Tuning on a supercharged 911.

[axl911]

I have a supercharged 993 with the 3.6 liter engine. The Eaton supercharger puts out 5.5lbs of boost. Unfortunately, I don't have access to the aftermarket controller that comes with the supercharer which changes the timing and fuel to cope with the superchanger.

It is currently running rich at 10.5-11 AFR (I guess to be safe). With a/w installed, I am very limited in what I can do to make best use of a/w. Can I simply up the boost to about 6-7 psi as a way to increase AFR to make best use of a/w? My concern here would be that I don't have access to change the timing.

Your suggestion would be appreciated.

[Richard L]

without adequate electronic sensors, it is very difficult to be absolute certain how close your knock limits are. running your current afr is the most sensible things to do.

Is the fuel delieved by a K or KE system? I am just guessing

[axl911]

Originally Posted by Richard L

without adequate electronic sensors, it is very difficult to be absolute certain how close your knock limits are. running your current afr is the most sensible things to do.

Is the fuel delieved by a K or KE system? I am just guessing

It is actually Motronic 2.1 with knock sensors. Does thing change things?

[Richard L]

If you up the psi (mechanically of course),wWill your aftermarket controller add more fuel and timing automatically or it will stay the same as the present boost of 5.5lb?

1. If it is does:
You will not gain much from th AW system, or at worse, you lose power due to retard timing and over rich mixture.

2. If it doesn't:
You will make a reasonable gain from AW system because you wil be able to take advantage of the leaner afr and same timing as 5.5lb.

There is always a possiblity of altering the signal from the sensors to the controller. It is the next best thing to alter the actual controller's fuel and iignition tables

Question: who make the piggyback controller?

[axl911]

The controller is Unichip with a boost sensor module. The system is TPC.

Now that you mention the controller and its reaction to the increased boost, I don't know how the unichip + boost sensor will work with the increased boost.

Sounds like too many unknown. I am going to look into getting access to the controller. And in the mean time probably just use the AW to prevent knock.

If the goal is to prevent knock (controller is already running rich AFR)...what's your recommendation on the mix and size? It's a 3.6 liter with a M90 supercharger running 5.5lbs of boost. The combination gives about 350-370hp at the flywheel.

What's your recommenation in nozzle size and aw mix to do this? I'd like to have some methanol in the mix to prevent freezing.

Originally Posted by Richard L

If you up the psi (mechanically of course),wWill your aftermarket controller add more fuel and timing automatically or it will stay the same as the present boost of 5.5lb?

1. If it is does:
You will not gain much from th AW system, or at worse, you lose power due to retard timing and over rich mixture.

2. If it doesn't:
You will make a reasonable gain from AW system because you wil be able to take advantage of the leaner afr and same timing as 5.5lb.

There is always a possiblity of altering the signal from the sensors to the controller. It is the next best thing to alter the actual controller's fuel and iignition tables

Question: who make the piggyback controller?

[Richard L]

Can you explain TPC?

If you have a unichip controller, the software should be able to allow you to control boost, fuel and ignition timing.

[axl911]

Originally Posted by Richard L

Can you explain TPC?

If you have a unichip controller, the software should be able to allow you to control boost, fuel and ignition timing.

TPC is Turbo Performance Center's aftermarket add-on supercharger kit for the 95-96 Porsche 993. Kit is made up of M90 supercharger and an external unichip controller to control engine timing and drive and extra injector for fuel.

The M90 provides the boost to 6lbs. The unichip senses the boost and control engine/spark timing and controls an extra injector (mounted onto the intake manifold) to provide extra fuel.

Problem is that I don't have the software to access the unichip, and it is probably password protected.

[Richard L]

I can see how it works now, TPC can passowrd lock the fuel and ignition table. I remember the unichip has a global ignition advance control input, I wonder if you can ask PTC can active this input for oyum allow 2-3 degree igbition advance and 1 point air fuel ratio drop.

You can always going to plan B. Eation SC is not very efficient (high exit air temperature), keep the wmi mixture below 50% methanol for the sole purpose of charge air and ncylinder cooling.