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Old 04-06-2015, 11:12 PM
v8volvo v8volvo is offline
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Join Date: Jun 2009
Location: Montana, USA
Vehicle: '86 745, '83 764
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Yes and fully-integrated charge pressure control, temp-responsive timing, etc would be great benefits too. It's an interesting discussion although strictly a theoretical one.

Yet, if mapping pump timing to engine load is the only goal, wonder if you could build a fairly simple external IP pressure circuit between the advance piston housing and the IP transfer pump inlet, with a duty-cycled solenoid (e.g. similar to k-jet frequency valve) to control pressure to the advance piston and thereby effect changes to dynamic timing. You'd still need some serious EMS wizardry to make it play, and at minimum you'd need some kind of crank and cam or IP timing reference inputs, maybe an optical trigger wheel on the front of the crank could work. Still seems like a lot more trouble than it's worth, but if you've maxed out the capability of the mechanical setup or your range of operating conditions is too broad to be able to optimize a "dumb" pump to fully take advantage of, perhaps it's the next realm of exploration...

Or if binary adjustments are good enough (or better than nothing), you could pretty easily use the existing high-altitude compensation solenoid wired to a throttle switch (or other mechanism) to make timing somewhat responsive to load. Could even design a fancy circuit that accounts for other variables (e.g. engine speed, charge pressure, etc) as well. That would at least give you some on-the-fly timing control, albeit not precise and only in one rather large step.

Very interesting to think about. All of this would be chasing the ideal of just having full electronic control, though, without that everything else is a band-aid -- the above is the same type of thought process that led to feedback carburetors. Probably better off just sticking in a 5cyl TDI if it became truly critical to have electronic control, even though the loss of the 6cyl sound and dynamics would be a downgrade...
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86 745 D24T/ZF 345k lifted 2.5"
83 764 D24T/M46 155k
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