Injector Sizing: REALLY dumb question -Reply

[Greg Hermann]

>10-4 but it all depends upon RPM. Each duration (overlap) value has a
>different scavenge RPM and when you are under it (or turbocharged) all kjinds
>of unpleasant things happen. I have seen fuel haze "standing" on top of a
>carburator from this..  Tom.
>
Tom-- I suspect you of a plot to keep me up late. I've tuned many Webers
from scratch. seen fuel standoff too. It's why Weber will sell you extended
boosters for IDA's and DCOE's. But the headers are still wrapped around the
cam grinder's neck. Fuel standoff is primarily due to standing (sound)
waves in the intake ports, which happen when the i valves are closed, not
to self egr. When it happens, you can put the extended boosters in, and, by
keeping the fuel that's way out there from falling onto the floor, you
bring the BSFC right back into line. Too bad Passini's books are out of
print, and somebody thought they need mine more than I did!

I will admit that if you are trying to run a cam that has no business
turning slower than 4 K on the street, you can get some burble,
particularly on a single plane manifolded V-8, but I thought that modern
valve spring materials and cam ramp rates had pretty much cured that crap.
The other side of that is that I can and have set up 1649 cc , 4 cyl.
(naturally aspirated) Alfas (80x82, 2mm over 1600) with cams that wouldn't
make any power below about 5000, with 11.5 compression and two 45 DCOE's
with 36mm chokes so they would make about 185-190 HP, and yet idle smoothly
at 700 RPM, and pull smoothly (if only about as hard as a clapped out 1300)
if you floored them at 1500 rpm in 5th gear. (P.S. Still only a single plug
head, but made best power with only 33 degrees total advance--go ahead,
ask!) Yeah, there was some fuel standoff, but I don't think much self egr.

Regards, Greg