SMC + Saab 900 t16

[alex_ander3@hotmail.com]

Hello!

My name is Alex, and i'm from Norway.
Have a saab 900 t16 1987, Equipped with autronic smc.
These old gearboxes are very bad, and dosent hold a lot of tourqe. So i have to do something!

Was thinking about this autronic Turbo wastegate control http://www.mamut.net/mrmracing/100023.jpg
Can this help me to increase tourqe in the lower RPM? By reducing the boost on certain levels.

Dont know how mutch HP i am gonna go for, but for about maximum 350 HP, can i use the 1/8 for that. (The little one)
The turbo is a Turbonetics 550 HP. Dont know how mutch boost i am gonna go for, to get a good engiene. How mutch can the autronic control handle of Boost? ( please wright in BAR)

http://www.trollhattansaab.net/wp-content/_landstreffvlerbanen013.jpg

//Alex

[Wroom]

You should use the small boost valve.

Robert or Ian can give you a more accurate figure on max boost using internal sensor, but at least 3,4 Bar.

Both the SMC, SM2 and especially SM4 is very good at regulating boost, so you can regulate the boost curve over rpm range very accurately.

And also on the SM4 you can have up to three different boost curves, active at different gears, or set by switch on the dash.

And when the traction control gets released after the testing it will be a whole different ballgame for FWD cars.

You should consider an upgrade to SM4 with traction control.

What type of wastegate do you have? Tial, HKS, ..? Must be an external you have, right?

[roberto arano]

on my sabb t-16, the stock APC solenoid works well with the sm2

the autronic valves are great though

for most of my projects i use the small autronic valve, for twin turbos i use the large one

[MRMRacing]

From my opinon it is best to use Autronic valve and in twin turbo apps use two small Autronic valvees.

[Wroom]

on my sabb t-16, the stock APC solenoid works well with the sm2
I have to confess that i have been running a SAAB APC valve on my Mitsubishi EVO6 because it is both quick in response, and also accurate since you can run it "floating" with a high PWM rate. :p

[alex_ander3@hotmail.com]

From my opinon it is best to use Autronic valve and in twin turbo apps use two small Autronic valvees.

Hello, and thank you all for the answers!

Mrm, do i have to get a big one (1/4) or can i manage with the small one. Just so i get this right:)

My Wastegate is a 40mm TIAL. I have also a Turboxs boost controller. How will this work with the Autronic valve? Can i use them both?
-The Turboxs for to controol max boost. and the Autronic valve to decide what boost i want on the specific RPM!?!
http://www.boostcontroller.com/products/BC-131thumb.gif

[roberto arano]

no, you just use the autronic valve, one small one,

i don't remember if the smC has different boost curves for each gear selected. if it does (sm2 &sm4 do this) then you can have different boost curves for each gear to protect the gearbox/avoid wheel spin.

you can tap the speed signal from the cruise controll speed input box under the dash, with a reluctor adapter as a "quick and dirty speed input".(Driven wheel) I noticed that i had to disconnect the "cruise box" from the wire(blue i think) that runs to the triggers (mounted to the speedo head) ,otherwise the wave was floating too high and the reluctor adapter would not trigger. Some years of 900 have slightly different cruise contol modules so it may make a difference.

The other way to get an easy speed input is to use a terratrip rally computer hall effect sender that splices into the speedo cable. It is about the same price as a reluctor adapter, so you can go either way. I would probably prefer the hall signal generator that splices into the cable,rather than adapting into the cruise control. I only did it that way because i had a spare reluctor adapter lying around.

[Wroom]

My Wastegate is a 40mm TIAL. I have also a Turboxs boost controller. How will this work with the Autronic valve? Can i use them both?

Since you have an external wastegate:
You can let the Autronic regulate the boost on one side of the Tial using a PWM table, to get the variation over rpm, and set the TurboXs to regulate the overall boost level on the other side of the Tial.

[alex_ander3@hotmail.com]

Hmm. My english is not THAT well. But if i understood you, you ment that i should connect both the turboxs and the valve from autronic, to regulate the boost.

What do you meen by booth sides? drawing:) ?

[Wroom]

Hmm. My english is not THAT well. But if i understood you, you ment that i should connect both the turboxs and the valve from autronic, to regulate the boost.

What do you meen by booth sides? drawing:) ?
Okey. Best advice is to start with only having the Autronic regulating the boost, and to follow the advice from the manual.

I don't have a drawing for it. But an external wastegate regulates the boost pressure from a number of parameters:
Pressure under the wastegate control membrane. This is exactly as for the standard builtin wastegate.
Spring on top of the wastegate membrane. The boost pressure is set by the stiffness of the spring used, and by adjusting the screw that sets the load on the spring. When the pressure under the membrane equals the pressure from the spring, the wastegate opens.
Pressure above the membrane. By setting a certain pressure above the membrane, instead of just connecting it to open air, one can raise the boost pressure, since the force of the pressure below the membrane must equal the combined force of the spring and the pressure above the membrane to open the wastegate.The Autronic can regulate the boost pressure either by bleeding off pressure under the membrane, as normally is done for an internal wastegate.

But it can also regulate the boost by controlling the pressure above the membrane.This gives the most accurate control of boost with least difficulty. The pressure from the turbo is then connected directly to the chamber under the membrane in the wastegate.

One can also combine the two. Say that the Autronic controls the pressure under the membrane with a PWM table. Then a Hallman device or similar can control the pressure above the membrane. Then we have a boost curve that varies over rpm, is set by the Autronic. And that one can linearly raise the boost pressure over the full range with the Hallman device connected to the chamber above the membrane.