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Chrysler (Plymouth - Dodge) 2.2 Liter and 2.5 Liter Turbo Engines

The high power, torque, and reliability of the 2.2 turbos sets them apart from many competing engines; the Turbo III could push out 224 horsepower back in 1990, which was exceptional considering that the 2.2 was not engineered with this in mind.

All Chrysler turbocharged engines had multiple-port fuel injection in the US, making them, for some time, the only Chrysler engines to hold that honor.

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The company ran through four basic designs:

  • Turbo I - the original, with multiple port injection, producing at least 142 hp
  • Turbo II - a more powerful version using a charge air cooler (usually but incorrectly called an intercooler), producing around 174 hp (starting in 1988, these had black manifolds).
  • Turbo III - the rare semi-experimental engine with dual overhead cams, four valves per cylinder, and returnless fuel injection, producing an absurd 224 horsepower
  • Turbo IV - a pioneering variable nozzle design developed with Garret, to reduce turbo lag (these had black manifolds).

Two other setups, even less well-known and rarer, were used in the Cosworth-head M4S and in the TC by Maserati.


The first production Chrysler turbocharged engine was a 2.2 liter four-cylinder, launched in 1984, and generation 142 hp at 5,600 rpm and 160 lb-ft of torque at 3,200 rpm - around 30 hp and 30 lb-ft more than the best power made by any other 2.2, and competing with the bigger 3-liter Mitsubishi V6 in power - while turning in superior fuel economy.

To make the engine, Chrysler dropped the compression ratio to 8.5:1 by using deep-dished, strutless, lightweight pistons. For durability, they strengthened the valves and springs, and used better-sealing rings, a special cam, select-fit bearings, and special exhaust manifold; a diecast aluminum cylinder head cover was added, mainly for looks. One key change was switching from a single throttle body injectors to four individual fuel injectors.

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Initially, Chrysler used a Garrett Research T-3 turbocharger, with an integral wastegate and maximum boost of 7.2 psi; the wastegate was controlled mechanically, using the difference between the compressor outlet pressure and the throttle body vacuum. When the outlet pressure got too high, the wastegate moved so exhaust gases went directly through the exhaust rather than into the turbine.

The compressor was aluminum, and driven by a turbine wheel in an iron housing with liquid-cooled bearings. The shaft bearing on the exhaust housing side was water-cooled, to reduce hot shutdown bearing failures. Turbocharger bearings were pressure lubricated with oil. A detonation sensor allowed people to use regular gas, with lower performance. The electronics were engineered and built by Chrysler.

Some words from the engine's creators

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

Turbocharger interview at acarplace

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.

We learned a lot about turbocharging and, yes, the 2.2 responded to everything we did.

Our biggest difficulties lay with detonation, or the detonation sensor which was, I think, unreliable. Given this, the specified fuel could not be regular octane. I fought this battle and eventually won something in the owners' manual saying better performance and longer life could result from the use of high octane fuels. This was a big breakthrough. I had several different turbo lease cars and they were fine; they never tasted low octane fuel.

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As to Mitsubishi, they became the [turbocharger] production source sometime after my retirement. And up till then, their only contact with us was regarding their turbos and nothing to do with future designs.

After working with the improved 2.2 turbo (not the 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.

Marc Rozman wrote: "Dick Winkles and his boss Pete Hagenbach fought the vehicle development group about the appearance of the top area of the Turbo II manifold. They wanted the flat top with the ribs, we wanted a nice round area that was more favorable to air flow. They won out and performance level might have suffered some (but not much)."

The variable geometry turbo was still being developed with Garrett when I retired. My right hand man, Dick Winkles, was deeply involved with the Turbo II, which was supposed to have both a charge cooler and the variable geometry turbocharger. Dick was the overseer of the LeBaron coupes which paced the 1987 Indy 500. They ended up without the variable geometry, but were really impressive just due to the charge coolers.

Dick had a ball at Indy. All the drivers wanted a drive in it. And they loved it..! Of course it wasn't sellable. Oh, yeah, it was a LeBaron convertible.

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[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.

One other thing I mention only because I am still disappointed that I couldn't even do a quick and dirty job setting up a car using the EYT Rootes-type supercharger for a demo. Chrysler wanted a turbo!

