What is a T3/T4 Turbo?

The T3/4 is a common hybrid turbocharger for custom, high-performance applications. There are different turbine/compressor wheel and bearing options available, but the one thing they have in common is the use of a Garrett T3 exhaust housing, and a larger T4/T04 compressor housing. The smaller exhaust housing (hot side) retains the responsiveness of a small turbo, so it can spool faster. The compressor housing (cold side) of the turbo is a little larger, but not by a lot; this allows it to flow more air without the lag traditionally expected from larger turbos.

While the name and size of the turbo are based on designs originally from Garrett, many manufacturers make their own version of the T3/T4. These turbochargers are commonly used on smaller engines, between 2.0 and 3.5 liters; you could use it on something larger, but at high RPM, the engine will already be flowing more air than this size of turbo is capable of, so you wouldn’t see much benefit. While power output varies wildly based on the engine the turbo is hooked up to, plus any supporting mods, most vehicles using a T3/4 are operating around 300-400 horsepower.

The T3/4 is very popular for custom applications because the connections required are standard. The T3 exhaust flange has a standard mounting pattern that bolts onto many exhaust manifolds for vehicles that are turbocharged from the factory. If that’s not the case, adapters and custom exhaust manifolds can be found for most engines suited for this turbo. The turbo’s connection to the exhaust downpipe is a V-band, so exhaust piping is easy to make. The same goes for air intake and intercooler piping on the compressor side, and like all turbos, you can loosen the bolts on the center section and re-clock the turbo to make it fit nearly anywhere. It’s also not very physically large either.