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Mopar (Chrysler, Dodge, Plymouth) 2.2 turbo engines

Time:2012-04-11 21:27Turbochargers information Click:

dodge mopar 2.2 trans four

Willem Weertman | Pete Hagenbuch

The Turbo II program continued with the objective of putting it into the Shelby CSX, and we even got so far as to facilitize the Saltillo Engine Plant to build the engine for Shelby in about 1989. I have forgotten what
A small, stainless steel turbine wheel, in a housing which is bolted to the exhaust manifold, is driven at tremendously high speeds by hot exhaust gases and it rotates a small aluminum compressor on the other end of the same drive shaft. The compressor is located ahead of the intake manifold where it rams air-fuel mixtures into the combustion chambers under pressure to produce greater power in each cylinder when the spark plug fires.

The turbocharger itself was cooled partly by the fresh oil circulated through its bearings, partly through a water jacket around the bearings and turbocharger itself, and partly through the air flowing through the engine compartment.

Turbo IV

Even more rare; this engine used variable-nozzle technology (VNT) to increase boost at lower rpms, and made 174 useful horsepower; balance shafts helped smoothness. Torque was relatively high (225 lb-ft rather than 200 in the Turbo II). It was used in the CSX. A defect in early-production turbochargers gave this engine a poor reputation for reliability, but the technology was advanced for its time, and has since come into common use, particularly on diesels.

- A 2.5L Naturally Aspirated 16 Valve Engine (program A-516)

When introduced in 1989, the 2.5 liter turbo engine replaced the original 2.2 Turbo I; its higher displacement provided faster initial acceleration, covering 10% more distance during the first five seconds of full-throttle acceleration. The longer stroke produced more turbulence for faster, smoother combustion, and the balance shafts helped damp out firing pulses, for a smoother idle. The block had diagonal cross-drilled coolant passages between cylinders, matching similar passages in the head, a feature common to the Turbo II engine; indeed, it was the same block as the Turbo II and base 2.2 and 2.5 liter engines. (This required a new head gasket with the passages built in.) The crank was a high hardness ductile iron, modified from the 2.2 for piston and block clearance; new aluminum alloy pistons had steel struts cast in, to control expansion. They had a dished crown to adjust the compression ratio.

There is a sensor the engine uses for determining the amount of vacuum or boost in the intake system. Its called the Manifold Absolute Pressure Sensor (MAP) The computer monitors it very closely, it also uses it to determine the barometric pressure of the ambient air (the slight miss at idle you might notice) it does this by briefly opening the MAP sensor to ambient air using the Baro-read solenoid.

The boost level is based off of the volume of exhaust the engine produces. The more load, the more exhaust volume is produced the more quickly the paddle wheel gets turned the more boost gets created. Depending on what the various sensors are reporting, the computer decides whether the wastegate lever is open or closed.

In 1989, the Turbo II (and Turbo I) gained a new throttle body with more reliable throttle levers; these automatically locked the cables into place, eliminating separate clips, and included a larger idle air control passage.

A new wastegate power source is used for 1988-pressurized air from the turbocharger instead of manifold vacuum. This allows for a leaner fuel mixture and increased spark advance which enhances fuel economy.

The computer controlled boost (air pressure coming out of the turbocharger) via the wastegate, which opened to allow exhaust gases to power the turbocharger. The system allowed overboost during “snap acceleration” for up to ten seconds, and generally tried to keep a balance between engine responsiveness and gas mileage/engine life.

The 1986 fast burn head helped; dyno tester Ed Poplawski wrote, “I worked on this a little bit. We ran Fast Burn heads on the 2.5L and the big advantage that I remember was that with the Fast Burn head, wide open throttle spark timing was lower than with the standard head, so you didn’t have to worry about spark knock too much and you didn’t need premium fuel. That made a big difference for the turbocharged engine.”

turbo car list

One Chrysler engineer wrote: “Incredible engine, not many left around here, but lots still in Mexico. Heads cracked in the 1991 version because some dummy decided to use cast iron plugs in the water jacket holes instead of aluminum.” (There was a recall for this and many were retrofitted with the aluminum plugs.)

After working with the improved 2.2 turbo (not Turbo II) with the long branch intake manifold, we picked up a nice gain in output which came from both the tuning effect and the improved fuel-air ratio distribution which allowed a better spark advance curve without detonation problems.

The 4WD G-24 program was cancelled in November 1987, again due to budget constraints, just as we were getting the car to perform and handle as well as the Audi Quattro, the target vehicle. John Miles, from Lotus, was leading the chassis development. Doug Shepherd, our esteemed rally driver and DC exec., when he drove one during some Goodyear tire evaluations at Chelsea, said "it needed much more power!"

2.2 turbo III

- A 2.2L turbocharged Intercooled 16 Valve Engine (program A-522),

I was the guy responsible for the performance of the 2.2 and later 2.5 turbos. We had no one in-house who knew much more than the very basics. It was pretty much learn as you go. The electronics folks at Chrysler were not any better off. Engine designers had one thing right; mount the turbocharger as close as possible to the exhaust manifold to reduce heat losses.

2.2 liter engine: never designed for turbocharging

One interesting tidbit is that the 2.2 was never designed for a turbo, according to Chrysler engineer Pete Hagenbuch; but its durability must have made engineers happy when they chose to force the air in. Pete wrote:

Michael Royce noted that the problem with timing belts was that:

[Of the production engines], the 1988 version with the longer branch tuned intake manifold was the best. I was driving an 1988 Daytona when I retired. The Turbo IV, with Garrett's switch-the-pitch turbine, was a bear, but I understand the thing froze up with a little carbon buildup. And then I retired! And anything I can tell you after that would be guessing.

A low intertia turbine and compressor resulted in fast reactions; internal changes to the turbocharger assembly were made to increase airflow, but otherwise it was similar to the original unit. The engine used the same connecting rods as the Turbo II, double weight sorted before assembly for accurate balance. In addition, the air cleaner was changed from round to oval in shape.

Turbocharger interview at acarplace

Some interesting aspects of this engine, Chrysler’s first dual overhead cam production model, included putting the cams alongside the valves due to height restrictions; and putting the spark plug at the center of the combustion chamber. The pistons were forged aluminum, with scalloped tops for valve clearance; boost was set to peak at 11 psi.

Michael Royce, of Lotus Engineering, wrote that development of the Turbo III (designated the A-522) started with a contract signed on March 1, 1985, by Bob Sinclair (Chrysler VP of Engineering) and Mike Kimberley (Managing Director of Lotus Cars Ltd). Royce was the program manager on all three of Chrysler’s programs with Lotus Engineering. Work on the Turbo III started before the Turbo IV (which came out earlier), hence the name.

Key 2.2 - 2.5 turbocharged engine links
  • Mopar 2.5 / 2.2 Turbo Engines Performance and Common Repairs
  • Interview with engine designer Pete Hagenbuch , which covers the 2.2 turbos and other topics.
  • Interview with engine designer Willem Weertman
  • Copyright infringement? Click Here!

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