The Camshaft Upgrade Guide for Chevy LS3. If you’re starting into the world of Chevy small blocks, you’re probably seeking to extract the most power out of one. The good news is that they are among the greatest engines to modify, and you won’t have to spend a bunch on components and work to see incredible results. The 6.2L Chevy LS3 is one of the most popular GM crate motors. Aside from its use in the C6 Corvette and Gen 5 Camaros, the LS3 is a popular engine swap option for practically everything. If you’re going for high horsepower in your build, an LS swap has most likely crossed your mind.
While the Chevy LS3 produces 430 horsepower and 428 pound-feet of torque, there’s a lot more pleasure to be had. That’s where an LS3 camshaft upgrade comes in. If a smooth idle and moderate power are important to you, the stock LS3 cam is not a bad alternative. That being said, a more aggressive cam has the potential to not only liven up, but completely revolutionize your LS3 engine.
There is no shortage of options when it comes to improved LS3 cams. Because aggressive camshafts make such a major difference on LS engines, the aftermarket LS camshaft scene is huge. The fact that huge cams are available for the LS3 does not necessarily imply that they are the best option for you. Before installing the largest LS3 camshaft you can find, understand how an improved LS3 camshaft would effect performance characteristics. We’ll go over just that in this guide. Continue reading to learn about some of the most common LS3 camshaft options and how they effect performance.
Considerations for Chevy 6.2L LS3 Camshaft Upgrade
In general, compared to alternative modifications that would give the same power improvements, an LS cam change is a piece of cake. They are not, however, a direct plug-and-play upgrade. Other factors come into play when it comes to replacing other supporting gear. Stiffer LS3 valve springs are the most major supporting enhancement. Upgraded locks, retainers, seals, and seats should also be discussed.
LS3 Valve Springs Upgrade
When installing a more aggressive camshaft into a 6.2L LS3, stronger valve springs are not an option; they are required. The reasons behind this is straightforward. The factory LS3 valve springs were made to work with the comparatively mild stock cam. As a result, the stock valve springs are incapable of keeping up with an upgraded cam with wider lobes.
Multiple possible issues could develop if you swapped in an upgraded LS3 cam without also upgrading the LS3 valve springs. The enhanced RPM capability of an aggressive LS3 cam allows the engine speed to outrun the capabilities of the valve spring. This can result in valve float, which is undesirable.
The greater lift values from an upgraded LS3 cam cause the other potential issue. In general, OEM LS3 springs are designed to handle 0.500 to 0.525 lift. Many LS3 performance cams will far outperform that figure. If you run an LS3 camshaft with more lift than the stock amount, you may get coil bind, which could permanently harm your valvetrain.
While LS3 valve float and coil bind can be major problems, the solution is straightforward. Just remember to replace your valve springs at the same time as you replace your cam. Upgraded LS3 valve springs, like cams, come in a variety of forms, sizes, and speeds. You’ll want to select LS3 valve springs that can resist the additional forces exerted by the cam without breaking. Overly stiff LS3 valve springs might sap power.
Piston to Valve Clearance 6.2L LS3
When it comes to improved LS3 cams, it is also crucial to consider piston-valve clearance in addition to potential valve spring concerns. When you replace the camshaft in your LS3, you reduce the distance between the valve head and the piston. Of course, the length and lift of the LS3 cam you select are critical here. As a general guideline, you’ll need at least 0.08-0.100-inch clearance on the intake side and 0.100-0.120-inch clearance on the exhaust side. When it comes to LS3 PTV clearance, it is far better to err on the side of caution, as the last thing you want is a bunch of smashed valves.
LS3 Pistons with Fly Cutting
There are a few options for dealing with the LS3 piston to valve clearance issue. Fly cutting your LS3 pistons is one of the most typical remedies. Fly cutting is the procedure of replacing the LS3 valves with a notching tool. The tool is then inserted back into the skull. Some individuals choose to spin the cutting tool, which forms a cut in the piston head, with an electric drill. That is obviously a shortened version of the processes required to properly fly cut an LS3 piston.
