"Streetability" be damned-this is an all out, big boy camshaft test for the diehard LS1 crowd. Our rules were simple: If it fits in a stock LS1 and you keep it on the shelf, we want to test it. Can it idle in gear with the A/C on? Who cares! This is a test for people looking for maximum power, torque, and brute force, without any compromises. Whether you're a hardcore drag racer or an internet chest thumper, the question of "what would happen if . . . " has probably crossed your mind, and we're here to try and figure it all out. Granted, testing camshafts for the average daily driver, like many of us, has its place, and we love doing in-depth testing on camshafts for those situations ("Battle of the Bumpsticks," Nov. '09 issue), but for the next couple of issues, our concern will be maximum power on a stock LS1 bottom end. Are these for everyone? No. Are they even a good idea on most streetcars? Maybe, maybe not, but that isn't our current concern.
After weeks of phone calls, meetings, and bench racing sessions, we contacted several companies about our test. For some, our all or nothing approach seemed a little strange, but to others, like Comp Cams and Vengeance Racing, the camshafts couldn't ship fast enough. We also decided to team up with Bob Wise and the crew at RaceKrafters in Lancaster, Pennsylvania, to make sure our testing was accurate, repeatable, and consistent. It didn't hurt that Bob was an old racer with a serious passion for quality testing, and once we got going, Bob was able to interject some excellent "side tests," which we will also feature as we go along. On the following pages, you will find the results of each camshaft versus the stock LS1 and notes on each test. If you're thinking about a cam swap or you're already running a large camshaft, most of the data here should be of interest to you. For those advanced readers, we have found some interesting nuances with lift, LSA, and header design, which should help tweak your combinations. For now, here's what Comp Cams and Vengeance Racing had to offer and the results should speak for themselves. Without further ado, we present the first part of our multi-issue test and we look forward to hearing from you if you have any questions, concerns, or ideas for future camshaft testing.
Testing Procedure and Camshaft Guidelines
As with any test, it's imperative to maintain strict guidelines to ensure valid results. Below, you will find our procedures for testing, along with our camshaft specification guidelines. While the former was very specific, the latter was left wide open, allowing manufacturers and builders to spec camshafts to their liking.
Install camshaft and related valvetrain components
Degree the camshaft, install to correct specs, +/- .5 degree
Establish solid idle, check base timing, set 27 degrees of total timing
Oil temperature: 130° F, +/- 10
Water temperature: 155° F, +/- 10
Power pull, maintain solid AFR and timing, validate data
Two additional power pulls, extract best run and record Rinse and repeat, allowing ample time for cool down
If it fits in a stock LS1, it's in the test
Must be an off-the-shelf grind, no custom camshafts
No fly cutting, no head gasket spacing, no tricks
Comp Cams springs, retainers, pushrods, and timing set Everything else goes!
Before running wild and changing parts, it was crucial to establish a solid baseline. Our test engine has lived most of its life on the engine dyno at RaceKrafters in Lancaster, Pennsylvania, and Bob Wise, RaceKrafters president, has made sure to keep it in tip-top shape to ensure valid testing. The short-block is actually from a '98 Corvette, with a completely stock rotating assembly right down to the factory rings. Up top, Bob replaced the factory LS1 heads with a fresh set of the later (241) casting LS1 units and swapped intake manifolds, ditching the LS1 in favor of a better flowing LS6, along with a matching throttle body. Since all testing was done on an engine dyno, we used a set of 1.75-inch long-tube headers, which flow into dual 2.5-inch exhaust pipes and 2.5-inch Flowmaster mufflers, to replicate real world results. Otherwise, everything else on our test engine remained stock, with the exception of the water pump, which was swapped for a Meziere electric unit, to help keep water flowing through the engine in between runs in order to maintain consistent temperatures and help prevent heat-soak. Comp's new line of Muscle Car & Street Rod engine oil, in the 10W30 variety, was used to keep the 5.7L well lubricated. As expected, our initial runs, after bringing the engine oil and water up to temperature, were in the 400hp range, hitting a maximum of 418 hp and 422 lb-ft of torque. If those numbers seem a bit high to you, keep in mind that they're on an engine dyno and not to the wheels, which would show a loss around 15 percent, bringing our estimated rear-wheel horsepower to 355.3, about perfect for a well appointed bolt-on LS1.
