GEN III HEMI® Engine Quick Reference Guide Part III

2 years ago How-To

BIGGER AND BADDER – 2005-2010 6.1L HEMI® V8 ENGINE

2005-2010 6.1L HEMI V8

Over the past few weeks, we’ve gone over the 5.7L HEMI engine from 2003-2008 and then followed up with the changes to the engine for 2009-Current. While the 5.7L HEMI engine was being developed, the SRT® engineers were already working on a bigger displacement version that would make this modern powerplant even better – the 6.1L HEMI engine. It produced 425 horsepower in the Challenger SRT8, Charger/Magnum SRT8 and Chrysler 300C SRT8 passenger cars, and 420 horsepower in the Jeep® Grand Cherokee SRT8. The 6.1L HEMI engine was built between 2005 and 2010 and despite the decent production numbers, finding a good used 6.1L HEMI engine is becoming more difficult as they are getting hard to locate in salvage yards and swap meets. Even a remanufactured 6.1L HEMI engine can be scarce due to lack of cores. But if you do some detective work, they’re still out there. If you’re lucky enough to find one, here’s some pertinent and helpful information you should know on how to spot the bigger and badder 6.1L HEMI V8 engine.

HEMI Engine

ENGINE BLOCKS AND ROTATING ASSEMBLY

Like its 5.7L counterpart, all 6.1L HEMI engines were built at Chrysler’s Saltillo Engine Plant in Mexico. The 6.1L HEMI blocks are cast iron and are painted orange. They have “6.1L” cast on the driver’s side of the block above the oil pan rail. If you convert the 6.1L displacement to cubic inches, it’s 372. To get to this, the 6.1L HEMI engine has a 4.055-inch bore and a 3.58-inch stroke. The stock compression ratio is 10.2:1, which requires the use of premium fuel for best performance.

HEMI Engine

Mopar® fans may think the factory-applied orange paint on the 6.1L engine block is to pay homage to the iconic 426 HEMI engine of the 1960s and early 1970s that were also painted orange. Actually, the orange paint on the 6.1L HEMI engine blocks serves as an identifier for the plant workers to distinguish it from the 5.7L HEMI blocks (which all get painted black) during the machining and assembly process at the Saltillo Engine Plant. However, the “HEMI Orange” paint on the 6.1L HEMI blocks (and current 6.4L and 6.2L HEMI blocks) is a nice throwback touch to the original and iconic 426 HEMI engine.

HEMI Engine

The casting number on 6.1L blocks can be found on the front of the engine where the timing chain cover attaches. The casting number on the 6.1L HEMI engine block is 05037388AB. These blocks are considered a thin wall casting but can safely be bored out to .030 inches during the rebuilding process.

HEMI Engine

When it comes to the rotating assembly, the SRT engineers beefed up the crankshaft on the 6.1L HEMI engine and went with forged steel versus cast iron on the 5.7L engines. The pistons are a hypereutectic style (like the 5.7L HEMI engine) but with a floating pin versus a pressed-pin design. The 6.1L HEMI pistons are 4.055 inches in diameter and weight 435 grams, and the connecting rods measure 6.242 inches centerline to centerline in length (same as the 5.7L). Remember, if you’re going to install an aftermarket supercharger or turbocharger on a 6.1L HEMI engine and still use the production pistons and connecting rods, you’ll be limited to how much boost you can run as to not hurt the engine.

HEMI Engine

INTAKE/EXHAUST MANIFOLDS AND CYLINDER HEADS

The 6.1L HEMI engine can also be identified by its long fixed runner/barrel-shaped aluminum intake manifold. It makes good power from 2,000 RPM all the way up to the 6,200 RPM redline. The 6.1L HEMI engine also has the dubious honor of being the last production Chrysler V8 engine to have a factory-installed aluminum intake manifold. The 6.1L HEMI engine used an 80mm throttle body that has enough airflow to handle many bolt-on engine modifications.

HEMI Engine

The 6.1L HEMI engine comes standard with aluminum tubular exhaust manifolds that are low-restriction and very efficient. They also provide a low-cost performance upgrade if you’re replacing the cast iron exhaust manifolds on a 5.7L HEMI engine project when your budget can’t afford aftermarket long tube headers.

HEMI Engine

Like all GEN III HEMI cylinder heads, the production 6.1L version is made from aluminum and features a twin-plug design. The intake valve head diameter is 2.08 inches (like the Mopar big-block engines of the 1960s and 1970s), and the exhaust valve head measures 1.60 inches. The cylinder heads weigh about 30 pounds each with valves and valve springs installed. Stock, the 6.1L HEMI cylinder head flows extremely well and doesn’t need extensive porting for most street and strip applications.

HEMI Engine

To identify a 6.1L HEMI cylinder head, it has a casting number of 5037369AA located above the exhaust ports. Remember, there are right and left cylinder heads based on the machining of the exhaust port flange. Because of the efficient design of the 6.1L HEMI engine’s intake and exhaust ports, the cylinder head moves a lot of air across the engine’s power band. A big part of this is due to the 6.1L HEMI engine’s more aggressive hydraulic roller camshaft. The SRT engineers increased the valve lift from 0.472 inches to 0.571 inches. If you compare this to performance camshafts of the 1960s and 1970s, the valve lift is a big number yet the 6.1L HEMI engine behaves very well in stop-and-go traffic without the traditional “choppy” idle qualities associated on some high-performance camshafts.

HEMI Engine
HEMI Engine
The 2006 Jeep® Grand Cherokee SRT8 is powered by an SRT®-developed 6.1-liter HEMI® V8 engine producing 415 horsepower and 410 lb-ft. of torque.

Like all GEN III HEMI engines, the 6.1L has the same exterior dimensions as the 5.7L, 6.2L and the 6.4L. As with all GEN III HEMI engines, any Mopar small-block transmission will bolt-up to the block. This will eliminate any mysteries when swapping a 6.1L GEN HEMI engine into an older Mopar car or truck. If you need more info and parts for your GEN III HEMI engine project, these companies have the goods to make your ride hit on all eight!

Mopar.com; Holley.com; Edelbrock.com; RosevilleMoparts.com; ManciniRacing.com; ShopHEMI.com; MMXModernMusclextreme

HEMI Engine

Next week in the GEN III HEMI Engine Quick Reference Guide, the mighty 392 is born and it rotates the earth!

All GENIII HEMI Engine Quick Reference Guides:
Part I
Part II
Part IV
Part V

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