Nissan's Xterra is a four-wheel-drive sport/utility vehicle, specifically designed to provide comfort when operated on the highways, while allowing its user to drive off-road. The Xterra is available with four different engines: one four-cylinder engine and three different six-cylinder engines of varying horsepower. Although the Xterra's stock horsepower ratings are respectable, the amount of horsepower produced can actually be increased fairly easily with just a few aftermarket parts.
Replace the stock air filter with a quality aftermarket unit. Air filters are specifically designed to filter microscopic particles from the outside air before the air is drawn into the engine. Unfiltered, these particles can damage an engine over time. The disadvantage of an air filter is that it restricts the engine's ability to withdraw air. The Xterra's stock air filter adequately filters the air, but is restrictive. Aftermarket air filters are available that can filter the air just as well, if not better, than the Xterra's stock filter. The advantage to a quality aftermarket air filter, however, is that it is not nearly as restrictive as the stock filter. This means the engine does not have to work as hard to withdraw air. As a result, the Xterra's engine is able to produce more horsepower with an aftermarket air filter than with the stock filter.
Replace the stock exhaust manifold with an exhaust header or headers, depending on the particular engine. Whereas the engine must withdraw air through the air filter, it must expel the spent gases through the exhaust system. The Xterra is produced with either a four- or six-cylinder engine. The four-cylinder engine uses a single exhaust manifold to rout the exhaust gases away from the engine, while the six cylinder uses two exhaust manifolds. These manifolds severely restrict the Xterra's ability to dispose of the exhaust gases, due in part because the manifold pushes the gases from each cylinder together. This pushing force reduces the engine's power. An exhaust header provides each cylinder with its own exhaust pipe, which substantially eliminates the amount of power the engine must use to expel the exhaust gases, translating into an increase in horsepower.
Replace the engine's computer chip with a high-performance computer chip. The Xterra's engine is controlled by a computer chip, which controls the power produced by the engine. Replacing the computer chip may seem like an intimidating task, but the replacement process is actually quite simple, provided the manufacture's instructions are carefully followed. The high-performance chip is specifically designed to allow the Xterra's engine to produce more horsepower by altering the Xterra's timing and fuel supply.