224/230 Duration, .581/.592-Inch Lift, 114 LSA
Comp Cams 224/230 duration, .581/.592-inch lift, 114 LSA camshaft (PN 54-444-11) serves as a mildly updated version of an LS1 favorite, the single pattern 224, which has served GMHTP enthusiasts well for over a decade. While certainly not a large camshaft by today's standards, the 224/230 has enough duration to give it a great idle, while still making a considerable amount of horsepower and torque over a stock camshaft. For our first test, we installed the 224/230 camshaft, along with a set of Comp Cams 918 valvesprings (PN 26918-16), 7-degree titanium retainers (PN 762-1), 7.350-inch pushrods (PN 7950-16), and Comp's keyway adjustable billet timing set (PN 7102). During the install, to ensure valid testing, Bob made sure to degree in, or at least verify the proper positioning of each camshaft prior to making runs. With the parts installed, we fired up the dyno and made some initial adjustments to the tune, using a FAST XFI engine management. From baseline to the end, we chose to run each camshaft with 27 degrees of total timing and safe air/fuel ratios. Of course, each camshaft profile could probably be further optimized by a change in timing or a different air/fuel ratio, but for our testing we chose to keep each locked to ensure quality scientific testing.
One of the 224/230's most obvious advantages over the stock camshaft was peak power, coming in at 463.2 hp at 6,300 rpm, a gain of 45.2 hp. Where the stock camshaft made peak power of 418 at 6,000, the 224/230 was already over 418 hp by 5,100 rpm, bringing in the power almost 900 rpm sooner and making 41.1 hp over the stock camshaft at that RPM. Up top, the stock camshaft fell off fast, making under 400 hp by 6,400 rpm. The 224/230, on the other hand, held to 441.1 hp at 6,900 rpm-just think of the enjoyment you'd get from allowing some extra time in each gear with this bumpstick. Torque was also up by 10.6 lb-ft, maxing out at 432.6 lb-ft at 4,800 rpm, the same RPM as the stock unit. More importantly, the 224/230 carried peak torque much further than the stock camshaft, making over 400 lb-ft from 3,200 to 6,000 rpm, which would make street driving this setup rewarding.
224/230-Duration, .581/.592-Inch Lift, 114 LSA -- FAST LSXR 102mm Intake Manifold
You didn't think we could test all of these camshafts without wondering what a new intake manifold would do, did you? In true go big or go home fashion, we decided to ditch the stock LS6 intake manifold and 75mm throttle body for a new FAST LSXR 102mm manifold (PN 146302) with a matching 102mm throttle body (PN 54102), fuel rails (PN 146033), and Precision-Flow 33 lb/hr injectors (PN 30332-8). On a stock cubic-inch LS1, the 102mm intake manifold may sound large, and many people have argued over its merits on such an application, which made it perfect for our test. As you would expect, the FAST intake bolts directly in place of the old LS6 and everything hooked back up perfectly. After bringing the engine up to temp and checking for leaks, Bob made a couple of test runs with the new manifold, recording a peak 475.5 hp and 437.5 lb-ft of torque, a gain of 12.3 hp and 4.9 lb-ft over our previous 224/230 testing. Interestingly, the FAST LSXR 102 did give up some low end torque below 4,000 rpm, to the tune of 7 lb-ft, but by 4,100 rpm, the FAST was already pulling ahead, carrying torque all the way to 6,900 rpm, where it was still up 11.3 lb-ft. Horsepower, obviously, followed suit, up 14.8 hp at 6,900 and holding over 470 hp from 6,000 rpm all the way until 6,800, as opposed to the LS6, which never even made 470hp peak. Peak power was moved up by 200 rpm, coming in at 6,500 compared to the LS6 peaking at 6,300. Going forward, all testing will be done with the FAST LSXR 102, for consistency and power.
