Testing Carb Combos on a Gen III LS Smallblock - Thoroughly Modern Mouse

Richard Holdener Feb 1, 2009 0 Comment(s)
Sucp_0902_06_z Small_block_chevy_engine_timing_control Lucas_oil_octane_booster 2/22

NA vs. NOS Plate (150-hp)-6.0L LS1
Of course there is no denying the power potential of a good nitrous system. Case in point, the simple NOS plate system installed on this 6.0L LS. With the push of a button, our humble street motor was transformed into a serious strip terror. Adding an extra 150 horsepower required only that we keep the bottle pressure constant (with a bottle warmer) and retard the timing by 4 degrees. We took the liberty of adding a bottle of Lucas Oil octane booster to the 91-octane pump gas (from Rockett Brand) as a hedge against detonation. We figured the 150 hp shot deserved no less. As if the extra 150 horsepower wasn't exciting enough, just wait till you feel the extra 170 lbs- ft. of torque!

While we had both LS1 and LS2 crate motors at our disposal, we decided to build one instead. Since we planned on running some juice to it, we decided forged internals were in order. A call to Lunati netted a steel crank (3.662 stroke) along with the necessary forged rods and pistons designed to fit into our 6.0L truck block. I know what you are thinking, where is all that wonderful weight savings we were raving about earlier? Truth be told, we have big plans for this particular mill, but the same components (or even factory equivalents) could be used at this power level, including the factory 5.7L LS1 or even 6.0L LS2 aluminum blocks. While the 6.0L block shared the 3.662-inch stroke with the smaller 5.7L, the additional displacement came from the larger bore offered in the 6.0L. With the Lunati internals stuffed inside our freshly machined 6.0L block, our short-block was ready for action.

Next up were the cam, heads, and intake. Originally, we wanted to start our testing with a factory LS1, but all we had at our disposal was an LS6 grind. Compared to the stock LS1 cam, the high-performance LS6 grind offered both more lift (0.525 versus 0.500) and duration (204/218 versus 198/209). The reason we wanted to start with the factory cam was that we had a mild Lunati Voodoo cam waiting in the wings. The Lunati Voodoo cam offered 0.531 lift (on both the intake and exhaust) along with a 212/218 duration split. Note that the Lunati specs were only slightly wilder than the factory LS6 cam, but the Voodoo grind offered accelerated ramp rates to further improve power production. Once on the dyno, we planned a direct cam comparison.

With the factory LS6 cam in place, we installed a set of AFR 205 Mongoose heads. The AFR heads featured full CNC porting to enhance flow. Designed for performance street use, these AFR 205s flowed nearly 300 cfm. The AFR heads were topped off with a single-plane intake from GM Performance Parts and a 750 HP carburetor from Holley. Finishing touches on the 6.0L motor included a set of Hooker long-tube (F-body) headers feeding a set of collector extensions and a Meziere electric water pump.


Chevrolet Performance Parts
Detroit, MI 48232




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