Stage II for PT is here!

[skripo]

PT Cruiser GT Stage II
By Michael Triffon

Many of us have been lamenting Daimler Chrysler Motor’s (DCM) unwillingness to release the Mopar Stage II upgrade for the PT Cruiser GT, especially when they have released Stage II AND III for our feisty little brethren, the SRT 4. This has led to much discussion of converting SRT 4 Stage II components for use in our beloved manual PT Cruiser GT’s. The automatic is not a contender because all SRT 4’s are manual.

At the time of this writing, no one to my knowledge has actually tried this. Theories have been bandied about and some seem convinced it can be done while others say the A/C and other functions will not work. My point of view is, why bother?

There are not only better options, but they can be more functional, flexible, and cheaper as well! But before we get to them, we need to take a close look at the SRT 4 Stage II components to truly understand the system.

Stage II Components for SRT 4:

1. Stage 2 PCM (Power Control Module)
• Increased WOT and part throttle boost.
• Waste gate control was retuned for better turbo response
• Boost hold feature during WOT shifts.
• Enhanced first gear boost schedule.
• Increased Rev Limit 6500 RPM from 6200 RPM.
2. 682 CC Fuel Injectors
3. Waste gate Actuator
4. 3.0 Bar MAP Sensor (Manifold Absolute Pressure)
5. 3.0 bar TIP Sensor (Throttle Input Pressure)
6. Turbo Toys
• Turbo Intercooler Sprayer
• Dial-A-Boost Switch

Street price of $1350.00, Turbo Toys included.

Very simply put, the Stage II core upgrade will allow more boost to develop and hold it longer before venting it. Increasing the boost means more pressure so the new wastegate has a stronger spring to hold the higher boost. More air will also lean out the fuel mixture which is why they include bigger fuel injectors. All of this lovely boost will overshoot the stock 2.25 Bar MAP (Manifold Absolute Pressure) sensor, so that needs to be upgraded to a 3 Bar sensor so the PCM can see and properly react to the higher boost and supply more fuel.

The last, and optional, components are the turbo toys which are a turbo intercooler sprayer that sprays water on the intercooler body to further refrigerate the air, and a pretty trick little boost wheel that tells the PCM to increase spark advance to take full advantage of 100 octane fuel.

Now that we understand what the components do let’s look at what we can do to get stage II performance in a PT GT. The very first thing you will need is Stage I:

Manual Transmission
• Increased WOT and part throttle boost
• Enhanced 1st gear boost schedule for a higher performance launch
• Optimized calibration for the MOPAR blow off valve conversion kit
• Improved turbo response
• Boost hold feature during WOT shifts
• Soft rev limiter

Automatic Transmission
• Increased WOT and part throttle boost
• Optimized calibration for the MOPAR blow off valve (BOV) conversion kit
• Improved turbo response
• Performance optimized transmission calibration

So far so good but to get Stage II performance we need more boost, and there are 2 ways achieve that goal. The first way is a wastegate upgrade.

The wastegate sits on the exhaust side, where exhaust pressure drives the turbo. It is also plumbed with a line from the pressure side of the turbo. There is a solenoid in between but we will explore that later. When the boost pressure builds up beyond the spring’s capacity to hold it, the wastegate gives and vents exhaust pressure to slow down the turbo and bring boost pressure back under 15 pounds.

It stands to reason that if you install a bigger spring in the waste gate, you could build and hold more boost. Unfortunately the PCM senses the higher boost through the MAP sensor and will immediately reduce the power output by pulling the timing. In order to realize any power gain we will have to keep the PCM from seeing the extra boost by modifying the MAP sensor output.

A MAP sensor works by converting ambient exhaust pressure into an electrical voltage, the higher the pressure, the higher the voltage. In ord

[Culprat]

Very well put, some of us are all ready there.

Keith

[TurbozCS2003]

Good article but do you have a part #/source for the diodes to clip
the voltage? Also you will have to experiment to get the tolerance correct so you will clip at the max boost so the computer will put max
fuel in. Note Dodge garage shows diode trick on old Map sensor for SMEC based computer(88-92 T1 and T2 cars) and early Logic Module(85-87 with MAP on module. where did you install the diode on your PT??

Have you dynoed and compared stg 1 vs stg 1 with the clamp and higher boost? Also why not use an EGT to tune?

Lastly the 41 TE will be weak link, especially the diff. Start doing a lot of peg leg burn outs and you will shoot the diff pin. I'll get you a link and it will show you failure mode.

[hoopdiewagon]

SIII can run 26psi because a different turbo comes in the package. A stock turbo will not like that much boost for very long.

[1ptturbo]

quote:Originally posted by hoopdiewagon

SIII can run 26psi because a different turbo comes in the package. A stock turbo will not like that much boost for very long.

He just means the engine itself can take up to 26 psi, our tiny weeny turbo will lose it's efficiency well before 26 psi and I really doubt whether it can hold 22psi all the way to red line.

Skripo, I don't see where you tied all these components together to form a complete system.
Are you recommending using a 3bar map and clamp it or just fool the stock map. What about the throttle inlet pressure sensor it also reads boost and needs to read 3bars, how do you control this sensor from pulling timing? Are you bypassing some or all the boost control solenoids, WGA, Surge Valve and Tip?
[:I]

[SuGamer]

PsiFi's PowerPaq (Skripo's finally recommendation) comes with a 3bar map sensor.

[skripo]

[/quote] He just means the engine itself can take up to 26 psi, our tiny weeny turbo will lose it's efficiency well before 26 psi and I really doubt whether it can hold 22psi all the way to red line.

Are you recommending using a 3bar map and clamp it or just fool the stock map. What about the throttle inlet pressure sensor it also reads boost and needs to read 3bars, how do you control this sensor from pulling timing? Are you bypassing some or all the boost control solenoids, WGA, Surge Valve and Tip?
[:I]
[/quote]

I am recommending clamping the MAP sensor at the closest level to 15 PSI to ensure maximum fuel flow. Clamping it will prevent it from pulling timing.

The best I can understand at this time is that the PCM uses the TIP map and temperature sensor to calculate air density in order to avoid over leaning the engine when the air is denser (usually colder or lower elevations).

Many on the SRT forums are simply pulling the TIP sensor plug so that the sensor always reads 0V. This will ensure that the PCM doesn't limit boost, or possibly pull timing. This was named the EDTIP mod after the guy at Exhaust Depot who first came up with it.

[knowyourturbo]

Very well written. You are the man. Thanx for this article. My parts can't arrive fast enough, but now sooo many more ideas thanx to you all! Stew

[AlexJB]

Part of the first post is missing?
any way I can get to read it?

[03electricbluegt]

Originally Posted by skripo

PT Cruiser GT Stage II
B

A MAP sensor works by converting ambient exhaust pressure into an electrical voltage, the higher the pressure, the higher the voltage. In ord

The MAP sensor reads pressure in the intake manifold, not the exhaust manifold.

Be careful with the map clamps guys. They are simple devices, but when set wrong, you can totally grenade your motor by leaning it out too much.