Chrysler's 2.2L engines have a bit of a strange reputation among performance enthusiasts. On the one hand, stock engines are often maligned for their tendency to self-destruct under stock boost levels. On the other, with a few minor modifications the 2.2L is capable of earning some serious respect even among V8 aficionados. Most of it comes down to preparing the engine for boost in ways that Chrysler didn't think of when it bolted on the turbo in the mid-1980s.
Unlike its counterparts from Mitsubishi and Nissan, the Chrysler 2.2L wasn't designed from the outset for use with a turbocharger. The turbo 2.2L worked fairly well in lightweight chassis that didn't load the engine too much, but could easily rattle itself to bits in larger sedans and minivans. To safely run more than 12 to 14 psi of boost you need to strengthen the engine with aftermarket rods, race-spec bearings, a main stud girdle, cylinder head studs and forged pistons.
Many modern turbocharger-specific heads use biased intake ports, meaning that the entire port is placed a little closer to the outside of the combustion chamber than toward the center. This promotes a natural swirling motion as the air/fuel mixture enters the chamber to enhance burn efficiency, decrease detonation and boost horsepower. When porting the 2.2L's intake ports, remove a little more material from the outer (a.k.a. "tangent") side of the intake port than from the inside portion to bias the port flow into the cylinder.
On most engines you'd open up the entrance to the intake port to the exact dimensions of the intake gasket, but not on the 2.2L. Gasket match only the tops and sides of the intake port and leave the bottom alone. Gasket matching the bottom will create more curve going into the chambers, which will ultimately decrease flow.
There's nothing inherently wrong with the 2.2L's stock exhaust manifold except that the exhaust ports are a little too small. This is easily remedied by matching the manifold's port openings to the exact dimensions of the manifold gasket, much as you might do to the intake ports on most engines. Open up the exhaust ports on the cylinder heads to within 1 mm of the gasket size to leave a small step-down between the cylinder head and manifold. This will help to reduce turbulence and increase exhaust gas velocity. If you want more power you'll need to step up to a set of super competition race headers.
