New to the forum. I current have the TSIO 520 (turbo-charged) in my Cessna 206G and metal contamination has caused me to do a rebuild, fix or replace. I see a lot of favorable discussion regarding the IO550 replacement but I do a lot of high altitude lake activity (>5000ft) and regularly fly over the rocks at >10,000ft. From what I can tell I shouldn't swap out the 520 for the 550 for high altitude performance reasons UNLESS I can put the turbo version of the 550 in. Has anyone done this yet or is there an STC for this upgrade? If not I'll rebuild the 520 and keep going...

I welcome all comments...

I know it's not apples to apples, but I put 1800 hours on a TSIO520 in my V35B - I decided I would upgrade to the 550 - I put 2100 hours on that combo LOP - Engine went far beyond TBO, but it did not feel like an upgrade: More weight, more fuel burn, less range, little performance improvement. I didn't love the CG like I did with the 520. If I could do it over, I would have stuck with 520.

Just my 2C's

First thing I’d do is find out what STCs are out there.

With your mission, I would stick with a turbo I think. Question is: Is there a TSIO 550 approval for your plane?

Also, changing a turbo 206 to normally aspirated requires some approvals as well. Check the 550 STCs to verify if they apply to the TU206. They may not.

MTV

I just put a normally aspirated IO 550 with a Hartzell 82 inch voyager prop on my 69 U206.

I’m based in Flagstaff and routinely see over 10,000 foot density altitude, on hot summer days and see over 500 ft./min climb, The heaviest I have been is. 32 to 3400 pounds, gross is 3600 pounds. Performance feels strong to me at 5000 feet, Cruising 12 to 14,000 feet has not been an issue. My plane does have Robertson STOL and flap gap seals (supposedly helps climb a bit at the expense of more effective flaps).

My useful load is just shy of 1600 pounds.

I just finished flight training with CC Pocock at Bush Air (Fantastic in my opinion!) using his short field techniques we were taking off and landing in under 400 feet, elevation was 2500 feet but it was north of 100° so I think that to the density altitude was close to 5000’ at a weight of about 2800 pounds.

Unless I’m mistaken, It sounded like the OP is operating on floats. If that’s the case, it’s a whole different world required for takeoff at higher altitude.

MTV

Right, thanks!

My 185 has the tsio-520 stc. I am in the middle of overhaul and had the same thoughts. Stuck with the 520 turbo. I just think the turbo offers more performance where it counts on a hot day on floats.......would have liked the lower RPM but it would mute the "song of my people"

Flew naturally aspirated 210 out of Denver front range over 14K' mountains for 14 yrs; then, T210N for 22 yrs= absolutely no comparison. Gross= 4000 lbs climbing over Longs Peak (14K+) in 35 miles in summer=no issues. Took that TSIO520R 200 past TBO before selling and it's still on that engine.
YMMV
Jack

Thanks all for your comments on the topic. As far as I can tell there is no STC for the turbo 550 for my 206 and so that means the 520 overhaul is the way to go in this instance. I would love to see a 550 turbo STC and I’ll report back here if I find one. I regularly pack a lot and land in high altitude lakes so regularly aspirated 550 isn’t going to work. I’m not dissatisfied with the 520T but can always appreciate more thrust at 8000 ft on a hot day on what appears to be a short lake. It’s easy to land on a short lake but they always appear much shorter on takeoff!

Man, you’ve got my respect landing a heavy floatplane at those altitudes!

MTV

landing is never an issue....

AlwaysanAdventure wrote:landing is never an issue....

Or an option

Maybe a dumb question, as I've never flown a turbocharged plane: what's preventing you from "accidentally" running a couple more inches of MP here and there for the "quesitonable" takeoffs? Is it something like a set screw on the wastegate, or the real possibility of popping the engine? Curious, because I know a lot of modern turbo cars (with modern engine management, of course) can run significantly more boost than stock without issue, and this could allow you TSIO-550 levels of power when you need it with (possibly) a whole lot less hassle....

Had a 68’ 185E turbo normalized Io520 on edo 3500 amphibs. Awhile back . Nothing stopping you from screwing that sucker to the wall when density altitude is 10 grand to get up and go . Probably not a great idea but ……..beats not taking off and climbing out of a hole

If it’s a turbo charged engine and not a manual wastegate(normalized) then you just pin it and get your 36 inches manifold pressure. Please , nobody quote me on that or take my advice .