The History Of the 2.2L and 2.5L Engines

This page is an attempt to chronicle the history of the 2.2L and 2.5L engines.  This first part of this page (1981 - 1984) was originally written by Craig Bower in the 2.2L Tech section of his NitrozoneV website.  With his permission, I have taken his version of the page and spliced into a page I was working on, which just happened to start at 1985 and go on.  Special thanks go to Craig for help me out since I was fairly clueless about the history of the 2.2L engine before 1985.  Special thanks also go to Dempsey Bowling for providing some of the details for the remainder of this page.  See his Turbo Engine Designations page for a quick rundown on the different turbocharged engines built by Chrysler.  If you see anything that is obviously wrong, please tell me.

1981 - From Humble Beginnings

Chrysler's 2.2 Liter 4 cylinder overhead camshaft engine first saw the light of production in 1981.  It was offered as either standard or optional equipment on many of Chrysler's current, and newly introduced body styles.  Having a bore of 3.44" (87.5 mm) and a stroke of 3.622" (92 mm) with a rod length of 5.945" (151mm) the engine displaced 2213 cubic centimeters.  Thus the 2.2L had been born.  In it's first year, the 2.2L did not have very much in the way of horsepower.  Rated for 84 horsepower at 4800 RPM, and 111 ft-lbs of torque at 2800 RMS.  This was an improvement of around 20 horsepower from the previously sourced out 4 cylinders (1.6L and 1.7L) Chrysler was using at the time.  The 2.2L was built at the Trenton engine manufacturing plant, which has the hallmark of having built the 225ci Slant Six engines, and the B-RB big blocks (383ci - 440ci) of many years ago.

1982 - Significant Design Improvements

For 1982, there would be no change in output of the 2.2L, still having the same 84 hp, and 111 ft-lbs of 1981.  However, numerous changes were effected to make the engine feel better throughout the rpm range, and to be more durable.  The list of changes includes: the removal of the under-head flat on the exhaust valve, an intake manifold change to one with shorter runners, and a larger plenum, the camshaft centerline was changed to accommodate a new set of timing sprockets, the exhaust valve seats were swapped out with better TRW pieces for improved durability, and finally the block received stock between the cup plugs, below the manifolds on the rear side.  It is interesting to note, that very late in 1982, Chrysler had it's first "mules" of the Daytona platform that would not see production until 1984.  This explains the need for the different intake manifold, and the stock being added between the cup plugs.  The intake was needed to push the engine's output up into higher RPM, to increase output.  The shorter the runner, the higher in the rpm band the torque peak will occur.  Consequently the higher the output will be, all needed to be a "better" engine for hauling around the base Daytona that would eventually receive the 2.2L as standard.  As for the stock being added between the cup plugs, Chrysler realized that as the output of the engine increased, the transaxle, in relation to the drive-axles, and wheel/hub assemblies would create sufficient torque steer to hinder the driving experience.  This necessitated the addition of equal-length half shafts to reduce the tendency for the front-drivers to torque steer themselves.  But I am getting ahead of myself, because you'll get to read all about equal-length half shafts in the 1984 section, when they were first introduced.

1983 - More Fine Tuning

As with all things that progress along a time line, the 2.2L 4 cylinder was no different.  The big news in 1983 was Caroll Shelby was giving large quantities of input into the development of the 2.2L engine, destined to enter production with the new 83 1/2 Dodge Shelby Charger, as the H.O. version.  All 2.2L engines in 1983 received the following updates in design: a switch to the (new) A511 cylinder head ("G" casting), a revised intake manifold sporting a new "D" for it's intake runner design, an updated exhaust manifold, low load valve springs (135# white), and an oil system anti-drainback valve to prevent valvetrain clatter during cold starts.  Many of the changes to the 2.2L were intended to increase durability and offer higher performance.  Thus the 2.2L had actually reached a higher output for 1983.  Horsepower was now 94 at 5200 RPM (remember that new intake and the new "D" ports?), and torque was slightly increased to 117 ft-lbs at 3200 RPM.  The big news though, was the introduction of a mildly modified 2.2L, designated the 2.2L H.O. (high output).  Offered only in the 83 1/2 Shelby Chargers, the new H.O. offered the following performance upgrades: a higher compression ratio due to a milled deck on the block, faster spark advance due to revised electronics, a revised camshaft (different centerline), a specially jetted carburetor, and a detonation sensor to keep things in check.  The net result was a large increase in horsepower to 107 at 5600 RPM, and a 15 ft-lb jump in torque to 126 at 3200 RPM.  The year 1983 could only be described as a foreshadow of things to come with the little 2.2L 4-cylinder...

