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Discussion Starter · #1 ·
Hey everyone,

I don't get over here as much as I would like to, but I think that this is worth mentioning, the difference between DI Cassettes. There is much more of a difference than the black and red color, one major difference being that T-7 utilizes alternating current and T-5 generates DC. A lot of people have been posting the compatability of the DI's on all of the Saab boards and 90% of the time, it is unfortunately wrong.

I have cut and pasted some old posts from "Dr. Boost", the chief engineer responsible for Trionic 5,7,8 and modern Turbo systems at Saab Sweden. Since some of you don't know me, I thought it would be be easier to post some of his quotes here to end any potential for an argument.

Quote #1:

"Hi !

RED cassette has got a DC spark.
We have two different RED cassettes:
----------
Then, BLACK cassettes:
BLACK cassettes has got an AC spark, and thus a longer spark duration.

NOTE:
Cars with DI or DI/APC (MY 90-92) can use the BLACK cassette as "Dr Boost's fix".
The longer spark duration will make the engine to run smoother.
Do NOT use BLACK cassette on a T5 car."

Quote #2: (in response to a question of using black DI on a T-5 9000 Aero)

"Hi !
For a "simple test", you can use a BLACK cassette in a T5 vehicle, or if you want the other way around.
However, the "signal interface" are slightly different, or in ither words, the combustion and knock signals are different.
that's why I don't want you to do this, unless it's a simple test.
Just to check if the engine starts or not. I really hope I'm making myself clear enough....."

Quote #3: (the best quote)

"Hi !
As some of you know I work at Saab.

All DI cassettes are "capacitive discharge".
Short description of RED cassette:

The DI Cassette is feed with B+(12V), the B+ is then converted to 400 VDC, inside the DI C. There are four individual ignition coils.
Between the 400 V capacitor and each coil there is one thyristor per coil.
When the ECM triggers the thyristor, energy that has been stored in the capacitor will be dumped into the primary (winding) side of the ignition coil.
As a result there will be a hi voltage across the secondary side.
The duration of the "spark" is quite short, because the use of a thyristor. (DC spark)

BLACK cassette, well more or less the same description, BUT with one important difference: we don't use a thyristor to dump the energy, we use a triac.

The difference between a thyristor and a triac is that the thyristor will only conduct current in one direction, triac in both directions.
And that's why we get a AC spark in the BLACK cassette.
The BLACK cassette's spark duration is approx. three times longer than the RED.

On the New 9-3 SportSedan we do not use capacitive discharge ignition system anymore, we've got an inductive system.
Still one coil per cylinder, and still the ionization concept to analyze the combustion conditions."

"The BLACK DI C will work on your MY/91 LH 2.4.1 But do not use the BLACK DI C as a replacement for a RED DI C if the car has got Trionic T5."

I hope that you all find this useful and informative, I may cut and paste this on some of the other boards as well. ;)
 

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Thats some good info there. I'm a firm believer in using the part the car was designed to use anyways :)
 

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mcrowley said:
Thats some good info there. I'm a firm believer in using the part the car was designed to use anyways :)
I agree as well - but I still don't know who this 'Dr Boost' fella is and since i don't even see a change in fuel mpg - I still belive it's all BS.
 

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Well if this is a guy who had a hand in engineering this system, I would tend to believe what he has to say...

Just because a DI functions does not mean it is functioning correctly :!:
 

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ahh, I knew I had heard that before, I just could remember that one used a thyristor and one used a triac, but now that I have read it, it has all come back to me..

With all the problems I have recently had with devices as simple as o2 sensors I think I am going to stay with the red cassette.

Plus the red just looks so much cooler :)
 

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Overall some very good info from Dr Boost via SilverHoran

And...I can use a T7 DI in my 1991 will no ill effects and I will get longer spark duration - I think I like that!
 

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Discussion Starter · #9 ·
BurnsSide42 said:
I agree as well - but I still don't know who this 'Dr Boost' fella is and since i don't even see a change in fuel mpg - I still belive it's all BS.
:eek: Dr. Boost used an alias so that his assisting us with tuning wouldn't get him fired, though I used to work for Saab and I know his real name. FWIW, he is not the only engineer in Sweden that I know who has provided me with this same info. I am surprised though, he actually designed your system and clearly states not to do this and you will dismiss that? The technical data that he provided wasn't enough to convince you? Oh well, I was just trying to help. :-?
 

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Whenever I would see a Dr. Boost post over on SC I read what he says carefully!

except when he talks about air filters, I like the extra turbo spool /whoosh noise no matter what he says :razz: :lol:
 

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abdukted1456 said:
Whenever I would see a Dr. Boost post over on SC I read what he says carefully!

except when he talks about air filters, I like the extra turbo spool /whoosh noise no matter what he says :razz: :lol:
well it's been pretty well proven that the "free flowing" airfilters are good for nothing. just about any test out there can prove that.
 

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I like the noise of an intake.

You may call me a ricer now.

And people who design things usually know how they work.
 

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shut up jeff you have one of those k&n non-filters too ;) :lol:
 

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Terry, that's excellent info.

Anders on TSN posted a great service bulletin once explaining some of the differences, but this post really nails it.
 

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Silver,

I am trying to get this to work with a Megasquirt triggering the cassette. This seems to be what it wants to fire properly. can you confirm or deny this?

http://ys3al35l.googlepages.com/DI_Waveform.jpg

The black is the specific pin (cyl 1) and the others 3 pins are in dotted as they affect the charge of the capacitor and hence the time it dwells at 12V to recharge.

What would be really awesome would be some specific info on the black (or red) cassette with respect to its knock signal output. MS has a knock signal in, but without knowing how the AC signal out is related to knock, it is not useful to us without destructive testing.

KeithG
 

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Hey Keith, I see you made it to the site! It's good to have a 3rd person who knows megasquirt here. can't wait till we get DI working with the megasquirt... should be good!
 
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