What: '71 Plymouth Duster
Owner: Steve Nitti
Where: Scandia, Minnesota. If you're in the area, visit the Erickson Log House Museum.
Short-block: The iron-block Slant Six was bored 0.020 over. Denny managed to find a forged factory crankshaft and had it offset-ground to add extra stroke, ending up with a spec of 4.30 inches. Carillo made a set of connecting rods for this application, and the pistons are custom forgings from Ross, made to Denny's specifications, that yield a conservative 8.0:1 compression ratio. To fit this package inside the block, the bottoms of the cylinders had to be clearanced, which is not unusual for a stroker build. What made this application interesting, however, was that the beams of the connecting rods interfered with the cylinder walls because the stroke was so much longer that the Chrysler engineers ever imagined when this engine was designed. So rather than the minor machining typically needed to clear a connecting rod bolt, lots of careful grinding had to be done inside the crankcase to make this rotating assembly to fit.
Long-block: Denny ordered a custom-ground Crower cam that's able to deliver 0.530 lift, a whopping 36 percent more than stock. It controls a set of oversized valves (1.80-/1.50-inch) inside a fully ported cylinder head. "We ruined one head trying to see how much bigger we could make the ports," Denny says. T&D makes the roller rocker arms, and Denny fitted a set of beehive springs under them. By their nature, inline-six engines have long cylinder heads that need lots of clamping force to remain sealed, especially if any power-adders are introduced. Denny told us that just 10 psi of boost pushed out the stock head gasket, and 20 psi lifted the head. Now they use a copper shim gasket with ARP head studs, and everything has been OK so far.
Supercharger: That's a Procharger D1 centrifugal supercharger breathing directly into the intake manifold. The Supercharger Store in Huachuca City, Arizona, actually makes the mounting brackets for this application. The blower delivers a maximum of 26 psi of boost, though Denny says the engine normally runs at about 20 psi. There's no intercooler because Steve was worried about clearance issues behind his cherished Shark's Tooth grille, so Denny decided to run the car on E85 fuel with a shot from a water/methanol injection kit to cool the intake charge.
Intake and fuel delivery: Stock intake manifolds for these engines are long, skinny affairs that do not have the cross-sectional area needed to deliver the amount of air this engine needs to go 10s. So knowing he'd need to have a custom intake manifold made, Denny decided to build an electronic fuel injection system to go with it. The sheetmetal intake is handmade for this application, and the FAST XFI monitors the engine's vitals and controls the 80-lb-hr fuel injectors accordingly. An Aeromotive A1000 pump in a sumped gas tank keeps up with the excessive fuel demands.
Exhaust: The header is a custom 3-2-1 setup with 2-inch primaries feeding a 3-inch exhaust.
Drivetrain: The trans is a Chrysler 904 with a 5,000-rpm Midwest converter. It turns a Victory Driveline driveshaft connected to an 83⁄4 rear axle with a Mopar Performance aluminum centersection, Moser axles, and 3.91:1 gears on a spool.
Suspension: Under the front of the car is a Magnum Force front tube chassis with QA1 double-adjustable front and rear shocks. Mopar Super Stock leaf springs and QA1 shocks are out back.
Interior: Legendary reupholstered the seats and interior to a like-new stock appearance. The chromoly six-point rollbar was bent and fitted by SharaDon Performance.
Paint/Body: Steve's Duster needed a complete restoration when he dropped it off at SharaDon Performance. It is basically a one-stop Mopar build shop that can do general repairs, performance modifications, and full restorations. Sharadon replaced all the rusty sheetmetal and massaged the remaining panels to an arrow-straight finish before respraying the car in its original Poly Gold Leaf Metallic. Along the way, Denny managed to persuade Steve to lighten the car as much as possible. You won't find windshield wipers, a heater, or air conditioning. They also replaced the hood and front bumper with fiberglass and were rewarded with a 2,995-pound curb weight. The one thing Steve wouldn't compromise was the radio. Guess his tunes are as important as his timeslips.
On the road: "It sounds crazy. Everyone looks over to see what's making the noise. They look over and keep looking at you like they can't process the sounds and the car that's making them," Denny says. "It drives like you'd expect a drag car to, but unlike a V8, it doesn't make a ton of power below 5,000 rpm. If you keep it above 5,000, it's really fun to drive."