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Now This Is Real Hybrid Technology! We Test An 8000 RPM, 339 Cubic Inch, LS3 Hybrid And It’s Awesome!


Now This Is Real Hybrid Technology! We Test An 8000 RPM, 339 Cubic Inch, LS3 Hybrid And It’s Awesome!

(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.

A dual-quad, Holley Hi-Ram isn’t right for every application, but it was perfect for our 8,000-rpm LS3 hybrid!

A dual-quad, Holley Hi-Ram isn’t right for every application, but it was perfect for our 8,000-rpm LS3 hybrid!

The key to our rev-happy combination? We dropped a short-stroke, 4.8L crank into a big-bore LS3 block!

The key to our rev-happy combination? We dropped a short-stroke, 4.8L crank into a big-bore LS3 block!

 

JE supplied the custom forged pistons for our short-stroke combination.

JE supplied the custom forged pistons for our short-stroke combination.

 

 

The JE pistons were combined with a set of 6.30-inch Lunati forged rods. Even more than power output, engine speed (rpm) is a rod killer, so if you plan on revving the piss out of your LS, better step up to some quality rods.

The JE pistons were combined with a set of 6.30-inch Lunati forged rods. Even more than power output, engine speed (rpm) is a rod killer, so if you plan on revving the piss out of your LS, better step up to some quality rods.

The camshaft plays a critical role in the rpm potential of the motor. More than just the lift and duration that help it make power, the lobe must be designed for high-rpm stability. This custom Comp cam allowed the hybrid to safely run to 8,000 rpm using hydraulic roller lifters.

The camshaft plays a critical role in the rpm potential of the motor. More than just the lift and duration that help it make power, the lobe must be designed for high-rpm stability. This custom Comp cam allowed the hybrid to safely run to 8,000 rpm using hydraulic roller lifters.

Knowing oil control was critical at high rpm, we installed a Moroso oil pan and matching windage tray.

Knowing oil control was critical at high rpm, we installed a Moroso oil pan and matching windage tray.

Another critical factory at high rpm was proper dampening. Coming to the rescue was this ATI Super Damper (and ARP retaining bolt).

Another critical factory at high rpm was proper dampening. Coming to the rescue was this ATI Super Damper (and ARP retaining bolt).

Topping the big-bore, short stroke short block was a set of TFS Gen X 255 Square-port heads. The TFS heads flowed 382 cfm, or more than enough for our healthy, hybrid application.

Topping the big-bore, short stroke short block was a set of TFS Gen X 255 Square-port heads. The TFS heads flowed 382 cfm, or more than enough for our healthy, hybrid application.

The heads were installed using ARP head studs and Fel Pro MLS head gaskets.

The heads were installed using ARP head studs and Fel Pro MLS head gaskets.

The TFS heads were supplied with adequate spring pressure to allow for 8,000 rpm use. To keep valve train weight down, we relied on the factory rockers (with a Comp Cams trunion upgrade kit).

The TFS heads were supplied with adequate spring pressure to allow for 8,000 rpm use. To keep valve train weight down, we relied on the factory rockers (with a Comp Cams trunion upgrade kit).

The Hi Ram intake was equipped with injector bungs, which we plugged with a set of Holley injectors.

The ignition timing was controlled using a Holley Dominator EFI system.

The ignition timing was controlled using a Holley Dominator EFI system.

BangShift LS Hybrid_013

The Holley Hi-Ram was designed to enhance high-rpm power production. We equipped the versatile Hi Ram with a top to accept dual 4150 carbs (or throttle bodies).

BangShift LS Hybrid_014

Equipped with a pair of 950 HP carburetors, the high-rpm, LS3 hybrid produced 614 hp and 446 lb-ft of torque.

Graph 1: 8,000-RPM LS3 Hybrid

Graph 1

 

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.

 


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8 thoughts on “Now This Is Real Hybrid Technology! We Test An 8000 RPM, 339 Cubic Inch, LS3 Hybrid And It’s Awesome!

  1. Sid in S.C.

    So, the reason it’s a ‘hybrid’ is because it uses carbs, and, injectors? Does it use both at the same time? I may be slow, but, I’ve never heard of such a thing. I need more information, or, I’m just stupid. could go either way.

  2. wayne

    Maybe you could explain why you chose to use carbs when you had everything including the holley dominator electronics and injectors installed.

  3. BennyB

    Applause from this direction:
    A new-school approach to the 1st-gen Chev 302 can’t be a bad thing.

  4. blizznd

    so I’m a old skool Ford guy, they mention the stroke a few times, and the rod length a few times, but what would the deck ht, and bore on this be??

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