Convert Cherokee 140 to 180?

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

--

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

Tim Long wrote:
Our 140 is coming up on 1600 hrs TBO.

We really hate what a dog it is and would like more power.

Planning ahead, we've thought of a few options:

1 - 160 hp conversion (this is almost the minimum we'd do)

If you're already doing an overhaul, this is probably the most
cost-effective option on your list.

2 - Powerflow exhaust (article in Plane and Pilot claims 20% power
improvement - can it be combined with #1?)

This one is good if your current exhaust system needs a lot of work
and replacement parts. It's a bit pricey otherwise. The 140 owners I
know that have installed it are very happy with its performance.

3 - 180 hp conversion

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.

That's the biggie. I know two people who have done the conversion
(was available from Avcon). It's popular out here in the mountainous
west because the 140 is somewhat limited at high density altitudes
found at mountain airports in the summer. Both of the owners were
happy with the resulting performance, but both said that they'd never
do it again. It was more expensive than they thought it would be (lots
of mods required), it took months to complete, they had difficulty
working with the current STC holders (not Avcon) and in the end, they
still had a 140.

John Galban=====N4BQ (PA28-180)

"Tim Long" wrote in message
...
Our 140 is coming up on 1600 hrs TBO.
I know that some may say sell the plane and buy a 180, but we have a plane
whose condition we know

In a plane like a Cherokee the engine is the number one point of concern- by
the time you've overhauled or done an engine swap you no longer have "a
plane whose condition you know" in one very significant sense. You may,
however, have a warranty, for a few years anyway.

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.

Easily avoided: there are guys like you out there selling above-average
PA-28-180s etc. trading up to even bigger faster planes. The higher up the
totem pole you go the more likely you'll find one with the goodies you want.

-cwk.

On Sat, 08 Jan 2005 20:43:01 GMT, "Colin W Kingsbury"
wrote:


"Tim Long" wrote in message
...
Our 140 is coming up on 1600 hrs TBO.
I know that some may say sell the plane and buy a 180, but we have a plane
whose condition we know

In a plane like a Cherokee the engine is the number one point of concern- by
the time you've overhauled or done an engine swap you no longer have "a
plane whose condition you know" in one very significant sense. You may,
however, have a warranty, for a few years anyway.


As I recall changing the engine to a 180 HP does not make the 140 a
180 as I believe the fuselage on the 140 is shorter.


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.

Spend a lot. That way the next guy saves a lot. :-))

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Easily avoided: there are guys like you out there selling above-average
PA-28-180s etc. trading up to even bigger faster planes. The higher up the
totem pole you go the more likely you'll find one with the goodies you want.

-cwk.

Roger wrote:
: As I recall changing the engine to a 180 HP does not make the 140 a
: 180 as I believe the fuselage on the 140 is shorter.

That's partially true. The 140/180 in general doesn't get you the updated
cowling or the third window (so it's like an older -180). It also doesn't give you a
baggage compartment or real back seats. We got a field approval to put a baggage
floor behind the rear seats in ours, but haven't actually done the modification yet.
The rear seats are the horribly uncomfortable plywood slab jumpseats. A buddy of mine
has a '65 -150 (same as a 'C' model 180 but with an 0-320) with a baggage floor and
bench seat in the rear. The PA28 airframe didn't get any longer until about '73 when
the 180 was briefly called a "Challenger." IIRC. There are lots of -180s without the
stretched fuselage. Fortunately I never ride back there, so I don't care...

The other thing it doesn't do is give you legally much more weight increase.
Our -140 was 2150 gross. With the 180, it's 2200 T.O., 2150 landing. Oh, and for
speed comparisons, I plan for 115 kts TAS and pretty much get it in still air at
reasonable altitudes and loading. At 6000' DA, 65% power, I'll get 130-135 mph TAS
depending on weight and CG. Loading doesn't seem to affect climb rate much at
all until you get over a certain point where it kill it. From my 2100 MSL airport,
it'll do between 800-600 fpm no matter if it's just me or am full with three people
and full fuel on board. Much more than that, and it's a pucker.

-Cory


--

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