Project Pinto: The Joy, Sorrow, and Work of Building a Race Car

Car and Driver

4 hours ago

From the March 1978 issue of Car and Driver.
Once again the intrepid editors of Car and Driver have thrust their necks into the thick of the Goodrich Radial Challenge, which, for all of you who came in late, is a road-racing series for small sedans sanctioned by the International Motor Sports Association. Four races were entered, two poles were captured, and one winner's circle was invaded. So much for what we did on our summer vacation.
Our car was a Ford Pinto, and the win was the first victory for a Pinto in two years of Goodrich racing. But the really fascinating part—to us, at least—is that the season's results strongly support a hunch we've been kicking around the office for years. We reckon that motor racing is almost entirely an intellectual game. Brains are trump. Bullfighter­-brave drivers will give the car a good run and Onassis budgets take the worry out of blown engines, but it is thoughtful selection and logical preparation of the car in the first place that wins races. There are no tricks and no short cuts. It's common sense all the way. At least, that's what we thought. And the Pinto project—winning in its second appearance, long after most of the serious racers had dismissed Ford's subcompact as a lost cause—rather grandly supports our theory.
Every racing project has to start with fundamentals. You must have a thorough understanding of the rules and complete specifications for all the eligible cars.
It would be easy to lapse into "The Anatomy of a Winning Pinto" at this point—everything from valve-seat angles to camber settings—but frankly, it would be pretty dull. The car, in fact, is completely conventional. It even scored its one victory (at Charlotte Motor Speedway) using its original hydraulic valve lifters. Any number of competent mechanics would have made the same modifications we did and, if they were thorough, probably would have ended up with the same results. So the real story is not in the car itself but in our approach to it: Why we chose a Pinto and how we knew what to do with it.
Every racing project has to start with fundamentals. You must have a thorough understanding of the rules and complete specifications for all the eligible cars. Ideally, you would also have first-hand and quantitative observations of the cars that you'll have to beat: how fast they are, where are they fast (corners, straights, or under braking), and how close are they to the limits of their development. You have to know all of this before you can choose the right car. And the right car is absolutely essential if you want to win.
The Top Cars: BMW 2002 and AMC Gremlin (Really)
We went into the 1974 Goodrich series with an excellent backlog of information. Car and Driver's Mazda Wankel race car had been a first-class observation platform during the 1973 races. We had been able to run with the leaders in every race and could compare their strengths and weaknesses to a car we knew. Apart from the Mazda (which IMSA subsequently hobbled with a rules change), there were only two other competitive cars in the series: the AMC Gremlin and the BMW 2002.
The Gremlin is an odd duck. It's really a big car made compact by chopping out about a third of the body. But it retains the control-arm front suspension, huge brakes, and six-inch-wide wheels of the big American Motors models, not to mention the 232-cubic-inch six-cylinder engine. Next to the Mazda, it was the fastest car on the straightaways and we considered it the one to beat.
But how do you recognize the third-best car? Durability is the most important factor—you have to finish to win. Speed is next, then handling, and finally brakes. Ties are broken by picking the least costly alternative.
The BMW ranked a close second. Its 2.0-liter engine is very powerful for its size, enabling the 2300-pound sedan to keep up with the 2700-pound Gremlins in acceleration, losing out only in top speed on long straights like those at Road Atlanta and Daytona. Handling and braking are about on a par with the Gremlins and better than you would expect, considering the BMW's MacPherson front suspension and rather small brakes. This can probably be attributed to the endless development work done by Miller & Norburn, the leading BMW team. And it would further suggest that these cars are nearing the limit of their potential.
At this point, a right-thinking racer should check the price difference between American Motors and (gasp!) BMW replacement parts, then slide himself into a Gremlin. If the point of the exercise were simply to win races, that's what we would have done. But we had a theory: that a logical and thoughtful approach applied to a lesser car could knock off the heavies. The only way to find out was to try.
Why We Picked the Third-Best Car
The search began for the third-best car. (We weren't willing to push our theory too far. Fourth or fifth best makes the job just a little too hard.) But how do you recognize the third-best car? Everyone has their own theories on that; this is ours. Durability is the most important factor—you have to finish to win. Speed is next, then handling and finally brakes. Ties are broken by picking the least costly alternative.
Car and Driver
While durability is most important, it is also the hardest to predict. You can examine the finishing records of various makes of cars for a clue, but usually you find only a reflection of how well they are prepared. And of course there can be exceptions. If there is a pattern to the failures—the crankshafts always break or the transmissions always fail—you can pinpoint a problem. But usually the failures are random, and you have to assume that you'll spot weak areas during preparation.
