Justin Gombos wrote:


I don't know. First off putting $80K into a $50K airplane won't
happen for that reason alone.


I used to fly a c172 trainer that was upgraded from the stock engine
to 180HP. Granted it had to be cheaper than a change in engines that
burn different fuels, but how much different?

Huge. An O-360 doesn't cost that much more new than the 320 it
replaces. Get yourself a field overhauled one and there really isn't
much difference. Those conversions can be done two ways, with a fixed
pitch and with a constant speed. Even going constant speed that's about
a $3K difference.




Here's the breakdown on the diesel upgrade:

parts: $29k
labor: $46-51k

More of the cost is labor. What's the cost of going from say 160HP to
180HP (both burning the same type of fuel)?

Hardly anything. The engine bolts right up. You'll have some labor
installing the prop cable but that's trivial.




I don't expect to see many folks making a lateral change to diesel for
the sake of economy or range, but if someone wants an upgrade in power
anyway, it may be viable to spend a little more and make it a diesel.
The $80k is not exactly a toss-away investment either, because they
can expect to sell the plane for more as well.


The diesel conversion is still a 230 HP aircraft albeit now
turbocharged. The value will certainly rise but not $80K worth. Not
even close.





Second the guy who has $80K to put into a 182 isn't the kind of guy
who homebrews his own biodiesel.


Perhaps that's the case with doctors and lawyers who are private
pilots. However, imagine a full-time flight school owner/CFI, who
might often be stuck at the airport 1-2 hours between student
sessions. It's not worth it to go home during this idle time, so they
might as well use the time to make more biodiesel. They would still
charge the same wet fee as they would for gasoline trainers, but the
diesel savings would directly increase profits. At $3-4/gal in
savings, the school would get $30-40/hr more profit on each flight.
And that's assuming fuel costs don't go up, and doesn't account for
the saving inherent in a diesel reguardless of type of diesel. So how
long does it take a busy school to put ~2200 hours on a plane? Unless
I made some gross error, I'd say in ~2-3 years the engine upgrade
would pay for itself.




First off it isn't legal. You got an STC for that biodiesel? Didn't
think so. That mom and pop flight school/FBO located at that nice
quaint airport doesn't sell jet fuel. A very common situation. Now what?