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The 2.2 was not designed for a turbo. Turbos are for racing. Too much heat for normal driving. We should have gone with that Eaton Rootes-type supercharger. We had a [supercharger] unit, from Eaton, but I couldn't even get permission to do a quick 'n' dirty job with it.

I begged for a test cell and six months to produce something that would counter the high friction and make decent economy. Nope, they were fixated on the turbo. After all, it was good enough for Formula One.
Dick Winkles added (2017), "As with any engine program at Chrysler, no one person can claim or deserves all the credit for any given program. I tell people this all the time when they say I did everything on the Viper engine and call me 'The Father of the V-10.' I was simply one of many on a team that pulled it together."

Marc Rozman, engine testing technician, wrote:

Shelby had some engines, but we did all the hardware and software work really. Think about what goes into building an engine for production: the emissions, calibration, hardware durability, electronics, supplier work. Seen and done it all. Shelby had the name recognition, though.

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The engineer I had for the Turbo II initially was Dick Winkles, the current Viper engine Chief Engineer; when we got into serious 4 cylinder racing he was moved into that capacity, a gentlemen named Adel Hanna took his place and we finished it up. My main engineer for the Turbo IV was Kim Lyon along with Dick again. [Stuart Davis was very involved in the program; he also did a lot of calibration work for people's cars on the outside.]

We started the Turbo II in May 1985 and ended the Turbo IV in February 1988. I took over the Turbo I work in Cell 10 when that operator moved down to Cell 13 to do some race/performance work, I was down the hall doing valve train work in Cell 7A for about a year and a half before moving over to Cell 10. They ended up doing the first Viper engine in Cell 13 also. Good memories in the building.

Just a year after the company came out with its first turbocharged engine, it gave the computer control over the turbocharger, dropping the mechanical control. Calibrated pressure limits were programmed in; the system turned the wastegate on via the wastegate actuator solenoid. Higher boost pressures compressed a spring connected to an actuator rod, opening the wastegate to bypass the turbocharger.

For year-by-year changes, see our 2.2 / 2.5 Engine Chronology.

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1986 also saw a new "fast burn" head design. 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 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."

In 1988, Chrysler described the system:

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.

For the 1990 model year, Chrysler added balance shafts to its turbo engines; they had previously only been used on the 2.5. With the release of the Turbo III in 1991 - one year after the Turbo IV - Chrysler also improved on the 2.5 Turbo I, adding torque through more low-speed boost, and changes to fuel and timing control. The Turbo IV did not make it to 1992; the 2.5 turbo was alone. See the full story on our 2.2 Chronology page.

Diving deeper into the five major turbocharged engines

Camshaft2.5 T2.5 TBI2.2 T III2.2 T I
2.2 T I
Intake duration228236228240228
Exhaust duration228232228240228
Turbo I

The most common engine, the 2.2 Turbo I, generated a respectable 142 hp to 150 hp, depending on the application, beating both the 3.0 V6 and the 1989 318 V8 in power and also boasting greater economy (both V-engines were later given power increases). It was relatively reliable and had good fuel economy.

In 1989, the 2.5 liter Turbo I replaced the 2.2 Turbo I; its longer stroke gave more low-end torque, covering 10% more distance during the first five seconds of full-throttle acceleration. It also produced more turbulence for faster, smoother combustion, and the balance shafts helped smooth the idle.

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The 2.5 Turbo I shared a block with the Turbo II, including diagonal cross-drilled coolant passages between cylinders, matching similar passages in the head. 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.

The engine had 150 horsepower at 4,800 rpm, with 180 lb-ft of torque (measured on premium gas). Boost calibration changes in 1991 added 2 horsepower and a full 30 lb-ft of torque, so the motor produced 152 horsepower and 211 lb-ft of torque at the same speeds. A different control setup gave it faster reactions, as well.

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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.
Turbo II

The Turbo II was also fairly popular; it added a charge air cooler (often referred to as an intercooler), forged crank, and other performance touches, including a heavy duty transmission. A full 174 hp came from this reliable engine, with 200 lb-ft of torque. The charge air cooler dropped air temperature by up to 120° Fahrenheit, allowing boost to go from 7.2 psi to 12 psi. Small tubes drilled between the cylinder bores at the top deck were added to cool the engine more effectively, an important modification.

