6.1 HEMI Upgrades

The 6.1 HEMI had a short production run and is a rather outdated, underpowered engine by modern standards. However, its large displacement allows for lots of opportunity to take the 6.1L V8 to the next level. A tune, intake, headers, and cam can push the HEMI to 400+whp. In this guide, we discuss these 6.1 HEMI upgrades as well as more mods to build a fast, awesome SRT8.

Best 6.1L HEMI Engine Upgrades

• Tune
• Intake
• Headers
• Cam

SRT8 models came from the factory with 425 horsepower and 420 lb-ft of torque. In stock form, they typically dyno in the ballpark of 350-375whp. Numbers can vary a lot depending on the dyno, correction factors, etc., but that’s a lengthy conversation for another day. The above modifications can push the 6.1 HEMI into the 410-450whp range. Ultimately, a tune, intake, headers, and cam show gains of roughly 60-75whp.

It’s an impressive performance boost for the SRT8 6.1 HEMI that makes it a competitive engine – even against newer more technologically advanced engines. That said, let’s jump in and discuss the 4 best upgrades for the 6.1L V8.

1) Tune & Fueling

Tuning is undoubtedly the single best power upgrade. Not only do tunes offer great power gains, but they also help maximize gains from additional mods. A tune is truly the foundation to making more power on the 6.1 HEMI. Benefits of tuning include:

• 10-20whp gains
• 10-20wtq gains
• Maximize gains from additional mods
• Better throttle response

With a tune only, you can expect to see power gains around 10-20whp and wtq. Some mods like cams require tuning. While it might not be required for basic bolt-on mods a tune will still help maximize power gains. A 6.1 HEMI tune also delivers better throttle response and potentially some other benefits depending on the tune and your end goals.

6.1 HEMI tunes will require a handheld tuner device, which usually cost ~$350-600 and include a few basic off-the-shelf tunes. The biggest gains will come from custom tuning, but that can add another $200-300. It’s also best to wait until all planned upgrades are done before opting for a custom tune. Otherwise, any changes will require revisions and add to the costs of 6.1 HEMI tuning.

6.1 HEMI Fueling

Another important topic that comes alongside tuning is fueling. Higher octane fuels will show the biggest gains when tuning the 370 HEMI. It’s best to opt for a 91 or 93 octane tune (or whatever the best octane you have easy access to) if you’re looking for maximum performance.

Popular alternatives to standard pump fuels are ethanol (E85) or race gas. These fuels can show additional 10-20whp gains. However, race gas is often expensive and harder to find. E85 can also be tough to find in some parts of the country, and is also very demanding on the fueling system. Ultimately, 91 or 93 octane tunes are going to be the best bet for most 6.1 HEMI owners.

2) Cold Air Intake Upgrades

Next on the list of 6.1 HEMI upgrades is a cold air intake. An intake upgrade offers the least impressive performance gains on our list. However, intakes are cheap, easy to install, and effective. Benefits of a 6.1 HEMI cold air intake include:

• 3-7whp gains
• Similar torque gains
• Louder engine & exhaust note

The stock intake system on the 6.1 HEMI is pretty efficient for the engines intended output. If you install an intake without any other mods you may not see any power gains at all. Though, once you begin adding mods like a tune, headers, and cams then it’s vital to have a better flowing, more efficient intake. With these mods, it’s common to see power gains of about 5-7whp with a cold air intake.

Additionally, in talking about power gains we are referring to peak gains. A 6.1 HEMI intake upgrade can show better power gains at different points in the powerband. Even though the peak gains aren’t massive, you may pick up 10+whp and 10+wtq at different points of the RPM range.

3) 6.1 HEMI Headers

Header upgrades are where things start getting a lot more exciting for the 6.1L HEMI. Long-tube, shorty, catless, and high-flow cats make up the different options for 6.1 HEMI headers. The catalytic converters lie in the mid-pipes, but long-tube headers also replace these.

