Chances are, if you are getting involved in the world of Chevy small blocks, you are looking to squeeze the most power out of one. The good news is that they are some of the best engines to modify and you don’t have to spend a fortune on parts and labor to see fantastic gains. The 6.2L Chevy LS3 is one of the most popular crate motors offered by GM. Beyond their placement in the C6 Corvette and Gen 5 Camaros, the LS3 is one of the most common swap options for nearly everything under the sun. If you’re aiming for high horsepower in your build, no doubt an LS swap has crossed your mind.
While the Chevy LS3 offers a stout 430 horsepower and 428 lb-ft of torque, there’s so much more fun to be had. That’s where an upgraded LS3 camshaft comes into play. The stock LS3 cam is by no means a bad option if a smooth idle and moderate power are of paramount importance for you. With that being said, a more aggressive cam has the potential to not just liven up your LS3 engine, but truly transform it.
When it comes to upgraded LS3 cams, there is no shortage of options. Since aggressive cams make such a big difference on LS engines, the aftermarket LS camshaft scene is very expansive. Just because massive cams are available for the LS3 doesn’t mean that they are necessarily the best option for you. It is important to take into consideration how an upgraded LS3 camshaft will affect performance characteristics before throwing in the biggest one that you can find. In this guide, we’ll cover exactly that. Keep reading if you are interested in learning about some of the most popular LS3 camshaft choices and how they affect performance.
Chevy 6.2L LS3 Camshaft Upgrade Considerations
Generally speaking, an LS cam upgrade is a piece of cake in comparison to other modifications that would yield the same power gains. However, they aren’t a direct plug-and-play upgrade. Other considerations come into play in terms of replacing other supporting hardware. The most significant supporting upgrade is stiffer LS3 valve springs. Upgraded locks, retainers, seals, and seats should also be part of the conversation.
Upgraded LS3 Valve Springs
When swapping a more aggressive camshaft into a 6.2L LS3, upgrading to stiffer valve springs isn’t an option, it’s a requirement. The reasoning behind that is relatively simple. The factory LS3 valve springs were designed for the relatively tame stock cam. As such, the stock valve springs can’t keep up with an upgraded cam with larger lobes.
If you were to swap in an upgraded LS3 cam without also upgrading the LS3 valve springs, multiple potential problems could arise. With the increased RPM potential that an aggressive LS3 cam provides, the engine speed has the potential to outpace the capabilities of the valve spring. That can cause valve float which is less than ideal.
The other potential issue arises due to the increased lift values from an upgraded LS3 cam. As a general rule, factory LS3 springs are equipped to handle between 0.500 and 0.525 lift. Quite a few LS3 performance cams will eclipse that figure substantially. If you decided to run an LS3 camshaft with lift over the stock amount you could encounter coil bind which could terminally damage your valvetrain.
While LS3 valve float and coil bind can be potentially serious issues, the solution is very simple. Just make sure to upgrade your valve springs at the same time you upgrade your cam. Just like the cams themselves, upgraded LS3 valve springs are sold in all shapes, sizes, and rates. You’ll want to find LS3 valve springs that can withstand the extra forces applied by the cam without going overboard. LS3 valve springs that are too stiff can zap power.
6.2L LS3 Piston to Valve Clearance
In addition to potential valve spring issues, it is also important to be thinking about piston-valve clearance when it comes to upgraded LS3 cams as well. When you upgrade the camshaft in your LS3, you are also decreasing the amount of distance between the valve head and the piston. Of course, the duration and lift of the LS3 cam that you choose matter a great deal here. A general rule of thumb is that you’ll want at least 0.08-0.100-inch clearance on the intake side and 0.100-0.120-inch clearance on the exhaust side. It is far better to err on the side of caution when it comes to LS3 PTV clearance, as the last thing you want is a bunch of smashed valves.
Fly Cutting LS3 Pistons
There are a couple of solutions to the LS3 piston to valve clearance issue. One of the most common solutions is fly cutting your LS3 pistons. Fly cutting is a process where a notching tool is put in the place of the LS3 valves. The head is then put back on with the tool in place. Some people choose to use an electric drill to spin the cutting tool which creates a cut in the piston head. That is obviously a simplified version of the proper steps to properly fly cut an LS3 piston.
