Injector Sizing: REALLY dumb question -Reply

[xxalexx at ix.netcom.com]

> Date:          Thu, 27 Aug 1998 21:55:09 -0600
> To:            diy_efi at efi332.eng.ohio-state.edu
> From:          bearbvd at sni.net (Greg Hermann)
> Subject:       Re: Injector Sizing: REALLY dumb question -Reply
> Reply-to:      diy_efi at efi332.eng.ohio-state.edu

> >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 worked on this problem in late 70's at Carter Carb on a Rabbit 
engine,  WOT  1500 RPM the fuel would be spraying out a few feet.
The fuel curve would run rich low rpm to lean high rpm.
For a O2 sensor engine you needed a flat fuel curve
I found by tuning the length of the fuel vent tube to the intake 
waves helped alot. The length was about 3.5".   VW decided to change 
the shape of there aircleaner and related plumbing to solve the 
problem. 
alex