Paxton-Powered 1995 Impala SS

Beware the Barge With the Supercharger

Mike Petralia Jul 1, 1998 0 Comment(s)

Step By Step

The original LT1 350 was punched 0.030 over and fitted with JE pistons and Speed-Pro rings. A Comp Cams hydraulic roller bumpstick moves the stainless valves in Twisted Wedge heads. The Paxton Novi 2000 supercharger was mounted with custom-made brackets to keep everything under the hood. An eight-rib drivebelt spools the blower up to 9 psi. Note how the Arizona Speed & Marine headers kick up above the valve cover on the passenger side.

Schaun left the interior stock except for the addition of a tach and a boost gauge from Auto Meter, both of which were mounted in the factory dash next to the steering column.

On pump gas, the Impala produced a very impressive 410 hp and 403 lb-ft of torque at the rear wheels on MTI's chassis dyno with 9-psi boost.

Motorsport Technologies in Houston performed the major engine overhaul and buildup. It also worked closely with Paxton in the development of the first Novi 2000 blower kit for the Impala SS. Schaun's car was the prototype for development of several key components.

The MSD Adjustable Boost Timing Control is hidden in the ashtray.

You wouldn't think this Impala could wax you on the street, would you? Better watch out--Schaun has been known to travel for business.

This is the only real place to test power! Schaun has wrung out the Impala for several passes down the 1320. And without really abusing the car, he turned in a best e.t. of 12.48 at 110 mph with slicks. That's cookin' for a 4,000-pound street car!

It's one of those hot, sultry, typical Houston nights. You're idling in your early Camaro at a stoplight when an ominous black Impala SS pulls beside you and you hear a strange hum. You've already dusted some 5.0 puke tonight on your way to the local Stop 'n' Pop, and this barge looks like easy pickin's. You blip the throttle, but it's difficult to tell if the Imp's driver is paying attention behind the car's dark, tinted glass.

The light turns green, and you jump on it. You realize the guy's a player as he stomps on the gas. But wait, what's the deal? Your Camaro is strong, but that land yacht is pulling on you. This ain't right, what's going on? You hear yourself saying, "What's he got in that thing?"

Beware the Barge.

In the early days of World War II, the Allies disguised their boats to look like trolling transports, but they were actually heavily armed gunships looking for a fight. They were called Q-Ships and were designed to lure unsuspecting German U-boats into a surface encounter where the Q-Ship would hold the upper hand. While the Houston street scenario might or might not have happened, it’s a classic sleeper scene. Our hero with the early Camaro was just sunk by the SS Q-Ship.

Schaun Gallagher didn't build his '95 Impala SS to pester punks with early Camaros. In fact, he bought the car as a great big cruiser to help him do his job as a sales manager for a local steel company. The used Impala was priced right and ran comfortably. But that wasn't quite enough for Schaun, so he made a call to his pal Jayson Cohen, the owner of Motorsport Technology (MTI) in Houston. It took 15 months and a few trips down the 1320 to produce this mid-12-second Impala SS. That and some help from a Paxton supercharger.

First up on the modification table was the engine. Schaun dropped the Impala off at MTI where Cohen and crew went to work on it. MTI bored out the factory block 0.030-inch over and reused the stock crank and rods. JE made up a set of forged pistons to fit the new 4.030-inch bore that would yield a 10.0:1 compression ratio. Speed-Pro rings were file-fitted to the bores, and Fel-Pro head gaskets seal the combustion chamber. Since this is a daily driver and Schaun didn't want a rough thumpin' idle that would shake his customers' fillings loose, MTI commissioned Comp Cams to grind a hydraulic roller camshaft that would idle respectably and work well with the planned blower. The cam was ground with 210 degrees intake and 220 degrees exhaust duration at 0.050-inch lift with 0.533-inch intake and 0.544-inch exhaust valve lift. Crane 1.6 aluminum roller rockers move the stainless 2.02 intake and 1.60 exhaust valves inside the ported TFS aluminum cylinder heads, and all are bolted together with ARP bolts. MTI ported the stock EFI manifold and added a 52mm throttle body.

Ignition duties are handled by an MSD-6AL box, a Jacobs Ultra Coil, Taylor wires, and NGK spark plugs. MTI also worked with Paxton Products to fabricate custom mounting brackets and the eight-rib serpentine drivebelt for the Novi blower that cranks out 9 pounds of boost. If you stuff a bunch more air into the engine than it was originally designed for, it has to escape somehow. For this, MTI used ceramic-coated Arizona Speed & Marine equal-length headers and a Borla Cat-Back exhaust system.

All this new power meant a drivetrain upgrade was in order. Preventative Maintenance Auto Center in Houston removed the stock 4L60E automatic and tweaked it heavily, replacing almost everything. It added a high-performance three-four clutch pack with Kevlar bands, a mechanical diode sprag, a hardened stator shaft, and Teflon pump bushings, and it modified the front pump. A 12-inch lockup converter with a 2,400 stall then found its way in between the engine and the trans. Out back, Schaun added a new 3.73 gearset and an NOS fuel pump to keep the engine fed.

Schaun chose to keep the interior and exterior stock except for a mild window tint and the installation of a tach and a boost gauge from Auto Meter. Now that the Impala is up and running, Schaun says he loves stomping on unsuspecting Mustangs and rolls through the local cruise spots where he has become a regular with his wife and three sons. Schaun is proud of what he has created, and rightfully so. He's got a 4,000-pound luxo cruiser that runs mid-12s at over 110 mph on pump gas. He can cruise comfortably in the 100-plus-degree heat and entertain customers in style. Sounds like a car for all seasons. CHP

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