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Hi,
I´m not trying to say that you are wrong with your opinions about APC and things like it´ll only ruin ones performance, no. But, before we are about to throw our APC´s away, I´d like to put down few words about it.
First, every one of them even the newest units are now at least roughly 8 years old (the unit itself). APC contains components that will loose their property when time goes by. Well, mostly capacitors only do that, but most of them will start to die slowly after three years after manufacturing date. After ten years at least 50% of them are worth nothing.. Get the point? We are talking about analogue deviceds that will go out of date as time goes by. I´ve done several tests (benchtests and live "in car"tests) with several APC´s and I´ve seen this happen. APC´s go bad in time. But not the way they cannot be used anymore (and of course, they can be "rebuilded" like almost everything!). Boost just starts to fluctuate without obvious reasons. Boost won´t go as high as it shuold. It starts to go mad with EMC interference etc, etc. Then add bad knock sensor cable with incorrectly torqued sensor, oh, and pressure sensor might have bad spots + sticking and other probs... Here you have good set up to go mad on bumps, or with chain rattles etc. (be it good or bad then..)
So before you´ll go and say APC is bad, it should be in good condition, wires, all the components and engine itself. Here everything has an effect on everything. But when it works, it´s darn awesome device. It is able to turn boost down slightly before there is ANY audible knock (tested this with function generator acting as knock signal source etc).
And when you have everything working as designed, boost should not be dropped immediately, but just taper slowly or never even got to the highest point. "Engine noise"- factor has a big role in this game.
On the other hand, when you are seeking the highest possible power, APC might not really be the one for you. Unless you adjust it (K) just to show you knock with led (+12/pin19), this can be done on a dyno with a guy who understands where are the limits of the engine.
I´ve seen T16 engine rushing 20psi of boost without APC and no problems, but this works only when A/F and temperature problems are solved totally.
Afer all, I´d say, don´t think APC as a modification itself, but more than a indicator, to show you if your mods are working as they should.
Remember, even inaudible knock could destroy an engine in seconds.
Then a little CAUTION here about APC mod found on Saabworks.com site.
This mod really messes up the way how APC detects knock, and it´s (based on my bench tests only, though) totally deaf for some frequencies, where stock APC lowers it´s output value really fast. I know this mod works somehow, good stabile boost at least ;o) , and it´s based on old G6 APC, but it´s totally different than ANY present commercial mods and I cannot recommend it to anyone.
Uh oh, that´s bit too much for my english skills, but I hope you get the point I´m trying to say here.
Good luck for all of your projects and keep sharing the information.
"Tweaker"
Marko A
posted by 212.50.192.2...
, Sun, 30 Dec 2001 00:35:20, Sat, 29 Dec 2001 21:43:17, Sun, 30 Dec 2001 00:54:46
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