diesel 160-200HP engines

On Fri, 26 Mar 2004 22:26:50 -0600, Dave Driscoll
wrote:

I'd be happy to answer any questions that
people may have regarding the project.


Hi Dave

How do you get a diesel restarted in the air if you happen
to have multiple fuel tanks and run one dry so the injection
system gets air in it? Is there a way around this problem?

Jim

Jim,

The engine is designed to be fairly fault tolerant of air bubbles in the
low pressure fuel lines (the returns from the pump element gallery are
positioned above the high pressure gallery inlet etc.) and will continue
to deliver solid fuel through the high pressure lines even with bubbles
in the low pressure ones. It will also repurge the high pressure lines
even in the event that you run them completely dry. You simply have to
reintroduce fuel to the system and keep spinning the prop at greater
than 150 rpm. How long it takes for a restart is based upon how dry the
system was and how fast you can spin the prop. This however is not a
good practice as the high pressure pumps will be operating without
lubrication on the top side until the fuel is reintroduced. The
collective thoughts of the group are that you can certainly get away
with it a couple of times, but better be thinking about inspecting the
high pressure plungers after the 2nd full dry restart.

Dave Driscoll
DeltaHawk LLC

jpollard###mnsi.net wrote:

On Fri, 26 Mar 2004 22:26:50 -0600, Dave Driscoll
wrote:



I'd be happy to answer any questions that
people may have regarding the project.




Hi Dave

How do you get a diesel restarted in the air if you happen
to have multiple fuel tanks and run one dry so the injection
system gets air in it? Is there a way around this problem?

Jim

On Sun, 28 Mar 2004, Dave Driscoll wrote:

This however is not a good practice as the high pressure pumps will be
operating without lubrication on the top side until the fuel is
reintroduced. The collective thoughts of the group are that you can
certainly get away with it a couple of times, but better be thinking
about inspecting the high pressure plungers after the 2nd full dry
restart.

Most of my diesel experience is with engines using Stanadyne DB2 injection
pumps. Stanadyne makes what they call an "Arctic kit" for this pump that
makes it insensitive to fuel lubricity by, if I understand correctly,
changing the material of some parts so any fuel, even gasoline, can be
used without damage to the injection pump. I've always wondered why they
don't make all the pumps that way to begin with; maybe there's a downside
I'm not aware of. Why doesn't DeltaHawk set up the injection pump that
way? Speaking strictly as a layman, it seems it would solve the run-dry
damage problem, as well as providing some emergency fuel flexibility.

-Dan

Dan,

The DB2 is a little different animal than what we use on the DeltaHawk.
The DeltaHawk uses an independent, high pressure, plunger style pump
element for each cylinder. These run at significantly higher pressure
than the DB2 and also allow for redundancy in that the failure of a
single pump element will only take out a cylinder not the entire fuel
system. While in the DeltaHawk application there are some significant
advantages to the plunger style pump, what is commercially available in
this style of pump is not as fault tolerant to fuel lubrisity as the
DB2. However, although we currently use an off the shelf element, there
are some improvements that can be realized when volumes will allow us to
create a high pressure injection pump tailored to our specific
application. The long and short of things, with the current pump is
that while repriming once or twice isn't going to destroy the engine, it
isn't something that should become routine.

Dave Driscoll
DeltaHawk LLC

Dan Youngquist wrote:

On Sun, 28 Mar 2004, Dave Driscoll wrote:



This however is not a good practice as the high pressure pumps will be
operating without lubrication on the top side until the fuel is
reintroduced. The collective thoughts of the group are that you can
certainly get away with it a couple of times, but better be thinking
about inspecting the high pressure plungers after the 2nd full dry
restart.



Most of my diesel experience is with engines using Stanadyne DB2 injection
pumps. Stanadyne makes what they call an "Arctic kit" for this pump that
makes it insensitive to fuel lubricity by, if I understand correctly,
changing the material of some parts so any fuel, even gasoline, can be
used without damage to the injection pump. I've always wondered why they
don't make all the pumps that way to begin with; maybe there's a downside
I'm not aware of. Why doesn't DeltaHawk set up the injection pump that
way? Speaking strictly as a layman, it seems it would solve the run-dry
damage problem, as well as providing some emergency fuel flexibility.

-Dan