The 2.0-liter Ford Zetec four-cylinder engine saw widespread use in motorsport following its introduction in a number of 1990s Fords. SVT versions of the engine in the Focus eventually produced as much as 170 horsepower naturally aspirated from 2.0 liters of displacement, which is respectable. All that said, other dual overhead-cam four-cylinders from the likes of Honda have much better-flowing cylinder heads, and to get a Zetec even close to that takes a lot of skilled labor.
YouTube channel Josh’s Engine Rehab recently documented the process of boosting the flow of a Zetec head with some port and valve adjustment. He does a variety of work on different manufacturers’ stuff, but it’s mostly modifying heads for performance. He thought he could get this particular Zetec out of a Caterham Seven up to flow levels of a comparable Honda engine, but as it turns out, that might’ve been a little ambitious.
Cylinder head port flow is typically evaluated on a flow bench using cubic feet-per-minute as the unit of measure. The stock Ford head came in around 160 CFM on the intake and 129 CFM on the exhaust. After removing a lot of metal and making some other modifications, those figures were eventually boosted to 233 CFM on the intake and 204 CFM on the exhaust.
Initially, the channel’s host Josh said he believed he could squeeze out 300 CFM on the intake with little effort. The Zetec’s head didn’t flow quite as he expected, though. An engine builder out of the U.K. with more experience with the Zetec tells him the motor has “a shit head to be honest and crap port design compared to other four bangers.” A blunt assessment.
Nevertheless, Josh’s work is still very good in the context of the Zetec. For reference, Ford itself couldn’t manage much better when it ported the 2.0-liter’s head for competition. The Blue Oval’s design flows similar CFM at lower valve lifts, but Josh’s port job beats it at the top on the intake and exhaust.
It’s impressive to see this kind of work still being done today. Hot-rodding has its roots in stuff like this. As opposed to buying new parts off the shelf, some skilled—and unskilled—individuals still opt to save some money, pick up a die grinder, and start removing metal in the right places to improve performance. Head porting is a science in terms of theory, but very much an art when it comes to actually doing the work without cutting into something like a water jacket. It takes time, skill, knowledge, and experience to do it right, but the gains from plenty of elbow grease are always satisfying to see.
Got a tip? Email us at tips@thedrive.com