DIY versus "red box" APC

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Ludwig - 20 Dec 2005 03:29 GMT

What differences would one expect between a DIY APC upgrade such as the
one outlined at http://www.saabworks.com/projects/apc.html and a ~$300
box from a professional tuner? Obviously the former involves more
effort, but is the final product qualitatively comparable, or is there
some additional voodoo that Group 9/Swedish Dynamics/etc are doing?

Thanks
1990 900T

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Paul Halliday - 20 Dec 2005 18:06 GMT

> What differences would one expect between a DIY APC upgrade such as the
> one outlined at http://www.saabworks.com/projects/apc.html and a ~$300
> box from a professional tuner? Obviously the former involves more
> effort, but is the final product qualitatively comparable, or is there
> some additional voodoo that Group 9/Swedish Dynamics/etc are doing?

Hi Ludwig,

My preference if a DIY box. The expensive boxes are no more than a DIY with
a badge :) The advice on SAAB Works is very good indeed and the guy knows
his stuff. Have a look at http://www.900aero.com as well - there's loads of
advice there and good forum boards for APC specific questions.

Once you've learned the voodoo (and it's not really that hard), you can fine
tune the box as you like. What SAAB Works is offering is a method of making
your own Red Box, which has some considerable differences to the standard
black boxes. You can tune the black boxes much more simply and get great
results ... As I said, learn the theory, too, so you'll be in control of
what you're doing.

Paul

1989 900 Turbo S
http://saab.go.dyndns.org/

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ma_twain - 22 Dec 2005 16:05 GMT

>>What differences would one expect between a DIY APC upgrade such as the
>>one outlined at http://www.saabworks.com/projects/apc.html and a ~$300
[quoted text clipped - 20 lines]
> 1989 900 Turbo S
> http://saab.go.dyndns.org/

With that said, think about what you have. There are no more Classic 900s

being made and parts (transmissions/engines) in good condition will be harder

to obtain. As some wrote in another post, he increased the power and
had to rebuild his transmission in 25,000 miles. There is the potential
increase torque and power, but use it wisely :-)

The other thought is have a balanced car - the suspension should be able
to handle the extra power generated by the modified Black box.
Otherwise you will have recreated the classic American muscle car that
can only use its power on straight roads. I had a Ford like that long
ago and now I really appreciate the handling of my SPG.

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Paul Halliday - 22 Dec 2005 22:32 GMT

>>> What differences would one expect between a DIY APC upgrade such as the
>>> one outlined at http://www.saabworks.com/projects/apc.html and a ~$300
>>> box from a professional tuner? Obviously the former involves more
>>> effort, but is the final product qualitatively comparable, or is there
>>> some additional voodoo that Group 9/Swedish Dynamics/etc are doing?

>> My preference if a DIY box. The expensive boxes are no more than a DIY with
>> a badge :) The advice on SAAB Works is very good indeed and the guy knows
[quoted text clipped - 7 lines]
>> results ... As I said, learn the theory, too, so you'll be in control of
>> what you're doing.

> With that said, think about what you have. There are no more Classic 900s
> being made and parts (transmissions/engines) in good condition will be harder
> to obtain. As some wrote in another post, he increased the power and
> had to rebuild his transmission in 25,000 miles. There is the potential
> increase torque and power, but use it wisely :-)

Wise words!

Funnily enough, after my rebuild I'm perfectly happy with the stock
performance. Nothing like a strip and rebuild for restoring lost power. I've
just had my electrics looked over, too, and it's a whole new car. I'm
determined to keep it stock ... and see if I can get the mechanics, interior
and exterior to all be perfect all at the same time :)

I think if APC could be a little more tuned, to prevent over-boosting in the
lower gears, higher boost is a perfectly reasonable goal. T8s do have the
problem of no "on the fly" fuel tuning without aftermarket secondary fuel
injection systems. T16s at least have more responsive fuelling, given
increased boost pressures. I have been very impressed with the DI
conversions I've seen on T16s, so much so, owning a T16 might well be on the
cards ... And that's saying something for a die-hard eight valver :) No,
seriously, the DI+APC transplant onto T16 seems to be an ideal base for
stable tuning where per gear setting can be made.

The spirit of what I was saying was it is better to understand and apply
when tuning, than to just buy an upgraded APC box. As you say, every car is
different and a balanced setup can only really be achieved by setting up the
APC system according to the car and there may well be other work that needs
to be done beforehand. A pre-set "faster" box is not going to be balanced.

God Yule/Merry Christmas everyone,

Paul

1989 900 Turbo S
http://saab.go.dyndns.org/

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Jeremy Brown - 23 Dec 2005 23:08 GMT

Quick question about those DIY/Swedish Dynamics boxes, how do they compare
to the OEM Red Box APC controls?

Jeremy

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