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Discussion Starter · #1 ·
Well I've always wanted DI on my Saab 900 because the DI cassette looks pretty cool when it's slotted into the top of that cylinder head. I also don't like the sound of all that trouble people have with timing and working around the distributor ect.. I started reading about DI quite a while ago and saw most of what I needed to know on Widdies site ( http://www.900aero.com ) As well as fitting DI I also like the idea of fitting a mappable fuel and boost control system. So I've stripped out the Lucas fuel system and I've sold the APC. I'm now in the process of buying the parts and designing the new system.

The information on Widdies site is just a DIY guide. If your doing nothing else to your car then the DI conversion would be fairly simple. Just a matter of finding the right parts. Where it gets tricky is that the Motec ECU I intend to buy also has ignition capabilities. So I'm kinda stuck between forgetting about DI altogether and just using the Motec or sticking in a combination of the two. I think what I might end-up doing would be use of the DI cassette but replacing the DI ECU with the Motec. So with that idea I would need to know the pin-out on the DI connector and just stick it in..


Here's a list of the DI links I have at the moment:

http://www.900aero.com - in the DIY section
http://www.findarticles.com/p/articles/mi_..._79/ai_68741482
http://www.findarticles.com/p/articles/mi_..._80/ai_70033503
http://www.findarticles.com/p/articles/mi_..._81/ai_87692990
http://www.pajjakid.com/ubipa/DI_APC.htm
http://saabnet.com/tsn/faq/lhoverview.html


If you read all of these you find that some of the sites say some stuff which directly contradicts what another says. So even though there's a lot of information here - there are still decisions to make and stuff that needs testing.


If anyone has any other DI links I would be pleased to see them.

Thanks
 

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had a quick squint at the Motec sight and it would seem that they claim that their ecu's can provide the triggering signal for any ignition system including multi coil systems (which the di pack is )
you would have to work out what signal the di pack needs and see if the motec unit is able to provide it ..there are several flavours of ecu available

I know there is some-one else running another ecu with a di pack...Autronic I believe so it is possible
Speaking to the guys who dyno'd my car last week they were speaking very highly of the motec unit
I think I am right in saying it its the only 32 bit system available
they were also saying that autronic were working on ion sensing as saab uses on the trionic but had not perfected it I have e-mailed them to ask as it would be a mappable system to replace the di/apc set up but no reply as of yet ...

very interesting

keep us informed on how you do...
 

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Discussion Starter · #3 ·
good info. I believe you are correct in saying that the Motec is the only 32bit system. Obviously this means double the calculation speed over the closest rival systems. This is key (in my view) as there are so many things for the ECU to do - it would be so rubbish if it ran out of processor power...!
 

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Mike, I had a look at the Emerald system and whilst it says that the calibration software will run on a windows 32bit platform, it doesn't actually say the ECU is 32bit.

However for anyone wanting to understand more about the theory of ECUs etc, they have a very good page on the Basics of Engine Management
 

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Excellent info' Mark. Learnt alot there
....although they did have nitrous oxide as NO2 rather than it's actual N2O
 

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We run a DTA ECU on our Hillclimb Pug (with Jenvey Throttle Bodies)

Very good for a budget ECU... I think its similar to Emerald.

www.dtafast.co.uk
Mapped by Noble Motorsport in Chesterfield. Again bothing but praise.

Cheers
 

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Mark - I'm sure the box itself is 32-bit (see here). I was at Emerald a number of times (when they were in Brixton) while it was in the early stages of development and remember being told it was genuinely 32-bit. OTOH I'm not convinced that it *needs* to be 32-bit.

Mike
 

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Originally posted by Mike Bz:
[qb]OTOH I'm not convinced that it *needs* to be 32-bit.[/qb][/b]
You're quite correct. It just needs to be fast enough to do its job (preferably with headroom for additional stuff) and a 32-bit bus isn't the only way to achieve that. For example, a 16-bit (or 8-bit for that matter) processor running at a higher clock speed could achieve the same thing, as could one with the same clock speed and a more efficient instruction set. Or one with more dedicated peripherals on-chip to take some of the specialised or time-critical tasks from the processor. There are many variables, though, depending on the requirements of the system. Microprocessor-based gadgets are often advertised using terms people are familiar with from PCs, where the processor family is largely the same and these comparisons can be made more directly.