If you are looking for more detailed instructions, check out this detailed guide: corvetteforum.com
The overall process of fly cutting is relatively simple. However, you do have to take into account your cam lobe and valvetrain geometry to determine how much material needs to be removed from the piston head. It is also important to keep in mind that milled heads and the gasket that you choose to run plays a significant role in fly cut depth. Be sure to factor those into the equation.
LS3 Pistons with Reliefs
If you aren’t interested in doing the DIY work, the option is always there to simply purchase LS3 pistons with reliefs already cut into them. As with most LS3 engine components, there is no lack of LS3 pistons that come with intake and exhaust valve reliefs. One of the most common LS3 piston options for high-horsepower applications is the JE piston set. In addition to having massive valve reliefs that will be suitable for almost any cam, they are also forged.
Tuning LS3 Upgraded Cam
After installing a new LS3 camshaft, it is essential to also tune the PCM. It is crucial that your LS3 PCM recognizes the change in cam timing. Since valve lift and duration are adjusted with an upgraded LS3 cam, the onboard computer needs to be able to adjust for the additional airflow. Without a tune, you’ll run into fueling issues. Additionally, your 6.2L V8’s idle will need to be adjusted as well. The stock idle control routines won’t be able to compensate for the altered cam timing which can cause the engine to surge and idle out.
An un-tuned PCM also does not know that your new cam’s overlap period is allowing some of your motor’s idle airflow (and fuel) to escape out the exhaust. For all of those reasons, a tune is a crucial element in upgrading your LS3 cam.
Choosing the Right LS3 Camshaft
With so many camshaft options out there for the LS3, the process of choosing can be difficult. With all of the above considerations taken into account, you’ll also want to start thinking about how you want your 6.2L LS3 to act. Swapping LS3 cams has a dramatic effect on how an engine performs. In general, high power figures come at the cost of daily drivability. The more aggressive that you go with your LS3 cam, the less streetable your LS3-powered car will be.
Before choosing a cam, it is extremely important to realistically think about what you plan on putting the engine through. Over-camming your LS3 is the worst thing that you can do if you aren’t building a dedicated track car. It’s easy to be persuaded into choosing a cam that provides max power, but that isn’t always the best option.
If you look at the factory LS3 204/211 .551/.525 117 camshaft, it was clearly chosen to find a middle ground between performance and streetability. The stock cam provides a smooth idle and peak fuel economy. Those are also two sacrifices that come with a more aggressive cam.
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 middle ground that can improve performance throughout the entire rev range.
In this guide, we’ll be focused primarily on cams for naturally aspirated LS3 applications. That is an important distinction because cams designed for LS3s running forced induction have different characteristics than N/A cams.
Common LS3 Cam Profiles
Before we jump into come of the most common LS camshaft profiles, let’s briefly discuss what the numbers associated with camshaft specifications mean. We’ll do a complete cam card breakdown in the near future which will provide even more detailed information about cam specifications. For now, we’ll just cover the basics.
There are three ways in which upgraded LS camshafts increase airflow. Those include valve lift, valve duration, and valve event timing. You’ll see that cam specifications are listed in the same way across the board.
For example, the factory LS3 camshaft’s specification is 204/211 .551/.525 117. In this sequence, the first designation (204/211) represents the valve lift for the intake and exhaust valves respectively. Valve lift is how far both intake and exhaust valves open. The further the valve opens, the more power is produced. The higher the lift, the more strain is put on your LS valvetrain.
The second group of figures (0.551/0.525) represents the valve duration. The valve duration represents the amount of time that the valve is open. By increasing the duration of a cam lobe, you are allowing cylinders more time to fill with air and fuel. The result is more power at the cost of extra valvetrain wear.
The last figure (117) represents lobe separation angle, which is directly correlated with valve event timing. The point in the motor’s rotation at which the intake and exhaust valves open and close has a strong effect on total airflow of a cam profile, as well as the RPM range where a motor will be efficient. Cam profiles with LSA characteristics that focus on high-RPM airflow will sacrifice low-RPM performance. The inverse is also true.
Now that we’ve covered some of the basics, let’s talk about some of the most common LS3 cams.