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The Turbo II was only made for three years, from 1987 to 1989; in its first year it was only used on the Daytona Shelby Z, and in its second year it appeared as an option on Lancer ES and standard on the TC automatic. For its final year, it was on the Daytona Shelby, Shelby Lancer, Daytona C/S, LeBaron GTS, and was optional on the LeBaron.
Turbo III

A rare engine, the "T3" was used on the Dodge Spirit R/T from 1991 to 1992 and in the Dodge Daytona IROC R/T from 1992 to 1993; in Mexico it was also used on the Stratus R/T. Generating 224 hp from 2.2 liters, this engine was a thrill to drive.

The Turbo III was a DOHC engine with distributorless ignition and four valves per cylinder at a time when few engines had distributorless ignition and no other Chrysler engine had four valves per cylinder. The heads were designed by Lotus.

Cross-flow porting (with the intake side facing front) helped air to get through; it also had individual intake manifold runners, a 52 mm throttle body, and divided ports. Intake valves had a 1.4 inch diameter; exhaust valves had a 1.28 inch diameter. They seated with a 45° contact. The valve springs were single, chrome-vanadiam steel units. The redline was enforced at 6,700 rpm. Equal-length cams were made from a common casting.

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One Chrysler engineer wrote: "Incredible engine. 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, to retrofit with aluminum plugs.)

Michael Royce 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. The Turbo IV was used first, but work on the Turbo III started before it.

Chrysler's first dual overhead cam production engine had the cams alongside the valves, due to height restrictions; and the spark plug was 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.

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Redline was 6,500 rpm; the 16 valve dual overhead cam engine was rated at 224 hp at 6,000 rpm, 210 lb-ft at 4,800 rpm. It had shallow pentroof chambers with central plugs. An engineer who was involved wrote,

I'm amazed that the Turbo III ever saw the light of day ... we had supercharged 2.2s running in the dynos in the mid 1980s and it looked like a go for a while. But the 2.2 and 2.0 have siamese bores (no cooling in between) and sealing them with o-rings would be necessary, which is money.

Some of us fought to have cooling between cylinders when the 2.0 was being developed, but the Neon was to be cheap at all costs, so the same bore spacing (87.5 mm) was carried over so Trenton Engine could use the existing line with same machinery.

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The main problem with the Turbo III was its tendency to go through timing belts quickly. Michael Royce wrote:

The timing belt tension had to be set so high to overcome "tow roping" of the timing belt, i.e. the
timing belt going into negative tension. Tow roping is a belt killer. This problem was caused by the extremely low valvetrain
friction from using roller rockers, combined with the DOHC setup. When an exhaust valve rocker goes over the nose of the camshaft, there is no
friction to slow it down and it tries to close the valve even faster,
causing the exhaust cam sprocket to rotate clockwise faster and decrease
the tension in the belt span between the sprockets.

See these directions on centerlining the Turbo III cam or our Dodge Spirit R/T page for more details on this engine.

With a bucket tappet,
which is used on most DOHC 4 cylinders, there is friction. On the 8 valve
SOHC engine, there is an intake lobe on the same
camshaft coming up to help out! So we had to crank up the initial belt
tension to solve the problem. An automatic belt tensioner would probably have helped, but belt life is probably improved if people watch their belt tension and keep it within spec.
Dyno operator Ed Poplawski wrote, "We evaluated a Lotus four-valve head and a Maserati four-valve head. If I remember right the power output of both heads was the same, but ... the Maserati had direct acting buckets to actuate the valves and the Lotus had a complicated rocker arm system that was expensive to make." This would be the weakest part of the engine, demanding an extremely high timing-belt tension that would break the belts (usually, by stripping the gears) and the belt tensioners.
Turbo IV

The most advanced of the Chrysler turbo engines, the 2.2 Turbo IV used variable-nozzle technology (VNT) to increase boost at lower rpms. While the top rating was 174 horsepower, the lack of turbo lag greatly helped driveability, and torque went from 200 lb-ft in the Turbo II up to 210 lb-ft.

