Lingenfelter Impala SS; Chevrolet Impala upgraded by Lingenfelter Performance Engineering by Don Sherman (Motor Trend, 9/96)

   John Lingenfelter isn't your average speed merchant. Two

things set him apart from other horsepower hounds: Lingenfelter

paid his dues working as an emissions engineer for a major

manufacturer, and he's a real racer with a dozen national event

wins behind the wheel of an NHRA A-econo dragster. In other

words, Lingenfelter Performance Engineering in Decatur, Indiana,

is where you buy engine mods that make genuine horsepower, not

just a rough idle and a funky

exhaust.



    A case in point is the Chevy Impala SS we recently hustled

down a Muncie, Indiana, dragstrip. After a massage session in

Lingenfeltet's shop, the big black beast clocked a quarter-mile

ticket that would do a Corvette ZR-1 proud: 12.9 seconds at 104.6

mph. The sprint to 60 mph took but 4.7 seconds, which just

happens to match the performance of the $130,000 Ferrari F355

Berlinetta.



    The traditional means to such ends would be a big-block under

the hood and fat tires in back. Lingenfelter resorted to neither

of those. For one thing, he left the original-equipment tires in

place, while everything upstream of them was modified, but well

within the limits of what the federal government deems 50-state

street legal.



    Lingenfelter's $18,350 drivetrain massage includes a

long-stroke crankshaft, forged-aluminum pistons that bump the

compression ratio to 11.0:1, tougher connecting rods, CNC -

ported heads, an all-new valvetrain with wilder cam timing and

bigger valves, a larger throttle body, a modified (less

restrictive) air filter, headers, and a Borla stainless steel

exhaust system. Its essentially the same engine assembly that

powered Lingenfelter's Corvette in our March '96 "Raw Power,

gathering of speed merchants. The crowning touch for the

fortified 383-cubic-inch small-block is what the motor maestro

calls his SuperRam intake manifold. This multipiece assembly

consists of a base casting, 25-inch-long intake runners packed

inside a box, and a lid to seal the top. A 58-millimeter throttle

body meters intake air, feeding the engine with healthy doses of

ram-tuned atmosphere. A $1000 transmission upgrade enhances

driveline longevity, while a $900 switch to a 3.42:1 axle ratio

quickens throttle response.



    The long intake runners boost the lower half of the torque

curve. To sustain free breathing to redline, the runners,

cross-sectional area must be carefully sized and an ample plenum

volume is necessary. The net result is a medium-size motor that

flexes he-man muscles irrespective of rpm. Curves from the dyno

room show CZ net horse-power at 5500 rpm and 467 pound-foot

maximum torque plateau between 3500 and 4000 rpm. That's

substantially more pure torque than Chevy squeezes out of its 7.4

liter big-block truck engine.



    The beauty of this package goes beyond sheer speed.

Driveability is flawless and throttle response is so

instantaneous you'd swear that the powertrain computer can read

your mind. A soft under-car cruise-mode rumble turns ferocious as

the pedal goes down. No car this big has any right to be this

fast.