1984 - The Advent Of Fuel Injection

For 1984, you could order a 2.2L engine, in one of three flavors, mild, spicy, and wild.  The mild version was now throttling out 96 horsepower at 5200 RPM, with a corresponding torque increase of 2 ft-lbs to 119 at 3200 RPM.  Not terribly great, but it was at least an improvement.  Spicy versions destined for Shelby Chargers still had the same bag of goodies to make the H.O. engine perform, but now they were also to be shared with a high-performance version of the Omni, dubbed the GLH (Goes Like Hell).  Output on the 2.2L H.O. was raised to 110 horsepower at 5600 RPM, and torque did likewise to 129 at 3600 RPM.  Herein again, nothing spectacular in the gains dept., but at least it was an improvement.  The piece d'resistance for 1984 however, was a newly introduced Turbocharged version of the 2.2L.  Generally referred to as the Turbo I.  With the debut of the 1984 Laser, and Daytona twins, Chrysler had hoped to build the first real "FWD performance car", and succeeded in making one hell of a great ride.  The Garret AiResearch (T03) turbocharger, along with reduced compression ratio pistons (8cc dish for 8.1:1) and big beam forged rods (691g), were capable of registering 7.5 psi of boost on the gauge.  The intake manifold, and exhaust manifold had to be completely re-designed to mate the turbocharger to the engine, and provide a mounting point/injection area for the newly introduced EFI (electronic fuel injection).  All this added up nicely to 142 horsepower at 5600 RPM, and a lofty torque rating of 160 ft-lbs at 3600 RPM!  Now things were starting to get interesting.  To handle the new-found power from the tried and true 2.2L, Chrysler engineers gave the Turbo I equipped cars a 3.56:1 final drive ratio, working through equal-length half shafts to keep the torque in check while wheeling away from a stop sign at a rapid pace.  Of small note is that in 1984, the wastegate actuator, was mechanically controlled, as opposed to later years 1985+ that would see the ECU monitoring, and controlling the same function.

With the advent of fuel injection, a new engine control unit (ECU) was designed to handle the task of controlling the fuel delivery via the injectors.  The hardware necessary for this was split into two modules: the logic module (located in the passenger compartment) and the power module (located in the engine compartment).  The CPU (central processing unit) inside the logic module used a series of timers to calculate the injector timing, while the power module had a logic circuit that determined which injector to fire, as well as the injector drivers themselves.  A new array of sensors was also required to keep the ECU informed on what was going on.  For more information on the ECU, see the  Understanding The Chrysler Engine Control Unit page.

Using the new fuel injection electronics, another release for 1984 was the 2.2L throttle body injected (TBI) engine.  This type of engine used a single, large fuel injector in the throttle body, operating at 36psi of fuel pressure, to provide fuel to the engine.  The intake manifold was similar in design to the carbureted engine.  In fact, this intake setup was basically a computer-controlled carburetor design that allowed the control of a fuel injected engine with the simplicity of a single fuel entry point, which is why TBI engines are sometimes called "pseudo-carb" engines.  There was no significant change in engine performance between the carbureted 2.2L engine and the 2.2L TBI engine.  The main reason for this new engine was to simplify production of the new line of cars coming out that were based off of the K platform (LeBaron, Daytona, etc).  A carbureted engine requires a completely different set of electronics and wiring because there is no logic and power modules, just a simple spark and fuel feedback (for emissions) controller.  Having a TBI engine gave non-turbo engines the benefit of the intelligent electronics of the turbocharged engines, and removed the need for completely different wiring harnesses and hardware throughout the vehicle's chassis.


