Is it really possible to add more than 100hp to your LS motor with a cam swap? The answer is obviously yes, or this would be one very short and disappointing tech story. Before we get to the test, we first need to understand why it might be possible to get such big gains for a simple cam swap.
Naturally, the presence of forced induction plays a major part, but LS engines have a lot more going for them than just their propensity to swallow copious amounts of positive pressure. In terms of responsiveness to changes in cam timing, the GM engineers set the stage with the LS platform. What do we mean by this? Well, any LS motor has basically everything else it needs to provide premium performance, except the cam.
Our test motor is one of the most common LS engines found in junkyards. The junkyard 5.3L retained all of its factory components for our test, including the short block and factory 706 heads. Prior to testing, the motor received increased ring gap, new head gaskets, and ARP head studs. Although, none of this was mandatory at this power and boost level. We were prepping it for future testing.
No single component can make a motor, but almost any single component can break one. All it takes to ruin an otherwise perfectly good performance motor is one wrong part. Install the wrong intake, cylinder heads, or (in our case) camshaft, and you’ll have less than ideal results. When you cure the one missing component, the results can be amazing. The LS has plenty of displacement, head flow, and a more than adequate intake manifold. The only thing missing in the otherwise-perfect combination is adequate cam timing!
Knowing we had a cam swap coming up, we replaced the factory truck springs with a set of 26918 springs from COMP Cams.
So, just how much power did GM leave on the table when designing the cams for the various LS applications? In all honesty, the design criteria for the engineers was never to maximize power, but believe me, they certainly could. The factory offerings were (by design) mild compared to what was ultimately possible.
But, even the factory cams differed in their performance ability. Low-man on the power totem pole was obviously the cam used in our 5.3L LM7 (shared with the 4.8L LR4 and early 6.0L LQ4). Designed for low-rpm truck applications, the LM7 cam offered a .466/.457 lift split, a 190/191-degree duration split and 116-degree lobe separation angle (LSA).
We selected a set of FAST 89-pound injectors and FAST fuel rail for the TBSS intake to supply the necessary fuel for our turbo motor .
Let’s put this mild cam timing into perspective. The LS9 – the most powerful of the factory LS cams – offered a .558/.562 lift split, a 211/230-degree lsa, and 122.5-degree lsa. Though it was designed for a supercharged application, the LS9 cam was all but identical to the 427-inch LS7 cam. The difference being the LS7 cam offered more lift due to the 1.8:1 ratio factory LS7 rockers. The rest of the production cams (LS1-LS6) fell somewhere between these two extremes. Given the mild factory cam timing, it should actually come as no surprise that cam swaps on a naturally aspirated 5.3L can yield 40, 50, or even 60-extra horsepower.
The gains offered by cam swaps on the LS have been well documented. But, what allows a gain of 40-60hp on a naturally aspirated LS to exceed 100hp on a boosted one? The answer is in the multiplier effect. A naturally aspirated engine is already running under an atmospheric pressure of 14.7 psi. So, all we have to do to double the power output of say, a 300hp engine, is double the pressure, right? If we apply 14.7 psi of boost to the same 300hp naturally aspirated engine, we can see 600hp.
Dialing in the air/fuel and timing values was a Holley HP engine management system. The A/F and timing curves were kept constant for the two cams.
Why we don’t always see that much power is often a function of things like the tune, charge cooling, and turbo efficiency, but rest assured, it is possible. In fact, it is possible to exceed this simple formula with sufficient charge cooling (by using things like ice water). The real exciting part is when we increase the power output of our naturally aspirated motor.
Suppose we add a cam to our 300hp test motor and increase the power output to 350hp. If we apply the same 14.7 psi of boost to the 350hp, we can now reach 700hp. The extra 50hp offered by the cam swap increased to 100hp under boost! The key here is to do everything you can to improve the power output of the naturally aspirated motor prior to adding boost, which includes cam timing.
To get things started, we ran the 5.3L motor naturally aspirated with a set of Hooker 1 7/8-inch headers. Not ideal for the mild 5.3L, but it’s what we had laying around.
