......Camaro- Untold Secrets125.gif (824 bytes) Feature Article

 

 

CAMARO SPOILER EQUIPMENT

STYLE AND FUNCTION COMBINED

By Wayne D. Guinn

An inside look at the development of the Camaro's spoiler equipment by the author of
"Camaro- Untold Secrets"

The Camaro's optional spoiler system is a true example of style and function... A harmonious addition that blends aesthetics into real performance.

Automotive aerodynamics plays a large part in how a car handles on the highway, and an even larger part on the race track. It's from actual racing experience that most high performance options for the '67-'69 Camaro were derived and the Camaro's aerodynamic spoiler equipment is one of the best examples of Chevrolet's race bred technology.


When it came to making the Camaro competitive, Chevrolet was serious, at both the consumer level and on the track. And it was through racing that Chevrolet was able to successfully promote the Camaro and tap into the fast growing youth market.
The formula was simple, Chevrolet put together the Camaro Z/28 package to compete against their rival, the Ford Mustang in the Sports Car Club of America's Trans-Am road racing series.

IT ALL BEGAN...

Back in September of 1966, when the Camaro Z/28 package was first being put together, Chevrolet called on Engineer Paul Van Valkenburgh to evaluate the Camaro for high speed stability and to suggest "aerodynamic fixes" if necessary. Chevrolet Engineering was meticulous when it came to preparing the Z/28 package for competition. The concentration was on winning, and every aspect of vehicle dynamics was addressed accordingly.
The opening event was to be held at Daytona where speeds are in excess of 140 MPH and they needed to be certain that the Camaro would be able to stick to the track. It was Chevrolets experience that production vehicles tend to exhibit front end "lift" which becomes excessive at high speed creating unsafe conditions in racing.
Prior to the Camaro inquiry, there wasn't much aerodynamic study done on production automobiles, the Corvair and Corvette being the two notable exceptions. The Corvair was found to wander excessively at highway speeds, dangerous nose lift was a real concern and for this reason aerodynamic studies were performed inside engineering. In those studies, it was determined that a front valance panel (plow) corrected this detrimental effect by decreasing under body air flow and, as a result, it became a production part of the Corvair. It was from this early developmental work that the Camaro would later benefit. The Corvette was a slightly different matter in that it was studied during competition at race tracks and again treated to a similar fix.
Although effective, both of these examples were tested crudely by trial and error. Essentially guess-tamating which aerodynamic fixes might work best. The Camaro, on the other hand, was more scientifically studied using a scale model in a wind tunnel to determine the base aerodynamic qualities. Lift was measured and, like most production vehicles, determined to be greater than the acceptable limit for racing at high speeds.


Scale model in wind tunnel helped establish aerodynamic base line from which the spoiler equipment was developed.

Valances of various sizes, angles and shapes were applied to the Camaro front end and the most effective was chosen. Once the problem of nose lift was countered using the front valence panel, engineers began contemplating how an inverse effect or -Down force- could be created and utilized to increase high speed cornering traction. The problem was not so much how to get down force as it was how distribute it between front and rear tires, and how to minimize the effect on air drag.
The first front valance was so effective that it produced massive over steer. To counter that, a smaller unit was substituted until the problem was corrected. Slight understeer is always more desirable for better handling. A rear spoiler was then added for additional downforce but the car began to understeer badly. It then became a balancing act to get the right combination of front and rear aerodynamic effects for vehicle stability.
The measurable effects of the "plows and tails" were recorded and the results with recommendations sent to Chevrolet's Style group for further consideration and development. The Style group determines what will and will not work from a stylistic stand point based vehicle lines and current trends of consumer acceptance.


Final configuretion on engineering Z/28



Graceful lines "blend in" to enhance the body design.

Although the initial recommendations (specifications) submitted by Van Valkenburgh would have been better in terms of optimum effect, the group made the necessary aesthetic compromises, blending lines and altering dimensions in order to create a design that would be acceptable to the consumer. Remember, prior to the Camaro, only "race cars" like Chapparals wore spoilers. They just weren't seen on production vehicles and were at first perceived as a radical departure from the "norm". A remarkable contrast to today where every other car, including four door sedans, sports a whale tail!

HOW EFFECTIVE?...

When asked about the effectiveness of this special equipment, Van Valkenburgh emphatically states; "The front valance and rear deck spoiler were more than mere styling gimmicks. They actually made a measurable contribution to cornering and stability at highway speeds and were indispensable on the race track".

