On Sat, 26 Jun 2004 09:58:44 +0200, Thomas Borchert wrote:

Greg,

After all, he makes it perfectly clear
that you have to have an engine monitor, which makes it a
hole-in-your-wallet type of commitment for many.


One could (succesfully) make the argument that the information gleaned
from an engine monitor will save you more in money than it costs.

This is true. I read one such example where he had an 18gph engine
running at 15gph. Anyone have any idea what can be done with some of the
smaller engines? Say, something in the 9-11gph range? If we assume the
same ratio of savings, that puts us at 7.5 - 9.2 gph, right? At a savings
(unsupported assumptions here) of 1.65gph, on average, at $2.40/g, that's
$3.96 saved per hour. At, say, 100hr/year, that's $396 saved per year.
If we assume the 700 series JP Instrument, installed, that's something
like $1700 - $2000 installed (right?). So, that means we can recoup our
investment in 4.3 to a little over 5 years. Ouch.

Granted, the more you fly and the bigger the fuel rate of your engine, the
quicker it's going to pay off, but I think it's hard to justify it across
the board on a economy savings basis.

If we run with the demoed 3gph savings, at $2.40g, that's $7.20/hr
savings. If we assume 200hr/yr, that's $1440 savings a year, which makes
the cheap JPI monitor paid for in about 1 1/4 years. And that is still
assuming that it's a four cylinder. Realistically, it's probably going to
be a 6-cylinder, which is going to raise the price again. So, again, even
with 200hr/yr, we're looking at something about two years for a return on
our investment.

So, it doesn't look like quite the sweatheart deal after all. Now, if
there are some supporting numbers which indicate a return on TBO, then we
might have something to sing about.

Just some fun numbers for food for thought.

Cheers!

Greg