atomization enhancement

[CLsnyder]

----- Original Message -----
From: James Montebello <jamesm at talarian.com>
To: <diy_efi at efi332.eng.ohio-state.edu>
Sent: Wednesday, May 05, 1999 1:53 PM
Subject: RE: atomization enhancement


> > I just looked this up. All the new german diesel engines use
> > common-rail
> > (BMW, Audi, Mercedes) and uses a pressures of approx 1350 bar.
> > VW has a new diesel at 1.9 liter that uses one separate diesel
> > pump/cyilinder and uses a pressure of 2050 bar. According to all these
> > manufacturers the higher the pressure the better the combustion.
>
> 1350 BAR!?!  2050 BAR?!?
>
> 20,000psi and 30,000 psi?  Tell me there's a missing decimal
> point, or a units mistake here. 13.5 and 20.5 bar sound more
> believable.
>
> james montebello
>
Hey guys, we are talking RAIL pressure here, not injector pressure. On these
camshaft or hydraulically operated injectors, rail pressure can be
multiplied by a factor of several hundred to one for injection. I can't
remember what make and model the engine was - I remember it was on a huge
generator in Zambia - I think it MAY have been an old Cummins - anyway, it
had a primary pump that ran about 10PSI, and a booster pump to about 150
PSI. That was rail pressure. Each cyl had its own "pump" in the injector,
which popped at about 28,000 PSI. Let's not get TOO confused.
On independent injector (distributor type) diesels like the Bosh, or Roosa
Master, the injection pressure is around the 28,000 PSI - and that fluid
pressure runs from the pump to the injector in those skinny little steel
lines that look like brake lines.  The tiny bore of the line leaves a pretty
thick wall - which still flexes enough that a Piezo sensor clamped to the
line can sense injection pulses to check injection timing and/or run a
tach!!
NEVER leave a bracket off on one of these lines as vibration can fatigue the
line, causing breakage - and at 28,000 + psi diesel fuel can puncture skin
from several feet away, and remove metal at a range of close to an inch.