The most powerful and most popular engine fitted into a muscle car both in the Muscle Car Era, and today, was known merely by a name, the Hemi. While to the naked eye, one look at a
Dodge Challenger Concept article provides most of the numbers anyone really needs to know; 6.1 liters, four hundred and twenty-five horsepower, four hundred and twenty pound feet of torque, simple addition of engine size and consequently, horsepower was not as short and sweet as it may sound.
During design the engineers looked at the popularity of the original Hemi, and that was where the horsepower measure comes from, but this Hemi offers 69.8 horsepower per liter ratio which far exceeds the old 426 Hemi.
To give the new Dodge Challenger 6.1L Hemi a nostalgic look, it bears the large black "crinkle finish" valve covers with HEMI in matching bright orange with silver trim. This 6.1 liter Hemi is actually just a beefed up version of the 5.7 liter Hemi found in the non-SRT Hemi cars in the Dodge and Chrysler lineup.
To increase the engine volume and horsepower the first step was increasing the cylinder size. Each cylinder was increased in diameter by three and a half millimeters. The compression ratio of this naturally aspirated power plant was increased from 9.6 to 1, to 10.3 to 1. The huge cylinder heads, which are what makes a Hemi a Hemi, were specially redesigned on the new 6.1 liter engine, with special care taken in the areas of the intake and exhaust ports, as well as increased size in the intake and exhaust valves which are one piece, and have hollow stems that are then injected with sodium to help control internal engine heat, allowing this head to breathe as freely as possible. In order to feed these larger finely tuned intake ports, an intake manifold designed specifically for use with this cylinder head pattern has been applied, featuring huge smooth intake runners. That intake manifold is fed by the large front mounted throttle body, which pulls air through the hood scoop which is mounted at the very front of the hood.
Once the air enters the new cylinder head design, camshafts redesigned specifically for this engine help to perfect the combustion process, allowing for smoother movement of the pre and post combustion gases, and at the same time allowing this new Hemi to have a higher redline for maximum performance. The engine block itself has been altered, with relocation of the water ports for more efficient cooling, and with the smoother interior of the cooling ports, the engine has less draw placed on it by the freer flow of the water pump. To protect the internals of this new 6.1 liter Hemi the bottom end is composed of a forged steel crankshaft, high strength light weight piston connecting rods, floating pin pistons, and keeping this all moving smoothly is the newly refined oiling system which includes oil injectors in each cylinder and a new oil pan design which helps top cut down on engine foaming at high RPMs.
On the other end of the combustion process ‘header’ style exhaust manifolds in which each exhaust port exhausts through a separate tube as opposed to all of them emptying into one large chamber which then heads to the exhaust system thus helping greatly to increase exhaust flow, have been added to this new Hemi and in order to contain the heat from these separate tubes and to preserve a nice clean engine bay look, as the tubes meet they are gathered in a stainless steel shell. These four tubes per engine bank meet in a two and three quarters inch collector, which meet up with the huge exhaust system baring the same diameter as the header collector.
Traveling to the rear of the car this increased size exhaust system goes through a set of high flow mufflers which allow for a great deep throaty Hemi sound bellowing from the wide, flat retro style chrome split exhaust tips which are just below the rear fascia.
Read more about the Dodge Challenger Concept car.
