Home > Auto Racing > Understanding Auto Racing > Road Racing > Can-Am

Can-Am

     Rules Were Apparently Optional

Most racing series begin with a rulebook and then spend the next several decades adding pages whenever somebody gets clever.

Can-Am began by getting the rulebook mostly out of the way.

The Canadian-American Challenge Cup launched in 1966 for Group 7 sports racers, and the technical freedom was astonishing even by 1960s standards. Engine displacement was effectively unrestricted. Supercharging and turbocharging were allowed. Aerodynamic development was wide open. There was no production-car formula forcing the machinery to resemble anything sitting in a dealership.

The result was exactly what happens when talented engineers are given money, horsepower and very few reasons to behave themselves.

Big-block Chevrolet V-8s went into lightweight McLarens and Lolas. Jim Hall’s Chaparrals experimented with high wings and fan-assisted ground effects. Porsche eventually arrived with turbocharged flat-12 power that pushed the series beyond 1,000 horsepower and into territory that still sounds unreasonable half a century later.

Can-Am lasted only from 1966 through 1974 in its original form. That was enough time to produce some of the fastest, strangest and least apologetic road-racing cars ever built.

Group 7 — The Rulebook With Plenty of White Space

Can-Am used the FIA Group 7 sports-racing category. Unlike production-based classes, Group 7 did not require manufacturers to build road versions or preserve much connection to a street car.

The cars needed basic sports-racer features such as enclosed wheels, two seats and the required safety equipment. Beyond that, designers enjoyed freedom that would make most modern technical directors reach for another binder.

There was no meaningful engine displacement ceiling. Naturally aspirated engines were legal. Superchargers were legal. Turbochargers were legal. Aerodynamics could be developed aggressively, and builders were free to explore materials, suspension layouts and packaging without trying to make a production shell fit over the idea.

That freedom did not remove engineering problems. It removed excuses.

If the car lacked power, there was little preventing the builder from finding more. If it lacked grip, the aerodynamics department could become more imaginative. If the chassis was too heavy, somebody could make it lighter.

The only unfortunate development was that everybody else received the same freedom.

The Basic Shape — Two Seats and Very Little Else

A classic Can-Am car was a low, wide sports racer with the wheels enclosed by bodywork and the driver sitting close to the centerline. The second-seat requirement technically existed, although nobody was preparing a picnic basket for the passenger.

The body was shaped around speed rather than identification. There was no need to maintain a Mustang roofline, Corvette grille or other showroom resemblance. Airflow, radiator placement, tire clearance and chassis packaging could dictate the shape.

That produced cars with enormous rear tires, very low noses, broad rear decks and increasingly dramatic wings. Some looked elegant. Others looked as though the wind tunnel had been allowed to finish the styling after the designer went home.

Underneath was usually a lightweight tube or monocoque structure carrying a mid-mounted engine, racing suspension and very little unnecessary mass.

Can-Am cars were not modified road cars. They were road-course weapons built with the inconvenience of public roads removed from the specification.

The Engine — Cubic Inches Were Easier Than Restraint

Early and mid-era Can-Am became closely associated with large-displacement American V-8 power, particularly aluminum Chevrolet engines installed in lightweight sports-racing chassis.

The appeal was obvious. Big-block V-8s could produce enormous torque and horsepower without the complexity of highly stressed small-displacement racing engines. In a car weighing far less than a normal automobile, even 600 or 700 horsepower was enough to create a power-to-weight ratio that made straightaways disappear quickly.

As development continued, displacement and output climbed. There was no class formula rewarding modesty, so engine builders concentrated on producing whatever the chassis, tires and fuel system could survive.

The engine also had to function as part of a road-racing package. It needed throttle response through corners, oil control under sustained lateral load, enough cooling to survive long races and durability beyond one heroic qualifying lap.

Can-Am did not merely allow large engines. It gave engineers a reason to make large engines behave like racing instruments instead of drag-strip blunt objects.

McLaren — When Dominance Came Painted Orange

Bruce McLaren understood Can-Am almost immediately. His team built cars specifically around the freedom of the rules rather than trying to adapt something designed for another championship.

The McLaren M6 and later M8 series combined lightweight construction, strong Chevrolet V-8 power, careful aerodynamics and development disciplined enough to make the outrageous formula repeatable.

