New Hemi Engines 2003-Present. Larry Shepard
posts are attached directly to the valve covers. You can’t see the actual engine or valve covers until you remove these covers. (Photo Courtesy FCA US LLC)
Short Blocks and Bare Blocks
If a block can’t be repaired, one approach is to use a new bare block or a short block. For the 5.7L and 6.4L Gen III Hemi engines, these parts were serviced a few years ago. Only a couple dealers were still listing them at this writing. Consider using a long block if these are not readily found.
Long Blocks
With new short blocks and bare blocks being in short supply, the next reasonable approach is a long block. Long blocks include heads but do not have the intake, front cover, valve covers, or oil pan. With a long block, one part number gets you a lot of parts and is a much better approach than ordering them one at a time.
Long-block assemblies should be available at Chrysler dealers. While prices may vary, purchasing a long block is not as expensive as buying a fully assembled crate motor. In the chart on the next page, I have listed some currently available long blocks that might be useful in a short-on-parts rebuild project. I picked the oldest and most popular engines (the 5.7 and 6.1) because they are the ones most likely to have worn-out parts. The dealer will have more versions available.
The largest piece of any engine rebuild and the foundation for your project is the actual engine block. The disassembly process gets down to the bare block, where all five cross-bolts are removed. At this point, the block can be sent to your machine shop and inspected for wear and usability. You cannot tell what is going to be required until this initial inspection is complete.
Head Assemblies
In a general rebuild project, you may have a failed engine that hurt the block, but you may also have a good block with a wounded head. You may also have found a usable bare block or a short block that needs heads. Once you have a usable block, you might need heads or want a spare set of heads. Similar to the block assembly approach, you can save time and money by ordering one part number rather than buying the head, valves, and springs separately. Keep in mind that Gen III Hemi production engines use a different head on the left and right sides and all head assemblies include valves and springs. The chart on the next page lists head assemblies available from Chrysler dealers for the long blocks in the previous section.
Tech Tip
Chrysler dealers, Mopar distributors, and many engine builders offer their own crate motors that may vary in specific details and performance ratings from some of the factory hardware. The new Mopar Performance 6.2L Hellcat crate engine should be very popular in 2018. There are several performance dealers offering supercharged 392 engines using the Magnuson supercharger that look very similar to the Hellcat. The 354 Drag Pak crate engine uses a Whipple supercharger, which also looks similar. ■
Crate Engines
The Chrysler crate engine options are constantly evolving. The 5.7L, 6.1L, and the 6.4L 392 have all been offered as crate motors dating back to the initial Gen III Hemi introduction in 2003. Specific details of the crate engines change frequently based on customer demand and parts availability. Today, the 5.7L Eagle and 6.4L 392 Apache engines are available as crate motor assemblies. The part numbers and performance ratings are listed below. Beginning in 2018, Chrysler’s Mopar Performance will also offer a 6.2L Hellcat Crate engine.
If you had a basic engine explosion or the inspection showed the block to be broken, a crate engine can be a possible solution. One part number gets you all the parts for the swap. This modified Hellcat crate engine may be just what you need. There are also 5.7L and 392 crate engines available. (Photo Courtesy FCA US LLC)
* The 5.7L crate engine rated at 383 hp replaces earlier 5.7L crate motors that were rated around 370 hp.
** The 6.4L crate engine above rated at 485 hp replaces an earlier 6.1 L crate motor that was rated at 425 hp and earlier versions of the 6.4L engine.
| Specials | ||
| Year | Engine | Note |
| 2014–2017 | 354 | The 354 is a race only package. |
| 2017–2018 | 362 | The 362 is a circle track crate engine offered by Prefix based on a sanctioning body specced carburetor and distributor. |
| 2013–2018 | 426 | The 426 aluminum crate engine was offered by Mopar Performance (MP) but intake availability caused supply problems, and it is not currently offered by MP. However, aluminum 426 crate engines are still offered by Prefix offer several variations with the max power package (big cam, big/tall intake, big 4-barrel throttle body) coming in around 780 hp. The large cam and tall intake used on this version may not be suitable for all applications. More streetable versions may be in the 600-plus-hp range. |
CHAPTER 2
IS IT TIME TO REBUILD?
There are many reasons to decide that it’s time to rebuild an engine, but typically the engine will give you a sign that will get your attention and convince you that it is time to get the wrenches out! Some of the key signs include high mileage, high oil consumption, oil leaks, or a smoking engine. Ominous noises are always good at getting our attention too.
These concerns can be grouped into three categories: performance-based (fuel economy or acceleration), mechanical (noises), and oil or lubrication (leaks or smoking). Another reason for a rebuild is an enthusiast is interested in a street rod, street machine, and/or custom build using the high-tech Gen III Hemi engine. An engine rebuild is a major project that will result in some downtime. However, it could pay for itself fairly quickly. A basic rebuild of a 2004 Gen III Hemi in a 2004 model that came with the engine is pretty straightforward. A 14-year-old engine is probably less expensive, but it may need to be rebuilt before an engine swap is completed. With any used engine, the history is unknown, so I would recommend a rebuild. You don’t want to take any chances.
Troubleshooting
When asking yourself if it is time to rebuild your Hemi engine, the answer should be based on mileage and tests indicating that a problem exists. High mileage alone may not require a rebuild if a maintenance cycle has been followed. Engine problems don’t always make noise. The loss of power and/or fuel economy is tough because it requires you to keep track of the engine performance over time. The key is to never rush into a rebuild. You should try to narrow down the problem with some specific tests.
The Gen III Hemi has been in production since 2003, so there should be lots of high-mileage examples around that need rebuilding. This 2006–2011 6.1L version averaged about 20,000 miles per year. There may be some of these in the pool too. The aluminum intake manifold was only used on the 6.1L engines.
Pro Mechanic Tip
Electrical concerns, such as an engine not starting, is usually related to the battery, the charging system, or the wiring. Any electrical problem would need to be fixed before any testing, engine rebuild, or engine change. ■
With a failed engine you know that you will have to rebuild