Chrysler's iconic 5.7L HEMI V8 engine has seen two distinct generations since its reintroduction the Pre-Eagle (2003-2008) and the Eagle (2009-present). Understanding the specifications, upgrades, and variations between these engine iterations can significantly benefit consumers considering a used vehicle or a replacement engine for their projects.
Historical Overview and Introduction
After discontinuing the second-generation 426 Hemi in 1971, Chrysler took over three decades to revive the legendary HEMI nameplate. The third-generation HEMI appeared initially in concept vehicles in the early 2000s, such as the 2000 Chrysler 300C Hemi Convertible Concept and the 2001 Dodge 5.7 Hemi engine. The first production version debuted in the 2003 Dodge Ram trucks, replacing the 5.2L and 5.9L Magnum V8 engines.
Vehicle Applications and Transmissions
Following its introduction, the 5.7L HEMI quickly expanded across Chrysler's lineup, featuring prominently in the Dodge Durango (2004), Chrysler 300C, Dodge Magnum RT, Jeep Grand Cherokee (2005), Dodge Charger RT, Jeep Commander (2006), and Chrysler Aspen (2007). Most of these vehicles utilized the Mercedes or Chrysler 545RFE 5-speed automatic transmissions. However, select Ram trucks employed Mercedes-Benz's NV4500 5-speed or G56 6-speed transmissions.
Power Output and Multi-Displacement System (MDS)
The Pre-Eagle engine boasted a displacement of 345 cubic inches (hence, also known as the 345 Hemi), with varied horsepower ratings ranging from 330-350 hp and torque between 370-390 lb-ft, depending on vehicle application. An essential addition in 2006 was Chrysler's Multi-Displacement System (MDS), which temporarily deactivates four of the eight cylinders under low-load conditions to improve fuel economy by 10-20%. This feature was not available in manual transmission models.
Eagle HEMI and Major Upgrades (2009-present)
In 2009, Chrysler introduced significant revisions to the 5.7L HEMI, including Variable Cam Timing (VCT) or Variable Valve Timing (VVT), which optimized torque and horsepower by controlling camshaft timing. This revised engine—dubbed the Eagle—featured improved cylinder heads, structural upgrades to the crankshaft, a higher compression ratio, and enhanced valve springs. The vehicles with the Eagle HEMI included the Dodge Charger and Challenger RT, Chrysler 300 series, Ram trucks, Jeep Grand Cherokee, Dodge Durango, and the Jeep Wagoneer (2022).
The Eagle engines typically produced higher power outputs: 390-395 hp in trucks and 363-375 hp in cars, with torque figures ranging from 394-410 lb-ft. Additionally, all transmissions eventually transitioned to the TorqueFlight ZF 8-speed automatic by 2015.
Camshaft and Intake Manifold Differences
In most models, Eagle engines utilized VCT technology to optimize cylinder deactivation under the MDS system, eliminating the need for an exhaust gas recirculation (EGR) valve. Five distinct camshaft profiles were tailored for specific vehicle groups, each non-interchangeable due to their precise tuning for different vehicle demands.
Active intake manifolds equipped with short runner valves appeared in the Ram trucks and early Durango and Aspen models. These manifolds improved low-end torque and top-end horsepower by dynamically adjusting air intake pathways.
Engine Blocks and Rotating Assembly
Both Pre-Eagle and Eagle blocks were cross-bolted cast iron and shared compatibility with classic Chrysler LA/Magnum small-block transmissions, allowing interchangeability with numerous older Mopar transmissions. The Eagle block had structural differences, such as additional oil passages for the VCT and a redesigned crankshaft with an extended snout.
Cylinder Heads: Pre-Eagle vs. Eagle
The cylinder head design marked a significant distinction between the two engines. Pre-Eagle heads featured an 85cc combustion chamber and square intake ports. In contrast, Eagle heads adopted a smaller 65cc closed chamber design, enhancing compression from 9.6:1 to 10.5:1. Intake runner volume increased from 161cc to 185cc, and intake valves grew slightly from 2 inches to 2.05 inches, resulting in improved airflow and combustion efficiency.
Flow testing revealed significant improvements in airflow for Eagle heads, which could handle 13.7% more air intake flow, directly contributing to enhanced engine performance.
Rotating Assembly Components
While connecting rods and pistons largely remained similar across generations, Eagle rods featured stiffer rod caps for improved strength due to increased horsepower. Pistons across both generations employed hyper-eutectic aluminum alloy, though Eagle pistons featured a narrower ring pack design.
Eagle engines were also upgraded to a 58-tooth crank sensor wheel from the original 32-tooth design, which provides more precise electronic engine management necessary for VCT and MDS optimization.
Additional Specifications and Known Flaws
Both engine generations share an 80mm throttle body and identical firing orders. However, fuel injector flow rates vary: the Pre-Eagle injectors flow at 26 lbs/hour at 58 psi, while Eagle injectors increase to 28 lbs/hour for trucks and 35 lbs/hour for cars at the same pressure. Additionally, Eagle HEMIs feature an oil pump with approximately 22% higher oil displacement and weigh about 31 kg more, totaling 591 lbs compared to 560 lbs for Pre-Eagle versions.
Major Flaws and Issues
The Pre-Eagle engines (2003-2008) are known for issues with prematurely dropping valve seats. This occurs due to differing thermal expansion rates between aluminum heads and steel valve seats, often exacerbated by engine overheating or heat soaking after shutdown. Dropped valve seats can cause severe engine damage, including cracked pistons and damaged cylinder heads, usually occurring after 100,000 miles.
The Eagle engines (2009-present) commonly experience a "HEMI tick," resulting from lifter roller bearing failures. Failed bearings cause lifters to seize, damaging camshaft lobes and causing misfires. Repairs necessitate replacing lifters and camshafts, typically at around 120,000 miles.
Both generations also face exhaust manifold bolt failures in trucks and SUVs, leading to exhaust leaks noticeable on cold starts. This recurring issue is less severe than others but remains a concern for HEMI owners.
Comments