All things being equal, more bits generally make for more speed/power, but all other things will rarely be equal...
 

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Fair comment, Mike, I hadn't read that bit

Ref 32 bit vs 16 or 8, I'd always thought that the main difference with a greater nubmer of bits is better processing accuracy. The fact that 32 bit systems are generally faster than their predecessors is simply down to advances in the technology, not an inherent clock speed advantage.
 

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Wouldnt it be much easier to find a GM900 Trionic 5 engine and simply swop it? That way you would also be able to use all the ECU tuneres software?? I know there will be some problems but I know that there are some sweeds who are stuffing a 9000 AERO engine in a old 900!
They will no doupt provide you with some tec. assitance!
 

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A later 'straight' engine will not fit in a c900, at least not without very extensive mods to the engine bay and a big fat hump on the bonnet. Why go through all the trouble trying to swap in a block that won't fit without extensive modification? I bet a c900 slant engine + T5/T7 head + T5 management would be close enough to a T5 or T7 engine to work well enough with 'standard' tuning software (if using the recommended turbo for that stage and an IC roughly the size and flow of the recommended one for the 9000/NG900/9-3 of that stage) to get OK driveability from the start - then drive to Sweden or Switzerland or wherever and have the final 10% nailed .

The main difference between a slant block/T5 or T7 head hybrid and a full 2.0 T5/T7 engine is that with the former you don't have any balancer shafts, which for performance is no bad thing
.
 

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Originally posted by Mark E:
[qb]Ref 32 bit vs 16 or 8, I'd always thought that the main difference with a greater nubmer of bits is better processing accuracy.[/qb][/b]
No, you can perform 32-bit (or 64-bit or 128-bit or whatever) arithmetic with any of those. You could, for example, write quite a simple programme for an 8-bit computer to calculate a number (e.g. pi) to any arbitrary precision.

The inherent performance advantage of more bits is higher data throughput. In a 32-bit processor system (assuming the architecture is 32-bit throughout, which many "32-bit" systems aren't), data is fetched from memory 32-bits at a time, operated on 32-bits at a time and stored back into memory 32-bits at a time. All other things being equal (which as I said before, is rare), this will mean everything happens four times as quickly as in an 8-bit system.

In reality, this sort of operation isn't all that processors do and for example program control like running round in loops x number of times is likely to be no more efficient (or not much more) on a 32-bit system than on an 8-bit system. So the real-life advantage will fall far short of fourfold to a degree that depends on the application.
 

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In certain cases a 32 bit system may be slower if the software is 8 bit or 16 bit. We had a case of an upgrade to some microprocessors at work being slower. It was explained to me that a 32 bit processor needed 32 bits at a time every time. if the software only provided 8, then the processor had to add 24 zeros to each processing string before it could act on the instruction.
 

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 then drive to Sweden or Switzerland or wherever and have the final 10% nailed  .[/b]
thats the problem..
My stage 6 is not performing as it should and I have driven to sweden to get the final 30 % nailed and it came back less than 10 %
It is really handy to have a system that some-one "local" (British Isles) can map.

I am in the process of tracking down dan ex from abbott who might be able to help me out

otherwise I will seriously consider fitting another system that can give the power my engine is capable of ...
Autronic with their ion sensing system (not available yet)
or the 32 bit motec
or the emerald system..I will be talking to dave about this when I am there ...
 

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My experience concurs directly with ylee's. I have parts, and in theory software, rated for 350hp, yet at the last dyno run was only achieving 309hp. It will be interesting to see how it performs at Emerald in a few weeks, when I will also be able to get some more diagnostic measurements.
 

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I tracked down Dan who was responsible for the tuning maps @ abbott
His advice was
It is difficult to intigrate a di pack into an aftermarket system but it is possible
Motec units are big money with all the add-ons
He suggested a New Zealand supplier.. http://www.link-electro.co.nz/home.html
which he says because they are smaller may be able to accomodate your needs
 

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Originally posted by Marky:
[qb] QUOTE
Originally posted by Eric van Spelde:
A later 'straight' engine will not fit in a c900,[/b]
The older 2.3's will fit, including the '93 aero engine. [/qb][/b][/quote]How? Methinks you would have a slight problem with shutting the bonnet at the very least..
 
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