There are two kinds of speed, and the importance of each depends upon the type of tracks on which you'll be racing. At Daytona and Talladega, top speed is critical, and it depends entirely upon horsepower and aerodynamic drag. Since the principal component of drag is frontal area (roughly the width multiplied by the height of the car), hp-to-frontal area ratios are good indications of performance. At all the other tracks, acceleration is more important. A comparison of horsepower to weight tells the story here; ties are decided by the car with the closest spacing in the transmission ratios and the widest choice of axle gears.
The value of handling once again depends on the track, ranging from being of relatively minor importance at Daytona and Talladega to being a critical factor at tight tracks such as Lime Rock and Mid-Ohio. In fact, cornering capability is more important than power at Lime Rock. Handling can generally be predicted from the following parameters, listed in order of importance: suspension type (unequal-length control arms are better than MacPherson struts), wheel width, track width, and car height. The more of these items that are relatively favorable, the better the car will handle.
The importance of brakes increases on tracks with long straights followed by tight turns, but only in cases where brakes don't have enough capacity to last through the race do they become truly critical. When you have the freedom to substitute racing linings for the stock equipment (which you do in the Goodrich series), brake capacity depends almost entirely upon the weight of the car and size of the brakes. Under those circumstances, almost all of the eligible cars have adequate brakes, the Mazda RX-2 being the chief exception.
Since speed depends upon horsepower, there comes a point at which you have to get down to numbers.
With all of these car-evaluation parameters in mind, it's time to take a look at the tracks. The Goodrich series includes eight to 10 races, only three of which are on the superspeedways. So acceleration and handling are the most important qualities because they will see you through the conventional road courses in the best fashion. But the three superspeedway races depend almost entirely upon top speed and nothing else, so you can't afford to overlook this aspect.
The Competitive Equation
Since speed depends upon horsepower, there comes a point at which you have to get down to numbers. We knew the Wankel Racer produced 218 horsepower on the dyno, weighed 2350 pounds, and had a frontal area of 3400 square inches. Assuming that the Gremlins and BMWs were down to minimum weight and calculating their frontal areas from the specifications, we estimated their power-to-weight and power-to-frontal-area ratios relative to the Mazda based on their comparative speeds on the track. Solving the equation for horsepower, we concluded that the Gremlins had about 215 hp and the BMWs about 185, and this seemed within their capabilities. (Horsepower numbers have to be viewed with a great deal of caution. Some dynos—and some dyno operators—are optimistic; others are pessimistic. If you don't know the predilections of each, you can be seriously misled by their test results.)
Setting the Gremlin's power-to-weight and power-to-frontal-area as a target, it was then possible to check out all of the other eligible cars by simply substituting their weights and frontal areas and solving the equation for horsepower necessary to match the Gremlin's speed. That left the key question: Could the engines of the cars in question produce the required horsepower?
The power-to-frontal-area equation eliminates all of the small-engine cars right off the bat. We were particularly interested in the Toyota Corolla because of its 1850-pound minimum weight, but its frontal area turns out to be only 15 percent smaller than the Gremlin's and therefore would need about 180 horsepower to be competitive on long tracks. That would never happen with a 1.6-liter engine set up according to IMSA rules. The Honda Civic, with roughly the same frontal area, would be even worse off with only a 1237-cc engine.
Car and Driver
So the search for the third-best car was confined to those with engines of at least 2.0 liters, and it narrowed down to the Toyota Celica, the Mercury Capri 2000, and the Ford Pinto with either the 2.0-liter or new 2.3-liter engine. The Datsun 610 had previously been rejected because its 4.5-inch wheels are too narrow to work well with wide Goodrich Radial T/A tires, and the 2.0-liter Dodge Colt will not be ap­proved by IMSA as long as it is only imported with an automatic transmission.
Further calculations eliminated the 2.0-liter Pinto. IMSA assigned it a mini­mum weight of 2100 pounds and speci­fied an additional 200 pounds if the 2.3-liter engine was used. The 15 percent displacement increase of the 2.3 engine more than outweighed the 9.5 percent weight increase. Further, since frontal area remains the same, the larger en­gine would have a much better shot at the superspeedways.
Handling shot down the Toyota Celi­ca. It's a narrow-track, MacPherson-sus­pension car and much too nose-heavy in street form. And IMSA's preparation rules don't allow enough latitude to fix its basic problems. Also, the engine was a complete unknown, and performance parts are rare.
