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.
Chevy LS3 Engine History
The Chevy LS3 belongs to the Gen IV group of LS engines and was first seen in the 2008 Corvette. Prior to the LS3, the LS2 and LS7 had already ushered in the fourth generation of engine block architecture from Chevrolet. Compared to the Gen III architecture that was shared by the LS1 and LS6, Gen IV architecture featured a new block casting method, larger displacement, repositioned sensor locations, and larger cylinder bore. Otherwise, Chevy Gen III and Gen IV blocks are pretty similar.
The LS3 was released from the factory producing 430 horsepower and 424 lb-ft of torque in base trim. That is 30 more horsepower than the first Gen IV LS2 engine than preceded it. Compared to the LS2, the LS3 featured a larger cylinder bore and therefore a larger displacement. The result was an extra 0.2L over the LS2, for an overall displacement of 6.2L. Other notable upgrades to the LS3 include higher flowing cylinder heads, a more aggressive factory camshaft, a slightly less intense 10.7:1 compression ratio (good for boost), a high-flow manifold, and upgraded injectors.
The general consensus in the Chevy community is that the LS3 is one of the best examples of the LS format that Chevrolet has ever released. Beyond being a good Chevy engine, the LS3 is a fantastic V8 in general. Its simplicity and robustness are two of its defining characteristics. Unlike many exotic performance engines, you’ll rarely see an LS3-powered car in the shop for anything beyond standard maintenance. While the LS3 engine features an antiquated pushrod design, the Chevy aftermarket community has had decades to perfect modifications. As a result, there are countless modifications to boost power from your LS3.
LS3 Engine Headers and X-Pipe Upgrade
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 LS3 headers, as there are quite a few considerations to take into account. For that reason, we’ll be writing a more comprehensive LS3 headers guide, which will be linked here.
LS3 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 LS3 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 LS3 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.
LS3 Engine 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 LS3 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.
LS3 Engine Cam Upgrade Considerations
Unfortunatly, upgraded LS3 cams aren’t just a plug and play modification. There are some very important considerations to take into account before you throw the biggest cam that you can find into your LS3. There are two significant problems that you have to take into account when doing an LS3 cam upgrade. In basic terms, they boil down to valve spring rates and piston-valve clearance.
In terms of the former, the problem is pretty self explanatory. The factory valve springs weren’t designed for the extra load and duration caused by larger camshaft lobes and therefore aren’t sufficient for aftermarket cam options. The solution to that problem is upgrading the factory springs to performance springs that are designed to withstand the additional forces. Without upgraded springs, you could face significant issues like valve float and coil bind.
The second, and perhaps more significant, issue is piston-valve clearance. As you increase cam profile size, you decrease the amount of space between the valves and the pistons. That becomes a significant problems on the LS3 engine with very aggressive cams, as the distance between them can become non existent. At that point, the pistons can make contact with the valves and we all know how that one ends. Not good. The only solution to this problem is upgrading your LS3’s pistons to ones that have valve reliefs which will give you a bit more clearance.
Common LS3 Engine Cam Profiles
Some of the most common cam profile options for the LS3 include (224/232 .624 /.590 113), (231/239 .617/.624 114), and (235/244 .647/.612 111) cams. Those are listed in ascending order from least to most aggressive.
If you are looking for a significant jump in usable power for street applications, a comparably more mild 224 cam might be your best bet. While not the most aggressive option out there, the 224 cam steps up the factory cam duration by 20 degrees, which is significant enough to make a very noticeable difference in power. It is estimated that an LS3 224 cam swap will give you an extra 50 ponies across the entire rev range.
After the 224 cam, a 231 profile is the next step up. Here is where the power really starts adding up. With a significantly increased duration than the stock cam, a 231 cam is one of the most talked about cam options in the LS3 community. The 231 profile falls right on the verge of needing to upgrade to pistons with valve reliefs, as the piston-valve clearance is a mere .041 in-Hg. That’s getting into dangerous territory. With that being said, that cam upgrade can yield power in the ballpark of 70 horsepower.
Lastly is the most aggressive cam profile on our list, a 235 grind. While an upgraded 235 cam will provide a power increase through the entire rev range, the sacrifice is idle quality. That pretty much directly translates to on street performance too, which will definity be compromised. You’ll also certinaly need valve relief pistons for a 235 LS3 cam as well.
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 LS3 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 arent 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 LS3 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.
6.2L LS3 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
GM Performance Parts LS3 CNC Ported Cylinder Heads
As we mentioned above, there are a few different routes that you can go in terms of ported LS3 heads. The go-to option is the GM Performance Parts ported LS3 head as who wouldn’t trust GM with their own product. The GMPP CNC Cylinder Head features 276cc intake runners and 92cc exhaust ports for dramatically increased flow to the “as-cast” LS3 cylinder head. Overall, the CNC ported heads will yield around 15% better flow than the stock heads. When tested by WeaponXMotorsports.com, they saw a 30 horsepower increase over their benchmark LS3 setup.
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LS3 Engine Tune
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
Popular LS3 Engine Tune
When it comes to LS3 off-the-shelf tunes, there’s really only one name that most LS3 enthusiasts swear by: DynoSteve. Steve and the team at RDP have been providing GM parts and services since 1996. They have built up a stellar reputation in the LS community for providing excellent tunes with unparalleled customer service. Steve offers remote tuning services. That means that all you have to do is purchase a SCT X4 tuner and give him a call. Additionally, if you purchase the tuner and performance parts from him, he’ll update your tune for new parts for free. Steve provides tunes that cover a wide range of bolt-on modifications including headers, intakes, ported heads, throttle bodies, and many more. If you have a lightly modified LS3-powered Chevy, DynoSteve is your best bet.
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Best 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.