is a different story; it’s getting an all-new cylinder head, along with a MultiAir2 version of Fiat’s variable valve timing and lift system.
“The 2.4-liter really gets bumped up in torque versus the World Engine,” said Merlo. “That MultiAir technology really allows us on a cylinder by cylinder basis to be able to vary the exhaust and intake strokes independently; so we get with a solenoid control a very fast and responsive changes in needs to both torque and throttle.”
Noise and vibration can just as well come from the intake side, Merlo pointed out, so they had to really work at that, too. “We spent a lot of time designing the intake system for this car, and we have five or six quarter and eighth-wave tuning elements that are part of the intake manifold,” he said, adding that the Dart has “a very interesting route that air flows through as it goes through the intake, meant to smooth out the sound as well as provide a very smooth flow.”