ok, some progress here...
ALDA pump now installed on ECO td 1.6...timed to 1mm
I put a boost gauge on it to see how much boost the turbo makes...with the manifold pressure directly connected to the wastegate, the gauge shows 11 psi maximum boost...does that seem about right?
Now I'm just trying to tune it a little...I figured I would try to turn up the fuel screw with the ALDA disconnected until performance matches the original 8mm non-boost enrichment pump..
with the original pump, it would accelerate from 20mph to 55mph in 3rd gear on a FF trans in 11.1 seconds...
without the pressure to the ALDA, I can get the car to match that acceleration, but I lose the ability to get a low idle, and it smokes like the 8mm pump never did...
I plan on ordering the 16 psi boost spring and pin mentioned here:
http://www.vwdiesel.net/forum/index.php?topic=12762.0I did insert a dial indicator into the ALDA top, to measure the travel of the boost pin vs boost pressure...with the original spring. I don't have much spring preload set via the starwheel, since the pin moves immediately under pressure.
I also chucked my boost pin into my lathe, and used a dial indicator to get initial dimensions of the pin. On the original ALDA pin, I measured a taper angleof about 6.5 degrees.
The angle is identical all around the pin, but it's eccentric to vary the offset, as the pin is rotated.
I took some video of these experiments, I'll post links when I get them uploaded.
My understanding is that the real LDA pins have a larger angle, and are cut deeper to add more fuel.
I also installed a solenoid valve between the manifold pressure and the pressure to my ALDA, and can now switch between ECO mode and "boost enrichment" mode...kinda cool
I flip the switch under load at 11 psi and you can feel it "kick in"....since my boost pin is so mild, it isn't much of a "kick"...but I yell "TURBO BOOST ON"...
Maybe I'll start grinding the pin today, and see how that affects things...
Does anybody know how deep the pin is cut on a stock pin? Mine is cut such that at no boost, the pin follower extends .090" into the ALDA pin bore, and at 11 psi boost the follower
extends .132" into the bore. I took a sharpie marker and painted the surface, to see the actual travel on the pin, which is about .360" over the 0 to 11 psi range, or .032 per psi.
So...pin travel is .0327" per psi (dependent on spring), however, the first 1/4 inch of travel is .040"per psi...I think I might be stretching the diaphragm a bit...
Boost pin follower movement is .00381" per psi....dependent on taper angle, and spring...
livin' large here...
Ken
1984 MkI Jetta..gasser converted to N/A diesel
1981 Rabbit Convertible (gasser converted to 1.6 ECO turbo diesel)