More than a gimmick... in this case a bill board!

INDEPENDENT TESTS VERIFY...

Results of independent tests conducted using a 1969 Camaro Z/28 clearly demonstrate the practical value of the optional spoiler equipment. The testing was conducted by the editors of CAR LIFE magazine and the results appear in the June 1969 issue.
In order to standardize the tests, a single Camaro Z/28 was evaluated both with and without the factory spoiler equipment installed. This testing method eliminated any vehicle/chassis variations that may occur between two different vehicles which can "factor in" affecting the validity of test results.
Parameters measured were lift and downforce. The two most important aerodynamic factors that affect traction and handling at speed. Speed intervals of at 65, 85, and 115 mph were chosen as a practical range of test points for analysis and comparison. The 65 mph mark representing a typical highway speed, 85 as the intermediate passing or top crusing speed, and 115 as an average race speed on medium and short road race courses.

EVALUATION CRITERIA...

In making value judgements on the effectiveness of the spoiler equipment, the desired results would be:

1. Normally, a slight lifting of the nose if there had to be a choice between nose or tail lift at speed;

2. Ideally, the nose would be forced down by the flow of air and the tail would be forced down even further than the nose.

THE RESULTS... (at 115 mph) (SEE GRAPH)

Without spoilers front or rear, the Camaro exhibited an excessive 375 lbs. of lift at the front. The rear had a positive 25 lbs down force which is typical for notchback cars.

With front and rear spoiler equipment installed, the vehicle exhibited a marked improvement overall. Lift decreased to 330 lbs. at the front and downforce at the rear increased to 130 lbs., resulting in a balanced and completely tractable vehicle.

CONCLUSION...

The spoilers produced the desirable effects of increased traction along with a slight understeer condition. In controlling the lift of the nose so well, there was an increase in stability that a sensitive driver is able to feel even at moderate speeds.
In referring to the graph, It should be noted that the effectiveness of the spoiler equipment is proportional to vehicle speed. The faster you go the more effect the equipment has. The best part is it looks as good as it works!

 

THE CELEBRATED DEBUT AT RIVERSIDE...

Camaro's spoiler equipment first appeared publicly November 1966, on a 1967 Camaro Z/28 during a press conference at Riverside California. The event was hosted by Chevrolet solely to introduce the new Z/28. At that time, a three page "Technical News" handout was distributed describing the new Z/28 with its "Special Equipment" and options.

As it turns out, not all of the special equipment listed became part of the RPO Z/28 package. Some ended up as separate RPO's and others as service options. The spoiler equipment was listed as a separate option (RPO D80) and referred to in the handout as auxiliary "aerodynamic" body panels.
The spoiler equipment did not appear in the regular 1967 or 1968 Camaro brochure. It was however, featured in a separate 1968 Z/28 brochure as optional equipment available with RPO Z/28. For 1969, it appeared in the Camaro brochure as optional equipment available on all Camaro models and, later in the year became a part of the Z/28 package.

SPOILER ODDITIES...

Some very early 1969 Camaro's ordered with RPO D80 Air Spoiler equipment came through with the narrower 1968 style spoiler as can be seen on the back of the 1969 Camaro dealer brochure. Therefore, if your 1969 Camaro was made very early in the model year and has a narrow spoiler, chances are that it is correct and was installed at the factory.

 



 

The strangeness of seeing the narrow spoiler on the rear deck of a 1969 car puzzled many restorers and experts, leading them to think that someone had later "added" the wrong piece and in turn would "correct" the mistake by substituting the wider piece. Unfortunately, these corrections have lead to even more confusion since it would then appear as if fewer early cars were produced with the narrow spoilers then actually were!

THE DYNAMICS OF AIR FLOW AND ITS EFFECTS ON AUTOMOBILES...

What actually causes lift? To some degree, body panel shape and to a larger extent, air that passes through the opening of the grille and under the front end sheet metal. At speed, this massive air stream builds up tremendous pressure under the hood where it is forced to exit rearward, below the chassis, resulting in body lift.

We can effectively counter lift by limiting the amount of air flowing under the front sheet metal with the use of "dams" and by down-sizing the opening in the grille. Furthermore, we can relieve pressure under the hood by incorporating exhaust vents in the fenders such as the ones used on the Trans-Am Firebirds and Corvettes. Any remaining lift may be countered by applying down force using additional aerodynamic "spoiler" devices at the front and rear of the vehicle.