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OK, just to clarify... APC working fine -127 box, stock Posted by nicknick [Email]  (#731) [Profile/Gallery]
(more from nicknick) on Wed, 9 Dec 2009 19:42:44
In Reply to: Quick Mitsu survey:How much free thread do you have, nicknick [Profile/Gallery]
, Wed, 9 Dec 2009 15:20:16
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but i just replaced the '88 SPG motor and trans for one from a '92t (with mitsu turbo). The mitsu was never giving great boost (unless disconnected), but i could usually see the red line (boost guage). The setup that i pulled from the SPG (because the trans was bad) would easily see 3/4 red zone (never checked PSI), and i have carried everything over, including fpr (3bar), fuel injectors, apc (of course), and vac advance module (basic mod to that). My first run was disappointing, to say the least. 3/4 yellow. APC working, as proved by tap on brakes- Dropped down to maybe 1/6th yellow. Disconnected runs to the end of the red, and feels great. Havn't bothered fishing out the calibrated boost guage yet. The original setup would drop down to 1/2 yellow with brakes. I mention this because guages are all different, but this is a control in this case. So then i get to thinking. I looked back to Zig's description of the APC, and how it works, and finally realized why setting base boost was so important. It is actually not the setting of the base boost, so much as the spring tension, that is important. The APC pulses at a certain frequency, which was designed around a specific spring pressure. As the spring gets weaker, those pulses of pressure do more to the WG than they did before. I'm not talking about knock conditions here, just general control of boost.
So, then i put in my modded APC, and boost gets to 1/4 red, but is very unstable. I re-read one of Jak's posts on the actuator rod being adjusted too far, and not having enough travel to adequately open WG to effectively modulate boost at required levels. This is what 24hrs of thinking has got me to. I need to back off the adjuster (which is used to compensate for the now very weak spring), and install the helper spring instead.
Thanks again (measurements, please!)
posted by 70.192.12...
, Wed, 9 Dec 2009 15:20:16, Thu, 10 Dec 2009 09:53:10, Thu, 10 Dec 2009 22:04:08, Wed, 9 Dec 2009 19:42:44 <-- Viewing This Message
, Wed, 9 Dec 2009 22:12:51
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