Upgrading The Turbocharger

[ Choosing | Mitsubishi TD04 | Garrett T03 | Garrett T04 | Garrett TB03 | Garrett VNT25 | MP Plus | Super 60 | Super 70 ]

Description

This page describes the options available for upgrading the turbocharger on 2.2L and 2.5L engines.  You should read the 2.2L/2.5L Turbo Engine Information page and the Turbocharger Concepts page if you are not familiar with Chrysler's turbocharged engines, or you don't understand turbo-lingo.  If you are trying to upgrade an early Turbo I engine, you will probably have to do some hybrid-type work using Garrett T04 parts inside the Garrett T03 housings.

Since there are several options available, I will describe the stock units as well as some of the more popular turbocharger models used as upgrades.  Special thanks go to Garry Mckissick for the technical specifications and to the late Gus Mahon for the information on the capabilities of many of these units.


Choosing Your Turbo

Choosing which turbocharger is best for you can be a tough decision.  The sections below give details about each turbocharger, ending with a table containing the details of it.  Use this information when ordering a custom turbo setup from Turbonetics or Turbo City.  Companies like Forward Motion and LRE offer custom turbo setups that may fit your needs as well.  Give them a call and see what they have that might work well for you.  Below is a quick rule of thumb that you can use to give you an idea of what to choose:

If you are not going to run boost levels above about 12psi, the Mitsubishi TD04 unit is probably the best choice.  It offers an amazingly fast response time because of it's small size.  Though it can be run at 17 or 18psi, these kinds of outputs will probably shorten the life of the turbo by spinning it too fast.  You might consider a Garrett T03 or T04 instead.  Running up to 14psi is probably safe, but the more restrictive exhaust housing will begin to effect top-end performance.  Try to get an '89 or later unit with to 2 1/2" downpipe to help the turbo flow at the top-end.  Also, if you are still using the 1984 - 1987 Turbo I intake setup, then you will have to use a Garrett T03 unit.

If you are going to run boost levels of 12psi to about 18psi, then you would probably want to consider a Garrett T03 or T04 unit.  Functionally, the two units are the same, it just depends what you can fit on your engine.  The T03 fits on 1984 - 1987 Turbo I engine, while the T04 fits on most other 8-valve engines.  The internals of the two units are also the same, so you can fit other T04 components into a T03 housing most of the time, if you like.

If you are going to run 18psi to 20psi, then you might consider a Super 60 with a 0.43 A/R housing.  Over about 21psi requires a 0.64 A/R housing.  The smaller housing will effect engine performance at the top-end.  Other race applcations usually demand a "real" Super 60 or a Super 70.  See the sections below for more details.

The Mitsubishi TD04 Unit

This was the smallest turbocharger that was used on 2.2L and 2.5L turbocharged engines.  It was first used on the 1988 2.2L Turbo I.  The switch to the smaller Mitsubishi unit was an attempt to improve the response of the Turbo I engine.  The smaller turbo would spin up faster at lower engine speeds to give the engine more bottem-end power.  The result was more torque at a lower engine speed than the 1984 - 1987 Turbo I.  It was also necessary because the blow-through intake setup was put in use on the Turbo I in 1988, which required a T04-style turbocharger.  In 1989 the downpipe on the exhaust housing was enlarged from 2 1/4" to 2 1/2" to accomodate the increased displacement of the new-for-1989 2.5L Turbo I.  The larger wastegate improved the ECU's ability to control the output of the small Mitsubishi unit.

The compressor wheel on this unit was quite a bit smaller than the Garrett units, as was the exhaust housing A/R ratio (exact numbers unknown).  This is why the unit can spool-up so quickly.  Because of this however, the maximum boost output of the Mitsubishi unit is about 17 to 18psi on a 2.5L Turbo I engine.  It may be slightly higher on a 2.2L Turbo I.  Since you are over-spinning the turbocharger at these pressures, I would recommend at least a Garrett T04 to reliably run 18psi of boost.
Make: Mitsubishi
Use: 1988 - 1993 Turbo I
Downpipe Size: 2 1/4" or 2 1/2"
Swing Valve: ?
Exhaust A/R: ?
Exhaust Turbine: ?
Compressor Inducer: ?
Compressor Exducer: ?

