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By Jay Storer

To some people the word “evacuate” conjures up unpleasant images, but to drag racers who want some free horsepower from their engine, the image is a win light at the end of the 1320. We’re talking here about taking away pressure from the engine’s crankcase and making the job of the piston rings a lot easier. It’s a simple, inexpensive addition to any sportsman or pro racecar that benefits engine life, and the results can be worth one to two tenths!
Up to 30 extra horses from a re-engineered pump originally designed for emissions purposes, who’d have thunk it? GZ Motorsports did, and their complete crankcase vacuum systems are now on many top Sportsman and Pro racecars.

Back in the '70s, drag racers realized there was more to releasing crankcase pressure than just having a pair of cool-looking aluminum breathers bolted to their valve covers. Yes, breathers kept undue pressure from accumulating in the crankcase and valve covers, but someone figured out that sucking the fumes out, rather than just letting them go, had more benefit by allowing the piston to seal better.

This is when everyone started plumbing breather hoses down to their header collectors and installing one-way valves. The valves were those typically found in OEM smog-system piping of the period and prevented exhaust pressure from going into the crankcase, but allowed the negative pressure of the fast-moving exhaust to deplete the pressure in the crankcase. It was worth some power, kept the engine cleaner, and helped the rings seal a little better.

Although the Pro Stock and a few other classes were using some form of vacuum pump even then, the header-evac was the state of crankcase evacuation for most racers until some years later when mufflers were first required on some classes at California tracks. For these cars, evacuation of the system through the header collectors was no longer going to be an option, since the draft in their system was virtually lost.

Greg Zucco, a structural engineer by profession and a dedicated sportsman racer going way back, started his company GZ Motorsports in 1985, making alternator mounting kits and supplying small performance alternators for racecars after being frustrated with ill-fitting kits he had purchased. Over the years, Zucco had seen some vacuum pumps applied to drag engines to affect a better suction on the crankcase to create more power, but he again envisioned the possibility of something better than what was generally available, as well as something more affordable to the average racer.

Opened up for a forensic look is the late-model Ford smog pump that is the basis of Zucco’s racing evac system. The carbon-coated drum (left) rotates inside the housing, and is equipped with vanes for pumping air. The OEM precision-die-cast housings are lighter than billet pumps.

Around 1995 he began experimenting with automotive AIR (Air Injection Reaction) pumps commonly called “smog” pumps. These are designed to pump air into the exhaust system with the goal of helping to finish off any tiny particles of unburned hydrocarbons that escaped the combustion chambers. Zucco bought rebuilt pumps designed for Toyotas because they were cheap, uncomplicated and didn’t take up a lot of space in the engine bay of his big-block-powered ‘34 Chevy Super Gas roadster. His engineer’s curiosity had him dismantling various types of pumps to see how they worked and how he could revamp them for drag racing.


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