I have a buddy who is right around the corner from a new motor. I've been noodling him to post this, but for some reason he's a bit shy... so here it is on his behalf.

It's a nice 170B and a good candidate for more ponies. To qualify where he's at... the bird has 180 gear, BAS harnesses, really nice interior/seats, FW battery and ext baggage, HD axles, alternator, Stratus TXP (ADSB). Desser 8.5x6 are ready to go on and Sportsman cuff is on the list for later this summer. (will prob do the VGs at that time) Bird has a flat cruise prop right now... Yes AV gas is the best purchase, but that's not the question...

I have (of course I do) my strong opinions, which he's heard, but its always good to toss it out to the community and see what the folks have to say.

So I'll toss it up in the air... What would you do? Rebuild the 0-300 or 180HP.

If money is no object, I'd go with the O-360.

Having said that, and I bet you're pishing the same, the question is whether or not he needs it for his mission.

The 172A that I flew all over the country had the O-300. Great engine, reliable, easy on fuel and got me every place I needed to go. Flew it from MN to Oregon this last summer with my son. He's it's current care taker and I would guess that eventually he's going to put an O-360 in it. He put the Sportsman cuff on soon after getting the plane. Told me it made a huge difference. He is looking for a flatter pitch prop though.

Guess what I am saying, does the guys flying need the extra HP? Yes, extra power is always nice to have.

Depends:

If $ is less an issue, neither. Stoots IO-370 (195hp) with an 83" hartzell trailblazer

No question the 180hp will perform better. But lots of extra cost. Prop, potential fuel changes, engine mount, the STC itself, etc. Factor in at least $50K+...if not closer to $70-80K. Doing it during a required overhaul likely minimizes the downtime which you'd have anyway, though. Then you have to increase the hull value and insurance will go up as a result as well.

Does your friend haul a bunch of gear and need climb rate? The O-300 is a dog in high DA / heavy (speak from personal experience with my own 170 with an O-300...). This is a good case for the 180hp -- but if $ is an issue, then try get that prop swapped. An O-300 with an 8042 prop will do pretty well, but you'll lose some cruise, although less an issue unless you're travelling hundreds of nm regularly.

If there's some time until overhaul, see if your friend can find a climb prop or 8042 and see if that will satisfy the need - will save a lot of money vs. converting and the O-300 is otherwise a great engine. If they still want to upgrade the engine come overhaul time, they'll likely get their money back on the prop (especially if it's an 8042).

Finishing up my first annual after DelAire conversion. I would do it again. 120hrs on it.

Its expensive but for me it transforms the plane and I haven’t even been back to Idaho with it yet.

Obviously depends on mission and budget but it feels right, like that was how it should have been.

YMMV

O-360
Port / polish
Flow match carb
10:1 pistons

I'd go 0-360. The added value at resale will make it worth it, on top of the added joy flying it until he decides to sell!

Hey! I'm not shy!

The O-360 or some madness from Stoots is obviously going to be a serious performance improvement from the O-300. If money was no object I would definitely go that route.

The real question at hand is how much more time can be wrung out of the O-300 that's hung on there now. The logbooks show that the engine was making nonferrous flakes of metal 40+ hours ago (identified as aluminum). The previous mechanic diagnosed this as a wrist pin cap failure (wear marks were visible on 2 cly walls, wrist pin caps are aluminum). Replaced 2 wrist pins and changed the oil at 10hr increments from there. After 2nd change no significant amount of metal was visible in the filter.

Because I'm a fool and an optimist... I believe the problem to be solved and hope to take this ol girl another 200+hrs to TBO and beyond. Dr BigRenna seems to think I should remain within gliding distance of the airport until a high comp o-360 can be fitted.

If the lead time on an engine overhaul wasn't currently 6 months I would strongly be in the wait for (further) signs of death from this engine camp. Because of the crazy lead times on an overhaul it makes sense to attempt to source another good core + accessories to have overhauled to then have a plug and play solution when my current engine goes kaput. It turns out that the cost of buying a pile of spare o-300 parts + overhaul comes out to 50ish vs 70-80k for the o360 swap (with a fixed pitch prop).

Currently I'm in the camp of keep flying until the engine says otherwise and worry about it then. Ideally it can make it a year or so and my wallet will have forgotten about buying an airplane and be seeking other bad ideas like a bigger engine.

Should I start taking bets on how long this thing lasts in an attempt to fund the overhaul? Sell a kidney? Start an onlyfans?

SmokeyTheBear wrote:Hey! I'm not shy!

The O-360 or some madness from Stoots is obviously going to be a serious performance improvement from the O-300. If money was no object I would definitely go that route.

The real question at hand is how much more time can be wrung out of the O-300 that's hung on there now. The logbooks show that the engine was making nonferrous flakes of metal 40+ hours ago (identified as aluminum). The previous mechanic diagnosed this as a wrist pin cap failure (wear marks were visible on 2 cly walls, wrist pin caps are aluminum). Replaced 2 wrist pins and changed the oil at 10hr increments from there. After 2nd change no significant amount of metal was visible in the filter.