For our test, we performed the cam swap on the turbo motor. We also included a naturally aspirated baseline run with the stock cam prior to the installation of the turbo kit. We did so mostly for our own benefit – making sure our DIY-turbo system was performing as it should before performing the cam swap. The test motor was your basic bread-n-butter beater – a junkyard 5.3L snatched from a local LKQ Pic-a-Part.
Run on the dyno in naturally-aspirated trim with the TBSS intake manifold and stock LM7 cam, the 5.3L produced 359hp at 5,300 rpm and 384 lb-ft of torque at 4,200 rpm.
The 5.3L LM7 is a favorite among turbo LS enthusiasts. Prior to our test, the 5.3L received increased ring gap, new Fel Pro head gaskets, and ARP head studs. With the cam swap in mind, we also upgraded the stock truck valve springs to a set of 26918 springs from COMP Cams. We replaced the stock (early) truck intake with a Trailblazer SS (TBSS) manifold equipped with FAST 89-pound injectors. The TBSS intake was fed by a FAST 92mm throttle body. Run with a set of 1 7/8-inch, Hooker Headers, the naturally aspirated 5.3L produced 357hp at 5,600 rpm and 383 lb-ft of torque at 4,200 rpm.
To run our turbo cam test, we configured the 5.3L with a homemade, DIY-turbo system. The basics of our turbo kit included Hooker cast manifolds, a custom 2.5-inch cross-under merge pipe, and 7675 PTE turbo. The Precision turbo was capable of supporting over 1,200hp, or more than enough for our little 5.3L. The PTE 7675 fed boost through a sizable air-to-water intercooler from Procharger. Like the turbo, the intercooler was oversized for our application and was fed a steady diet of 85-degree dyno water.
The manifolds featured a cross-under tube to channel the exhaust from the driver’s side to the passenger’s side merge manifold.
We fabricated a single 90-degree bend that connected the T4 turbo-flange on one end to the 3.0-inch V-band on the exit of the Hooker turbo manifold. This custom adapter also featured a provision for a single 45mm Hypergate wastegate from TurboSmart. In addition to the wastegate, TurboSmart also supplied a Race Port blow-off valve and manual wastegate controller. However, we relied on a 10-psi spring for this test.
Exhaust from the turbo exited through a single 4.0-inch V-band exhaust equipped with an oxygen sensor bung. Run with the stock cam at a peak boost of 11.0 psi, the turbocharged 5.3L produced 603hp at 5,600 rpm and 612 lb-ft of torque at 4,600 rpm. Now it was time for the stage 2.
The exhaust energy was supplied to a single Precision 7675 turbo. The GT42 PTE turbo featured a 76mm billet wheel, 88mm turbine, and 1.28 AR, divided T4 turbine housing.
After allowing for a cool down, we tore into the 5.3L to perform the cam swap. Off came the damper, front cover, and cam gear, followed by the cam retaining plate, rockers, and pushrods. Using custom tools (no longer available), we made sure to keep the lifters in place during the cam swap. Out came the stock stick and in went the LJMS Stage 2 turbo cam supplied by Brian Tooley Racing.
The Stage 2 cam offered a sizable increase in specs, jumping to a .605/.598 lift split, a 226/231-degree duration split and 113-degree lsa. The lift increased by roughly .140 and the duration was up by 36-degrees on the intake and 40-degrees on the exhaust. The lsa shifted down by 3-degrees, but the important point is that the opening and closing events were designed specifically for a turbo LS application.
Boost was controlled by a single Hyper-Gate45 wastegate from Turbo Smart. The wastegate was equipped with a 10-psi spring.
After installation of the DIY-turbo system, the turbo 5.3L produced 603hp at 5,600 rpm and 612 lb-ft of torque at 4,600 rpm. Now, it was time for a cam change.
Removal of the front cover provided access to the factory timing gear. After lining up the marks for TDC, we removed the cam gear, followed by the cam retaining plate.
Designed by LJMS and supplied by Brian Tooley Racing, the Stage 2 turbo cam was made specifically for a turbo application. The Stage 2 cam offered a .605/.598 lift split, a 226/231-degree duration split, and 113-degree lsa.
In went the LJMS/BTR stage-2 turbo cam.