The overall procedure of fly cutting is straightforward. However, you must consider your cam lobe and valvetrain geometry to calculate how much material must be removed from the piston head. It is also crucial to remember that milled heads and the gasket you use have a considerable impact on fly cut depth. Make careful to include these in your calculations.
Reliefs on LS3 Pistons
If you don’t want to do the job yourself, you can always buy LS3 pistons with the reliefs already cut into them. As with most LS3 engine components, LS3 pistons with intake and exhaust valve reliefs are plentiful. The JE piston set is a popular LS3 piston choice for high-horsepower applications. They are forged, as well as having enormous valve reliefs that will work with practically any cam.
Tuning LS3 Cam Upgrade
It is critical to tune the PCM after installing a new LS3 camshaft. It is critical that your LS3 PCM detects the cam timing change. Because valve lift and duration are modified with an improved LS3 cam, the onboard computer must be able to compensate for the increased airflow. You’ll have fuelling troubles if you don’t tweak it. In addition, the idle speed of your 6.2L V8 will need to be modified. The stock idle control algorithms will be unable to adapt for the changed cam timing, causing the engine to surge and idle out.
An untuned PCM is also unaware that the overlap period of your new cam is allowing part of your engine’s idle airflow (and fuel) to escape into the exhaust. A tune is essential in modifying your LS3 cam for all of these reasons.
Selecting the Best LS3 Camshaft
With so many camshaft options for the LS3, making a decision can be difficult. With all of the above factors in mind, you should start thinking about how you want your 6.2L LS3 to behave. The performance of an engine is dramatically improved by swapping LS3 cams. High power figures, in general, come at the expense of daily drivability. The more aggressive your LS3 cam, the less streetable your LS3-powered vehicle will be.
Before selecting a cam, it is critical to consider seriously what you intend to put the engine through. If you aren’t creating a specialist track vehicle, overpowering your LS3 is the worst thing you can do. It’s easy to get seduced into selecting the most powerful cam, but this isn’t always the greatest option.
The factory LS3 204/211.551/.525 117 camshaft was clearly intended to strike a balance between performance and streetability. The standard cam offers a smooth idle and excellent fuel economy. These are two of the trade-offs that come with a more aggressive cam.
In terms of cam profiles, generally speaking, the wilder the cam, the less performance you’ll get down low. There is a direct tradeoff between low-end performance and more power at the top. There is, however, a strong middle ground that can increase performance across the whole rev range.
This tutorial will mostly cover cams for naturally aspirated LS3 applications. This is significant since cams made for LS3s running forced induction have different properties than N/A cams.
Typical LS3 Cam Profiles
Before we get into some of the most common LS camshaft profiles, let’s go over what the numbers in camshaft specifications represent. In the near future, we’ll publish a thorough cam card analysis, which will provide even more detailed information about cam characteristics. For the time being, we’ll merely go over the fundamentals.
Airflow is increased by improved LS camshafts in three ways. These include valve lift, duration, and timing of valve events. You’ll notice that cam specifications are all presented in the same format.
The OEM LS3 camshaft specification, for example, is 204/211.551/.525 117. The first identifier (204/211) in this sequence specifies the valve lift for the intake and exhaust valves, respectively. Valve lift is the amount that both the intake and exhaust valves open. The greater the opening of the valve, the more power is produced. The greater the lift, the greater the strain on your LS valvetrain.
The valve duration is represented by the second set of values (0.551/0.525). The valve duration is the length of time the valve is open. By extending the life of a cam lobe, you give cylinders more time to fill with air and fuel. More power is gained at the expense of increased valvetrain wear.
The final picture (117) depicts the lobe separation angle, which is directly related to the timing of valve events. The point in the rotation of the motor at which the intake and exhaust valves open and close has a significant impact on total airflow of a cam profile, as well as the RPM range where a motor will be efficient. Cam profiles having LSA characteristics that prioritize high-RPM airflow at the expense of low-RPM performance. The opposite is also true.
Now that we’ve covered the fundamentals, let’s look at some of the most prevalent LS3 cams.
Camshaft for the LS3 224
.624 in/.590 ex lift
@.050, the duration is 224 in/232 ex.
