SCORE Journal - The Official Publication of SCORE Off-Road Racing
Issue link: http://read.uberflip.com/i/693984
HEAD TEST-LS1 VS TFS GEN X 235 (408 STROKER) Cylinder head upgrades on a cathedral-port application can make some serious power as indicated by this test on a 408 stroker engine. This test involved a comparison between the stock LS1 heads (with a valve spring upgrade) and a set of CNC-ported, Gen X 235 heads from Trick Flow Specialties. The test motor was a 408 stroker produced by the installation of a SCAT 4.0-inch stroker crank, rods and JE pistons into an iron 6.0L block (bored .030 over). The test was run with a Fast LSXR intake and 102-mm throttle body and long-tube headers. Equipped with the stock LS1 heads, the 408 stroker produced 549 hp at 6,200 rpm and 517 lb-ft of torque at 4,800 rpm. After installation of the TFS 235 heads, the power jumped to 601 hp at 6,300 rpm and 546 hp at 4,800 rpm. The head swap was worth over 50 hp, but remember, the power gains will be a function of the output (airflow needs) of the test motor. HEAD TEST-LS3 VS GM CNC L92 (LS3 CRATE MOTOR) This test illustrates what happens when you add ported cylinder heads to a motor that already has sufficient head flow. The stock GM LS3 crate motor from Gandrud Chevrolet was basically a Corvette LS3 pulled from the assembly line. The LS3 was factory equipped with rectangular-port, LS3 heads that flowed 315 cfm, or enough to support well over 600 hp. This motor was rated by GM at 430 hp, but run in our configuration on the engine dyno (headers, no accessories and tuned to perfection), produced 495 hp and 484 lb-ft of torque. After adding the CNC-ported L92 (automatic- equipped Camaro LS3) heads that flowed 350 cfm, the power output jumped by just 7 hp (to 502 hp). This doesn't mean the ported heads don't work, it is just that this mild test motor could not take advantage of the extra 35 cfm offered by the ported heads. Run on a wilder 468-inch stroker application, the ported heads were worth 26 hp. POWER PRODUCTION MADE SIMPLE 086 SCORE JOURNAL