1970 Chevelle SS LS6 & Drivetrain - Modern Muscle, Part 2

Part 2: Making the "new" LS6 Fit

Barry Kluczyk Sep 1, 2003 0 Comment(s)
Sucp_0309_14_z 1970_chevelle_ss_ls6_drivetrain Airbox 2/19

The air box is from a '96 Impala SS. The placement of the airbox behind the driver side headlamps (seen here) proved to be an airflow restriction (see sidebar story).

Locating the Chevelle's axle is a catalog's worth of Hotchkis A-body suspension goodies. Control arms, springs, sway bars...you name it. All-new urethane bushings were used throughout, too, including the front suspension. And, like the rear axle, Chevy threw whatever Hotchkis parts would stick to the Chevelle's front suspension. "It's great stuff," says Mark McPhail. "The Hotchkis parts make the car drive like it weighs 500 pounds less than it really does."

Interestingly, the Chevelle rides on 16-inch wheels originally found on an S-10 with the ZQ8 suspension package. These great looking five-spoke aluminum wheels have been released by GM as an over-the-counter package (PN 12498299), which includes four rims, the center caps, etc. "The offset of the wheels looks right in the fenders of GM rear-drive cars of the '70s and '80s," says McPhail. "The ZQ8 wheels look modern and fit right; I think it's a great option for anyone with a GM car looking for new wheels."

Sucp_0309_15_z 1970_chevelle_ss_ls6_drivetrain Rear_axle 3/19

The 12-bolt Posi rear axle was rebuilt, painted and re-installed with the stock 3.31 gears. Check out the custom driveshaft and Flowmaster exhaust system, too.

With its modern powertrain and tightened suspension, this "new" LS6 Chevelle performs on the street with daily-driver ease. And though it's an easy cruiser, don't think this Chevelle's performance is tepid. There is, after all, a Z06 engine under the cowl induction hood. (After our photos were completed, the Chevelle was returned to the garage to make the cowl induction system functional for the engine.)

The LS6 gives the Chevelle a 400-horse punch (see sidebar story) and with the aluminum engine's considerable weight advantage over an iron big-block, the power-to-weight ratio is remarkably favorable. "We did this project to prove that, with a little ingenuity, any enthusiast can perform a similar swap into his own early GM car," says McPhail. "Almost everything you need to do it can be ordered from a GM dealer's parts department."

That doesn't make the job necessarily easy, but it takes much of the trial and error out of the equation. And with the results we've seen in this Chevelle, it seems very much like a worthwhile project.

Sucp_0309_16_z 1970_chevelle_ss_ls6_drivetrain Fuel_tank 4/19

A custom, baffled fuel tank was created by Rock Valley Antiques for the Chevelle, because of the high-pressure requirements of LS6's fuel system. The LS6 has a returnless fuel system, which means there's no return line from the engine to the tank, but the fuel system needs the C5 Vette's integrated, inline fuel filter/pressure regulator. It feeds the engine with a single high-pressure line, but has its own return line to the tank. Fuel pressure for the LS6 is 58 psi.

Not surprisingly, after GM's "new" LS6 Chevelle was completed, GM's Mark McPhail wanted to see "what she would do." After finishing up our last photos of the car's assembly, we called Greg Banish at Detroit Speedworks. His Warren, Michigan, dyno and tuning shop happened to be only a couple of miles from the facility where the Chevelle was built. Banish juggled his schedule to make some room on his Mustang chassis dyno for the Chevelle.

With the car strapped down, Banish started turning the Mustang's big rollers with the LS6-powered A-body. The first couple of pulls were OK-consistently putting down more than 300 horses to the rear tires. But the pulls revealed the engine seemed to lack for air at higher rpm.

We all stared under the hood of the Chevelle with a collective, unspoken, "Hmm..." McPhail started fiddling with the air box, which was from a '96 Impala SS. It was located in the corner of the engine compartment behind the driver side headlamps. "This might not be the best spot for the air box," he pondered.

He was right. After inverting it so that the air filter was exposed, Banish got back behind the wheel and made another pull on the dyno. The Chevelle instantly picked up nearly 10 hp and the engine's improved breathing was confirmed by the dyno's computer printout.

When the session was over, the Chevelle put down 319.5 horses to the rear wheels, or 400 horses at the flywheel-just about even with Chevy's 405-horse rating for the LS6 engine.

Better still, the Chevelle left breathing a lot better than when it arrived.


Detroit Speedworks
Warren, MI 48092




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