By David Reher, Reher-Morrison Racing Engines
“If you want to move forward, you have to look where you’ve been.”
In the 11th century, it was a fact that the world was flat. Any medieval scholar, astronomer or captain could affirm the self-evident truth that the Earth was the center of the universe and that anyone who ventured too close to the edge would fall off into the abyss. It wasn’t until centuries later that skeptics like Copernicus, Galileo and Columbus reasoned that our world was actually a tiny globe orbiting a distant star. Reality hadn’t changed, but people’s perceptions did.
Racing has its share of flat earth “facts” that are later revealed as fictions. For example, when I started racing, it was an unassailable fact that the small-block Chevy’s stud-mounted rocker arms were the ultimate high-rpm valvetrain; now, of course, shaft-mounted rockers are nearly universal. It was an indisputable fact that cylinder head ports should be polished like a mirror; today we prize the machining marks left by CNC cutters as aids to atomizing fuel. We once knew that lightweight pushrods and flyweight lifters were essential for a high-speed engine; now these components are as stout and as stiff as Roman columns. The physics of racing engines haven’t changed, but collectively we have revised the “facts” to fit our new view of reality.
History teaches us that technology is constantly in a state of flux. Some of the mistaken beliefs that we regarded as gospel 20 years ago weren’t foolish – they simply fit with what we knew at the time. Our flexible pushrods worked fine because we didn’t have the stiff valve springs that are available today. They helped to suppress some of the nastier valvetrain dynamics that harsh cam profiles produced. They were cheap, readily available, and offered plenty of clearance for port walls. Consequently it was obvious that lightweight pushrods made a race car run faster.
I’m sure that many of the facts about racing engines that we ardently believe today will eventually be proven to be as wrong-headed as the notion that the world was flat. The people who are willing to question conventional wisdom often become the innovators who expand the performance envelope. After all, if drag racers had believed the pundits who proclaimed that the maximum achievable speed in a quarter-mile was 160 mph, we wouldn’t have 330 mph Top Fuel dragsters and 208 mph Pro Stocks. If engine builders had subscribed to the rule that an engine couldn’t survive with an average piston speed over 4000 feet per second, we wouldn’t have 500 cubic inch engines that are capable of running at nearly 10,000 rpm.
The past is a mirror that reflects the future – if you want to move forward, you often need to look where you’ve been. Ten years ago, if you had asked me where we would find gains in engine performance, I’d probably have answered that we’d just about reached the end of the road in development. And yet in the last decade, engine builders have made tremendous strides in performance, efficiency and reliability.
Using Pro Stock as an example, the national speed record has climbed from 199 to 208 mph in 10 years. Given that Pro Stock engines are among the most refined powerplants in racing, a nine-mph increase is an incredible achievement. Neither the rules nor the basic hardware has changed, so that improvement is the result of hundreds of small, incremental steps.
Consider the advances in valvetrain technology, which is just one area of development. The valve springs that were the hot setup a decade ago wouldn’t survive a minute with today’s high-lift camshaft profiles. Similarly, we couldn’t lift the valves an inch off their seats without the high-tech springs that are now available. It’s a continuous, self-propelled cycle: Better springs enable more aggressive cams, which in turn spur the development of better springs . . .
Technology is the fuel that drives development. The advent of coatings such as DLC (diamond-like carbon) and Casidium has permitted engine builders to do things that were once thought to be impossible. The wear resistance of these coatings has allowed valve seat angles in high-end cylinder heads to become steeper without sticking the valves and reduced wrist pin galling with ultra-efficient dry-sump and crankcase vacuum systems.
What’s the next step in engine development? I wish I could tell you. But I’m certain that 10 years from now, we’ll look back at the state of the art in 2006 and ask, “What were we thinking?”