Run with the new turbo cam, the boosted 5.3L produced 730hp (actually 729.8hp) at 6,600 rpm and 649 lb-ft of torque at 4,900 rpm. The peak was almost identical (11.0 vs 11.3 psi), so the cam offered peak-to-peak gains of nearly 130hp. The gains out past 6,000 rpm exceeded 150hp (at the same boost!), which obviously sets the stage for even more power.
Obviously, they did their homework over at LJMS, as the turbo cam improved the power output of the boosted 5.3L to 730hp (729.8) at a higher 6,600 rpm and 649 lb-ft of torque at 4,900 rpm. The wilder cam timing traded off a few lb-ft of torque below 4,300 rpm, but offered peak-to-peak gains of 127hp and 37 lb-ft of torque.
The gains exceeded 150hp higher in the rev range and all the extra power is right where it can be taken full advantage of at the drag strip (or for any run through the gears).Since we ran this test at just 11 psi, the stage is set for even more power from this LJMS-cammed 5.3L with higher boost!
Adding boost to any LS motor improves the power output greatly, even one with a stock bottom end, stock cam, and stock heads. This 5.3L featured all stock (original) internals with extra ring gap (on the original stock rings), stock 706 heads with a spring upgrade, and a stock TBSS intake manifold. Run with the stock LM7 cam, headers, and the Holley HP management system, the naturally aspirated 5.3L produced 357hp at 5,300 rpm and 383 lb-ft of torque at 4,200 rpm.
After adding 11.0 psi of boost from the Holley turbo system, Precision 7675 turbo, and Procharger intercooler, the power output jumped to 603hp at 6,500 rpm and 612 lb-ft of torque at 4,600 rpm. Though this was a solid gain, we couldn’t help but wonder how much the stock cam was holding us back.
It seems obvious from the looks of the graph that the stock LM7 cam was indeed holding us back. After installation of the BTR/LJMS Stage 2 turbo cam, the power output of the turbo 5.3L jumped from a hair above 600hp to 730hp at 6,600 rpm and 649 lb-ft of torque at 4,900 rpm.
The cam improved the power output by nearly 130hp, with gains exceeding 150hp higher in the rev range. Not only did the motor make considerably more power at the same boost level, but it allowed us to rev the motor past 6,500 rpm. The extra RPM would certainly come in handy at the drag strip.
The Stage 3 LS1 camshaft is the largest camshaft that we recommend with the stock torque converter. This Cam Motion hydraulic roller cam delivers mild performance idle, excellent low end torque, and extended RPM capabilities over the stock camshaft.What is a Stage 2 LS cam? ›
The LS1 Stage 2 camshaft was designed for enthusiast who want to increase power while maintaining excellent drivability and manners. This cams can be used with stock torque converters, stock rear gears, stock intake manifold, stock exhaust manifolds etc.How much HP does a Cammed 5.3 LS make? ›
(Image/Richard Holdener) Run on the dyno with the FAST LSXR intake, Katech-ported 706 heads and Summit Racing Pro LS Stage 4 cam, the Strictly Performance 5.3L produced 508.6 hp at 6,700 rpm and 445.7 lb-ft of torque at 57,00 rpm.Is every cam a turbo cam? ›
Actually, every LS cam is a turbo cam, in fact EVERY cam for EVERY motor ever made is a turbo cam. They all work under boost. Plus A quickie life hack for determining your boosted power output-simple math!How much HP will a Stage 3 cam add? ›
It is a lot more aggressive and worth an additional 20 hp on top of the gains from the 8710 grind or 123 hp over a stock LS3 when combined with a stroker kit.How much HP does a Stage 3 cam have? ›
The BTR Stage 3 N/A Camshaft (LS1/LS2/LS6) is the go to for people desiring an aggresive idle matched with a powerband that will stretch into the 450+ whp range around 6000 RPM when paired with quality supporting modifications.How much horsepower does a Stage 3 cam add to a 5.3 LS? ›
This cam gained 67.1 HP and 26.8 TQ at the flywheel on our in-house SuperFlow 902 engine dyno using an otherwise stock 5.3L engine! This cam uses proprietary TSP lobe profiles that are designed to work with any single or dual valve spring kit that is rated to support at least .How much horsepower does a Stage 2 cam add? ›
A Stage 2 performance upgrade is a cam change upgrade. In any engine, the cam drives the valves and the valves open to allow air in for combustion. The kits for improved lift, duration and timing focus on either torque or power upgrades. The Stage 2 upgrade delivers up to 30% more horsepower and 10% more torque.Can you turbo a stock 5.3 LS? ›
Over the years turbochargers have gotten much better and will work with a wide variety of applications. For a turbocharged 5.3 LS engine there are a variety of brands that will work great whether you want a little more power at low rpms, or you want a high horsepower 5.3 LS and rev it past 6,000 rpm on a regular basis.What's the difference between a Stage 1 cam and a Stage 2 cam? ›
Most Stage 1 type modifications are typically in the +10-15% power increase over stock. Stage 2: this is typically referred to an engine with a performance cam upgrade as well as the other components within a Stage 1 combination. A typical Stage 2 has generally +20-25% more HP than stock.
