Hydraulic Roller Cam
The bolt-on
Isky Retro Fit Hydraulic Roller camshaft and lifters, 0.485/0.505 inch lift (intake/exhaust), 217/225 degrees duration at 0.050, ground with a 108-degree LSA. $835
The Mule
A 10.5:1-compression 350 small-block with 64cc Vortec heads, an Edelbrock Performer RPM intake, 650-cfm Holley carb, and an Isky hydraulic flat-tappet cam with 0.465 inch lift (intake and exhaust), 221 degrees duration at 0.050, and a 108-degree LSA. Power measured at the flywheel.
Our Take
The specs on these two cams are very similar, but the advantages of running a hydraulic roller cam--specifically the increase in area under the curve and the reduction of frictional losses--are clearly demonstrated.
Before
Max torque: 429 lb-ft @ 3,800 rpm
Max power: 376 hp @ 5,500 rpm
Average torque: 373 lb-ft
Average power: 296 hp
| After
Max torque: 438 lb-ft @ 3,700 rpm
Max power: 403 hp @ 5,700 rpm
Average torque: 384 lb-ft
Average power: 349 hp | Difference
+ 9 lb-ft
+ 27 hp
|
Small-Block Cylinder Heads
The bolt-on
Brodix IK 180 aluminum cylinder heads, which have 180cc intake runners, 64cc chambers, and 2.02/1.60-inch valves. $1,014/pair
The Mule
A 10.5:1, 355ci small-block with a Comp Cams XE268 cam (0.477/0.480 inch lift intake/exhaust, 224/230 degrees duration at 0.050, 110-degree LSA), ported GM double-hump iron heads, an Edelbrock Performer RPM intake, and a 750-cfm Quick Fuel double-pumper carburetor. Power measured at the flywheel.
Our Take
The "IK" stands for Iron Killer, and that's exactly what happened here. You can spend your money on porting a set of old heads or spend it on a set of new heads that produces way more power.
Before
Max torque: 407 lb-ft @ 4,400 rpm
Max power: 369 hp @ 5,100 rpm
Average torque: 381 lb-ft
Average power: 315 hp | After
Max torque: 431 lb-ft @ 4,400 rpm
Max power: 418 hp @ 5,800 rpm
Average torque: 408 lb-ft
Average power: 334 hp | Difference
+ 24 lb-ft
+ 49 hp
|