The Garrett T03 Unit

This unit was used on 2.2L Turbo I engines from 1984 through 1987.  It featured a special adapter on the compressor housing so that the intake of the turbocharger pointed straight up to accomodate the configuration of the pull-through intake (see the Turbocharger Concepts page for more details).  It also had to accomodate the EGR valve.  The compressor housing was also rotated such that it pointed straight up to mate with the "log" intake manifold.

The maximum boost output of this turbo (overspinning) is estimated at about 21 - 23psi.
Make: Garrett (AlliedSignal)
Use: 1984 - 1987 Turbo I
Downpipe Size: 2 1/4"
Swing Valve: ?
Exhaust Scroll: 0.48 A/R
Exhaust Turbine: Standard Chrysler
Compressor Inducer: 40mm
Compressor Exducer: 60mm

The Garrett T04 Unit

This unit was used on the 2.2L Turbo II engines from 1987 through 1990.  Its only major difference from the T03 was that it used housings that were compatable with the manifolds on the blow-through engines.  The layout of the exhaust and compressor housings are the same as on the Mitsubishi TD04 unit.  Also, the downpipe size was increased to 2 1/2" in 1989 on this unit as well.

The maximum boost output of this turbo (overspinning) is also estimated at about 21 - 23psi.
Make: Garrett (AlliedSignal)
Use: 1987 - 1990 Turbo II
Downpipe Size: 2 1/4" or 2 1/2"
Swing Valve: ?
Exhaust Scroll: 0.48 A/R
Exhaust Turbine: Standard Chrysler
Compressor Inducer: 40mm
Compressor Exducer: 60mm

The Garrett TB03 Unit

This turbocharger was used on the Turbo III 16 valve engine.  It used an exhaust and compressor housing similar to the T03 unit, but featured a larger compressor wheel.  Maximum output is unkown.
Make: Garrett (AlliedSignal)
Use: 1991 - 1993 Turbo III
Downpipe Size: 2 1/2"
Swing Valve: ?
Exhaust Scroll: 0.48 A/R
Exhaust Turbine: Standard Chrysler
Compressor Inducer: 45mm
Compressor Exducer: 60mm

The Garrett VNT25 Unit

Chrysler was the first to put a variable nozzle turbo into a production vehicle in 1990 (it was also used in the 1989 Shelby CSX).  It was put in the LeBaron, the Shadow, and the Daytona.  It was the answer to and exhaust housing A/R dilemma.  It featured a Garrett T25 turbo with 0.63 A/R (?) exhaust housing and veins that surrounded the exhaust turbine.  Tthese veins could open and close, which in effect varied the A/R ratio of the housing.  When the veins closed, this resulted in a very small effective A/R that spun the turbine up quickly.  Then the veins would open up, increasing the effective A/R ratio and decreasing exhaust restriction.  The effective A/R could go high enough so that a wastegate wasn't even necessary.  By playing some games with the timing of the positions of the veins, turbo lag was almost completely eliminated!  When boost was not needed (deceleration and idle), the veins would open to remove the needless restriction of the turbo.
Make: Garrett (AlliedSignal)
Use: 1989 - 1990 Turbo IV
Downpipe Size: 2 1/2"
Swing Valve: ?
Exhaust Scroll: 0.63 A/R ?
Exhaust Turbine: ?
Compressor Inducer: ?
Compressor Exducer: ?

