British Firm develops Independently Variable Timing for Push

Conventional wisdom holds that pushrod engines are low-tech. Almost all foreign cars are overhead-cam, and Detroit has gradually moved away from them for all but its big V-8 engines.

But as any good hot-rodder will tell you, pushrod engines are capable of making plenty of power, and in some ways doing it better than comparable overhead-cam counterparts.

Pushrod engines can be more compact than overhead cam engines, and can allow a larger-displacement engine to fit in a space that might be too small for an equivalent overhead-cam engine. They also generally generate plenty of torque, and can be surprisingly fuel-efficient. Compare the mileage of the 505-horse Corvette Z06 (16/26) versus the 483-horse Ferrari F430, (12/17).

Yet, there have been a few things that pushrod engines couldn't do that overhead-cam engines could...until now. Previously, independently-variable intake and exhaust timing was only possible with dual overhead cams. But thanks to the engineering wizards at the British firm Mechadyne, pushrod engines can now benefit from this technology as well.

The first production car to showcase this technology is the 2008 Dodge Viper. With only a mere .1 liter increase of displacement, the engine's output jumped a staggering 90 horsepower to 600.

Though detailed diagrams and specifications are hard to find, the basic idea is two concentric camshafts, an inner shaft and an outer tubular shaft. The exhaust valves are driven by the outer lobes, and the intake valves by the inner lobes. The intake and exhaust lobes can phase independently of one another, allowing extremely precise control of valve timing.

Though pushrod engines may not be around forever, thanks to innovations like this, it appears their death sentence has been given an indefinite stay of execution.