(Words and Photos by Richard Holdener) The big question behind this BangShift build up was, would a hydraulic-roller cam LS rev cleanly to 8,000 rpm? But getting that answer was only half the fun! This question also allowed us to apply some REAL hybrid technology. Not that limp-wristed, politically correct, drive-in-the-carpool-lane kind, but rather the combination of a short-stroke 4.8L with the big bore of an LS3. That’s right folks, the LS family interchanges, and that 4.8L truck crank will bolt right into the aluminum, 4.065-bore LS3 block. We all know short stroke motors love to rev, and boy howdy did this 339-incher sound mean as we approached 8,000 rpm. Of course an 8,000-rpm motor is much more than just a favorable combination of bore and stoke, and any motor running elevated engine speeds needs not just plenty of airflow, but the proper cam and attending valve train. Let’s take a look at what went into this hybrid to make it so BangShifty!
Starting with a brand-new, all-aluminum LS3 block from Chevy Performance Parts (Gandrud Chevrolet), we added a 3.267-inch stroke (4.8L) crank, JE asymmetrical (5-cc dome) pistons and 6.30-inch, 4340 forged-steel connecting rods from Lunati. The 10.7:1 short block was assembled using Fel Pro race bearings, timing chain and oil pump along with a Moroso oil pan, pick up and windage tray. Finishing off the short block was a custom Comp cam that offered .637 lift, a 253/269-degree duration split and 118-degree lsa. The cam was teamed with a set of Crane hydraulic roller lifters and a set of TFS Gen X 255 Square Port heads. The hi-flow TFS head were then fed by a Holley Hi Ram intake configured with a pair of Holley 950 HP carburetors. Also present on the high-rpm hybrid was an ATI Super Damper, Moroso oiling system filled with Lucas 5W-30 oil and a set of 1 7/8-inch headers from American Racing Headers. Once on the dyno at Westech Performance Group, with a Holley Dominator EFI system controlling the ignition, the hydraulic-roller hybrid screamed as it wound its way successfully to 8,000 rpm, making peak numbers of 614 hp at 7,800 rpm and 446 lb-ft of torque at 6,100 rpm.
Graph 1: 8,000-RPM LS3 Hybrid
The idea with this combination was to see if it was possible to rev an LS motor to 8,000 rpm using a hydraulic roller valve train. In addition to the amazing engine speed, we also wanted the motor to produce big power. The big bore (LS3) block and short stroke (4.8L) crank teamed with the Comp cam, TFS 255 heads and Holley Hi Ram intake to provide not only rpm potential, but also plenty of power. When the shrieking ended, the hybrid spit out numbers of 614 hp and 446 lb-ft of torque.