LS3 224 Camshaft
Lift: .624 in/ .590 ex
Duration @ .050: 224 in/232 ex
One of the most common mild LS3 camshaft options is a 224 duration cam. A 224 option provides a very good balance between increased performance and daily drivability. While other specifications like lift and LSA vary depending on the application, the added duration over the stock camshaft will provide a sizable boost in power. On a factory LS crate motor, a 224 cam with these specifications boosted baseline power figures by 45 horsepower as reported by MotorTrend. Additionally, since the overall profile of the LS 224 cam is relatively mild, there isn’t a loss of torque at the bottom of the rev range.
While a 224 LS camshaft might not provide the most sizable power gains, it is a fantastic option for those that are looking for a 35-45 horsepower gain through most of the rev range without sacrificing a smooth idle and too much fuel economy. A 224 duration cam is also a small enough option to work from a factory piston to valve clearance perspective without the need for piston reliefs. Obviously, that could change based on other factors like a thinner head gasket or milled heads.
LS3 227 Camshaft
Lift: .621 in/ .604 ex
Duration @ .050: 227 in/237 ex
Stepping up the intensity a little bit, or next suggestion is a 227 duration cam. Once again, the specific lift and LSA figures can vary a significant amount based on your intended application, but a 227 cam has the potential to increase power and torque dramatically while remaining on the cusp of daily drivable. Depending on how the cam is tuned, lope will start to enter into the equation with an LS 227 cam. Since the cam duration is significantly longer than stock, there will be some overlap with the intake and exhaust valves.
Ultimately, LS3 owners who run 227 cams claim that they are a pretty good option to run on an LS3 with stock heads. With that being said, the power increase will be much more notable with ported or milled heads. Going off of dyno figures provided by CamMotion.com, which supplies a 227 cam with the above specs. The gains are impressive. On a stock LS3 crate motor, the 227 camshaft produced 53 additional peak horsepower. The 227 LS cam is another option that will not sacrifice low-end performance. Dyno readings show an increase in power from 3,000 onwards.
LS3 231 Camshaft
Lift: .640 in/ .615 ex
Duration @ .050: 231 in/246 ex
A 231 duration camshaft is really pushing the factory limitations of the LS3, especially from a piston-to-valve clearance standpoint. For that reason, fly cut or valve relief pistons are a requirement. At this level of aggression, an LS cam of this caliber is suited primarily for on-track use. You’ll likely have a very difficult time daily driving an LS-powered car with such an aggressive cam. With that being said, a 231 duration cam provides massive top-end performance. Texas Speed, a manufacturer that supplies an LS3 231 cam with the above specs, reports an 88 peak horsepower gain.
At this size, high-RPM performance does sacrifice low-RPM performance. As such, this isn’t a cam that would work for street use without significant surge, bucking, and compromised gas mileage. With such an aggressive LS cam, you will unquestionably need a quality tune. Without one, there is no way that your LS3 will be taking full advantage of the extra valve duration.
LS3 Camshaft Upgrade Summary
Upgrading your LS camshaft is one of the most worthwhile and cost-effective upgrades that you can do. Since LS3’s factory heads and intake are so highly optimized, the stock cam is really the limiting factor. There are a ton of LS camshafts available due to the fact that they are such an effective modification. However, there are a few key considerations to take into account before jumping on an upgraded LS camshaft.
There are a few limiting factors associated with installing an extremely aggressive LS3 camshaft. The first is the factory valve springs which aren’t equipped to deal with the forces that an upgraded LS camshaft produces. The second is piston to valve clearance, which can be solved with either fly-cut pistons or valve reliefs.
Once those issues have been thought through, you’ll have to decide on the right LS camshaft for your application. Bigger doesn’t always mean better. That is especially true if you plan on daily driving your LS-powered car. High-RPM performance LS cams often sacrifice low-RPM performance which tanks drivability. An upgraded LS camshaft needs to work in unison with a number of different engine components and is therefore highly specialized to your own individual setup. Your respective LS cam tune needs to reflect that as well. If you are having trouble picking the right cam for your LS3 project, it is a fantastic idea to contact a GM performance shop and ask them. Don’t gamble on a cam that might not work for your needs. Consult a professional to guarantee that you’ll be satisfied.