Bruce McLaren and Denny Hulme turned the late 1960s into the era often remembered as the Bruce and Denny Show. The cars were usually orange, usually fast and frequently at the front.

That success is important because Can-Am was not merely a contest to build the strangest machine. A clever idea still had to finish races, work at different circuits and be understandable enough for the team to tune.

McLaren won by combining freedom with engineering discipline. Anybody could exploit the thin rulebook. McLaren repeatedly exploited it without losing track of the stopwatch.

Aerodynamics — Then Everybody Started Looking Up

Can-Am arrived just as racing engineers were beginning to understand how aggressively aerodynamic downforce could be used on road cars.

Early wings appeared high above the body because engineers wanted them operating in cleaner air. Some were mounted directly to suspension uprights so aerodynamic load went more directly into the tires rather than first compressing the chassis springs.

The potential was obvious. More downforce meant more cornering grip without adding the same amount of static weight. The faster the car went, the harder the air could push it into the pavement.

The danger was equally obvious once failures began occurring. A wing or mounting failure at speed could instantly remove a large portion of the grip the driver was depending on. Regulations eventually became more restrictive about how wings could be mounted and operated.

Can-Am engineers learned quickly that air could function like invisible ballast.

They also learned invisible ballast could leave without warning.

Chaparral — Jim Hall Brought Different Questions

Jim Hall’s Chaparrals were among the most inventive cars in Can-Am because Hall kept asking questions other teams had not reached yet.

Could a wing be placed high enough to work in cleaner air? Could aerodynamic load be connected more directly to the wheels? Could the car create suction underneath itself rather than depending only on air flowing over a conventional wing?

The most famous answer was the Chaparral 2J. It used separate fans at the rear to evacuate air from beneath the car while skirts helped seal the low-pressure area to the track.

The important part was that the suction did not depend primarily on vehicle speed. Conventional wings make more downforce as the car goes faster. The 2J could generate substantial grip even in slower corners because the fans were actively pulling air from underneath.

It looked like a large white box with racing tires attached.

That was unfortunate for anybody hoping appearance might be an accurate measure of sophistication.

Mechanical Grip Still Had to Do the Dirty Work

For all the wings and experimental aerodynamics, a Can-Am car still needed suspension and tires capable of handling enormous loads.

The cars used independent racing suspension, large brakes and wide racing tires designed to cope with a combination of acceleration, braking and lateral force far beyond ordinary road cars.

Setup remained a compromise. More front grip could help turn-in but make the rear nervous. More rear stability could create understeer. Springs, shocks, anti-roll stiffness, alignment and ride height all influenced both mechanical grip and aerodynamic attitude.

As wings became more powerful, chassis setup became even more complicated because aerodynamic load increased with speed. A car could feel one way in a slow corner and substantially different in a fast one.

The suspension therefore had to work with both the pavement and the atmosphere.

Can-Am engineers were not short of things to adjust.

The Tires — Wider Became a Perfectly Reasonable Answer

Large engines create a predictable problem: the rear tires eventually have to do something useful with the horsepower.

Can-Am cars became famous for enormous rear rubber because traction was one of the few limits the rulebook could not repeal. Wider tires increased the available contact patch and gave the chassis a better chance of turning engine torque into acceleration.

The front tires had their own assignment. They needed enough grip to change direction under braking and cornering loads that continued climbing as aerodynamic development improved.

Tire temperature and wear could change the balance over a race. A driver who abused the rears early might spend the final laps owning all the horsepower and very little ability to apply it.

There is always a final rule in racing: the pavement gets the last vote.

Brakes — Arriving at the Corner Was Only Half the Experiment

Can-Am cars accelerated brutally, which meant every major braking zone became an equally serious engineering problem.

Large racing disc brakes had to repeatedly turn high speed into heat without fading, cracking or changing pedal feel enough to surprise the driver. Cooling ducts became part of the package, and brake balance had to remain adjustable enough to suit the circuit and fuel load.

The driver wanted maximum deceleration without locking the tires. Then the brake had to be released smoothly enough for the front tires to transition from slowing the car to turning it.

Extra horsepower could produce a larger top speed on the straight. That simply gave the brake system more work at the other end.

Can-Am engineers were allowed to solve one problem by creating another almost immediately.