Because I'm a fool and an optimist... I believe the problem to be solved and hope to take this ol girl another 200+hrs to TBO and beyond. Dr BigRenna seems to think I should remain within gliding distance of the airport until a high comp o-360 can be fitted.

If the lead time on an engine overhaul wasn't currently 6 months I would strongly be in the wait for (further) signs of death from this engine camp. Because of the crazy lead times on an overhaul it makes sense to attempt to source another good core + accessories to have overhauled to then have a plug and play solution when my current engine goes kaput. It turns out that the cost of buying a pile of spare o-300 parts + overhaul comes out to 50ish vs 70-80k for the o360 swap (with a fixed pitch prop).

Currently I'm in the camp of keep flying until the engine says otherwise and worry about it then. Ideally it can make it a year or so and my wallet will have forgotten about buying an airplane and be seeking other bad ideas like a bigger engine.

Should I start taking bets on how long this thing lasts in an attempt to fund the overhaul? Sell a kidney? Start an onlyfans?

How'd the cam look when you had the cylinders off? If it looked good and there's no sign of other metal floating around then I'd say run it. And while running it start your search for the 360. They aren't super easy to find, and getting harder with the current parts shortage.

As said if the cam looked good when the cylinders were off - I don't see an overhaul around the corner. Run it until it tells you it needs attention. Cylinders/pistons are wear items. A high hr maintained and monitored engine is the SAFEST engine you will ever fly behind, bar none!

My O-300 did a similar thing about 200 hrs before I pulled it. Flakes of aluminium from a stuck gudgeon pin cap. Swapped out that cylinder and back to normal.

A light 170 with an o-300, sportsman and 80 x 42 is a hoot. But more power is even better.

SmokeyTheBear wrote:Start an onlyfans?

You're a dude, right? Better apply for that kidney exchange program.

Zzz wrote:You're a dude, right? Better apply for that kidney exchange program.

haha!

Photos of cam and cylinders in question. Carbon buildup was cleaned from the cylinders.








Glad to hear that you guys have had a similar experience with the wrist pin caps!

@Zzz Worse than that I'm not even very good looking! Do you know any good surgeons south of the border? hahah

There's an I0-360 on Barnstomer posted for sale today, however it is April 01 so !!!

Piston pin caps can get popped when the cylinders get hot. I knew a guy that was constantly fighting popped caps on the middle cylinders of his O300 and couldn’t figure out what was going on. Then he installed an engine monitor and realize those cylinders were running a lot hotter than the other 4. He fixed the baffling which brought the CHTs down and no more popped caps. I popped the caps on one of my C85 cylinders and I think it was a heat related issue. I replaced the pin, fixed up the baffling and had no more issues.

Personally, I see no reason to get excited about an engine replacement. Just make sure the temps stay where they should and I’d bet your engine will last a few years which will allow you to get everything together for the O360 swap.

Spending other people’s money is FUN, get the 360 variant

Sounds like you’re open to converting it some day. If that’s really the case, start enjoying 180hp as soon as you can and don’t look back. Like Daedaluscan said, if feels like how it was meant to be.
-DP

SmokeyTheBear wrote:Dr BigRenna seems to think I should remain within gliding distance of the airport until a high comp o-360 can be fitted.

To be fair, Greg is scared to fly anything that isn't brand new, or polished, or both

I was in a similar position last Spring, obvious engine issues "developing". After "costing" it all out and presented with an opportunity to aquire a good early life, recently overhauled 0-360 I pulled the trigger. I did have to accept losing one year of fun flying to complete the work required. I may have been able to complete it a bit earlier but by taking the time I was also able to include some other "refinements" as part of the upgrade, instruments, interior etc. I flew it last week and I'm extremely happy with the outcome. The empty weight is below 1400 lbs, the engine pulls like an ox, it takes off like a scared cat and climbs like a homesick Angel.

If your engine is "functional" I'd suggest flying it for the Summer to have some immediate return on the recent investment. In the meantime source a suitable heart transplant while also collecting all the required bits and pieces, that effort alone comes with it's on kind of fun.

I'll echo what other's have said, be it a Lycoming or Conti 180-200 hp turns the round tailed lady into a wonderful airplane, its a match made in heaven.

If it’s within the realm of possibilities, an O-360 with an 83” MT prop will make about the best backcountry plane possible out of a nice 170B. If I didn’t take my family camping several times a year, I’d trade my skywagon in for a 180/170.

You can flight plan for 115 knots on 6 gph with that combo. With its light weight it will handle rough stuff better than a 180 and like all 170Bs, will land almost as short as most cubs. The difference is that with the 180hp Lyc, it will get out of that same short field.

Don’t know what it would cost to convert one, but I’m guessing 60-ish… Used to be you could get a mediocre 180 for the cost of converting a 170 to 180hp. I believe that has changed. All 180s are through the roof. I don’t think that converting a 170 is as much of a losing proposition as it once was.