absurd pressures figures was: atomization enhancement

[Howard Wilkinson]

Fredrik:
    Not to beat a dead horse here, but there is an error somewhere
either in decimal placement or actual units.  Let me give a few
examples of injector breaking pressures.  The popular Cummins B series
engine used in pickups which is considered very high technology only
runs 4200 lbs. injector breaking pressure.  (about 290 bar)  The max
listed breaking pressure our local pump shop was able to find on an
injector was 4500 lbs. (310 bar){note that these people are the
licensed service rep for Stanadyne, Bosch, CAV, and numerous other
companies and have data available for servicing virtually all
currently available injection systems}.
    The cummins people talk about a system on the new ISB engine which
has a pump that will put out 800 bar (11600 psi).  They can't keep
lines on these engines due to the extreme pressures.
    Here are some real life injector breaking pressures as listed in
service manuals I happened to have handy:
VW diesel:   1564 PSI   (108 bar)
Ford Tractor:   2594psi  (179 bar)
Perkins  (4-236 engine):  2500 psi  (172 bar)
John Deere:  2600 psi  (179.3 bar)
International (466 truck engine):  3000 psi (207 bar)

Note that the cummins PT common rail system pressures run from 80 lbs
to about 300 lbs rail pressure (5.5 bar - 20.7 bar)

I don't doubt that Bosch has experimented with extreme pressures, but
find it impossible to believe the they have actually released systems
with the figures you quote.  As I said previously these pressures are
deadly, not to mention problems of nozzle erosion when extreme
pressures are used.

These numbers are in my opinion nonsense...... regardless of what the
Bosch book says.... there's an error someplace.          H.W.




  -----Original Message-----
From: Fredrik Skog <c95fsg at cs.umu.se>
To: diy_efi at efi332.eng.ohio-state.edu
<diy_efi at efi332.eng.ohio-state.edu>
Date: Thursday, May 06, 1999 6:02 AM
Subject: Re: atomization enhancement


On Fri, 7 May 1999, Howard Wilkinson wrote:

First: I live in europe and we don't use the unlogical imperial
measurements and I have double checked these figures and it says bar
not
psi. Second: I have the "Bosch Automotive Handbook" in my hand
right now and it says that Bosch common rail uses pressures of up to
1600
bar in their common-rail systems.
Third: I have actually driven these vehicles and they work, and they
work
very good, you can't believe it is a diesel engine when you drive it.

This is not bad information, and just because Cummins don't have a way
to
achieve these pressures don't mean that others don't...please, we live
in
1999 now and technology are still getting better. And remember that
all of
these engines where presented to the market last year or this year so
they
are very new.

> James:
>     I'm firmly in your camp.......Statements recently made about
> Cummins and other engines are absurd.  Either someone is mixing up
> decimal points or mistaking bar for PSI.  I can speak from
experience
> with Cummins common rail systems when I say that they are nowhere
> close to these numbers (I've guaged them).  Also The injector pop
> pressures of most diesel engines I've worked with would make me
think
> that someone is mistaking bar and psi pressures.  1500 psi would be
a
> reasonable breaking pressure for a typical injector, and 4k-5k psi
> would be a very high pressure injector.  I believe that Cummins B
> series and C series engines (not common rail) operate in the latter
> range.... don't quote me here as I have only hearsay numbers on
these.
> There is no way on God's earth that a CAV, Roosamaster, or Stanadyne
> rotary pump can produce the pressures people have been throwing
about,
> and I have grave doubts that any of the piston pumps can do this
> either.  There is no doubt that diesels develop more power with
better
> atomization, and run more efficiently.... as do gas engines...this
has
> long been known, but pressures of 20,000 psi are not only difficult
to
> achieve, but EXTREMELY DANGEROUS.  The only safe way to achieve
these
> kind of pressures safely would be to do it with an injector which
did
> the pumping so that there was no danger of line breakage.
>     We are being deluged with bad information here, but
unfortunately
> I have no way of convincingly refuting it.  In my opinion it's utter
> nonsense!!    H.W.
>
>
>
> >> 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
> >
>
>

----------------------------------------------------------------------
--------
Student at the Department of Computing Science Umeå University

Fredrik Skog     E-mail:   c95fsg at cs.umu.se
Taffelstråket 51        WWW:      http://www.acc.umu.se/~skog
903 53 Umeå                         Phone:    +46-(0)90-136365
            Mobile:   +46-(0)70-3041729