The Driver — A Thousand Horsepower Still Needed Finesse

The cars looked brutal, but simply standing on the throttle was not enough. A Can-Am driver had to manage enormous power while balancing braking, steering and tire grip through road-course corners.

Throttle application was especially important. A large-displacement V-8 could overwhelm the rear tires on corner exit, while the later turbocharged cars added another complication: power delivery could rise dramatically as boost arrived.

The driver therefore had to feed power in according to steering angle and available grip. Too much too soon turned horsepower into wheelspin. Too little gave away acceleration to somebody willing to use more.

High-speed corners demanded trust in wings and chassis balance. Slow corners demanded mechanical grip. Braking zones demanded precision because there was a great deal of speed to remove before the scenery became relevant.

Can-Am rewarded bravery.

It rewarded drivers who knew exactly when bravery stopped being useful even more.

Porsche and Turbocharging — Apparently 800 Horsepower Wasn’t Enough

By the early 1970s, Porsche entered Can-Am with turbocharged versions of the 917 and changed the scale of the horsepower discussion.

The 917/10 showed what turbocharging could do in a lightweight sports racer. Then the 917/30 arrived in 1973 with a 5.4-liter turbocharged flat-12 producing about 1,200 horsepower in race specification, with even larger figures associated with maximum qualifying trim.

That was not simply more power than the Chevrolet-powered cars. Turbocharging gave Porsche a way to make extraordinary output without relying on ever-larger naturally aspirated displacement.

Mark Donohue and Penske Racing turned the 917/30 into the ultimate expression of the original Can-Am formula: extremely light, aerodynamically developed and carrying more power than the tires could use casually.

The series had started by asking what engineers would build if engine restrictions were mostly removed.

Porsche eventually delivered the invoice.

Why the Formula Could Not Stay Wild Forever

Unlimited development is wonderful until somebody has to pay for it.

Can-Am’s freedom encouraged rapid innovation, but rapid innovation made yesterday’s competitive car obsolete quickly. Teams with the resources to develop new engines, aerodynamics and chassis ideas could move ahead faster than smaller entrants could respond.

Porsche’s turbo program pushed that problem to an extreme. Once the 917/30 demonstrated what manufacturer-level development could achieve under the existing formula, competing required more than a clever chassis and a Chevrolet V-8.

Rules tightened, fuel economy entered the discussion and Porsche withdrew after 1973. The original championship continued through 1974, when Shadow won the title, but the era everybody remembers was effectively finished.

The lesson was not that technical freedom had failed. It had succeeded so thoroughly that the cost of keeping up became part of the competition.

Why Can-Am Still Looks Modern

Many ideas that seem normal in modern racing were being explored aggressively in Can-Am when most road cars still had carburetors, bias-ply tires and chrome bumpers.

Large aerodynamic wings, sophisticated lightweight construction, turbocharging, unusual cooling arrangements and active attempts to control underbody pressure all appeared because engineers were free to chase lap time directly.

The series became a laboratory where an idea could move from sketch to race car without first surviving several committees devoted to preventing it.

Not every experiment worked. Some were expensive, unreliable or quickly restricted. That was part of the value. Racing discovered the weaknesses at speed instead of in a conference room.

Can-Am was not ahead of its time because everybody knew the future.

It was ahead because the rules allowed somebody to try it first.

Reading a Can-Am Car

Start with the proportions. The low nose, wide track, enormous rear tires and mid-engine layout tell you the car is built around acceleration, cornering grip and minimum frontal area rather than production-car packaging.

Then look at the aerodynamics. Early cars may appear relatively clean, while later machines carry larger wings, more developed noses and increasingly deliberate airflow management. Chaparrals deserve special attention because their bodywork often reveals an engineering question nobody else was asking yet.

Look at the engine installation. A large Chevrolet V-8 explains one branch of Can-Am thinking: simple, powerful displacement in a light chassis. A turbocharged Porsche flat-12 represents the other extreme, where expensive engineering pushed the same freedom into four-figure horsepower.

Watch the driver’s hands and throttle application in old race footage. The cars move around more than modern prototypes, especially under power, and the driver is often balancing substantial mechanical grip against an engine capable of exceeding it.

Finally, remember that the diversity is the point. A McLaren, Chaparral, Lola, Porsche and Shadow did not need to reach the same answer.

They only had to reach the finish line first.

↑ Back to the Top — Before Somebody Finds Another 200 Horsepower