Adjusting the camshafts so the cams are slightly ahead or behind will alter the engine's performance. Advancing the timing will cause the fuel intakes to open and close earlier, which improves low-end torque. Conversely, retarding the cam will improve high-end horsepower at the expense of low-end torque.What makes a cam high performance? ›
Performance cams typically have durations ranging from 220 up to 280 degrees or more. The longer the duration, the rougher the idle and the higher the cam's power range on the rpm scale. A cam with a duration of 240 degrees of higher will typically produce the most power from 3,500 to 7,000 rpm.Is Sloppy Stage 2 a good turbo cam? ›
a budget cam that seems to tick all the boxes, cheap, effective, lower lift, good for all motor and turbo applications making it an easy go to. 2200-7000, great mid range torque and power.What should a Cammed LS idle at? ›
Be Realistic With Your Target Idle Speed
With a stock LS, the factory idle speed will be around 550 - 600 RPM. When you modify that engine and fit a large aggressive cam, you need to consider what RPM that engine is now going to want to idle at. You need to make sure your target idle speed is sensible.
Replacing the factory cam in a 4.8L, 5.3L, or 6.0L will make an extra 40, 50, or even 60 horsepower. No other single change to the LS motor will gain you as much power, until you start talking about power adders.How much HP does a Stage 4 camshaft add? ›
After installation of the Stage 4 cam from Summit Racing, the power output of the 5.3L jumped by nearly 50 hp, to a peak of 475 hp (at 6,600 rpm) and 418 lb-ft (at 5,300 rpm).How much HP does a Stage 4 cam have? ›
LQ4 vs Comp vs Summit Stage 4
Basically, the Summit cam was more aggressive and responded just as you would expect a wilder cam to. Equipped with the Summit Stage-4 cam, the peak power output jumped to 568 hp, but peak torque dropped slightly to 510 lb-ft.
The Stage 4 grind is a popular choice for those looking to delete DOD/AFM, or just add some pep to your trucks step. With great power gains and driving characteristics, this camshaft works well with 2800-3200 stall torque converters.How much HP does a Stage 2 cam add to a LS3? ›
This camshaft was desgined for boost engines, but typical gains of approximately 60 rear wheel horsepower can be seen on stock LS3 cars without a supercharger!Does camming a car make it louder? ›
Yes, especially if it has a nice lope to it. All my cammed cars got louder after adding a cam.
Stage 3 modifications are known by most as a track day modification. Similarly, to stage 2, they will also require other mods to support them but they are usually less ideal for road use due to there aggressiveness. A stage 3 modified car will need to be regularly overhauled and serviced.What's the difference between a Stage 2 and Stage 3 cam? ›
Running a stage 2 is better than a stage 3 on a supercharger set up because of the overlap in the cam. It will let out the vacuum pressure and you end up loosing boost. the valves don't close fast enough. That is what I have read about them and was told that from a number of people.What does a Stage 3 engine mean? ›
Stage 3 tuning = engine reinforcement, complete exhaust system, modified intake/air flow. You're basically getting ready for the race track. Papers that look like scientific experience reports and high-cost material picking is vital.