Tuning The Zetec Motor: Adjusting Fuel Pressure For Performance

The Zetec is a long-running engine block that has been used in many Ford, Mercury, and Mazda vehicles. It has been a popular choice for tuners due to the variety of parts available and the potential for performance gains. One aspect of tuning the Zetec engine is optimising the fuel pressure to ensure proper fuel delivery and efficient combustion. The standard fuel pressure for a Zetec engine is around 2.5 to 3.0 Bar or 35-45 psi. However, the fuel pressure may vary depending on the specific injectors used and can be adjusted to increase the flow capacity of the injectors. It is important to ensure that the fuel pressure is within the appropriate range to avoid issues such as flooding the engine.

Fuel pressure regulators and injectors

The fuel pressure regulator consists of a diaphragm that controls the bypass valve, which can open and close to adjust fuel delivery. This ensures the fuel injector can maintain the perfect ratio between fuel and boost. A proper fuel pressure is required to accommodate a successful fuel and air mixture, both at low and high revolutions per minute (RPM), regardless of power output.

When tuning a vehicle for performance, it is important to consider the fuel injector capacity. The rule of thumb is to add 20% when specifying an injector, allowing for injector deterioration and providing spare capacity. Upgrading the fuel injector can be a part of stage 2 mods, which also include sports catalysts, performance exhausts, ported and polished heads, induction kits, and fuel pump upgrades.

Additionally, when tuning a custom turbo setup, it is important to consider the entire fuel map and make adjustments to the fuel injector calibration. This can involve running the fuel injector calibration on the rich side for safety and then making adjustments to the fuel maps to fine-tune the air-fuel (A/F) ratios.

Turbochargers

How Turbochargers Work

Tuning a Turbocharged Engine

When tuning a turbocharged engine, the aim is to optimise fuel delivery and ignition timing to achieve maximum torque. This is referred to as MBT (Maximum Brake Torque) timing.

One key consideration when tuning a turbocharged engine is the boost pressure, which refers to the amount of airflow and power produced. As boost pressure increases, you need to move towards a richer air-fuel ratio to prevent engine damage from excess heat. Additionally, the ignition timing needs to be retarded to prevent the combustion process from happening too fast.

Another important aspect of tuning a turbocharged engine is managing the heat generated. Proper heat management can be achieved by monitoring various temperatures such as engine coolant temperature, intake air temperature, and oil temperature.

Zetec Turbo Upgrades

Upgrading to a larger turbocharger can result in massive power gains, but it is important to lower the compression ratio before adding a turbo to prevent engine damage.

When upgrading the turbocharger, consider the size and type of turbo, as well as the boost control system. Variable vane turbochargers, for example, can lower lag and increase top-end power by altering the vane profile according to speed.

Fuel Delivery

When boosting the performance of a turbocharged engine, it is crucial to upgrade the fuel delivery system. This typically involves upgrading the fuel injectors and fuel pump to ensure sufficient fuel is delivered to match the increased airflow.

Exhaust System

Upgrading the exhaust system is usually not necessary unless it is creating a flow problem. However, when pushing the power levels higher, a better-flowing exhaust can help increase the airflow through the engine.

In summary, turbochargers offer a significant increase in power output for Zetec engines, but proper tuning, heat management, and fuel delivery upgrades are essential to ensure reliable and safe performance.

Camshafts

Fast road camshafts usually push up the performance throughout the rpm range, although you could drop a little bottom-end bhp, but higher rpm power will be better. Motorsport camshafts, on the other hand, push up the higher rpm power band but as a result, the car will not idle smoothly and low-end power nearly always suffers.

For a typical daily driver, it is ideal to match your bhp range to your usage of the car. A motorsport cam is unlikely to be a pleasure to live with when in heavy traffic because low-end power will be very lumpy. Competition cams are designed for maximum power at the top end of the RPM range, a place that most daily commutes will not permit.

Some Zetec engines respond better to less aggressive camshaft durations, so it is recommended to check your engine on a rolling road.

When it comes to replacing camshafts on the Zetec engine, the procedure is best performed on a stone-cold engine. This is for your own safety, as working on a warm engine may result in burns from hot oil or other mechanical parts.