1985 - The Engine Control Unit Gets Smarter

With the new turbocharged version of the 2.2L engine now on the market, Chrysler continued development of this engine throughout the rest of its history.  For 1985, the logic and power modules were redesigned.  The 1984 power module had much of the injector control electronics inside the power module, which was controlled remotely by the logic module.  The idea for 1985 was to move all of the sensitive electronics into the logic module and have only the high power output electronics in the power module.  So, the 1985 power module had only the injector drivers and some protection circuitry, while the CPU inside the logic module took care of deciding which injectors to fire and when, without the use of separate timers.  This was because a more powerful CPU was used in the 1985 electronics.  With more computing power, the logic module also continuously performed many on-board diagnostics on itself and on the various components it used throughout the vehicle.  These diagnostics would yield "fault codes" that would be stored in memory so that they could be viewed later to aid technicians in the location of bad components.  For more information on fault codes, see the Fault Code Description Pages.  Also, the voltage regulator function was moved to the logic module's control with the alternator field coil driver for it in the power module.  Previously, the regulator was internal to the alternator.

Another change in the 1985 electronics was the addition of a vacuum-controlled wastegate for the turbocharger.  The vacuum was controlled directly by the logic module through the use of a vacuum solenoid.  This gave the ECU direct control over the amount of boost the turbo could generate.  With this change, the turbo was spooled-up more smoothly to improve driveability and increase the longevity of the drivetrain.  Also, a peak boost timer was added, which increased engine performance by allowing 9psi of boost for up to 10 seconds at WOT (wide-open throttle).  When the 10 seconds was up, boost would return to the nominal level of 7psi.  When the engine was not at WOT, the boost timer would start racking up seconds again, up to 10.  Whatever amount of time was on the clock would be the maximum amount of time that the engine was allowed to run at 9psi.  This was all to maintain the longevity of the drivetrain.

These improvements yielded additional power on the Turbo I, which now boasted 146 hp at 5200 rpm and 168 ft-lbs at 3600 rpm.  The new electronics and boost control also resulted in a new fuel rail setup with a different style injectors.  Also, the new version of the Garrett T03 turbocharger featured a water jacket in the bearing housing.  Turbochargers are primarily cooled by the oil supplied to the bearings while it is running.  The oil flows through the bearings, absorbs the heat out of them, the shaft, and the casting, and flows back into the oil pan.  A severe reliability problem occurred when the engine was shut off.  With no new oil being supplied to the turbo, the heat transfer from the exhaust turbine housing would heat up the bearing housing and "cook" the bearings and seals.  This cooking would slowly damage the surface of the bearings and seals, as well as causing the oil to "coke" inside the housing and in the oil supply line.  The coking would slowly pinch off the oil supply, which also contributed to short bearing life.  The net result of this was smoking engine, from oil being passed into the exhaust and/or a loss of boost because the turbo shaft seized up.  The new Garrett turbocharger had a passage through the bearing housing for coolant.  While the coolant didn't contribute much to cooling the turbo while the engine was running (coolant temperatures are typically higher than oil temperatures), it did do the turbo a great service when the engine was shut off.  As the oil drained away and the heat began transferring to the bearing housing, the coolant in the housing would boil.  Since the coolant outlet was on top and the inlet was on the bottom of the bearing housing, the result was a convection system that allowed the boiling coolant to exit the housing out the top while new coolant flowed in through the bottom.  This simple system solved the bearing cooking problem and turbochargers could easily outlast the life of the engine.

1986 - The First 2.5L TBI and 2.2L Turbo II Engines

New for 1986 was the 2.5L TBI engine.  This was a new spin-off of the 2.2L engine that featured a new block with a taller deck height (called the "tall block"), a new crankshaft with a 4.090" (104mm) stroke and longer connecting rods (6.181"/157mm) to achieve the displacement of the new engine using the same 3.44" (87.5mm) bore.  It used a redesigned low profile throttle body that operated at a lower fuel pressure (15psi), all of which provided increased output power and torque.  The result was a compression ratio of 9.0:1 and an engine output of 100 hp at ???? rpm and ??? ft-lbs of torque at ???? rpm.  This engine also featured counter-rotating balance shafts, which were there to cancel out the increased vibration from the longer stroke of the 2.5L engine. 

