Let's do the math. If we go by Squires' observation that you pick up 1/2 hp per degree you drop the intake temperature, then by dropping the IAT (inlet air temperature) from 250 degrees to 150, you will pick up 50 hp. Talk about huge! That's because the cooler charge allows for a more aggressive ignition timing curve, and we know that equals more power.
"Turbo engines are more subject to detonation due to the elevated temperature of the pressurized air, so anything that lowers air temperature will help make more power and keep the engine safe by reducing the chance of detonation," Napier says.
So how do you choose an intercooler, and which type is more effective? "[In aftermarket applications] air-to-air intercoolers are generally used on street cars, while air-to-water inter-coolers are generally used on race cars," Napier says. According to Campbell, however, an air-to-water intercooler is more effective that an air-to-air. "With an air-to-air intercooler, on a 100-degree day, you can see an IAT around 130-150 degrees," he says. "The problem is, with an air-to-air, you are dependent on the outside temperature. With an air-to-water inter-cooler, which uses ice water to cool the IAT, the IAT will cool quicker and with more predictability and consistency."
"With an intercooler, fin count is also impor-tant," Horne says. "The more fins an intercooler has, the more efficient it is. Ideally, look for an intercooler that has 12-15 fins per inch."
Methanol injection is another form of intercooling, such as the systems from Snow Performance. A methanol injection system squirts a mix of methanol and water, usually in a 50/50 mix, into the intake tract to cool the incoming air charge. This is also an efficient way to lower IATs.
Final Notes
As you can see, turbocharging your Ford can be a sure-fire way to make some serious horsepower, but to make that power, you need to do things the right way and have all of your ducks in a row. "Obviously, there are many components on the vehicle that need consideration based on the new horsepower and torque available when running a turbo," Squires says. "Turbochargers are the friendliest of the power adders for keeping the stock components and drivetrain in one piece because of their incredibly smooth application of big power." Unlike nitrous, which needs to be refilled after a certain amount of use, a turbo's power is always available. All you have to do is flex your right foot and get all spooled up.