Tim Long wrote:
: Our 140 is coming up on 1600 hrs TBO.
So? If you're Part 91 and the engine isn't having any issues, keep flying!

: We really hate what a dog it is and would like more power.
It's a Cherokee... what do you expect (I own one too).

: Anybody know about praciticalities, costs of #3 above? I know it would
: require extra $$ for dissimilar engine exchange, STC costs, and
: cowling/engine mount mods.
I don't know about the cost, but our plane was modified before we got it.
It's a 140 with a 180 hp engine, AND it's been modified to have the later-style
cowling. The fiberglass clamshell type, not the aluminum flip-side style. As such,
it has the dual exhaust with mufflers under the carb, not by the firewall. I have no
idea how much all that cost, but I'm sure it was expensive... even way back when the
guy we got it from did it.

: I know that some may say sell the plane and buy a 180, but we have a plane
: whose condition we know, it has a pretty fresh paint job, it has all ADs
: complied with, and we just spent ~$7K for a panel mount GPS. We have better
: avionics than most and would hate to do the new buy thing and then spend a
: lot extra getting the plane's condition up to that of our current one.

I've flown a number of different Cherokees, and I can attest that the 140/150
varieties are quite doggy. As far as climb goes, a 180 doesn't really buy you that
much as far as making the fpm more, but it will hold the same fpm with more load and
at a higher altitude. The PA-28 Hershey airframe just sucks at climbing. What
really does help the low-speed performance (and to some degree climb) are Matteson's
VG's. Four little tabs on each wing root lowers light-weight stall by 10-15mph from
my experimentation.

If you have any thoughts of autogassing, you're kinda stuck with what you've
got. Both the 160 and 180 require the new cowling (as someone else mentioned). The
O-360 HP STC that I've got (Avcon) does allow for a low-compression version, which
would be 168hp. You'd want to check for sure from Peterson if that airframe/engine
combo is approved (it's awfully weird so it may not be). It's be just as expensive as
a 180hp, but would allow you to run autogas.

I've got a friend with a 140/160 with the prop mod, powerflow exhaust,
Matteson VG's, etc and at least with 2 people it climbs as good or a bit better than
my 180. If you're overhauling the engine anyway, your best bang for the buck is
probably a 160hp conversion. If you need a new exhaust maybe do the powerflow, but
it's pricey for what you get.

It really boils down to if you want better climb (or reduced-pucker hauling
capacity) or cruise speed. If the former, enjoy the 160 with a non-repitched (thus a
climb) prop. If the latter, sell the plane and buy one that's faster. Speed mods are
almost always not worth it.

Sorry for the ramblings, but maybe some of them helped.

-Cory

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************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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