As a preview of what's to come in the world of 2.2 liters, Shelby Automobiles, Inc. released the 1986 Shelby GLHS, which was a souped-up version of the Dodge Omni GLH Turbo.  This car featured the first intercooled 2.2L turbo engine made in production.  What would later become the Turbo II, was now a modified Turbo I engine with a new intake configuration sporting the new blow-through setup with an intercooler, which will be explained when it gets put into production at Chrysler in 1987 (see the Turbocharger Concepts page for more information).  This engine boasted 175 hp at 5200 rpm and the torque peak measured 175 ft-lbs from 2200-4800 rpm.

The 1986 engines featured a new "782", "fast-burn", or "swirl" head.  It featured a smaller displacement and a new intake runner and bowl configuration that allowed the air and fuel to combust more quickly and completely.  The result was better emissions and a slight increase in low-end torque.  To compensate for the decrease in head displacement in the Turbo I engine, new 14cc dished pistons were introduced to maintain a compression ratio of 8.1:1.  Also, the engine lost it's big-beam rods that it earned in 1984.  These were replaced with lighter (659g) forged rods that were still strong enough, but increased engine output by decreasing its rotating and reciprocating masses.  All the blocks got upgraded to 11mm head bolts (from 10mm).

Some changes in the electronics occurred again in 1986, mostly to the configuration of the sensors and wiring.  Another change was the elimination of some of the diagnostics.  One was the detonation sensor diagnostic and the other was a limp-in mode for the fuel injector sync sensor on the turbocharged engine.  Functionally, the turbo logic and power modules were the same, but the changes make them unswappable.

1987 - More Fine Tuning And More Power

The 2.2L and 2.5L engines received some additional refinements to the electronics in 1987.  One change was to the oxygen sensor, which changed to the 3 wire setup.  The three wire oxygen sensor featured a built-in heater (the reason for the extra wires) that brought the sensor to operating temperature more quickly.  This reduced emissions by allowing the ECU to go into closed-loop sooner and it also increased the life of the sensor because higher operating temperatures allows the sensor to better repel contaminants.  Another change was moving the MAP sensor from the logic module to the right strut tower under the hood.  The new bracket on which it was mounted prevented moisture from entering the sensor.  The previous design allowed moisture to enter and when the moisture would freeze in cold weather, it would damage the sensor.  Also, the canister purge and EGR control solenoids were combined into one since their functionality paralleled one another.  None of these changes were implemented in the L-body, however.

The big news for 1987 was the introduction of the production 2.2L Turbo II engine for the Daytona Shelby Z.  It featured the new intake setup first used in the 1986 Shelby GLHS.  It was the first production blow-through setup where the air box was connected right to the turbo and the air was blown through the intercooler, then through the throttle body and into the intake manifold (i.e. the turbo "blows through" the throttle body).  This differed from the Turbo I's carb-like pull-through setup with the throttle body before the turbo so that the turbo had to "pull" the air "through" the throttle body (see the Turbocharger Concepts page for more information).  1987 would be the last year for the pull-through intake.  The new setup also featured a tuned intake with long runners (called the "two piece" because it could be disassembled) to improve air distribution to the cylinders.  Like the GLHS, this intake setup also featured a larger turbo.  Unlike the GLHS however, the production Turbo II had a significantly beefed-up bottom end with a stronger cross-drilled block, a forged crankshaft, the big beam rods of the '84 - '85 Turbo I with even stronger bearing caps and full-floating pins, and high-quality cast pistons by Mahle.  A newly programmed computer and large fuel injectors were installed to increase the boost and control the new AIS motor of the blow-through.  One thing to note is that even though the 1987 Shelby GLHS, CSX, and Lancer were intercooled, they did not feature this bottom end.  Apparently it was not in production soon enough for Shelby to be able to use it.

