Just found out there's a 180hp option for the 172!

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simnettpratt
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Just found out there's a 180hp option for the 172!

Post by simnettpratt »

Sneaky are those devils at A2A. While they deliberately left out of the manual hypoxia and windshield fogging, they only left a small clue you could swap the 160hp engine for a 172S' 180hp engine. On page 97 of the Shift-7 Maintenance Hangar section, the picture of the compression test results show the alternate propeller, which I knew about, but look, the engine also changes, to a 172S' 180hp with a new 2700 redline. You get a new RPM gauge and everything.

A lot of you will already know this, but I'm a Cherokee driver that just started to learn the 172, with three whole flights so far. Sneaky sneaky sneaky. I had to learn about hypoxia and windshield fogging on my own in the Cherokee, too.

So, for those of you that didn't know there were two available engines, open the maintenance hangar with Shift-7 and change the prop! See your rpm gauge change too.

flapman
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Re: Just found out there's a 180hp option for the 172!

Post by flapman »

It should just be the same engine. When you swap out propellers, the maximum RPM changes from 2400RPM to 2700RPM, causing the same engine to produce 20HP extra. The whole process probably involves an STC, and the re-marking of the RPM gauge.

I haven't looked too far into it, but I can't remember which propeller is which? Is the 'cruise prop' the standard R variant? Is the 'climb prop' the S version which authorizes the HP increase? My 172 is set up in a trainer configuration, with no fairings/wheel pants/gap seals/ "/A" equipment code and with the climb prop.

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Paughco
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Re: Just found out there's a 180hp option for the 172!

Post by Paughco »

A long time ago I helped a friend drive down to Paso Robles Airport to retrieve a Piper Tri-Pacer that had flipped over during a wind storm. We took his Dad's '59 El Camino up to Daly City and rented a car trailer. The rental guy asked us where we were going and my buddy told him the East Bay. He almost didn't rent us the trailer because it he thought that was too far away. Good thing we didn't tell him we were actually going to Paso Robles! We drove down there with no problems, and got the wings and horizontal stab off the Tri-Pacer, and got everything loaded onto the trailer. We thought we were really cool when we pulled into the McDonald's parking lot for dinner before the drive back to [censored]. The 135 horse Lycoming replaced the 90-hp Continental in my buddie's Cessna 140. Awright! Now there's a horsepower increase!

Seeya
ATB
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simnettpratt
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Re: Just found out there's a 180hp option for the 172!

Post by simnettpratt »

Ah. Thanks flapman. So it's just the flatter pitch of the optional prop that allows you to zing to 2700, getting the extra 20 horses. Cool.

Factory prop:
McCauley 75' 70° 160hp @ 2400rpm

Optional 172S prop:
McCauley 76' 60° 180hp @ 2700rpm

Thought I was getting a whole new engine. The 60° 2700rpm prop would lower the TBO though, right?

BTW, I was one of the ones that was at first disappointed the new plane was another GA piston single and not a light twin, but seeing how different this Skyhawk flies from my Cherokee, I'm now fine with it. I'll be interested in how many doctors it kills when they forget to level the wings first ;)

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AKar
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Re: Just found out there's a 180hp option for the 172!

Post by AKar »

simnettpratt wrote:Thought I was getting a whole new engine. The 60° 2700rpm prop would lower the TBO though, right?
No, it remains 2000 hours on the letter. However, if one uses 172 as a travel airplane, I'd argue the 160 hp power plant is probably a wiser option, because you'll remain at slightly lower cruise rpm doing wide-open throttle, which probably is more comfortable to the engine, is perhaps somewhat quieter and saves some gasolino.
flapman wrote:The whole process probably involves an STC, and the re-marking of the RPM gauge.
There exists at least this one. I have good recollections of Air Plains, and they do EASA STCs as well. The RPM gauge is not remarked, but replaced. User-remarked instruments are generally both "illegal" and retain zero component value, as the instrument won't match its P/N's design anymore.

-Esa

simnettpratt
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Re: Just found out there's a 180hp option for the 172!

Post by simnettpratt »

Hmm. The Air Plains guys you linked gave a 300-400 fpm climb increase for the new propeller, 'increased payload', and a 130 KTAS cruise speed (no temp or altitude mentioned).

If the TBO stays the same at 2000, would then that just be a case of how fast do you want to spend? The KTAS cruise speed in the manual for standard temp 80% power says 117 at 4000 ASL, and 120 at 6000.

The extra 300-400 fpm climb rate, 10-13 extra knots, and 'increased payload' would cost you the price of the new prop, installation and more gas, but isn't that the exact reason you'd spend for a 182 - more speed and payload?

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