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At the time, the company wrote that, compared with the Turbo II, it reached full boost in half the time, was smoother, and had a broader torque curve. The new turbocharger was accompanied by balance shafts to smooth the idle; sequential multiple port injections to lower fuel use and increase economy; and a new PCV system with a better oil separator.

The unit itself eschewed a wastegate, instead using a "double acting actuator" which positioned the vanes and was moved by manifold pressure signals provided by the computer, through three solenoids. A "unison ring" moved the twelve vanes to adjust the flow of gas to the turbine; each vane pivoted in a "nozzle ring" around the turbine wheel.

The Turbo IV was used in the Shelby CSX, Chrysler LeBaron coupe and convertible, and Dodge Daytona. A defect in early-production turbochargers gave this engine a poor reputation for reliability, but the technology has since come into common use.

Burke Brown, leader of LX engineering, said that exhaust rust and dirt clogging was an issue for the Turbo IV, but they ended up setting it up so that on startup, it would "flip the nozzles back and forth a few times to clean off any deposits."
Lotus Engineering and "what might have been"

Lotus' Michael Royce wrote:

On March 1st 1985, Bob Sinclair, the Chrysler VP of Engineering, and Mike
Kimberley, Managing Director of Lotus Cars, signed a contract for
three related programs:

- A 2.5L Naturally Aspirated 16 Valve Engine (program A-516)
- A 2.2L Turbocharged Intercooled 16 Valve Engine (program A-522),
- A Four Wheel Drive System (Vehicle) for the G-24 Daytona using the 2.2L
Turbo (program A-544).

In the fall of 1986, the 2.5L NA Program was cancelled due to engineering budget constraints. The long stroke (104 mm) with the 16 valve head fixed the 2.5L's breathing problems, and gave a nice smooth engine that would rev easily up to about 7500 rpm. It gave about the
same performance in a vehicle as a Turbo I. The last example I know of was
in a P-Body with a manual trans with the emissions people out at the Chelsea
PG about 15 years ago.

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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, when he drove one during some Goodyear tire evaluations at Chelsea,
said "it needed much more power!"

The Turbo III program continued with the objective of putting it into the
Shelby CSX, and we even got so far as to ready the Saltillo Engine
Plant to build the engine in about 1989. I have forgotten what caused it to be cancelled, as about that time I handed the program over to
another program manager, Greg Boznyck. The engine did make it into

2.2 and 2.5 liter engines are all noninterference designs, so they generally are not damaged when the timing belt breaks. Turbo III owners often know this from experience.

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There were several different engine blocks, but all had siamesed cylinder bores, a short crankcase skirt, and partial open deck. The block was designed to be milled for lighter weight; it was cast iron rather than aluminum due to the state of technology at the time, and weighs around 90 pounds. The oil pump was mounted internally. Pistons (which vary by engine and year) were aluminum with steel struts, and rings were iron.

Stefan Mullikin noted:

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

The ECU is rather sophisticated; it monitors the oxygen, coolant, manifold pressure and throttle position sensors, battery and intake temperatures, A/C relay, engine RPM, knock sensor and vehicle speed, etc to determine what values to use to control the engine. It varies when the fan comes on by monitoring the speed sensor and the coolant sensor (this came in after 1984).

The engine uses the Manifold Absolute Pressure Sensor (MAP) to determine the level of vacuum or boost. The computer monitors it closely, and also uses it to determine the barometric pressure of the ambient air by briefly opening the MAP sensor to ambient air using the Baro-read solenoid (the slight miss at idle you might notice).

The stock ECU limits boost at low speed/throttle opening on
many models to preserve the transaxle. but there's not a load sensor as such.
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The post-1984 engines had controlled the turbocharger, via the wastegate (except with the Turbo IV), allowing overboost for up to ten seconds; it tried to keep a balance between engine responsiveness and engine life.

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.

Crankshafts were cast on the Turbo I, and forged on the Turbo II, III, and IV, due to their higher power.

Starting in 1989, all Chrysler four-cylinders, including those in the Dakota and Chrysler TC by Maserati, used the same engine block. The 2.5 swapped its old lengthened deck for a shortened piston.

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Key 2.2 - 2.5 turbocharged engine links

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