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Discussion Starter · #1 ·
I've been intending to do an APC mod for a while but have'nt seen anything like this posted so hopefully there are some electronics bods out there who can clarify a few things for me.

Rather than just swapping the resistors and tweeking the Max Boost and rise rate I want to have 3 settings on the APC.

I'm thinking of using a 3 pole switch with each circuit connecting + to the Base on 3 or 4 different transistors, when the current flows to the base of the transistor (in theory) it will then allow current to flow through that particular circuit(12 transistors in total), so the first setting on the switch would close the transistors on the base circuit which would run through the normal value resistors and pots, then the following 2 settings on the switch would have varing degrees of the APC mods.

I want to keep the standard boost levels for fuel econ & when i'm pottering about, then have a fast road setting and a final track setting.

I'm hoping to put it together this weekend as a mate whose a bit more knowledgable is comming over but I'd be gratefull for any advise.
 

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Sounds like a good idea:)

I seen a product on ebay that you may be after? let me see if i can find the link.
 

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Discussion Starter · #3 · (Edited)
Apc

Hopefully if i get the first bit sorted i'm gonna start working on something that can set the boost according to the gear your in, so i can restrict it in 1st & 2nd and then have it kick in hard in 3rd and 4th.

I may end up using the -87 gear selector as that's got a section on it that lines up the gear shaft, should be able to utilize that to create another switch.
 

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I used to just have a switch on the dash which cut the power to the APC - base boost for normal driving and APC for overtaking and fun on the open road. No APC setting will give you economy (even base boost) - that's all down to your right foot. A properly setup engine and APC will give you everything you need with your right foot - the more you press it the more power you get. It's all about getting a nice smooth power curve rather than the huge midrange, gearbox destroying, torque lump that most APC mods give you. Stock APC settings are pretty good at providing a nice smooth power curve - you can extract more power by timing, exhaust and IC improvements and still keep the smooth power curve. Remember the APC is not just a boost limiter it's a controler of how fast the boost rises and fast boost rise does not automaticaly give you the best all round perfromance and drivability.
 

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good point, well put TrackSide

Ive only just put the APC system on my car, and so far i reckon mile mpg has gone down from 30 to 25 (ish).....

when you say you cut power to the apc, do you mean that it basically ran as an LPT, until power was restored?

G
 

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Discussion Starter · #7 ·
Apc

It also sets the boost at rpm so if i can map it slightly differently in each gear, i should be able to extend the boost rage in 3rd and 4th without chancing destroying the box. I've got 2 APC's so one will remain standard just incase the mods ar'nt as effective as i want. If i kill the APC i'll just swap back, but for the price of an plastic box and a few components i think it's well worth a go.

I've aleady done a few mods, hopefully will finish off (for the mean time) with the 3" downpipe, will leave that till the end of the month as i've got plenty to work on. Sitting on the cash to get the parts to weld one up, so hoping to have it all sorted for SOC.
 

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Si said:
It also sets the boost at rpm so if i can map it slightly differently in each gear, i should be able to extend the boost rage in 3rd and 4th without chancing destroying the box.
- The RED box mod extends the boost slightly in the higher rev range and it's still driveable. Extending it further and remapping without a corresponding hump in the lower RPM will require a redesign of the APC not just a few tweaks. Once you have redesigned the APC to deliver higher RPM boost and no midrange surge you also have to make sure the control system can now react quickly enough at high RPM boost to control detonation and make the knock sensing side of things sophisticated enough to filter knock from engine noise at high rpm. Additionaly you have to fight against the valve setup which is not designed to deliver high power at high rpm - new cams and possibly fueling and timing changes as there is no additional advance with higher RPM which further robs high rpm power.
 

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Discussion Starter · #9 ·
mods

I'll be adding a Catcam Fast Road Cam in a few months, just don't want to fork out for it until i've sorted everything else, I'll also be adding a 5th injector and maybe a water injector, ideally i want them to be linked into the APC.

After that i'm going to look at the 8v fueling, see if I can figure out how to convert a 16v fuel rail & Fi unit to fit with a T8, i hav'nt looked into it at all yet but i'm guessing that i'd have to custom build the fuel rail to take the different position of the injectors, once i've done the thing's on the current list i'll prob find a scrapped T16 and pull out all the FI bits.

I'm kinda into experimentation, if i can mod something without doing permenant harm i'll give it a go, if it does'nt work at the most i'll have wasted a few ££, nothing more.

I've also got a 2nd engine which will hopefully be the power plant in a Mid Engine RWD Caterham 7 style sports car, so the more I learn and mess with my T8 the more I'll be able to do the that when i put it together.

Any idea if the changes in the Red box are shown anywhere? as I could mod my box to have either standard or Red box settings.
 

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Sorry Si - just noticed you have an 8v - you do have ignition advance with rpm.
Maybe worth looking at getting a 16v head on your block and keeping the existing FI. Swopping over EFI from a 16V car may be more complicated. You will get better high RPM flow = better power and also no worries about the head cracking. You could do away with the need for water injecton and other add on's.
 

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Si said:
Any idea if the changes in the Red box are shown anywhere? as I could mod my box to have either standard or Red box settings.
goto 900aero.com, and look in tech, then APC modifying. That should give you all the resistor values for the different boxes.
 

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The basic boost will need modifying, also, to a higher stock setting. I wonder if the standard APC function will work properly. I can see the use of an electrically actuated MBC for setting up the basic boost for a modified APC setup and allowing a totally standard setup otherwise. Turbosmart make one.

The other idea would be to have two APC boxes, spliced to a switch box. The switch box could also actuate said MBC. That would allow for the legality of using a modified box on the road, since you'd be using a stock box for road use and switch over to modified for private road/track use :cheesy:
 
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