The Turbo II was first introduced in 2.2L form, initially for the 1987 Dodge Daytona Z, and it later appeared in the Chrysler LeBaron GTC Convertible. Turbo II's were never offered in 2.5L blocks and Turbo II's never had counter balancers.

To meet our minivan's reliability and torque goals, we'll be building up a 2.5L (89 -92)  common-block using 2.2L Turbo II components. We will also leave the power-robbing counter balancer assembly on the bench.

Chrysler's Turbo II improvements vs. Turbo I included:

	Forged Crankshaft
	Forged Rods
	Floating wrist pins
	Boost increased to 12 psi
	Higher flowing injectors
	Intercooler
	Blow-through intake/throttle body with dual tuned-length intakes

Here's the upgrade strategy we used:

1) A larger Garrett turbo is much preferred over the stock Mitsubishi. The smaller Mitsu (Turbo I) spools faster, but does not have the ability to provide sustained pressure at the airflow required. Our larger Garrett T04E-46 trim/T3 hybrid turbo will also operate at cooler charge air (output) temperatures, permitting a installation of a relatively smaller intercooler package.

2) Properly sized fuel injectors are required. The Turbo I injectors are 28 lbs/hr, the stock Turbo II's are 34 lbs/hr. It's critical to provide more fuel to handle higher boost pressures. An adjustable fuel pressure regulator  permits setting static fuel pressure at 58 - 60 PSI for the 34 pounders. 

3) Wastegate (over-boost) control strategy: So many different ways to go here, but I personally, want to base-line test using a stock Turbo I SBEC calibration with the Grainger valve, while retaining SBEC over-boost (MAP sensor) fuel cut out at approximately 13 -14 PSI.  Eventually a Two-stage (driver selectable) boost control can also be effective in reducing wheelspin and will be tested.  Eventually, a custom calibration SBEC, 3-bar MAP and larger injectors will also be tested.

4) Use a Blow-through intake manifold. the early Turbo I used an aptly named, "suck-through" intake manifold. The throttle plate controlled the amount of air the turbo could suck in. If a piece of debris cuts the intake hose, on a suck-thru, you will instantly go to full throttle. (Don't forget the Ignition switch!). We'll start out with the later-style Blow-through intake as it will facilitate lowering charge air temperatures with intercooling.

5) Use an Intercooler. (Inter)Cooling the turbo's output charge air temperature is critical in order to run higher boost levels without destructive pre-ignition on pump gas. Don't leave turbo-home without one. Front-mounting an intercoller can prove to be a installation and fitment headache, but the results are worth it.

6) Use the 2.5L Common block without balance shafts. Our 2.5L common block was carefully blue-printed and electronically balanced. The counter-balance shaft assembly was not installed and it's oil-supply passage was plugged.  It's much smoother running that the original 2.5 TBI and a lot more fun-to-gun! If the original 2.5 TBI hadn't thrown it's counter-balancer chain, we wouldn't be here. If you do run a counter-balancer -- check its condition and tension or get rid of it.