The following is an overview of the development of my turbocharger system for a 2002 Chrysler PT Cruiser. There is a lot of information to go on this page, so please bear with me as I get it all together.

Yes, you may be asking “Didn’t Chrysler produce a PT Cruiser with a turbocharger?” the answer is yes, in 2003 they released a turbo PT. However, my car is a 2002 and did not have the option available. When originally released in late 2000, the only thing the PT lacked was some serious get-up-and-go. With its retro styling, one would think DCX would have had the foresight of public demand for more power. The 2001-2002 (well, all PTs, really) have a 2.4L DOHC motor (in the USA) based off the DSM 420a motor (head is rotated 180 degrees and block is taller for more stroke).

Hahn Racecraft, Jackson Racing, and Whipple all sought to remedy this problem with a forced induction system for the PT. Hahn was first off the line, as they already had an existing turbocharger system for the Dodge Neon which uses the same motor and similar fuel management. The other two offered superchargers of very different styles. None of these systems are currently available anymore; the emersion of factory-turboed cars made demand much lower.

I decided to pursue a different route; custom fabrication. I had already modified my car, and a turbo system seemed within reach. I started collecting parts and doing research, and spent an exceptional amount of time figuring out how to build a low-cost system that performed well and was reliable. Being very ignorant, I started looking for any and all parts that I might need. I finally decided to do one part of the system at a time, in the following order:

-Intake system (manifold, intercooler, piping, etc)
-Fuel system (pump, return line, regulator, injectors)
-Oil system
-Electrical
-Exhaust / turbine

I bought the first turbo that I could find, on eBay: a used Garrett T3 with a .48 A/R turbine housing, internal wastegate, and 45 trim compressor. I wanted to stick with a T3-style flange because I was aware that many of the existing exhaust manifolds for my car and the Neon used the T3 flange. After doing some of the math (which I should have done first), I realized that this compressor was excessively small for my engine’s flow requirements. Eventually, I ended up going with a Garrett hybrid T3/T4 with that existing .48 A/R turbine on a T04E-40 Trim compressor.

This is much more suited to my application. I plotted the compressor map based on the following assumptions:
-Redline of 6250 rpm
-Displacement of (87mm bore x 101mm stroke; 2.4L)
-Volumetric efficiency of 74%
-Air / Fuel ratio of 12:1
-Manifold boost pressure of 7.5 psi

As you can see, the flow at peak RPM is still within the secondary efficiency island.

The intake system was upgraded with an aluminum intake manifold which is ported to a larger size, allowing much more airflow through to the head. The fuel injectors were also upgraded to 30 lb/hr low-impedance Bosch injectors.

An intercooler seemed more than necessary for this application; the small area under the hood and lack of flow across the engine makes under-hood temperatures skyrocket. Pouring more heat into the engine seemed a bad idea. I decided to buy a standard sized one on eBay. This, along with a universal intercooler pipe set (2.5”), fit fairly easily in my bumper, with some modifications. I later upgraded to a much larger intercooler which provided better mid-range power and torque.

The bumper is aftermarket and required some trimming to improve airflow, and to allow room for couplings and pipes.

The fuel system was slightly more complicated; Chrysler decided to not use a return line for the fuel system on this car. The fuel pressure regulator requires a return line, and is both adjustable at idle, as well as under boost; also known as a rising rate fuel pressure regulator or fuel management unit (FMU), this nifty contraption increases fuel pressure at a rate proportional to manifold boost. The ratio on my regulator was 5:1, meaning in the simplest of terms that for every 1psi of boost, my fuel pressure would increase an additional 5 psi. Set points on both ends of the pressure limits had “gain” and “offset” adjustments to make tuning more flexible. This may seem extremely cave-man for engine tuning, but it works very well for the cost.

