• 2017



The Gen III HEMI® engine was introduced in 2003, has been in production through 2016, and is still going strong! By last year, there had been over 3 million new HEMI engines built and that number is growing larger every day! Compare that to just over 10,000 in eight years of production for the 426 Gen II engines.

There are lots of variations of the new Gen III HEMI engine: the original 5.7L, the 6.1L, the 6.4L, the 426 all-aluminum engine, the 6.2L Supercharged SRT® Hellcat engine and the 354 Drag Pak supercharged version. Add to these six different displacements, features like MDS (multi-displacement system) and VVT (variable valve timing), and fuel injection and carburetion options. There are four different cylinder heads, cast iron and aluminum blocks, and many other variations.

This new HEMI engine can do it all — high production, racing, lots of power and lots of technology.


Any engine project must have a complete engine assembly, and creating this assembly is one of the major challenges of any automotive project. The aftermarket isn’t quite ready to supply all the new parts to build the GEN III HEMI engine but they are getting close. You could take one out of a new car, which could be very expensive. The junkyard approach (where crashed cars go) could also be rather expensive since these are relatively new engines — probably with low mileage. For most of the older small blocks and big blocks, worn-out engines could be rebuilt, but these engines are somewhat new and may not be worn out yet! The original 2003s might be getting close.


Another possible approach is to use what is called a long block that would be available at your OEM dealer. For example, 68259163AA is a long block 5.7L Eagle HEMI® engine for the 2010-2012 Chrysler Aspen, Jeep® Commander, Chrysler 300, Dodge Durango and Jeep Grand Cherokee. The long block is not a complete engine. It has no valve covers, no intake manifold, no front cover and no oil pan. Because these long blocks are designed as service replacements, they tend to be year and model specific. If you didn’t want the stock intake, but you needed cylinder heads, this may not be a bad deal.

Other long block options include the 68253461AA 6.1L unit for the 2006-2010 Chrysler 300, Dodge Challenger, Dodge Charger and Dodge Magnum models, or the 68293007AA 6.4L block for those vehicles in newer models through 2016 (minus the Dodge Magnum).


Since the mid-1990s, perhaps the most popular way to approach getting a HEMI engine assembly is called a crate engine. Its popularity comes from having one part number that gets you a complete engine assembly. Mopar® Performance started designing and selling crate engines in the early 1990s based on a carburetor. Add a carb, ignition and engine oil (hopefully) and off you went. New engines (any engine built after the early 1990s) are much fussier. On these engines, the ECM (engine control module) controls both the fuel and the spark, so they are electronically controlled. This means that you must have six or seven sensors along with the computer and fuel injection hardware. So, if you are doing a conversion or a custom install, the electronics can make it more difficult. However, this situation is constantly evolving and we are much better off today than we were 10 years ago!

The somewhat baseline HEMI crate engine would be the 5.7L Eagle (68303088AA). The Eagle is an upgrade over the original 5.7L engine built from 2003-2008. It makes about 30 horsepower more than the original engine package. These engines make about 375-390 horsepower depending on accessories, upgrades and revisions. Check with your dealer for specific details prior to ordering.

The next step up is the 6.4L Apache crate engine (68303090AA) or the “392”. The “Apache” is the production nickname for the high-performance package used on this engine — big heads, bigger valves and more lift from the cam. The horsepower hardware and extra cubic inches move the horsepower numbers up to about 485 horsepower, depending on accessories.

For the past eight years, Mopar Performance has been offering special drag race cars, which are generally called Drag Pak cars (very limited builds). In most cases, they are built with several engine options to give the customer some choices. Typically, the basic car is a Dodge Challenger. Mopar Performance offers crate engines for some of these popular vehicles. The 5.7L Drag Pak crate engine is P5155190 and the 6.1L Drag Pak crate engine is P5155189. You could consider these “race” engines and they might have to be converted (milder cam, etc.) to be used on the street.

The current biggest (and baddest) crate engine is the 426 all-aluminum engine (P5155513AC). It currently makes 540 horsepower — naturally aspirated! While it is not a race engine, it could be used in racing! The actual race versions make much more power! Similar to the Gen II engines, there seems to be no end to the power increases.


All the new HEMI production engines use multi-point injection (MPI). There are almost no intake manifolds for these HEMI engines offered in the aftermarket that are based on using fuel injection except those offered by Mopar Performance. Most customers seem to want to use a carburetor and there are manifolds designed for that purpose. This is an easy swap and a personal decision, but there is a trick. If you don’t use the computer, you will need a distributor for the ignition. The new HEMI engines use distributor-less ignitions. Arrow Racing Engines (arrowracingengines.com) makes an adapter which replaces the front cover and accepts a distributor. There is also a machined boss for the mechanical fuel pump, which will also be helpful. Tip: Run the engine as a single plug head by plugging one of the two-machined plugholes in the head. There is no difference in power in this engine between the A and B positions plug location. For racing applications, there is also no difference in horsepower between dual-plug and single-plug configurations.MoparDotCom

There are many options for long blocks, head assemblies, crate engines and basic hardware. I have only discussed some of the more popular ones. For more information and added details, please contact the Mopar Performance Tech Line – 1-888-528-HEMI (4364) or go to the website – www.mopar.com.

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