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    MAKING GAS

    Alternative-fuel sources and hybrid cars are all the rage today. Everyone from major automakers to backyard inventors is pursuing alternative fuels and energy sources. While the ultimate goal is generally to eliminate dependence on foreign oil, for hot rodders there is also the desire to invent and create a better-performing engine.

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    LS1 CAM SWAP AND DYNO TEST

    We Set Out and Found 33 hp and 18 lb-ft of Torque With an LS1 Camshaft Upgrade

    When it comes to adding power to your small-block Chevy, the camshaft is an integral part of the performance equation. Luckily for owners of Chevy’s latest iteration (Gen III) of the famous small block, the modern fuel-injected LS1 responds just as well to camshaft upgrades as the LT1s, L79s and L48s of old. Naturally, cam technology has come a long way since the days of the Duntov 30-30 profile. The improvements in cam technology are important, as the new LS1 is head and shoulders above any of the old ’60s and ’70s muscle-car small blocks, regardless of the advertised power ratings.

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    Picture of Richard Holdener

    Richard Holdener

    Words & Photography

    Just like the carbureted small-block Chevys of yesteryear, the newer fuel-injected LS1/LS6 engines respond favorably to cam changes.
    Just like the carbureted small-block Chevys of yesteryear, the newer fuel-injected LS1/LS6 engines respond favorably to cam changes.

    The Modern LS1 Dyno Performance

    Run on the dyno, the modern LS1 would easily out-power even the 370hp LT1 offered in the ’70 Corvette, to say nothing of the more powerful LS6 version. Both LS1-based engines would not only out-power the earlier engines but would do so with improved fuel mileage and reduced emissions. While the last 30 to 40 years have improved the small block, it is nice to know that they still respond to the right cam profile to the tune of 35 to 50 hp.

    Testing the New Cam at Westech Dyno Facility

    To find out just how well the new LS1 engines respond to a cam change, we ventured over to the Westech dyno facility, where the wrenches started to fly. The idea was to dyno-run an LS1 equipped with a stock cam and then, with the engine still on the dyno, swap in a new Comp performance-grind camshaft. The LS1 test mule came straight out of the GM Performance Parts catalog. Designated PN 25534322, the GMPP engine assembly included a complete F-body LS1 engine rated at 320 hp and 330 lb-ft of torque.

    Preparing the LS1 for Dyno Testing

    The LS1 assembly also included a complete street rod wiring harness and pre-programmed ECU designed to allow installation of the engine into any pre-’76 vehicle equipped with a 4L60E automatic overdrive transmission. For our needs, the harness allowed us to run the engine on the engine dyno by hooking up a few 12-volt and ground wires to the dyno along with the various sensors and harness plugs. Everything was well labeled, making the hookup pretty straightforward.

    The Benefits of an Engine Dyno Setup

    Running the LS1 on the engine dyno rather than in the car on a chassis dyno made swapping the cams much easier and less time-consuming. Another big part of our time reduction was the fact that our test engine was not equipped with any accessories (A/C, power steering, alternator, etc.). We installed a Meziere electric water pump that allowed removal of the entire serpentine system, along with all the unnecessary accessories.

    Initial Testing with Stock Setup

    The increase in baseline power over the rated power output of 320 hp, achieved during initial testing, can be attributed to the fact that we ran the engine sans accessories, with long-tube Hooker headers, and a free-flowing air-intake system, rather than all of the factory LS1 hardware. The crate motor rating came from the factory LS1 combination equipped with all accessories and a complete intake and exhaust system, including the catalytic converters.

    Setting Up the Engine for Cam Installation

    After a few back-up runs to verify the power curve, we tore into the LS1 for its very first cam change. The test engine was fresh from the crate, so we were sure to break it in properly before subjecting it to the rigors of the dyno.

    Cam Removal and Installation Process

    With the stock cam removed, we installed the Comp Cams Xtreme RPM XR265HR (PN 54-412-11). Comp also offers Xtreme RPM High Lift and Xtreme XE-R profiles. The dual-pattern XR265HR cam offers 0.522 intake lift and 0.529 exhaust lift.

