In 2003, Chrysler introduced the third-generation HEMI referred to as 345 HEMI in commemoration of its 345 cubic inch displacement. It is a long-time pushrod engine that debuted in the 2003 Dodge Ram but underwent significant developments for better efficiency and performance.
A great sounding engine with a lot of things to known. But what are these engines really? Let’s find out.
What are Dodge Hemi 5.7L Engines?
The Dodge Hemi, a 5.7 Liter engine, is a third-generation iteration of the “HEMI” engine, starting in the early 1950s. In those times, the concept was already established and applied to their military trucks back then. Chrysler developed the engine for the Republic P-47 Thunderbolt fighter aircraft.
The first HEMI V8 engines were not badged as HEMIs but called ‘Firepower.’ It does have the same hemispherical combustion chambers and two spark plugs per cylinder. Due to these attributes, Briggs Cunningham installed these engines to his race cars used for international motorsports and won the race in 1953.
Fast forward to the present, the HEMI engines continue to succeed and what we have now is a decade-long of expertise and commitment to the craft. It was even awarded as one of Ward’s Ten Best Engines for four consecutive years from 2003 until 2007 and again in 2009.
The third-generation HEMI picked up where the second-generation left. The combustion is different, with more complex engine heads, a coil-on-plug distributor-less ignition system, and two spark plugs per cylinder. Chrysler introduced a variable valve timing system into these machines achieving a nearly 4% better fuel economy.
The HEMI 5.7 also has a variable displacement technology, same with Mercedes’ cylinder deactivation system, that shuts off two cylinders under light load to improve the fuel economy.
Engine Specifications and Design:
- Production Run: 2003 – Present
- Cylinder Head Material: Aluminum
- Cylinder Block Material: Cast-iron
- Configuration: V8
- Bore: 99.49 mm
- Stroke: 90.88 mm
- Valvetrain: SOHC pushrod V8, two valves per cylinder
- Displacement: 5.7 L (5,654 cc)
- Compression Ratio: 9.6 and 10.5 (MY 2009+ )
- Weight: 560 lbs.
- Maximum HP: 395 HP at 5,600 RPM
- Maximum Torque: 410 lb-ft at 3,950 – 4,400 RPM
The 5.7 Liter HEMI is the only available gasoline engine in the Ram Heavy Duty. Chrysler released this machine for the model year 2002 on the Dodge Ram 2500 and 3500 as well as on 2003 models of 1500 model pickup trucks to augment the Magnum 5.9 engine.
Chrysler made the HEMI 5.7 available across all 2004 Dodge Durango, Dodge Ram, 2005 Chrysler 300C, Jeep Grand Cherokee, Dodge Magnum R/T, and many more. Manual transmission applications do not have cylinder deactivation.
The framework design of 5.7 Liter HEMI started from the board; it does not have any design basis. Similar to the 4.7 Liter PowerTech V8, the HEMI 5.7 has a deep-skirt design cast-iron cylinder block with a 90-degree angle between cylinder banks. The crankshaft is made from cast nodular iron supported by four main bolts per bearing.
The engine uses a forged powdered metal connecting rods and skirt-coated aluminum pistons. Until 2008, the pistons had narrow piston rings but were later narrowed in the 2009 revision. The chain-driven overhead camshaft is situated between the cylinder banks and has a longer timing chain to reduce the length of the pushers.
The cross-flow cylinder heads are made from aluminum with two spark plugs and two valves per cylinder. The combustion chambers of the new-generation HEMIs are different from those of the earlier ones. Chrysler used a flatter design with a taper squish on both sides to accommodate a higher efficiency and reduce output emissions.
The camshafts actuate both the intake and exhaust valves through pushrods via rocker arms. The engine is also installed with roller-style hydraulic lifters and beehive valve springs. The cylinder deactivation system called Multi-Displacement System (MDS) has been integrated into the gas variant of the 5.7 HEMI. This system minimizes fuel consumption and emissions.
The system controls the oil flow through the lifters of the corresponding valves by cutting the fuel supply in four cylinders (two for each bank) by keeping the intake and exhaust valves closed. The intake manifold is plastic-made and drive-by-wire throttle body.
The initial engine release produced 345 HP with 375 lb-ft of torque, but a lower 340 HP with 390 lb-ft of torque for the Magnum R/T and 300C.
Applications of 5.7L HEMI Engine:
- 2003 – Present Ram Pickup
- 2004 – 2009, 2011 – Present Dodge Durango
- 2005 – 2008 Dodge Magnum R/T
- 2005 – Present Chrysler 300C, 300S V8 (Since 2012)
- 2005 – Present Jeep Grand Cherokee
- 2006 – Present Dodge Charger R/T
- 2006 – 2010 Jeep Commander
- 2007 – 2009 Chrysler Aspen
- 2009 – Present Dodge Challenger R/T
- 2022 – Present Jeep Wagoneer
However, in 2009, Chrysler released a revised 5.7 Liter Hemi Engine, also known as 5.7 Eagle. There are significant changes made for this machine to improve this large engine’s efficiency, reliability, and overall stability.
