Chevrolet LT5 Impala SS Tim Allen's Way of Saying
'Get Me to the Show on Time' (PR Newswire, 11/11/96)
Chevrolet isn't normally in the "made- to-order" custom
automobile business. But for the right opportunity, exceptions
can be made. Several months ago television star Tim Allen
approached Chevy with a fervent desire to create the Impala SS of
his dreams. Chevrolet Specialty Vehicles Manager Jon Moss
acknowledged that Allen's vision had promise. And, it might
serve as the perfect send-off for Chevy's renowned SS in its
final months of production. After due consideration, Moss agreed
to help Allen build this interesting variation on the SS theme.
Allen dreamed of a ride to special events in a carriage
distinctively different from the customary stretched limousine.
He was thinking of something very black and menacingly fast but
also supremely comfortable for two formally-attired,
chauffeur-driven luminaries. He was imagining a custom- built,
power-packed Impala SS, exactly the kind of machine his macho
character Tim Taylor might create in his garage on Home
Improvement.
Allen already owned and enjoyed a 1995 Impala SS. (That car's
tune-up is another story.) What he longed for was a DOHC 32-valve
Corvette ZR1 V8 under the hood of a '96 edition.
That transplant sounds simple, but it turned out to be a
sizable undertaking.
The LT5 is a rather bulky powerhouse that didn't exactly drop
into the space left by the original engine. Adapting it to an
automatic transmission was another challenge because this engine
was engineered solely for use with a manual transmission in the
Corvette ZR1. The number of systems to be created rapidly grew
to arm's length: engine mounts, wiring, cooling, air induction,
exhaust, power steering and driveline. The frame's front
crossmember had to be radically modified to provide the necessary
clearance for the LT5's nine- quart oil pan. The windshield
wiper motor, ABS hardware, heater core and AC evaporator all
required some fiddling.
Soon this project grew beyond the scope of an engine swap into
a full- blown engineering program. Instead of using a
salvage-yard engine, a new LT5 was acquired from GM's Service
Parts Operation and extensively modified for better-than-stock
performance. An aftermarket crankshaft raised the stroke to 3.82
inches, while the cylinders were bored to 4.00 inches and new
pistons boosted the compression ratio to 12.2:1. Those changes
resulted in a new piston displacement of 385 cubic inches or 6.3
liters versus the standard LT5's 350 cubic inches or 5.7 liters.
Ported intake and exhaust passages in the otherwise stock
32-valve cylinder heads improved flow characteristics.
Custom-made stainless-steel tubular headers routed exhaust to a
pair of LT1 Camaro catalytic converters. The use of a specially
calibrated PROM module in a Corvette engine control computer
helped manage all of the LT5's original functions including
emissions controls. During dynamometer tests, Tim Allen's highly
tuned prime ride delivered a peak 446 net horsepower at 5500 rpm
and well over 400 lb-ft of torque from 3250 to 5750 rpm.
To transport Allen to "openings" and the like without fail,
various driveline upgrades were deemed necessary. The Impala's
4L60-E automatic transmission was modified by Hydra-matic for
high-rpm longevity and fitted with a 2000 rpm stall speed torque
converter. A custom four-inch aluminum driveshaft was fortified
with heavy-duty universal joints. A new 4.10:1 ratio
limited-slip differential was specified to help provide the
desired 'off the line' acceleration. A quicker steering-gear
ratio should aid maneuverability through crowds of paparazzi.
Once the powertrain engineering was in hand, Allen focused on
aesthetic details to achieve just the right look for his dream
ride: Lower-profile BF Goodrich radials ride on wider Enkei alloy
wheels; vent holes drilled through the disc brake rotors and
aftermarket brake pads improve this hot Impala's stopping
performance; and a tasteful crossed-flag LT5 SS emblem on each
front fender affirms the source of the commotion under the hood.
To acknowledge credit where it's due, Chevy's bowtie badge floats
on a blacked-out grille, while a new "Binford 6100" logo has been
attached to the decklid. (Binford is the hypothetical tool
manufacturer that sponsors Allen's Tool Time TV show on Home
Improvement. Every hand tool, drill press and band saw featured
on the show is supposedly from that firm's 6100 product line.)
Inside, seating accommodations were altered to maximize
comfort for four passengers. Front-bucket side bolsters were
enlarged for additional lateral support, and fold-down trays have
been added to each front-seat backrest.
The center console is configured for auxiliary power jacks and
the requisite cellular telephone. Seats and door panels are
upholstered with supple leather trim and finished with wood- and
carbon-fiber-motif accents. Bose Corporation created a
one-of-a-kind entertainment system for Tim Allen's enjoyment by
using the same amplifier and speaker technology fitted to $30-
million Gulfstream V business jets. Engineers first mapped the
car's passenger-cell acoustics and then established speaker
locations, equalization curves and the sound system's frequency
response. In total, 10 speakers are placed in the doors, the
A-pillars, the center console and on the rear package shelf. The
10 distinct channels of amplification and equalization provide
117 decibel listening levels with no audible distortion. Source
material is provided by a Rockford Fosgate head unit working in
conjunction with a trunk- mounted six-disc CD changer. Opening
night may never be the same after this black sheep rolls forth
with dual pipes and 10 speakers serenading the crowd.
Specifications for Tim Allen's Impala LT5 SS
Engine
Type ...... DOHC 32-valve LT5 V8
Bore x stroke ...... 4.00 in. x 3.82 in.
Displacement ......... 385 cu. in. (6.3 liters)
Compression ratio ...... 12.2:1
Horsepower (SAE net) ....... 446 @ 5500 rpm
Torque, lb-ft (SAE net) ....... 448 @ 4250 rpm
Pistons ..... J-E
Piston rings .... Speed Pro
Connecting rods ..... Oliver
Crankshaft ..... Doug Rippie Motorsports
Air Cleaner and induction tube .... Wheel to Wheel
Exhaust system
Stainless-steel headers and pipes ..... Wheel to Wheel
Mufflers ........ Exhaust Tech
Resonators ..... Walker
Driveline
Transmission ....... modified Hydra-matic 4L60-E
Driveshaft ...... Dyno-Tech 4.0-inch aluminum with
Dana-Spicer universal joints
Limited-slip differential ...... Auburn Gear Company
Final drive ratio ......... 4.10:1
Chassis
Power steering ratio ............ 12:1
Wheels ........... Enkei 17 x 9.0-inch aluminum
Tires ...... B F Goodrich 275/40ZR-17
Front springs .... stock trimmed by 3/4 coil
Rear springs ..... Eibach variable rate
Brake rotors ..... cross-drilled
Brake pads ...... Raybestos Super Stop
SOURCE Chevrolet Motor Division