Thoughts on the ALDA and off-idle performance improvement

[R Leo]

I've been reading of Lance's ALDA trials and tribulations (ALDA 1 & ALDA 2 and got to thinking (dangerous, I know) about the ALDA, it's function and how OM617.952 off-idle performance might be improved.

If I understand it's functon correctly, the ALDA limits the amount of fueling that occurs at high IP power settings (ie WOT) when a low-boost condition exists. Adjusting the ALDA screw CCW incrementally increases this initial fueling at low/no boost and, as boost increases up to a certain point, so does the ALDA fueling due to expansion of the aneroid capsule in the ALDA. I'm assuming, that at higher power settings some other mechanisim in the IP takes over from the ALDA for fueling.

In Lance's case, he ran experimentally without the ALDA and noticed an improvement in off-idle performance. This leads me to believe that some sort of mechanism or device that provided a false boost signal to the ALDA while the turbo spooled-up might just be a solution to off-idle sluggishness. Granted, using it in that fashion would cause smoke but, the device could easily be demand invoked so that you would have extra pickup 'just in case.'

A regulated, switched ~10psi compressed air source, plumbed into the ALDA line between the banjo fitting and the overboost valve would probably do the job without risking damage to the ALDA's aneroid capsule. Some sort of backflow preventer would be necessary to prevent the pressurized air from escaping into the intake manifold.

Very little air volume would be necessary so a belt driven air pump from an 80's era gasser or, a 12VDC compressor plumbed to a small pressure cylinder could provide the necessary pressure signal.

Ideas? Comments?