1984 Chevrolet Citation IV Concept
Motivation for the Citation
To propel the Citation IV, Chevrolet decided to use a 2.8-liter, V6 engine with iron block and cast aluminum heads.
Fitted with a complete engine cooling system, air conditioning and full emissions control equipment, it delivered 140-horsepower which was up from the Citation II V6’s 112 horsepower. Power was fed to the front wheels through a three-speed automatic transmission with lock-up torque converter.
In general terms, the motor was unchanged but some of the details needed adjustment.
The Citation IV adopted most of the Aero 2002’s design characteristics, including the wedge-shaped front end. In order to meet lofty aerodynamic goals, the hoodline continues at the same angle as the windshield. If you’re curious what that angle is, from bumper-tip to windshield-top, it slopes at 68-degrees and the hoodline measures a full five inches lower than the hoodline of the production Citation II’s. It’s that dramatic lowering of the hoodline that posed an obstacle for drivetrain packaging.
The diagram to the left shows the engine/hoodline configuration for the Citation II, in blue, and Citation IV, in red.
With fuel injection only beginning to proliferate through the automotive world, much of a motor’s vertical clearance at the time was needed for the carbureted, as indicated in the diagram. To work around that, Chevrolet logically went with (electronic port) fuel injection. Even so, there was still not enough room to feed air to the motor in a conventional fashion.
To solve that problem, without altering the exterior design, both valve covers and the intake manifold were made from a one-piece aluminum casting which fed tuned passages to each cylinder. Air was sourced from a unique “snorkel” mounted in front of the left wheel well then channeled through an in-line filter. By replacing the top-mounted carburetor, air filter and separate intake manifold, roughly five inches of vertical clearance were saved. As a result of the intake design, torque and horsepower were reported to be on par with a high-output carbureted motor of the period.
Freeing up even more space underhood is the distributor-less ignition system that utilizes three high-tension coils, triggered by an electromagnetic sensor on the crankshaft.
Other space-saving measures include an oil sump that is two inches shorter than its contemporary counterpart, and a modified housing for the Turbo Hydra-matic transaxle that was rotated twelve degrees allowing the engine to be mounted two inches lower and a half-inch farther forward in the chassis.
A low, wide radiator was fed by the narrow, centered opening located below the bumper.
Interestingly, the three-slot opening that spans the front between the turn signals did not serve the engine bay but rather fed the passenger ventilation system. This was unique since cabin ventilation was typically pulled from the base of the windshield, a contoured area on Citation IV.
The flush mounted headlight lenses were highly effective but would not have been legal on US roads. There’s a reason domestic vehicles weren’t available with the so-called “European” lenses until the mid-1980s, but that’s a topic for a separate, forthcoming post.
Potential for Greatness
Despite serious efforts to reduce weight, the unibody Citation IV concept weighed in at about 2,600 pounds which was over sixty more than a production Citation II. Even so, thanks to the peppy engine, the Citation IV would scoot to 60 MPH in ten seconds flat and had a theoretical top speed of over 140 MPH.
While acceleration and top speed make for great talking points, the concept’s more practical goals had to do with efficiency. Chevrolet engineers anticipated the Citation IV would achieve 50 miles per gallon on the highway and, while traveling at 50 MPH, only require seven-horsepower of effort to push.