The Mopar Performance Turbo Plus Units

This turbocharger is available as a Garrett T03 or T04-style unit through Mopar Performance (P4452780 and P4452781, respectively).  It features a 0.63 A/R ratio exhaust housing and a 45mm/60mm compressor wheel (like the TB03).  The slightly larger compressor wheel yields more output than a stock unit, but the large A/R ratio housing decreases mid-range performance and increases turbo lag.  However the high-end performance is improved because of the large housing.
Make: Garrett (AlliedSignal)
Use: Performance Upgrade
Downpipe Size: 2 1/2"
Swing Valve: ?
Exhaust Scroll: 0.63 A/R
Exhaust Turbine: Standard Chrysler
Compressor Inducer: 45mm
Compressor Exducer: 60mm

The Super 60 Unit

This unit is a Garrett T04-type turbocharger that is available through Mopar Performance (P4529980, kit includes +40% injectors and 3-bar MAP sensor), LRE, and Turbonetics.  It features a 0.63 A/R ratio exhaust housing and a 55mm/60mm compressor wheel.  The result was more high-end power because of the reduced exhaust restriction and large compressor wheel, but also more turbo lag and less mid-range performance because of the higher A/R ratio.  You can usually have this unit put together with a 0.48 A/R exhaust housing, which should bring that mid-range performance back and reduce some of the lag.  It will still lag more than the stock Garrett T04 because of the larger compressor wheel.  Companies such as Turbonetics and Texas Turbo can do this.

The Super 60 turbo with the 0.48 A/R ratio housing will limit the realistic boost output to about 21psi.  This is because the more restrictive housing generates too much backpressure and boost above 21psi does not yield a significant increase in engine output.  The unit will still boost over 21psi, if desired.  The restriction can be reduced somewhat by having the turbine clipped, but then you hurt mid-range performance again (but not as much).  The Super 60 turbo with the 0.63 A/R housing can put out up to 27 to 28psi (overspinning).

Because of its response characteristics, the Mopar Performance Super 60 turbocharger is probably not the best choice for a daily driver.  If you are going to be running 18 - 20psi on the street, then perhaps you could consider the Super 60 with a 0.48 A/R housing to improve driveability.  If you want to run more than that (and not waste it), then you will have to deal with the lag of the 0.63 A/R housing.
Make: Garrett (AlliedSignal)
Use: Performance Upgrade
Downpipe Size: 2 1/2"
Swing Valve: ?
Exhaust Scroll: 0.63 A/R
Exhaust Turbine: Standard Chrysler
Compressor Inducer: 55mm
Compressor Exducer: 60mm

The Super 70 Unit

This unit is a Garrett T04 unit usually with a ported 0.48 A/R exhaust housing and features a 50mm/70mm compressor wheel.  The smaller A/R ratio results in an earlier spool-up than the 0.63 A/R, but it still has more lag.  One advantage of the Super 70 is that it produces more air output at lower engine speeds than the Super 60 because of the larger compressor wheel.  So if you can get a Super 70 with a 0.63 A/R housing, it yields more engine output in the mid-range than the Super 60, but takes longer to get there (turbo lag) because of the bigger wheel.

Like the Super 60, the smaller A/R does limit the realistic boost output to about 21psi.  A clipped exhaust turbine will yield a couple of psi more.  A 0.63 A/R housing on this turbo will probably yield boost levels up to 30psi or more!  Another problem associated with the Super 70 and the 0.48 exhaust housing is driveability.  Gus Mahon's experience with it is that the small housing caused the turbo to spin more like a stock Turbo I or II and the large compressor wheel generated way too much pressure at part throttle.  The result is a pressure surge that builds up in the turbo output hose and makes driving smoothly at part throttle very difficult.  This turbo with the 0.48 A/R housing should only be used for racing.
Make: Garrett (AlliedSignal)
Use: Performance Upgrade
Downpipe Size: 2 1/2"
Swing Valve: ?
Exhaust Scroll: 0.48 A/R
Exhaust Turbine: Standard Chrysler
Compressor Inducer: 50mm
Compressor Exducer: 70mm


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This page is maintained by Russell W. Knize and was last updated 01/19/99. Comments? Questions? Email minimopar@myrealbox.com.

Copyright © 1996-2003 Russ W. Knize