In a sea of mundane, daily driven, boredom-inducing commuter cars,police cars are special.
In the classic film, The Blues Brothers, Dan Akroyd said it best when describing the merits of a cop car to John Belushi. "It's got a cop motor, a 440ci plant. It's got cop tires, cop suspension, and cop shocks; it was a model made before catalytic converters, so it'll run good on regular gas."
In a sea of mundane, daily driven, boredom-inducing commuter cars, police cars are special. They are generally four-door sedans, equipped with high-output V-8 engines, heavy-duty suspensions, cooling and electrical systems--all packaged in a very unassuming wrapper. Cop cars are built to sustain high speeds, bumper-to-bumper traffic in sweltering heat or subzero temperatures, repeated high-speed cornering and braking, and do it day in and day out. A cop car is built to take whatever is thrown at it, and reliability is paramount to law enforcement agencies. The old Chrysler Corporation's long history and love affair with law enforcement agencies ended abruptly after the '89 model year with the last V-8, rear-drive Mopar pursuit vehicle--the Dodge Diplomat and its Plymouth counterpart, the Gran Fury.y.
We thought we would take this opportunity to introduce a brand-new Mopar Muscle project car to our loyal readership. It's an '89 Dodge Diplomat police car, we've aptly named Project Stealth Bomber. Why a cop car? Glad you asked. It's quite simple. These are the closest things to musclecars that Chrysler produced in the era. It sports four-barrel V-8 power, rear-wheel drive, and a 120 mph top speed. It has a heavy-duty suspension, featuring sway bars front and rear, 11-inch disc brakes in the front, finned 11-inch drums out back, coolers on everything but the windshield wiper motor, and a cooling system that won't heat up during a Sunday drive through hell at high noon. It also has slotted (for brake cooling) 15x7-inch steel wheels shod with high-speed-rated radial tires, a 2.94-geared 81/4-inch rearend, and an A999 auto trans. It is virtually the end of an era for Chrysler in the realm of police car production. While not as sexy as a '69 440 Polara cop car, you probably won't be able to buy a '69 version without taking out a second mortgage on your house (especially on an editor's pay). Plus, the asking price was right and the car wasn't beat up.
Our Goals
Since a '69 Polara police car is the high-water mark in police car production, performance on par with the '69 Polara squad car is a goal from a top-speed standpoint--meaning our Diplomat must be able to top 147 mph. We feel this is well within reach, despite the barn-door aerodynamics. So, we have set the Polara's top-end performance as our goal. After having participated in the Silver State Classic Challenge in September, we figured this form of open-road racing would be the perfect arena for this type of vehicle. We want to enter the Diplomat in the upcoming Nevada Open Road Challenge in May of '04 (this is the identical race to the Silver State Classic Challenge). We will also attempt to keep all modifications subtle and stealthily hidden, when possible. The first item on the agenda will be a transmission rebuild in an upcoming issue. A shift kit and special converter will be added in the process. We will also add a large free-flowing exhaust system to the current combination and test its benefits. A full suspension rebuild will also be part of the game plan. Then we will swap mills, as a serious horsepower infusion will be necessary to move the aerodynamically-challenged 3,800-pound beast to the 150 mph mark. Any suggestions? We are open to input.
Large sway bars adorn the front and back of the car. The 8-1/4 rearend ispacked with a 2.94 gearset ensuring ho-hum acceleration, but greattop-end. | 
Click picture above for dyno numbers. | 
These will be staying on for the ride, but wrapped in sticky,corner-carving rubbers. |
Dyno Testing and the Big Surprise
We had to find out what we were starting with before we began digging into this unmolested small-block. We are happy to report that, in yet another case, Ma Mopar underrated an engine. The factory claimed 175 hp, and we were a bit surprised by the 176 horses the Diplomat cranked out at the wheels. Not a bad baseline considering the restrictive exhaust system, with not one or two catalytic converters, but three! Because of questionable tire condition, all pulls were made in second gear to limit tire speed. Even still, we saw 89-mph tire speed. Gotta' love those 2.94 gears!
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