Most vehicles have a silencer built into the air box someplace. This is usually a restriction along with some expansion chambers. These fit and work very well in the nearest trash can. There is minimal noise reduction at full throttle but the air restriction kills power and acceleration. For example, a 1991 1.9L has a tube that comes in from the driver's side fender. How it pulls much air from there is anyone's guess. Then it goes through a very small restriction, much smaller than the throttle body or air flow meter passage. The size of this restriction limits the maximum airflow of the engine. No wonder the engine is only rated at 88 hp.

By removing this plumbing and replacing the air filter, the power will be more like 100 hp. There is a big difference in the rate off acceleration as the engine revs. Look for any restriction to airflow into the air filter and remove it or open it up one way or another. Removing everything past the filter also helps to get slightly warmer air from the engine bay. This results in a leaner condition and helps with gas mileage. Modification is quite an easy procedure and simply requires cutting everything past the filter, as long as the plastic piece that holds the filter on itself is still present. Or if creating a bracket to hold up the intake is not desired, everything after the supports of the filter housing can be cut so that it can still bolt to the frame. This is best done with a K&N filter upgrade at the same time, if one hasn't be installed already.

Below is an example done to a 3rd gen, and a picture of the stock intake assembly demonstrating how restrictive it is.

The K&N filter, available at any auto parts store, it's one of the easiest modifications to do and one that creates a noticeable increase in gas mileage and acceleration when upgrading from a stock paper filter. Aftermarket washable oiled cotton/gauze filters have double the flow capacity of new paper filters, and will outflow a new paper filter even when dirty. The 2nd and 3rd generation filter fits on a large variety of Ford vehicles, part # E-0995.

Also see

• Escort intake upgrades
• Intake air temp sensor relocation
• Mass air flow sensor porting
• Mass air flow sensor cleaning
• Ford Escort & ZX2 section for the entire index of all Ford Escort and ZX2 related articles.