We were attracted to the Capri primar­ily because of its fine aerodynamics. Its smaller frontal area would require about 15 less horsepower than the Pinto for the same top speed, and its uncommon­ly slippery shape would help even more. It was, however, 100 pounds heavier than the Pinto with the same 2.0-liter en­gine, its track was two inches narrower in front and three inches narrower in back and, finally, it had a MacPherson front suspension. All of this was tem­pered by the fact that a street Capri han­dles better than the stock versions of most of the cars it would race against and therefore wouldn't need as much improvement to be competitive.
We try to benefit from our own experience. When we find products or suppliers that do the job, we stick with them.
At this point, neither the Pinto nor the Capri had a firm advantage. The Pinto promised high aerodynamic drag (due to its width and poor shape), excellent han­dling potential (control-arm front suspen­sion, wide track, and low car), and a large engine. The Capri offered low drag and moderately good handling.
It was the 2.3-liter engine that finally tipped the scale in favor of the Pinto. The 2.0-liter Pinto/Capri engine, on the other hand, had been around long enough so that all of the race shops had experience with it. And they all said the same thing: The intake ports are shaped wrong, severely limiting its potential for racing. At this point, nothing was known about Ford's new 2.3 engine except that it was the first U.S. engine to be pro­duced with all metric dimensions—which hardly counts when the starter waves the green flag. So we bought a cylinder head and shipped it off to Doug Fraser Racing Engines in Marblehead, Massachusetts, for a candid opinion. Fraser specializes in Formula Fords but has broad four-cylinder experience including 2.0-liter Pinto, Colt, and BMW engines built to IMSA specifications. We were also familiar enough with his work to know that his engines were durable and his horsepower quotes quite conserva­tive. Fraser pronounced the 2.3-liter ports substantially better than those of the 2.0 and predicted that the 2.3 would not only make more power than the 2.0 but would produce more power per cu­bic inch as well. At the same time, he was pessimistic about equaling the out­put of the 2.0-liter BMW, which has ex­cellent ports. But with enough work, he thought the big Ford could come close.
Adding up the Pinto's advantages and disadvantages, we could predict with fair accuracy its performance on various tracks. Its high drag and shortage of horsepower would hold it back on the superspeedways, but on short tracks its excellent chassis would probably compensate for any lack of power.
Our Car
This was as far as the project could go on a slide rule, so we went out and bought a solid 30,000-mile 1972 Pinto two-door. A new car would have been an easier way to go—there are no hidden cracks in the unit-body and no worn parts to rebuild—but the 1974 Pinto is a substantially heavier car, and we could see no way to trim the weight down to the 2300-pound IMSA minimum.
The job of converting a street car into a racing car is time-consuming, but it's not particularly complicated. Making the car fast is a straightforward application of physics. The engines were farmed out to Doug Fraser, since professional en­gine builders usually save you money in the long run. You need good engines if you want to win, and good engines are the products of machine shops, airflow benches, and dynamometers. Not many amateur racers have this kind of equip­ment in their garages—or, for that mat­ter, have enough time to build engines and keep their cars in first-class shape too. So we concentrated our efforts on the car, pausing occasionally to encour­age Fraser when the horsepower was elusive and to threaten him when he was late. His plan was to build the first en­gine according to the dictates of his own experience, using whatever special parts (pistons, camshafts, valves, springs, etc.) could be obtained in time to meet our deadline. The second engine, to be available later in the season, was to be the product of much camshaft and cylin­der-head development and would —hopefully—produce more power.
By having engines built outside, we were free to concentrate on the chassis. Since this figured to be the Pinto's only strong point, we wanted to optimize ev­ery detail right from the start. And the only way to have complete control, to make sure no shortcuts were taken, was to do the work in our own shop. For­tunately, C/D is equipped to do this.
When it comes to building racing cars, there are a very few key guidelines to follow, and if they are kept firmly in mind, the car will almost always turn out well. The most important is safety. The car has to be structurally strong to prevent breakage and it has to be reinforced to protect the driver in case of a crash. Like most of the other construction guide­lines, safety has side benefits that show up in performance. If a car is structurally strong, it will also be rigid. And a rigid car will be predictable to its driver and re­spond to fine tuning adjustments of the brakes and suspension.
