Diesel engine

Richard Lamb wrote:

Pete Schaefer wrote:


Heat is usually the big one. How you get rid of it is critical, of course.
Dave Driskoll (DH) can probably tell us all more about this. One of the
things that is really cool about the DeltaHawk engines is that they are
designed to be run continuously at max (pretty sure about this.....Dave, are
you there?). That's a lot of full-time horses.




That't what it takes for aircraft ops.


Pete is quite correct, dumping heat is major hurdle to continuous power
operations and unfortunately it is generally not as simple as adding
larger radiators or oil coolers. Extracting BTU's from the oil or
coolant is really the simple part of the problem. Getting BTU's from
the combustion chamber, through the cylinder sleeves, piston crowns, and
fire plates without cooking the coolant, your bearings, or any of the
aforementioned parts can be quite challenging.

As a simple example, the VW TDI uses an oil squirter to spray cooling
oil on the bottom of the piston. That system is designed to remove a
BTU's at a certain rate and remain in equilibrium, IE stable oil
temperature at a certain HP (this would be the maximum continuous HP).
If we decide to increase the max. HP we now have to remove more BTU's
with the oil to maintain a stable temperature, this means more oil needs
to be sprayed. Ok put a bigger orifice on the oil jet. Unfortunately
putting on a larger jet reduces oil pressure which is bad for the main
bearings, so in addition to the larger jet, we now need to put a larger
oil pump on the engine to give us the required oil pressure. Oops that
bigger pump uses some of the additional HP that you thought you were
going to get and now we repeat the process with a larger jet and oil
pump so we net out the HP we are really after. Ok now that we've go
that solved, we notice that all the extra oil flinging around in the
crank case is too much for our current ring pack and we need a new
design there for better oil control. This new ring pack will of course
mean more friction, less net HP, etc., etc., etc. (bang head here)......

As Pete commented, the DeltaHawk is rated for continuos duty throughout
its HP range (as are most aircraft engines), most automotive engines are
not. While there certainly have been a number of very successful
automotive conversions, all of the successful ones have been the result
of a significant engineering and test efforts (a program which I suspect
is probably not unlike developing an aviation diesel from scratch).


Dave Driscoll
DeltaHawk LLC