    Checking and Adjusting for Valve Clearance

    Using air pressure in the cylinder (from a leak-down tester) kept the valves in place while compressing each spring. Compressing the springs allowed removal of the keepers, retainers, and finally the stock springs themselves. Before installing the new Comp beehive springs (PN 26918-16), we installed a set of soft checker springs to check piston-to-valve clearance with the new cam.

    Dyno Results with Comp Cams XR265HR

    After finishing up the valve covers, coil packs, and hooking up the various sensor plugs and vacuum lines, we allowed the engine time to acquaint itself with the new cam. The idle quality was still very good with the new cam, something we expected given the relatively short 212/218 duration and minor lift increase.

    Power Gains and Performance Improvements

    While only slightly larger than the stock LS1 cam, the new Comp profile really made itself known in the power department, upping the peak power from 405 hp at 5,500 rpm to 438 hp at 5,900 rpm. The result here is that the new Comp LS1 cam not only upped the peak torque from 408 lb-ft to 426 lb-ft, but it also increased the torque curve across the rev range.

    Summary of the Comp Cams LS1 Performance Gains

    Couple this with a net gain of 33 hp, and all for a very simple cam swap, and you could say life is good above 400 hp.

    1.) To test the effectiveness of the new Comp Cam LS1 profile, we ran the LS1 crate motor on the dyno with the stock cam to establish a baseline. The GMPP crate motor was run with the supplied street rod wiring harness and ECU along with a set of Hooker long-tube (F-body) headers and an AccuFab billet throttle body. So equipped, the crate engine produced 405 hp and 408 lb-ft of torque. Note the Ford fuel rails used on the LS1 engine.
    2.) The Meziere electric water pump allowed us to run the GMPP crate motor sans accessories, making the dyno testing and cam swap much easier.
    3.) Comp Cams supplied an XR265HR-14 grind that offered a 0.522/0.529-inch lift split, a 212/218 duration split at 0.050 inch, with a 114-degree lobe separation angle.
    4.) Unlike traditional small-block Chevy cams, the LS1 model featured a provision for the cam sensor.
    5.) The LS1 Comp cam required a valve spring upgrade. Comp offers a set of Beehive valve springs (PN 26918) to work with the more aggressive cam profile. Note both the stock and Comp LS1 springs are beehive designs, and not the constant diameter shape used on conventional valve springs.
    6.) After running the baseline test with the stock LS1 cam, we removed the coil packs, valve cover, stock rockers and pushrods (Comp Cams pushrods shown).
    7.) A three-jaw puller was used to remove the LS1 dampener.
    8.) After removing the electric water pump, we pulled the front cover to allow access to the timing gear.
    9.) The timing gear was secured to the cam via three retaining bolts. Our stock chain had some slop, which we will replace in future tests with a gear set from Comp.
    10.) Next came the four bolts securing the cam retaining plate.
    11.) Here is a little trick we discovered. Although it specifically says not to attempt cam removal without securing the lifters in place (which requires a special magnetic tool), we simply rotated the cam to push the lifters up. After rotating the cam, the lifters held in place, allowing us to pull the cam free.
    12.) Out came the stock cam, and without removing the intake, dropping the pan or any of the headaches usually associated with cam swaps on a typical Chevy.
    13.) This small spring compressor was used to swap out the stock valve springs in favor of the Comp springs.
    14.) Before starting the engine, we made sure to check piston-to-valve clearance, since the new Comp cam increased both lift and duration over the stock LS1 cam. There was more than adequate clearance to run the new cam.
    15.) With the new valve springs installed, and plenty of piston-to-valve clearance, we reinstalled the new Comp Cams pushrods (PN 7955-16) and stock rockers. We will also be testing the new Comp Cams roller rockers.
    16.) The cam upgrade was well worth the effort, as the Comp cam increased power output from 405 hp to 438 hp, a gain of 33 hp. The torque was up as well, from 408 lb-ft to 426 lb-ft.

    ARTICLE SOURCES

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    Comp Cams

    1 (800) 999-0853

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