1988 - The End Of The Pull-Through Intakes

Chrysler's 2.2L Turbo engines saw some pretty significant changes in 1988.  Probably the biggest were the introduction of the roller cam and the conversion of the Turbo I engine to a blow-through intake setup like the Turbo II.  All 2.2L and 2.5L engines now received a roller cam setup to reduce friction and noise, along with a new cam profile for the turbo engines.  Duration and overlap were decreased in an attempt to get the turbocharged engines to idle smoother.  The new Turbo I engine setup also featured a smaller turbocharger made by Mitsubishi.  The small turbo could spool-up more quickly than the old Garrett T03, reducing turbo lag and giving the engine more boost at lower engine speeds.  This gave the engine more bottom end punch, which is apparent by the increased, low rpm torque of 170 ft-lbs at 2400 rpm.  Another change to all turbocharged engines was the new one-piece tuned long runner intake manifold, which now replaced the two-piece manifold on the Turbo II, as well as the log manifold of the Turbo I.  No gains in performance on the Turbo II resulted, but this manifold may have contributed to the gain in bottom end torque on the Turbo I.  One other change to the 2.2L turbo engines and also the 2.5L TBI engine was a slight decrease in compression ratio.  8.0:1 for the turbo engines and 8.9:1 for the 2.5L TBI engine.  This may be the result of a slight increase in piston dish volume.  The bottom end of both turbo engines remained unchanged for 1998 and the 2.2L carbureted, 2.2L TBI, and 2.5L TBI engines remained largely unchanged, otherwise.

New for 1988 was the Mitsubishi 3.0L V6, which slowly became available on all platforms.  This marked the beginning of the V6 craze that eventually killed the turbocharged engines on most vehicles, even though the V6 was less powerful than even the early 2.2L turbocharged engines.

There were significant changes to the electronics of the fuel injected (TBI and Turbo) engines for 1988.  The primary difference was the end of the logic and power module setup.  Both modules were combined into a combination logic/power module called the SMEC (single module engine controller).  It still featured distinct logic and power sections because it was split into two circuit boards.  The new logic board received a more powerful CPU and more sophisticated programming.  This new programming gave the SMEC the ability to adapt to fuel delivery changes and also to return from limp-in mode.  The older logic modules, once in limp-in mode, would stay there until the engine was shut off.  The SMEC would constantly monitor the problem area and would automatically continue using it if it returned to operational status.  Otherwise, it worked the same way as the logic and power modules did.  One other functional change was the omission of the air charge temperature sensor for the Turbo I engine.  Since it was not intercooled, the SMEC could interpolate the air charge temperature based on incoming air temperature (battery temp sensor), engine coolant temperature, and boost pressure.

1989 - The Age Of The Common Block

There were some major changes to the whole 2.2L and 2.5L lineup in 1989.  Basically, Chrysler wanted to cut manufacturing costs by eliminating the need for a special assembly line for the 2.5L block and keeping special track of the Turbo II blocks.  They accomplished this by designing the "common block".  It would be used on all 2.2L and 2.5L engines until both of their demise.  It had very strong features for the powerful engines that were being built, and for those that were to come.  It had reinforced main bearing supports and huge main bearing caps, thicker cylinder walls, balance shafts, and cross drilling between the cylinders.  As such, the 2.2L carbureted and TBI engines were dropped.  With this strong block, the Turbo I was changed from 2.2L to 2.5L and the boost was upped by 2psi, which brought the output to 150 hp at 4800 rpm and 180 ft-lbs at 2000rpm.  The smaller Mitsubishi turbocharger was kept, but the down pipe was upgraded from 2 1/4" to 2 1/2" for all engines to improve exhaust flow.  The Turbo II stayed a 2.2L with the Garret T04 turbo and remained largely unchanged.  It also was the only engine to lack balance shafts at first, though they were added later to simplify production.  The 2.5L TBI engine received some minor changes with a new injector and upped fuel pressure (39psi), but it remained unchanged performance-wise.  It should be noted that the common block did not have the additional deck height of the 2.5L tall block.  They all used the same rods, which were basically like the older Turbo II rods with floating pins.  The 2.5L pistons had a shortened compression height (the pin was raised and the piston shortened) to accommodate the longer stroke of the 2.5L crankshaft.  All 2.5L crankshafts were cast, while the 2.2L Turbo II was forged and used the same Mahle pistons as before.  At the top end, the engine's received an even milder camshaft, reducing duration and overlap for a smoother-running engine.

