1979-1993 Mustang Turbocharger Guide

The way a turbocharger works is pretty simple. The engine’s hot exhaust gases are captured and circulated through the turbine before being emitted back into the regular exhaust path and out of the tail pipes. The motion and heat of the exhaust gases cause the turbine to spin. The turbine is coupled to a secondary compressor via a shaft, and as the turbine spins, this output shaft spins in conjunction and subsequently turns the compressor blades as well. The compressor draws in fresh air and, as the name implies, packs the cylinders with air at a positive pressure, called boost (measured in PSI). Going back to our basic engine principle, the more air we can shove into a cylinder, the more fuel we can mix and ignite. It is a simple concept that works marvellously well. Turbochargers can add anywhere from 70hp to a couple hundred, depending on what size turbo is used as well what engine modifications are in place.

Regarding ease of use, install and overall quality, in the Foxbody Mustang world there is but one company that gets it all right. Hellion turbo systems are a very high quality kit and have been engineered to retain all factory accessories. Another area of concern to look at when selecting a turbo kit is piping and weld quality. Because of the additional pressures and temperatures of the air, cheap piping and imperfect welds will show up right away under boost, often resulting in cracked pipes.

Another indication of a quality kit is one that includes a waste gate. A waste gate (another turbo specific term) is a device that bleeds off pressure when the turbo reaches maximum rotational velocity. As engine RPM goes up, more exhaust gas is pushed out and the turbo will spin faster. However, all turbos do have a maximum RPM that when exceeded can cause catastrophic failure, usually in the form of exploding vanes. The job of the waste gate is to divert exhaust gases from the turbine when the turbo has reached its maximum speed, thus minimizing the chance of an explosion due to overspeed (for reference, many turbos spin at around 150 000 RPM).

Unfortunately, a turbo is one of those modifications that require other modifications to really maximize its potential. First and foremost, fuel system upgrades are in order if they haven’t already been done. Larger injectors and a higher capacity fuel pump (maybe even two) are needed to be able to use all that extra air a turbo is pumping in. Secondly, the extra pressure can easily lift a head or blow a head gasket or even both when using the stock head bolts. Converting to a stronger stud setup is highly recommended. Finally, there is the issue of computer tuning. It is highly recommended to get an aftermarket tune on your Fox when running a turbo. Compressing the air increases the temperature of the air, which makes the combustion mixture more prone to detonation. An aftermarket tune ensures that the fuel is being delivered both in the right amount and right time. At a very minimum, retarding the engine timing is needed. Running with a lower compression is advised as well.

A method to combat these increased temperatures (and can also increase power levels) is to use an intercooler. An intercooler is basically a mini radiator that is plumbed into the cold side of the turbo such that the intake charge is run through the intercooler prior entering the cylinder head. Not all kits include these, so double check beforehand (the Hellion does, another reason why it is one of the best kits out there).