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After months of successful “bolt-on” parts testing with the Pennsylvania College of Technology (PCT) 5.7L HEMI Charger, this month the choice was made to dive into the engine to make a serious internal modification. Crane Cams opened up their catalog to us and offered full access to their selection of ’03-‘10 Hemi camshafts. After many discussions with the Crane Cams representatives, a decent streetable camshaft was selected that would require no internal engine modifications and would work well with the stock engine and stock drivetrain.
There are very few components that can change the characteristics of an engine like a camshaft. The camshaft has an unbelievable impact on the airflow movement through the engine. A camshaft selection can be very overwhelming and without the advice of experienced people from camshaft manufacturers, such as Crane Cams, a novice can get lost in a hurry and make a selection that is inappropriate for their application. More than one person has fallen into the “bigger is better” thinking and ended up with a camshaft that resulted in an engine combination that lacked low end torque, did not work well with their tight torque converter, or worked in an RPM range that was well beyond the rear gear ratio. In general, the performance suffered and the camshaft was blamed as the reason for the poor performance.
On the other hand, a well-selected camshaft can make the engine come to life. The camshaft will work well with the ability of the cylinder head(s) to flow air, will function perfectly with the valvetrain, and perform with the drivetrain without any drivability concerns. The proper camshaft selection will make the vehicle a pleasure to drive, meet the needs of the driver, and there will be more punch to your whip to impress your friends.
Once a Mopar enthusiast gets to the point where the decision to install a camshaft has been made, their Hemi has probably has already been fitted with a full aftermarket exhaust system. To optimize the benefits of the aftermarket exhaust, the owner most likely would have taken advantage of some type of aftermarket tuner. The PCT Charger was very much like an enthusiast’s vehicle, the Charger has Hedman Hedders (shorty headers), MagnaFlow’s Direct Fit Catalytic Converters and Cat-Back exhaust. The Charger also had a DiabloSport InTune tune to take advantage of the free flowing exhaust.
The baseline was performed with the Charger’s Hemi in stock tune with MagnaFlow’ Direct Fit Catalytic Converters and Cat-Back exhaust. Refer to February 2015, Performance Pipes: MagnaFlow Converters and Cat-Back Exhaust Put to the Test for information about the MagnaFlow exhaust components. In addition to the MagnaFlow pipes was a pair of Hedman Hedders stainless steel shorty headers to round out the aftermarket exhaust. Refer to September 2014, Get Shorty: Factory Exhaust Manifolds vs. Hedman Hedders Shorty Headers for the testing of the Hedman Hedders exhaust parts. All the engine testing would be performed in the range of 2800-5500 rpm. The series of baseline runs, all within 1% of each other, performed on the Penn College Mustang chassis dyno resulted in a best of 309.9 lb/ft of torque at 4400 rpm and a peak of 283.2 horsepower at 5200 rpm. The average torque was 290.9 lb/ft and the average horsepower was 231.5 hp.
Crane Cams Camshaft Selection
After some discussion about the best camshaft for the PCT Charger, the choice was narrowed down to two camshafts, part number 1989491 (grind number HR-208/297-2S-16) or part number 1989501 (grind number HR-210/3236-2S-12). The 1989491 camshaft has an advertised max lift of 0.505 inches and 268 degree intake duration @.004” and 274 degree exhaust duration @.004” (208 degree intake duration @.050” and 214 degree exhaust duration @.050”). The 1989501 camshaft is more aggressive with an advertised max lift of 0.550 inches and the same degrees of duration @.004” as the 491 camshaft (210 degree intake duration @.050” and 216 degree exhaust duration @.050”). The 501 camshaft also required the factory valve springs to be replaced with Crane Cams valve springs part number 99831-16. All of the numbers are based on zero lash and a theoretical rocker ratio of 1.70:1; the numbers will change if different rocker ratios are used (the 5.7L Hemi has 1.65:1 rockers). The smaller of the two camshafts (part number 1989491, 0.505-inch lift) was finally selected for the series of testing in the Hemi.