Home Can-Am at Laguna Seca Inside of the Can-Am Cars

Inside of the Can-Am Cars

by Karl Ludvigsen

editor's note: This article appeared in the 1969 program guide for the Monterey Castrol GTX Grand Prix.

Handsome purses and liberal rules have led to the development of the fastest road-racing cars in the world for the booming Can-Am series. Here's a look inside them.

No one knows just how fast they'll go, these Can-Am cars, but they're the fastest racing cars in the world, fastest in the sense of getting around a road course as quickly as possible. They've proved it several times, with faster lap times at tracks like Mosport where Formula 1 Grand Prix cars also run.

At the tracks in the U.S. and Canada they've geared down for maximum acceleration instead of top speed. Even so, at Riverside they'll appraoch 200 on the back straight. Considering that the Le Mans Mark IV Fords could do 200 mph with 100 less horsepower and a higher roof line, a top Can-Am car might be able to go 250 with the right gearing!

One thing is certain: In spite of the fact that this is a championship for drivers, it's equipment that gets the job done in these events. Even some of the best drivers admit that there are some places on some tracks, like the downhill right-hander at Bridgehampton, where the cars are just too fast.

With no limits on engine size, type or power (except for a limit on turbines which make them ineligible), there are certain to be some teams who have more power, and more durable power, than the others. As Dan Gurney found out last year, you can try to beat them with lightness and smartness, but it's very nearly impossible.

Even though there's no limit on engine size and type, most of the Can-Am cars are powered by modified stock American V8 engines. There have been exceptions. Ferrari had cars two years ago for Ludovico Scarfiotti, Chris Amon and Johnathan Williams, last year for Pedro Rodriguez and Amon, the latter a very fast special V12 racer with four overhead cams that will be back in refined form this year.

The Ferraris have to be taken seriously because they've stopped trying to prove that a small engine can beat a big one by revving faster, and have built a big one instead. Meanwhile the big ones are even bigger this year.

In 1968 most of the aluminum block ZL-1 Chevrolets and "wedge" Fords were even-steven at 7 liters, or 427 cubic inches. They were able to produce between 580 and 620 horsepower, revving safely to 7000.

This year will see more of them at 8 liters, nearer 488 cubic inches, larger than the biggest production car engine in the world, the 472-cube Cadillac V8.

Because the additional liter in '69 is intended mainly to boost torque through the middle speed ranges, it won't increase the horsepower in direct proportion. Even so some of the big engines this year, the stroked Chevys and the "marine" 490-cube version of Ford's semi-hemi V8, will reach and exceed the 660hp level.

These very large engines could never have been used if Chevy and Ford hadn't moved, as they did, to cast cylinder blocks in aluminum instead of iron. This saves just enough weight to allow the big V8s, also with aluminum heads, to be usable in the back of a light car. The aluminum block actually causes the engine to lose power, compared to an iron block, but they make up for that by slicing off weight the power has to push. In 1967 McLaren annihilated the opposition in Can-Am racing (for the first time) with fuel injection. His were British Lucas injection systems, which gave his engines a little bit more poser and a lot better, sharper responce to the throttle.

McLaren also used the vaporization of fuel in the manifold to cool the gasoline in the system, reducing the cause of vapor lock. This slick little trick had been borrowed from Grand Prox engines and was copied in 1968 by Traco and Bartz, the most important builders of Can-Am engines in the U.S. They also used Lucas injection, while Jim Hall uses a special Rochester injection on his Chaparral engines, prepared this year by Gary Knutson, McLaren's engine-builder.

Ford's Can-Am power units have had modified Hilborn injectors much like those used on the Indy Ford V8s.

Another important trend has been to what racers call "dry sump" engine oil systems. Now, the sump (oil pan) isn't dry, but neigher is it asked to hold all the engine oil, as it probably does in your car, unless you have a 300SL Mercedes or a Porsche Carrera. Instead there's an extra big oil pump whose only job is to suck the oil out of a shallow pan as it falls from the engine, and pump it to a seperate oil tank. From there the oil pressure pump sends it to the bearings.

The seperate oil tank can hold much more oil than a conventional sump, allowing an engine to finish a race even if it's using a lot. A larger oil volume also stays cooler, helped by the seperate oil radiators that are always used, and a properly designed tank can extract unwanted air from the oil.

Further, removel of the oil from the bottom of the engine means that the block can be placed closer to the ground, lowering the car's center of gravity and overall height — vital advantages these days. That's why the trend in sumps is towards the extra-dry.

Most Can-Am cars also carry a seperate cooler for the oil in the transaxle, which can get pretty warm carrying high torques at high speeds. This is catered to by Mike Hewland, whose LG500 (four-speed) and LG600 (five-speed) transmissions are used in most of the top cars.

The fastest don't always have more speeds; Team McLaren used only four with the big Chevy in his M8A because it had so much torque it didn't need five speeds.