LSA: 113
A 224 duration cam is one of the most prevalent mild LS3 camshaft alternatives. A 224 option strikes an excellent compromise between greater performance and everyday drivability. While other variables such as lift and LSA will vary depending on the application, the additional duration over the factory camshaft will deliver a significant power boost. According to MotorTrend, a 224 cam with these characteristics increased baseline power statistics by 45 horsepower on a factory LS crate motor. Furthermore, because the overall profile of the LS 224 cam is rather mild, there is no torque loss at the bottom of the rev range.
While a 224 LS camshaft may not deliver the most significant power gains, it is an excellent choice for individuals seeking a 35-45 horsepower gain across the most of the rev range without losing a smooth idle or excessive fuel economy. A 224 duration cam is also tiny enough to work with factory piston to valve clearance without the use of piston reliefs. That, of course, could change depending on other things such as a thinner head gasket or milled heads.
Camshaft for the LS3 227
Lift:.621 in/.604 in ex
@.050, the duration is 227 in/237 ex.
LSA: 113+3.5
Increasing the intensity somewhat, our next proposal is a 227 duration cam. Again, depending on your intended application, the particular lift and LSA figures can vary somewhat, but a 227 cam has the ability to significantly enhance power and torque while remaining drivable on a daily basis. With an LS 227 cam, lope will begin to enter the equation depending on how the cam is tuned. Because the cam duration is substantially longer than stock, some overlap with the intake and exhaust valves will occur.
Finally, LS3 owners that utilize 227 cams feel that they are a good choice for an LS3 with factory heads. That being said, ported or milled heads will provide significantly greater power. Based on dyno results provided by CamMotion.com, which sells a 227 cam with the above specifications. The gains are significant. The 227 camshaft added 53 peak horsepower to a basic LS3 crate motor. Another option that will not sacrifice low-end performance is the 227 LS cam. Power increases from 3,000 onwards, according to dyno data.
Related : The Throttle Body Guide for Chevy LS3
LS3 Camshaft 231
.640 in/.615 ex lift
@.050, the duration is 231 in/246 ex.
LSA: 111
A 231 duration camshaft is certainly stretching the LS3’s factory limits, especially in terms of piston-to-valve clearance. As a result, fly cut or valve relief pistons are required. An LS cam of this caliber is best suited for on-track use at this degree of intensity. You’ll probably have a difficult time driving an LS-powered car with such an aggressive cam on a daily basis. Having stated that, a 231 duration cam offers tremendous top-end performance. Texas Speed, a vendor that sells an LS3 231 cam with the above specifications, claims an 88 peak horsepower increase.
At this size, high-RPM performance comes at the expense of low-RPM performance. As a result, this isn’t a cam for street use without severe surge, bucking, and worse gas mileage. With such a powerful LS cam, you will undoubtedly require a high-quality tune. Without one, your LS3 will not be able to fully utilize the additional valve duration.
Summary of LS3 Camshaft Upgrades
One of the most worthwhile and cost-effective changes you can do is to upgrade your LS camshaft. Because the LS3’s factory heads and intake are so well tuned, the stock cam is truly the limiting factor. Because LS camshafts are such a successful adjustment, there are a plethora of them available. However, there are a few important factors to consider before upgrading your LS camshaft.
There are some drawbacks to installing a highly aggressive LS3 camshaft. The first is that the OEM valve springs aren’t designed to withstand the forces generated by an upgraded LS camshaft. The second issue is piston to valve clearance, which can be addressed with fly-cut pistons or valve reliefs.
After you’ve considered those issues, you’ll need to select the best LS camshaft for your application. Bigger is not necessarily better. This is especially true if you intend to drive your LS-powered vehicle on a daily basis. High-RPM performance LS cams frequently sacrifice low-RPM performance, reducing drivability. An improved LS camshaft must function in tandem with a variety of different engine components and is thus highly customized to your specific setup. That should be reflected in your LS cam tune as well. If you’re having difficulties deciding on the correct cam for your LS3 project, contact a GM performance shop and ask them. Don’t take a chance on a cam that could not suit your needs. Consult a specialist to ensure your satisfaction.