The main source of rigidity is the tubu­lar-steel roll cage. It not only protects the driver but stiffens the car as well. To do this properly, it must tie into any sus­pension mounting points that are of questionable rigidity. Finding them is pure educated guesswork. Usually you tie into as many as you can reach and gusset the ones you can't, all the while trying to add the least weight. There are no textbooks for guidance, so we brazed up a scale model of the roll cage using straight sections of stiff wire. This proved to be only a rough aid, since it is impossible to simulate the structure of the car to which the cage will be at­tached. The job of stiffening the car is simpler in the Goodrich series because the rules specify street radial tires, which don't generate the cornering forces of racing tires and therefore don't load the chassis as much.
When we rubbed a hole in the oil pan during the car's third race (at Lime Rock), we knew how low is too low.
Next in importance to a rigid, safe car is—in the interest of both handling and aerodynamics—a low car. For handling, the important thing is to have the weight (center of gravity) low. This can be achieved in part by lowering the body/chassis unit as far as possible on the suspension, which obviously lowers every single pound in the car. But you can also lower the center of gravity by mounting various components (the seat, fuel cell, oil cooler, and other movables) as low in the car as possible.
To reduce aerodynamic drag, you want to minimize the space for air to flow under the car. A low car is the most di­rect way of doing so—but there is a limit. If you go too far, you'll either bottom out the suspension or scrape something off the underside. The only way to know is try and see what happens. With the Pin­to at IMSA's minimum height (six inches from the ground to the center of the rocker panel) we rubbed a hole in the oil pan during the car's third race (at Lime Rock). Now we know how low is too low.
The next item is to make sure that all moving parts travel in exactly the paths you intend with no interferences. This applies mainly to the suspension. We fa­vor hard bushings instead of rubber in all of the suspension pivots. It's also impor­tant to make sure the shocks don't bot­tom out, the ball joints aren't over-an­gled, and the brake hoses are neither pulled tight nor pinched as the suspen­sion moves through its travel.
It's also a good idea to build in extra capacity in those areas where there is no serious penalty for doing so: Overde­sign the cooling system (our Pinto has a Corvette aluminum radiator); use the largest brake ducts that will fit, and mas­ter cylinders with ample reservoirs; build in two electric fuel pumps with a large-di­ameter line to the carburetor; choose oversize filters where possible; and use heavy electrical wiring and high-quality bolts, clamps, and fasteners. The car may turn out somewhat heavier, but you won't have to waste time reworking systems that prove to be inadequate during the first few test sessions.
We also try to consult specialists whenever we can find them, since it al­ways saves time to benefit from some­body else's experience. Sometimes oth­er teams will even give away a tip or two. Bob Negstad, who modified the suspen­sion on Larry Campbell's quick Pinto, suggested that we use the 1974 Pinto steering gear because it was stronger and told us how to fabricate the neces­sary mountings. He also showed us how to adapt the larger 1974 disc brakes to the 1972 car.
The final point to remember about building a race car is that there is no single right answer for any part of the car.
Finally, we try to benefit from our own experience. When we find products or suppliers that do the job, we stick with them. Much of the special equipment on the Pinto was proven on the previous Mazda Rotary Racer project: Stewart­Warner instruments, Superior Industries steering wheel, Cibie lights, Raybestos disc brake linings, and Velvetouch drum brake lining specially made at Rochester Brake and Clutch in Rochester, New York. The Pinto also has certain prob­lems of its own that require special attention. A Hurst shifter happily replaces that standard Ford part that has been known to periodically pop out of the top of the transmission if the driver pulls too hard. And Hurst/Schiefer also makes 4.10 and 4.30 axle ratios to supplement the standard Ford gears, which are correct only for superspeedways. For the most part, we used Koni shock absor­bers in front, Bilsteins in back, and did some promising experimentation with Gabriel Striders along the way. Unfortu­nately, four races didn't give us enough time to find all of the answers in the shocks department.
Which brings us to the final point about building a racing car: There is no one single right answer for any part of the car. There is no perfect spring rate, no optimum chassis stiffness, and no ide­al sway-bar setting. Cars will work well with a broad range of these valves so long as they are all compatible. The only way to know what works and what doesn't is to try them. This applies par­ticularly to the suspension. Our plan was to make the best estimate going in and then provide plenty of adjustment. It has proven to be a workable approach. The Pinto required only half a day on the skidpad and half a day of testing at Lime Rock to iron out its problems. With no more proving than that, it finished at Tal­ladega (where two pit stops to replace flat tires—not Goodrichs—dropped it to 24th place) and then went on to win at Charlotte a week later.
Would we do it all again? Well, if our mechanical insight gets much better, we figure that soon there won't even be any point in going to the track. We'll be able to decide the outcome of the races without ever leaving our desks.