Ultimately, catless long-tube headers are going to offer the biggest power gains. Shorty headers can also show respectable results, but 6.1 HEMI long-tube headers are a no brainer if power is the end goal. Benefits of headers are:

• 10-20whp
• Similar torque gains
• Loud, aggressive exhaust note

Peak gains of 10-20whp is already impressive enough. However, headers offer a lot more than just peak gains as the power is consistent throughout the entire powerband. As far as simple bolt-on mods, headers are up there with tuning as the best 6.1 HEMI upgrades.

4) Camshaft Upgrades

6.1 HEMI cam upgrades are venturing into the territory of more complex and advanced mods. A cam is the most expensive mod and the most time consuming install out of everything on the list. Although, cams also offer the best performance and power so they made the list for good reason. Here are some of the benefits of 6.1L HEMI cam upgrades:

• 30-50whp gains
• 10-30wtq gains
• Incredible sounds

A proper cam upgrade offers insane 30-50+whp gains. That’s about as good as it gets without even more expensive mods like forced induction. Some aggressive cams may trade-off a little low-end torque in favor of big peak gains. Others may keep the full low-end potential while still offering great peak gains.

Now, there’s a lot that goes into camshaft upgrades and we’re just focusing on the basics for this article. Lift, duration, and LSA are all important cam specs. Not any one 6.1 HEMI cam upgrade is the best for every build. If you’re looking into a cam then it’s best to spend some time researching what options best fit your specific build and modifications. For more info, check out our complete 6.1 HEMI cam upgrade guide.

Additional 6.1 HEMI Mods

The four upgrades discussed throughout the bulk of the article are generally a great starting point for the 6.1 HEMI. They’re some of the simpler (with the exception of a cam) and best-bang-for-your-buck mods. However, there are tons of upgrades available to extract even more power from the 6.1L V8.

While these mods didn’t quite make the primary list they’re worth a quick mention for those wanting even more power and performance. That said, let’s jump in and discuss intake manifold, throttle body, ported heads, and forced induction upgrades.

Intake Manifold Upgrade

Upgrading the 6.1 HEMI intake manifold is another great bolt-on mod to maximize power and performance. You can also port the stock 6.1 HEMI manifold. True upgrades will often offer the better power gains and can also help shave some weight from the engine.

Expect power gains in the ballpark of 5-10whp with an upgraded manifold. You may even see slightly more power if you have all the bolt-ons and are pushing the 370 HEMI to 450+whp. We have an in-depth 6.1 HEMI intake manifold guide for anyone looking to learn more.

Upgraded Throttle Body

Throttle bodies didn’t quite make the main list as the OEM TB is very effective for stock or lightly modified applications. It often doesn’t make sense to upgrade the TB unless you’re planning to do all the mods. Without a tune, headers, cam, intake manifold, etc. a throttle body is unlikely to show notable performance benefits.

However, once you push into the 425-450+whp ballpark an upgraded 6.1 HEMI throttle body starts to help. It’s also a relatively inexpensive upgrade so it may be worthwhile even if the gains are only a minor 3-5whp.

Ported Heads

These final two upgrades are getting into much larger, more expensive, and complicated projects. Ported heads – especially when combined with cam upgrades – can offer impressive an impressive 15-20+whp. It’s an expensive upgrade for those power gains, though.

If you’re dead-set on keeping the 6.1 HEMI naturally aspirated then ported heads will boost things to the next level. However, those open to actual boost would be better spending the money on a forced induction setup.

Forced Induction

Superchargers or turbos are the best method to build an insane 6.1 HEMI. There really isn’t any limit other than what the budget allows for. The 6.1 HEMI can handle low boost and modest setups on the stock block and heads. Around 500-600whp is a reasonable goal for a conservative setup. 600-800+whp is realistic with the proper setup, but we would recommend building the motor to venture into this territory.

Ultimately, the sky is the limit with forced induction and these setups can make 1,000+whp. It’s expensive, though. Even a conservative supercharger kit with supporting mods will set you back roughly $7,000-10,000. The superchargers to make more power aren’t much more expensive, but the list of supporting mods gets lengthy for 550-600+whp builds. Check out our 6.1 HEMI supercharge guide for more details.