• Remove the spark plug leads, spark plugs, and camshaft cover.
• With the car in gear and the plugs removed, rock the car backwards/forwards until the pistons #1 and #4 are at TDC (Top Dead Centre), and the slots in the ends of the camshafts are horizontal and above the level of the end of the cylinder head.
• Slacken the cam belt tensioner and remove the timing belt from the two camshaft pulleys.
• Lock both camshafts using the slots in the ends of the cams or use the appropriate tool to hold the pulleys in place, undo the pulley bolts, and remove the pulleys.
• Undo the camshaft bearing caps and place them in a safe place, ensuring you note their original positions for refitting. The caps nearest the pulleys (#0 and #5) house an oil seal, which should be replaced.
• Remove the camshafts and store them in a safe place.
• Liberally coat the cam bearings with clean engine oil.
• Replace the camshafts with the new items, taking care to place them the correct way round. On the Zetec, the inlet and exhaust camshafts can be identified by an extra casting on the end of the inlet camshaft.
• Fit the new camshaft oil seals in the end caps, #0 and #5.
• Replace the bearing caps in the same order they were removed and tighten them down to the appropriate torque setting.
• Fit the vernier pulleys and finger-tighten the pulley bolts.
• Time the camshafts according to the specifications supplied by the camshaft manufacturer. For the Piper BP270's, both camshafts are set to give full lift at 110°.
• To fine-tune the position of the camshafts, you will need to use a set of vernier pulleys, as the stock pulleys have no adjustment in them. Vernier pulleys allow adjustment +/- to 1/10ths of a degree, ensuring accurate positioning.
• Carefully fit the timing belt so as not to disturb the position of the camshaft.
• Repeat the timing procedure for the exhaust camshaft, turning it to roughly the same orientation as the inlet camshaft.
• Remove any slack from the timing belt and adjust the timing tensioner accordingly.
• Turn the crankshaft anticlockwise back to the 0° (TDC) position, and then turn it anticlockwise again, through to 110° BTDC.
• Lock the four vernier pulley adjuster bolts securely.
• Rotate the engine by hand through two clockwise revolutions and check the timing figures again at 110° ATDC and 110° BTDC for both camshafts. You will likely need to adjust the timing again as it will have slipped.
• Drill and fit the supplied steel dowels so that the centres of the new vernier pulleys cannot rotate on the ends of the cams, should the pulley bolts come loose.
• Mark the position of the hole through the hole in the aluminium vernier pulley, and remove both the camshafts.
• Carefully drill 6.5mm holes in the ends of the camshafts and fit the dowel pins using threadlock to prevent them from falling out.
• Refit the camshafts to the engine, refit the pulleys, and repeat the timing procedure above.
• Tighten the camshaft retaining bolts to 50-60ft/lb and rotate the engine another couple of turns.
• Use the vernier pulleys to accurately set the timing to that specified by the manufacturer.
• You should still get the car dyno-tuned so that the dyno operator can swing the cam timing to get maximum power from the engine.
• Refit the cam cover, plugs, and plug leads, and start the engine. You must run it at 2000rpm for 20 minutes when you first run the new cams to bed them in.

It is important to note that some of the steps outlined above may vary depending on the specific make and model of your Zetec engine. Always refer to the manufacturer's guidelines or seek professional assistance if you are unsure about any aspect of the camshaft replacement process.

Intake and exhaust manifolds

The intake and exhaust manifolds are essential components of the Zetec engine, and upgrading them can significantly improve performance. Intake manifolds carry and channel air from the filter into the engine cylinders, where it mixes with fuel for combustion. Upgrading to a high-flow intake manifold can enhance the engine's fuel efficiency.

Exhaust manifolds, on the other hand, direct the exhaust gases away from the engine cylinders. Upgrading these can improve the airflow into the combustion chamber and are often necessary when trying to increase the engine's performance.

There are various options for intake and exhaust manifolds on the market, such as the Jay Racing High Flow Intake Manifold for the Ford Zetec 2.0L engine. Additionally, some tuners suggest that the ST170 intake manifold can be a suitable upgrade for the Zetec engine, depending on the year of manufacture.

When considering intake and exhaust manifold upgrades, it is important to ensure compatibility with your specific Zetec engine variant. There are several different versions, and while some parts are interchangeable, others are not.

Furthermore, keep in mind that intake and exhaust manifold upgrades are just one aspect of tuning the Zetec engine. Other modifications, such as camshaft upgrades, remapping the ECU, and improving airflow with larger valve kits, can also enhance performance.

ECU remapping

Remapping the Engine Control Unit (ECU) of your Zetec engine can offer significant advantages compared to your outlay. ECU remapping can be done on both turbocharged and naturally aspirated (NA) engines.

Remapping the ECU involves adjusting the software within the unit to change various parameters, such as fuel pressure, ignition timing, and boost pressure limits, to optimise the engine's performance. This process can be done by flashing the factory ECU or installing an aftermarket ECU.

For turbocharged Zetec engines, ECU remapping can result in a power increase of around 30%. On the other hand, NA engines typically see a power gain of about 15%. However, the actual results may vary depending on the specific upgrades and the condition of your engine.

It's important to note that ECU remapping should be done by professionals who are familiar with the process and can ensure proper setup, especially regarding knock protection.

Additionally, when boosting the performance of your Zetec engine, it's crucial to upgrade the fuel delivery system. Generous injector capacity is recommended by tuners to accommodate potential injector deterioration and provide a margin for higher fuel requirements.

• Stage 1: This stage involves software modifications only, with no additional performance parts required. It offers full performance tuning for petrol vehicles and the option of performance, economy, or blend tuning for diesel vehicles.
• Stage 2: This stage requires hardware modifications, including a full-performance exhaust, cold air intake, performance intercooler, and fuel pump upgrades. Once these modifications are in place, a Stage 2 tune can be performed.

Frequently asked questions