And in the last few years Jim Hall's famous automatic box has become progressively less so, after starting out with only a hydraulic torque converter, like an old Buick Dynaflow. Then a second speed was added and finally a third one in the manually-shifted box back of the converter.

To put all the power on the road, Can-Am car designers move as much weight as they can to the rear (driving) wheels. That's one reason Hall put his radiators in the rear, for example, to bring about two-thirds of the car's laden weight on those tires to give them the best possible bite.

Some weight has to be left on the front wheels, of course, so you can steer the car! But another approach is being taken this year with new drive systems, to all four wheels. At least three builders are looking at four-wheel drive.

Bruce McLaren's designing his own four-wheel-drive system to use on his Grand Prix cars and his Can-Am cars. Here's his reason why: "Putting all the drive through the rear wheels means that you're only working the front tires for braking, you might as well use them for traction too. Once we get four-wheel drive working, we expect the speed through the last half of the corner and the exit speed from the corners to be up quite a bit."

For similar reasons Lola has built a new Can-Am racer with Mike Hewland's 4WD system, like the one on the Indy Lolas of the Penske team, and Armco Steel has sponsored Bob McKee's latest car, with four-wheel drive by Britian's Ferguson Research, a pioneer in the field.

Some of the most dramatic tire development has taken place in Can-Am racing, again because there are no limits to the expansion of tire width. On an open-wheel car the tire offers a lot of the aerodynamic drag; a wider one can sometimes slow the car down! Not so in the envelope-bodoed Can-Am car, which can have tires as wide as the car is, and sometimes probably will. They won't go quite that far this year, but Goodyear and Firestone are still giving fits to the wheel designers at Lola and McLaren as they come up with wider and wider tires.

To use the latest rubber, Can-Am teams often get help from Ted Halibrand, whose cast magnesium wheels are world-famous, or from Fred Phun, whose new spun aluminum wheels can be adjusted in width, thanks to their two-piece construction.

Around 1960 Lola and Lotus were setting the style for the kind of independent supension, with tubular links and concentric coil-shock units, that future racing cars would use. Today's Can-Am cars are pretty much the same. There have been some attempts to be different, such as the King Cobra of late 1967 and the solit-axle Caldwell D7 and D7B of 1967-68, but they haven't been consistently successful. The solit-axle approach may well bear fruit in the future, though, with wider and wider tires which like to be kept flat on the road.

What holds all this machinery together in most of the Can-Am cars? A great big fuel tank with a hole in it for the driver to sit in, that's what. The tubular space frame, once considered the end of the line for a racing car chassis, is now completly obsolete.

New Can-Am cars today have frames riveted and glued together of steel, aluminum and magnesium sheets to form what looks like, and is often called a "tub." Fiberglass can also be used and was for the first successful Can-Am "tub," that of the Chaparral 2. The size of the center hole in the "tub" is governed by the pertinent rules in Appendix A of the SCCA's General Competition Rules, which rather loosely require that there be room for a passenger.

Inside the "tub" there are rubber bladders, built to be resistant to tearing in a crash, retaining the more than 60 gallons of fuel these thirsty cars need to finish a race of 150 to 200 miles without a pit stop.

For the M8A, McLaren made a radical departure from his competitors by using the engine, with some tubular braces, as the rear part of the frame. The front of the engine was attached to the "tub" and the rear part, where the transaxle and attached, carried the rear suspension. This helped Bruce keep the weight of his championship-winning car down to only 1450 pounds, a lettle less than a Healey Sprite, an MB Midget or a fiat 850 Roadster.

How does it go with more than 600 horsepower? Pretty well, like zero to 100 in little more than 5 seconds and certainly less than 6.

Both Chaparral and McLaren have led the way in designing bodies for these cars that help hold the tires against the highway, replacing older styles that looked nice but tended to take off and fly.

Certain features are evedent: a wide, scoop-like nose that's as close to the ground as possible; an upward flow of air out of the back of th radiator; vents in the front fenders that keep aire pressure from building up there, and a high, wide rear spoiler that deflects the air upward as it's departing. If the complete shape is a little like a wedge, or a doorstep, it's deliberate, made to shove its way under the air, producing forces that hold the car and its tires lightly against the road.

Last year Hall and Surtees were the only Can-Ammers to use rear wings. McLaren tried them in the development phase but didn't use them in racing.

This year, following a season in which wings proved themselves in Grand Prix racing, we'll see a lot more. And probably have the same trouble the G. P. car makers have in keeping them attached to the car. What are the wings for? To keep the tires pressed against the ground, in the same manner as the latest bodies but hopefully in a more powerful way, with less resulting drag to slow down the car.

Those who really make the most of wings on a Can-Am car will have designed new body shapes to complement them correctly. Jim Hall, of course, did that long ago.

 

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