Best Chevy LS3 Engine Upgrades

By the time that the LS3 rolled around in 2008, Chevy had already firmly established their updated LS small-block formula. The modern LS layout was largely a blank sheet design but borrowed learned elements from the Gen I and Gen II Chevy small blocks, originally released in 1954. Despite being released four decades later, the LS family has a couple of interchangeable parts with earlier Gen I and Gen II small-blocks including connecting rod bearings and valve lifters.

Not only does the LS3 come from a long line of all-American pedigree, but it is also one of the strongest and most receptive engines out there as far as modifications are concerned. With some choice LS3 engine upgrades, you can easily boost horsepower by a significant amount without spending a fortune. In this guide, we’ll cover some of the best LS3 engine upgrades and recommend a few parts while we’re at it. 

LS3 Performance Upgrades

• Headers
• X-Pipe
• Camshaft
• Ported Cylinder Heads
• ECU Tuning

1) Headers

When it comes to initial modification for the LS3, it is almost unanimously said that upgraded headers and an X-pipe are your best bet. As with all performance exhaust modifications, the ultimate goal of upgrading to performance headers is to remove any factory restrictions and decrease back pressure within the exhaust system. 

Headers are a fancy name for aftermarket exhaust manifolds and the two are often used interchangeably. Since the headers are the first component of your LS3’s exhaust system, they are truly an integral piece of the puzzle as far as exhaust flow characteristics are concerned. The factory LS3 exhaust manifolds aren’t bad, per se, but upgrading to a set of long tube headers with high-flow catalytic converters can yield a significant amount of power from a naturally aspirated LS3 engine.

While there are multiple different kinds of headers out there, primarily “shorty” and “long tube” headers, there’s pretty much only one commonly suggested kind of upgraded header for the LS3. While shorty headers can definitely make your engine bay pop when compared to the stock exhaust manifolds, the horsepower yield from them is much less significant than with long tube headers. 

Header diameter plays a massive role in determining the amount of power generated by upgraded LS3 headers. With that being said, larger headers don’t always equate to more power. Most people in the LS3 community advocate for 1-⅞” headers. They maximize power output and allow some room to grow if you opt to upgrade your camshaft or add ported cylinder heads in the future.

There is a lot more to cover in terms of headers, as there are quite a few considerations to take into account. For that reason, we’ve compiled a more comprehensive LS3 headers guide.

2) X-Pipe Upgrade

If you are interested in doing some additional exhaust modifications while you are messing with headers, an upgraded X-pipe should also be on your radar. Before we jump into the specifics, let’s cover the purpose of an X-pipe first. Vehicles that have more than one bank of cylinders (like V6s, V8s, V10s, etc.) have midpipes, which is where exhaust gasses from both banks meet. A midpipe’s purpose is to equalize the exhaust gas pulses that come from both sides of the engine. On LS3s, there are typically two midpipe options, an X-pipe or an H-pipe. There’s quite a debate raging in the community regarding X vs H-pipes and which is better for sound and performance. 

Overall, X-pipes and H-pipes work in a very similar way to equalize gas flow. Both feature long runner pipes that come off of the headers. Where X-pipes and H-pipes differ is how they merge. While the two separate exhaust pipes are connected by a 90-degree connecting pipe on an H-pipe, the two pipes curve into each other and connect directly with an X-pipe. This has a direct effect on sound and performance. LS3 enthusiasts often say that an X-pipe will give deliver a much more modern-sounding exhaust tone. An H-pipe is the way to go if you want a more raspy, old-school-muscle exhaust tone. 

In terms of performance, both will add a couple of extra ponies, but it won’t be anything to write home about. In general, you can expect around a 5-10 horsepower bump from an X-pipe and a few less from an H-pipe. 

3) Camshaft Upgrades

One of the most no-nonsense performance-increasing modifications that you can do to an LS3 is upgrading the stock cam. The LS3 is a prime candidate for hotter cams, as it already has a recipe ripe for more aggressive cam timing. The stock LS3 camshaft is unquestionably one of the most limiting elements of the engine from the factory. Generally, there is always a tradeoff in terms of running a more aggressive cam profile. From the factory, Chevy opted to go with a relatively tame 204/211 .551/.525 117 cam to preserve fuel economy and retain good daily drivabiliy. With that being said, the LS3 can withstand much more aggressive cams. The question is, how aggressive do you want to go?

As far as cam profiles are concerned, it is generally the case that the wilder the cam, the less performance you’ll have down low. It’s a direct tradeoff between low-end performance and increased power up top. However, there is a solid middleground that can improve performance throughout the entire rev range. A larger cam doesn’t necessarily mean better overall performance, either. While a massive LS3 camshaft will increase top end performance, it will make your Corvette or Camaro a nightmare to drive on the road.