Brand-new for 1989 was the 2.2L Turbo IV VNT engine found only in the 1989 Shelby CSX.  It featured an intercooled Garrett VNT25 variable nozzle turbo that virtually eliminated turbo lag.  It was basically a 1988 Turbo II bottom end, so it did not receive the common block.  Power output was still 175 hp at 5200 rpm, but had a better torque curve of 200 ft-lbs at 3700 rpm.

Other changes included an upgraded SMEC with a better CPU, but no other major changes.

1990 - The Brief Life Of The Turbo IV

New for 1990 was the production version of the 2.2L Turbo IV engine that debuted on the Shelby CSX in 1989.  This time the common block was used and they apparently received balance shafts.  Engine output was the same as in 1989 and it was only available in the Shadow ES, the Daytona CS and Daytona Shelby, and the LeBaron GTC.  Unfortunately, the Turbo IV engine was only in production for one year, apparently due to reliability problems with the turbo.  All other engines remained unchanged.

One major change to the electronics was the introduction of the SBEC (single board engine controller).  The SBEC marked the end of the separate logic and power sections of the SMEC and the earlier modules.  The unit was completely redesigned into one board with a more powerful processor, but sat in the same spot as the power modules and SMECs, but in a smaller package with only one connector.

1991 - The 2.2L Turbo III Is Born

In 1991, the latest news was the introduction of what became known as the 2.2L Turbo III engine.  It featured a 2.2L Turbo IV bottom end but with forged pistons and a 16 valve DOHC head designed by Lotus.  This was the most powerful 2.2L engine ever put into production by Chrysler, which boasted a whopping 224 hp at 6000 rpm and 217 ft-lbs at 2800 rpm.  It was only available in the Dodge Spirit R/T, in an attempt to compete with the Ford Taurus SHO.  Since it had the Turbo IV bottom end, it received balance shafts and was fed 11psi of intercooled boost from a Garret TB03 turbocharger.  The camshafts actually sit along side the head so that they didn't stick out of the hood, and used real roller rocker arms (instead of cam followers) to actuate the valves.  As such, the valves were arranged in a pent-roof design instead of the direct-overhead setup of the 8 valve head, and unlike many other DOHC engines, the Turbo III had valve reliefs on the pistons to keep from destroying them if the timing belt ever failed.  The Lotus head did, however have reliability problems with poor castings that resulted in heads cracking and rapid camshaft wear.

Gone in 1991 was the Turbo IV engine, as well as the Turbo II because is was being replaced by the Turbo III.  The 2.5L Turbo I was still the same, except the computer was reprogrammed in mid-year to improve its torque curve, which rose to 210 ft-lbs.  Power output was unchanged.  The 2.5L TBI engine remained the same.

1992 - Daytona Gets the Turbo III

Not much happened in 1992.  The 2.5L Turbo I was still the same as in late 1991, and the Turbo III engine became available on the new Daytona IROC R/T.  The 2.5L TBI engine remained unchanged.

1993 - The End of An Era

This would be the last year for the 2.2L and 2.5L engines.  The 2.5L Turbo I remained unchanged and the 2.2L Turbo III was only available on the Daytona IROC R/T because the Dodge Spirit R/T was discontinued.  The 2.5L TBI engine was unchanged

1993 marked the end of the reign of the 2.2L and 2.5L engines and the abandonment of turbocharged engines at Chrysler for a decade.  They had to make way for the next generation 2.0L and 2.4L engines that were to be used in Chrysler's upcoming vehicle line-up, which at first included the Neon.  In fact, most of the last K-car descendants that were powered by these engines met their demise in 1993 and were slowly replaced by the "cloud cars" (Cirrus, Stratus, and Breeze), the LH sedans (Intrepid, etc), and their descendants which are beyond the scope of this website.

Then, in 2003, the turbo returned....

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Updated 04/26/2004.

Copyright © 1996-2004 Russ W. Knize.