The application of the Variable Camshaft Timing or VCT is the most significant change, which requires an extended front cam bearing and three additional oil passages in the block. The VCT also uses an oil control valve to control the oil flow going to the unique camshaft sprocket, which has a phasing device.
A new crankshaft comes with the redesigned cylinder block, a dual-mass crankshaft damper, new pistons with a narrower ring, and reinforced connecting rods.
The cylinder heads also underwent significant changes. Compared to the initial release, it has a better airflow due to larger and almost square intake ports, 14% more air than the prior rectangular ones. The intake valves are more extensive—a higher roof due to the D-shaped exhaust ports and an increased compression rating to 10.5.
Even though the intake manifold has been revamped on all HEMI vehicles, it is model-specific. Non-Hybrid Chrysler Aspens, Dodge Ram, and non-HEV Durango employ an active intake manifold with a shorter runner valve to optimize power and torque. Valve is closed at lower engine speeds, resulting in better low-end torque in contrast to longer runners.
Meanwhile, the valve is open at higher engine speeds redirecting the incoming air into the manifold center.
All Heavy Duty trucks and six-speed manual transmission applications differ by not having a multi-displacement system.
Power Ratings of 5.7 HEMI Vehicles:
- 300C/300S V8: 363 HP and 394 lb-ft
- Charger R/T: 370 HP and 395 lb-ft
- Challenger R/T Automatic: 372 HP and 400 lb-ft
- Challenger R/T Manual: 375 HP and 410 lb-ft
- 2009 – 2012 Ram 1500 Truck: 390 HP and 407 lb-ft
- 2013 Ram 1500 Truck: 395 HP and 410 lb-ft
- Ram 2500/3500: 383 HP and 400 lb-ft
- Jeep Commander and Jeep Grand Cherokee: 360 HP and 390 lb-ft
- 2011 Dodge Durango: 360 HP and 390 lb-ft
- Dodge Durango non-HEV and 2009 Chrysler Aspen: 376 HP and 401 lb-ft
- Dodge Durango HEV and 2009 Chrysler Aspen: 399 HP and 390 lb-ft
- 2022 Jeep Wagoneer: 392 HP and 404 lb-ft
Engine Tuning, Upgrades, and Modifications
Getting more power out of a 5.7 HEMI requires effort and the right items to build your desired machine. Though it’s an old engine, the power ratings can still be increased with its proven reliability throughout the years.
The first thing you do in upgrading the 5.7 HEMI is to unlock the PCM. This will enable the tuners to tune the vehicle the way you want it. Next is to integrate a high-performance exhaust running two high-flow catalytic converters into an X-pipe have an easier time producing more HPs since it does not have that many restrictions as the stock ones.
In parallel to exhaust replacement, you will also need to replace the intake to allow more air to go at higher RPM; a bigger throttle body, replacing downpipe, high-performance air filter, and a throttle body spacer.
You can also put a Hellcat Supercharger on the HEMI 5.7, but you need an adapter kit.
Problems Surrounding the HEMI 5.7 Liter Engine:
The Chrysler 5.7 Liter HEMI is a highly reliable engine and does not have any significant design flaws. Chrysler used this 5.78 Liter for their flagship cars and truck for about two decades, so there’s no question that these machines are good as it sounds. But there is no perfect engine, and at some point, you may encounter troubles. Here are some concerns that can occur in the 5.7 HEMI:
The most common, not only for the HEMI but most engines, is the engine tick problem. 345 HEMI owners have different views regarding this issue; some say this is normal while the others gave up and replaced their engines. But what are the causes really?
Faulty lifters and lifter rollers are the culprits for this; they have to be the severe cause of the engine ticking in 5.7 HEMIs. It is prevalent in 2009 models leading some to believe that the multi-displacement is the one to blame, which is not valid. The issues most likely are due to insufficient oil flow to the lifter rollers resulting in seizures.
The lifters contact the lobes resulting in ticking noise. If left unattended, it could seriously damage the engine and will require camshaft replacements as well as having metal shavings in the oil.
The 5.7 HEMI uses 16 spark plugs, and considering that spark plugs are standard maintenance items, replacing them periodically can save you troubles from misfiring. Again, 16 spark plugs is a lot to deal with, all it takes is one spark plug to fail, and you know what it is. Spark plug failures are not common, but they should be changed every 30,000 – 40,000 miles on the 5.7 HEMI.
And lastly, broken exhaust manifolds bots on the engine. This has to be the number one common problem for the 5.7 HEMI. A lot of owners have encountered this problem multiple times. The rear passenger side manifold bolt is the first to give in, presumably due to a higher temperature in that location. This is because the manifold warps towards the rear, thus causing the bolt failures.
This may also be the cause of ticking noise, at some point, and exhaust leaks.
The 5.7 HEMI is a fun-to-drive engine. Highly reliable, durable, and a well-designed pushrod engine that can push the reputation of large machines to a higher standard. However, it is not the best engine to be built but certainly way better than engines on its competition level.
With proper care and maintenance, the 5.7 HEMI can last up to 250,000 – 300,000 miles. Though it has some significant problems, as mentioned above, stay to the usual routine and schedule.