231/239-Duration, .617/.624-Inch Lift, 113 LSA
Knowing what our 224/230 camshaft did, the next logical step was to add more duration and lift to see what effect they would have on the overall power and the general curve. Comp Cams sent us a nice 231/239-duration, .617/.624-inch lift camshaft on a 113 LSA (PN 54-459-11), which serves as a great camshaft for someone looking for a little more power without giving up huge chunks of mid-range torque. Along with the camshaft, we also installed a set of double valvesprings (PN 26926TI-KIT), which are rated to .675-inch of lift, to help keep us safe. Compared to the stock camshaft, we saw nice gains of 67.9 hp and 17.0 lb-ft of torque, bringing our final numbers to 485.9 hp and 439.0 lb-ft of torque. Where the stock camshaft peaked at 6,000 rpm, the 231/239 was already over that power by 5,100 and then it came on strong, making over 480 hp from 6,200-6,900, and finally falling off around 7,200 rpm. No doubt, the 231/239 can be spun much harder than the stock camshaft without giving up any power. Torque was also up 17 lb-ft and, amazingly, made over 400 lb-ft from 3,500 to 6,300 rpm, which tells us this camshaft would pull great on the street with a little bit of gear or a mild stall converter. Of course, to make all that steam up top, the 231/239 did give up some torque down low, but came in stride by 4,100 rpm.
240/244-duration, .608/.596-inch lift, 112 LSA
Known to many as the Vindicator, our next camshaft in the test was ground by Comp Cams to Vengeance Racing's specifications. With 240/244 degrees of duration and a somewhat mild .608/.596-inches of lift, the Vindicator works hard by keeping the valves open longer, instead of pushing the valve farther into the stock combustion chamber. Right off the bat, we noticed the 240/244 had the most wicked idle of the group and sounded mean throughout the dyno session. Peak power recorded at 496.2 hp and 436.6 lb-ft of torque, gains of 78.2 hp and 14.6 lb-ft of torque over our stock baseline. The 240/244 brought massive power up top, with 400 hp on tap from 4,900 to 7,200 rpm, where power was still above 482 hp. In fact, from 6,200 to 6,900 rpm, horsepower never fell below 490, which was impressive. Average torque from 3,000-4,500 was up 2 lb-ft from stock, although the engine exhibited a noticeable dip from 3,700 to 4,300 rpm, something that all of the larger camshafts in our test did to some degree. For a daily driver with mild gearing or a small stall, the 240/244 would be sluggish down low, although once it was moving, power would be on tap for as long as you cared to stay in the throttle.
Step By Step
237/247-duration, .674/.674-inch lift, 115 LSA
Next up for testing, Comp Cams sent us the only custom grind unit in this test (we know, we said no custom grinds, but we had to try it!), a massive 237/247-duration, .674/.674-inch lift camshaft, which carries a 115-degree lobe separation angle. Being a custom, non-shelf unit, we were excited to see what this large cam was capable of, and after a couple of runs, the results were clear. With the engine up to operating temperature, we recorded 512.5 hp and 436.7 lb-ft of torque, gains of 94.5 hp and 14.7 lb-ft of torque over stock. The increased lift and duration of the Comp Cams custom grind laid on the power up top, recording over 500 hp from 6,300 to 7,000 rpm. Compared to the stock camshaft, which made 405.6 at 6,300, the 237/247 made 500.6, a truly impressive feat. Of course, with anything this impressive up top, low- and mid-range torque did drop, with average torque from 3,000 to 4,500 actually dropping 3.3 lb-ft off of the stock camshaft. Where we once had a small flat spot in torque, we now had a rather considerable dip from 3,700 to 4,400 rpm, although the 237/247 was able to best the stock cam as early as 4,600 rpm. Obviously, this isn't a camshaft for a daily driver or mild streetcar, but in the right combination, the 237/247 custom ground Comp cam would rock.
Step By Step
237/247-Duration, .674/.674-inch lift, 115 LSA + Open Long-tube Headers
Exploring our theory of the 237/247 in a more radical race build, Bob decided to unhook the 2.5-inch exhaust from our dyno mule and run the combination with open long-tube headers. The results fit in line with traditional thinking-we lost power and torque down low and gained it up top. Peak horsepower came in at 6,800 rpm, recording 527.3 hp, a gain of 109.3 over stock and 14.8 over the full exhaust. Peak torque was also up to 443.0, a gain of 21.0 over stock and 6.3 lb-ft over the full exhaust, but average torque from 3,000 to 4,500 rpm dropped 10.3 lb-ft over the stock camshaft and 7 lb-ft compared to the full exhaust. Comparing the two 237/247 graphs side by side, you can really get an idea of how important camshaft and exhaust relation is to a build, as one would drive rather crisply, while one with no exhaust would be sluggish off of an idle. According to Bob Wise, a longer collector would probably help our open exhaust testing, although we will have to leave that for another day. For now, our LS1 testing is complete . . . that is, until the next shipment of camshafts comes in, which should be any day now!