Back on subject, the fuel regulator increases pressure by restricting the return side of the fuel loop (back from the tank). The OEM returnless system was modified by adding an additional connection on the opposite end of the fuel rail (I welded a fitting on mine), running this into the FMU and then having the excess pumped back to the tank through a custom made return line made of copper tubing. Here is a diagram depicting the basic idea:

An additional fuel pump was required to guarantee the additional fuel flow requirements of a turbocharged system, not to mention the larger injectors! This is the majority of the work required for the fuel system. The injectors I ended up using were Bosch-style 30 lb/hr injectors at 55psi of fuel pressure. These low-impedance injectors flow very well and sustain higher flow rates at proportionally higher fuel pressures.


The next system that I spent some time working on was the oil.  The turbocharger is lubricated with the very same oil that lubricates your engine, unlike some superchargers where the lubrication is self-contained.  The turbo needs an oil source and a drain. 
The source came from a ½” NTP tee that I installed at the oil pressure sensor, which is located on the driver’s side of the engine block, under the exhaust manifold.  I used a -4AN stainless steel braided hose for this, the other end of which goes in the top of the turbo via a 1/8” NTP to -4AN fitting. 

The drain is slightly more complicated.  Turbochargers are setup for gravity drain, which means the turbo needs to be “clocked” in such a way that the oil goes straight down.  I didn’t have the turbo on yet, but I decided to put the modified oil pan on anyways and just plug it for the time being.  There is a rib on the pan (cast aluminum) which can be removed and is an ideal place for the return line to go in.  You could just tap it for a large barbed hose fitting, but I decided to custom weld a block onto it that fed the drain at a more ideal angle than along the horizontal tangent of the pan.








The electrical system for the turbo was actually very easy.  I purchased a “MAP Clamp” from Hahn Racercaft, which they call their “black box”.  The stock ECU in the PT is able to handle most of the tuning you will require, but the one thing it doesn’t like is positive manifold pressure.  The black box prevents the ECU from seeing values outside of the norm.  My black box didn’t have an adjustment screw for offset or gain, but I have seen some other aftermarket ones that do have those adjustments. 

Additionally, I opted to run a wideband 02 sensor.  Normal ECU systems use narrow band sensors which are lower on resolution and accuracy than a wideband.  I went with the LC-1 from Innovate Motorsports, which I highly recommend.  The wiring is easy and follows the documentation provided with the unit very closely.  All in all, the wideband doesn’t provide any signals to the ECU.  It is there for you to tune with; you observe the Air / Fuel ratio during engine pulls and the information you get (rich or lean) allows you to make adjustments to your fuel pressure gain and offset settings to make the maximum amount of power that is safe.


With the exception of the manifold, the exhaust system was completely custom fabricated.  I purchased a manifold on eBay for around $150 bucks.  Be careful, because the manifolds out there for the 420a will NOT work for the PT because of the location of the turbine flange.  It needs to be in the middle of the manifold, not off to one side or another.  If you get one where there is an offset, the turbo will not clear the alternator. 
I wanted to be able to convert the car back to stock if need be, so the entire downpipe from the turbo was welded up in one night.  I removed the catalytic converter in the process.  It is important to have a very good flowing exhaust (aftermarket muffler at LEAST) to make the best performance; turbochargers flow better with less to no backpressure from the exhaust.

I purchased 2x 90 degree “weld ells” from McMaster Carr to help fabricate the curves and bends that I needed.   I also bought a flex coupling and some assorted bent stainless pipe.  All in all, a few hours on the TIG and a few energy drinks was enough to get it fabricated and installed.  I also wrapped the downpipe in fiberglass woven header wrap, to assist in insulation.  A big thanks to my friend John Smerczak for helping me with this downpipe.









I have had the car turbocharged for about one year (Done on July 4th, 2007).  Since then, I have added some additional mods that help improve performance.




This is an exhaust valve.  It is controlled electronically from inside the car via a switch.  When opened, the exhaust flow bypasses the muffler and allows for incredible power when compared to the stock exhaust system.  It also sounds AMAZING to hear the turbo spool up and wind down.  It is very, very loud.  I also later upgraded the turbine housing to a .63 A/R from my original .48 A/R.  This improved flow through the turbo, making more power and more volume too.