If you are interested in learning more about camshaft upgrades for the Chevy LS3, check out our complete cam guide here.

4) LS3 Ported Cylinder Head

It’s no secret that the LS community is a big fan of porting cylinder heads. While that is certainly the case, it isn’t like the LS3, or any other LS motor for that matter, has poor-flowing cylinder heads. In fact, the LS3 has some very impressive flow numbers for a factory engine. In stock trim, the factory heads topped out somewhere around 312cfm at .600-in. lift on the intake side, and 223cfm at .700-in. lift on the exhaust. With a quality hand or CNC port job on either factory or aftermarket heads, flow numbers can be significantly increased, boosting power with it.

If you aren’t familiar with how ported heads work, we’ll break it down in very simplistic terms. The basic goal of porting LS3 heads is to reshape and smooth the internal passageway of the cylinder heads. In general, the cylinder head casting process isn’t ideal for performance applications. There is typically leftover debris or obstructions within the heads from the process itself. This can cause turbulence within the passageways which limits the amount of air that enters the combustion chamber. By porting the heads, you are removing these internal imperfections which increases flow and power.

There are a few ways to implement ported heads into your LS3 build. The first way is to send off your LS3 head to a specialty machine shop that can hand/CNC port your heads for you. Alternatively, there are quite a few aftermarket suppliers of quality ported LS3 heads that generally use LS3 crate engine top ends as a base. The LS3 head kit ported by GM Performance Parts is one of the most popular options. 

Ported Heads Benefits

• Dramatically improved intake and exhaust flow numbers
• Better fuel atomization / fuel economy
• Significant power increase of around 20-30 horsepower and similar torque gains

5) ECU Tuning

In this guide, we’ve covered some of the best bolt-on modifications that you can do to your LS3. While the modifications themselves can yield increased power figures on their own, they won’t truly come alive until you introduce an LS3 tune into the mix as well. The purpose of an engine tune is to let your LS3’s PCM recognize the installed parts. A tune will adjust engine characteristics like air/fuel ratio, ignition timing, and idle adjustments.

Generally speaking, there are two main routes that you can take in terms of tuning your LS3. The first option is to install an off-the-shelf tune that aligns with the modifications that you have installed. For most naturally aspirated LS3s, this is probably the best option. There are a number of very reputable tuning companies that have developed off-the-shelf tuning solutions that encompass a wide variety of common LS3 mods. Off-the-shelf LS3 tunes are typically installed using a programming device that plugs into your vehicle’s OBD port. The SCT X4 programmer is by far the most common option for LS3-equipped vehicles and comes prepackaged with downloadable tunes.

The other, more costly, tuning option is to have your LS3-equipped vehicle dyno tuned by a nearby tuning company. In that case, your vehicle will be put onto a dyno and a professional with extensive tuning knowledge will make adjustments to your vehicle’s tune on the fly based on your installed modifications. A dyno tune will increase performance more than a “canned” tune as it is customized for your build specifically. With that being said, it will come at a significantly higher premium. 

LS3 Engine Tune Benefits

• Improved support for existing modifications
• Full customization of engine characteristics
• Easy install for off-the-shelf tunes
• Huge power gains anywhere from 30-100 horsepower depending on other modifications

Chevy LS3 Engine Mods Summary

As one of the premier engines in the Gen IV Chevy lineup, the LS3 is truly a modern classic. The 6.2L, 430 horsepower V8 has all of the trademarks of a Chevy small block that you like to see. The LS3’s simplicity and robustness make it a great engine to modify as it can withstand a ton of abuse. 

Exhaust modifications are always a good starting place for most naturally aspirated engines and the LS3 is no exception. A quality set of performance headers can decrease LS3 backpressure significantly while simultaneously boosting horsepower as a result. An upgraded X or H-pipe can also change up your LS-powered Chevy’s exhaust tone and make it stand out among the rest. 

A larger LS3 camshaft is another fan favorite in the LS community as the stock LS3 cam is one of the primary components holding the LS3 back from the factory. Larger cams have the potential to increase horsepower by a truly crazy amount, but you have to be wary about stock valve springs and piston-valve clearance with extremely aggressive LS3 cam options. 

While the LS3 cylinder head already has impressive flow numbers in stock form, ported heads can boost performance by tens of horsepower. Eliminating imperfections within the factory LS3 cylinder head can improve airflow into and out of the combustion chamber. That directly correlates with higher power figures. 

Finally, none of the LS3 engine mods listed above would be providing their true potential without a proper tune to back them up. Tuning is an essential step in the LS3 modification process. You need to adjust the engine to take full advantage of improved flow, changed valve timing, etc. There are plenty of quality LS3 off-the-shelf tunes available for the most common bolt-ons.