Experiences with Cessna 172 upgrade to 180hp?

[Leonard Ellis]

We're nearing time to overhaul the Lycoming O-320H2AD (6210 hours since new)
in our C172N. This will be its 3rd major overhaul and we're interested in
learning about the experiences of those who upgraded to the O-360.
Specifically, the changes you found in performance, impacts on range, or
other relevant information including recommendations on where to get it done
will be appreciated.

Cheers,
Leonard Ellis
Dallas, Texas

[[email protected]]

Leonard Ellis > wrote:
: We're nearing time to overhaul the Lycoming O-320H2AD (6210 hours since new)
: in our C172N. This will be its 3rd major overhaul and we're interested in
: learning about the experiences of those who upgraded to the O-360.
: Specifically, the changes you found in performance, impacts on range, or
: other relevant information including recommendations on where to get it done
: will be appreciated.

We've got a Cherokee 140 that was upgraded to a fixed-pitch 180 before we
bought it. Aside from the outright cost of the new engine and STC paperwork, it is a
no-brainer as far as performance. The "impacts on range" argument is silly, really...
just because you have a larger engine doesn't mean you need to run at higher cruise
powers. I run our Cherokee 180 at 65%, which is about the same as 75% for a 150/160.
Same fuel burn, but cooler engine, and you got more power when you need it.

Where the decision gets more difficult is whether or not to go CS prop or not.
For the most part, with fixed-gear I'd say it's not worth it. It won't buy you much
speed (if any). It WILL buy you faster climb and more load hauling, but most STCs
I've seen do not allow a gross weight increase with a larger engine. I know ours does
not. Also, the CS prop is expensive, more maintanance prone, and adds quite a few
pounds on the nose of the plane.

-Cory


--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Andrew Gideon]

On Thu, 05 Oct 2006 19:35:30 +0000, papenfussDIESPAM wrote:

> but most STCs I've seen do not allow a gross weight increase with
> a larger engine.

We've two 172s upgraded to O-360s (180HP). Penn Yan's STC, fixed pitch,
and a 100 lb gross increase.

I cannot give much comparison, though, to 160HP 172s as I only flew them
during my PPL training and I simply don't recall. I think that, then, I
was too astounded at the flying to consider the quality of flying.

- Andrew

[skym]

Leonard,

I own a C172 180hp, Airplains conversion, fixed prop. I trained in a
regular C172, 160hp. Handling is identical, from my experience. I
recently damaged my plane (taxiing, damage to wing) and have been back
to flying a 160hp rental while my plane is being worked on and having
some long range tanks being put in, so I do have a little experience
going back and forth.
Airspeed in the 180hp is a reliable 124 knots true, plus or minus 1 or
2 knots. I don't recall the airspeed now in the 160hp except that it
seems to be about 10-15 knots slower based on travel time to and fro
some familiar destinations. YMMV. Fuel burn in the 180hp is about 9.6
gph, but this varies from 9.1 to over 10 depending on length of flight,
climb/descent profile and practice. I flight plan 10gph to be safe.
The 10+ gph is on short flights where I climb up and cruise for only
about an hour. The longer the flight the better the gph, which makes
sense of course. Not sure about the fuel burn in the 160hp since I
rent it "wet" and don't pay too much attention since I haven't flown
more than an hour and a half one direction. (I do check the tanks using
the old wet finger method.)
Climb is definitely better in the 180hp, from my limited experience
probably 500fpm better. Since I live in the West, this is also nice
due to the occasional DA issues that can arise.
You can do the math on the range. At my home airport (BIL), alt 3550,
with full fuel, 2 people, and probably 100-150 lbs of stuff, I'm easily
off at 60-65 knots w/in 1500' w/o short field procedures, depending on
temp, etc.
Useful load is about 200 lbs better. Consult the specs.
Frankly, I wouldn't own a 172 with less. My plane is a true 4 person
plane, full fuel, plus 90 lbs left for stuff. 95% of my flying is just
me and the wife, so we can really load it up. That's why I'm adding 30
gals capacity to the 40 gal tanks. We'll be able to fly good IFR legs
with plenty of reserves. Of course I do need the portable pee bags now
for her. ;)
Oil access door is more easily accessible, too, since it is over
towards the side rather than right on top like the 160hp.

[Kyle Boatright]

"Leonard Ellis" > wrote in message
m...
> We're nearing time to overhaul the Lycoming O-320H2AD (6210 hours since
> new) in our C172N. This will be its 3rd major overhaul and we're
> interested in learning about the experiences of those who upgraded to the
> O-360. Specifically, the changes you found in performance, impacts on
> range, or other relevant information including recommendations on where to
> get it done will be appreciated.
>
> Cheers,
> Leonard Ellis
> Dallas, Texas

I've never flown a 180 hp 172, but the math indicates the 20 hp increase
will net you a 4% increase in speed. Since speed increase is proportionate
to the cube root of the ratio of the horsepowers, it should equal
(180/160)^(1/3) = 1.04 = 104%. That's about 5 knots on a 115 knot airplane.

On a 2,000 lb C-172, a 20 hp increase will net about 264 fpm. Alternately,
about 210 fpm at 2,500 lbs. The math is based on the fact that 1 hp will
lift 1 pound 33,000 ft in a minute. So, 20 hp will lift a 2,000 lb airplane
= 20 x 33,000/2,000 = 330 fpm, but you need to reduce that by multiplying it
by a prop efficiency factor. If we assume 80% efficiency, then the
increased rate of climb = 264 fpm.

One thing you should keep in mind is that a "tired" 0-320 probably isn't
producing 160 hp. So, a rebuild would net you a performance increase over
what you currently experience. An upgrade would net you an even bigger
performance increase.

KB

[Ross Richardson[_2_]]

Leonard Ellis wrote:
> We're nearing time to overhaul the Lycoming O-320H2AD (6210 hours since new)
> in our C172N. This will be its 3rd major overhaul and we're interested in
> learning about the experiences of those who upgraded to the O-360.
> Specifically, the changes you found in performance, impacts on range, or
> other relevant information including recommendations on where to get it done
> will be appreciated.
>
> Cheers,
> Leonard Ellis
> Dallas, Texas
>
>

I have a '65 C-172 that came with this conversion. It has the
Doyn/Bush/Avcom conversion. The owners of the STC are not cooperative.
However, the conversion is fantastic. I have the Lycoming O-360-A1A
spinning a C/S prop. You really gain in rate of climb, and a little in
cruise. My model of Skyhawk does not get a GW increase. Airplains and
Penn-Yann do these conversions. AirPlains is in OK. Fuel burn is more so
understand that with the same tanks you have. I usually fly around 60 -
65% and I am OK with 36 gal tanks.

--

Regards, Ross
C-172F 180HP
KSWI

[Doug[_1_]]

Takeoffs and climbs at high altitude are the biggest benefit. I would
go for the STC that gives the best increase in gross weight. Best 172 I
ever flew was a late model, but still 40 degrees of flaps with a 180 hp
conversion (not the constant speed prop). I got my private in that
plane. Great plane!

[JJS]

snip

AirPlains is in OK. Fuel burn is more so
> understand that with the same tanks you have. I usually fly around 60 - 65% and I am OK with 36 gal tanks.
>
> --
>
> Regards, Ross
> C-172F 180HP
> KSWI
>

Hi Ross,
They are in Wellington, Ks.

http://www.airplains.com/

Joe Schneider
Cherokee N8437R



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