Looking into 206’s.

It seems that the IO-550 is the best choice. However, most airplanes have the 520, IO or TSIO.

Field elevation < 1000’. About 2/3 running around at 1500’, 1/3 trips over the east coast mountains at 8-9000’.

Are the turbos that maintenance intensive, as in stay away? Do they need a cool down period?(many, many short floatplane rides given). Other comments?

And what are the RPM on these different engines? I understand the IO-520 is 2850 or thereabouts. The local 185 howls in comparison to our PPonk 180(which is 2700 RPM)

Thanks!

IO550 in a 206 on floats is such a great combo. 520's are great but to maximize a 206 it seems that a 550 is needed. Spins at 2700, noise difference is notable. I fly a 185 with io520 and 206s with 550's both daily. In the 185 I have to give pax a briefing that the plane is loud, 206s I don't.

aqua wrote:Looking into 206’s.

It seems that the IO-550 is the best choice. However, most airplanes have the 520, IO or TSIO.

Field elevation < 1000’. About 2/3 running around at 1500’, 1/3 trips over the east coast mountains at 8-9000’.

Are the turbos that maintenance intensive, as in stay away? Do they need a cool down period?(many, many short floatplane rides given). Other comments?

And what are the RPM on these different engines? I understand the IO-520 is 2850 or thereabouts. The local 185 howls in comparison to our PPonk 180(which is 2700 RPM)

Thanks!

The turbos themselves don’t require heaps of maintenance, just care during operation.

Continental cylinders don’t seem to handle the boost quite as well as Lycoming cylinders do. Unless you are really careful with engine management, cylinders will need attention more frequently with a turbocharged engine.

You definitely need to babysit a turbocharged Continental. Don’t exceed TIT limits, which can happen in an instant if you adjust the mixture and divert your attention elsewhere.

Shutting down with hot turbos will effect the properties of the metal. If they are abused, they can come apart over time, which would not be good.

I don’t have any amphib experience, but have heard that turbos are highly preferred for operations at altitudes other than sea level or thereabouts.

I’m inclined towards turbos, but not for your stated mission. If your takeoffs are at lower elevations and you don’t want to climb over 10,000’ on floats then a NA will do the job with less complexity and 40-50 lb. less empty weight.

520 or 550? Buy the nicest airframe you can find. Run out the engine and make the next engine the one you want. I had an IO520 in my 185. Upgraded to IO550. I kinda miss the IO520 2 blade. It was classic. Performance? I didn’t test before and after, but they both put a smile on my face. The difference is there, but unless you’re in and out of 1/2 mile long lakes, I wouldn’t worry about it.

My vote would be an IO-550, every day, period. The 206 on floats with a 520 is not a sparkling performer. Yes, you can fiddle with different props, etc, but you'll NEVER get a 206 to perform like it does with a 550 as long as you're running a 520 up front. Seriously.

I worked both engines and there simply is no comparison. The 550, as noted, runs at 2700, so the neighbors will like you a lot better, the 550 runs cooler, and isn't near as stessed as the 520 is, assuming you're actually USING the thing. To get the performance out of a 520, you need to run it at 2850 on takeoff. That makes a lot of noise and puts a lot of stress on the engine.

The 550, in some installations, permits the airplane to go out at 3800 pounds, vs 3600 pounds. I ran a 206 with a 550 on Wip straight floats for some time. Launching at 3800 pounds, on a narrow float pond, that plane would launch within a few feet of where the 185s with 520s were getting off. I had pilots there call me a liar, till they watched a launch.....then they were believers.

Turbo vs non: I really like Scolopax' discussion.....to paraphrase, turbos aren't that maintenance intensive, except for........all that stuff.

Frankly, the normally aspirated 550 gives you better performance than a turbo'd Continental can, and you don't even want tot think about a Turbo Tech Lycoming conversion..... I routinely launched at 430 msl in that 3800 pound 206, and climbed to 7500 or so to clear the mountains to the north....going and coming home. That's not turbo country, admitted, but that thing never even broke a sweat in that deal.

A turbo Continental will eat your lunch in repair bills. And, as Scolopax noted, you'd best treat it REALLY well, or it can cost you even more.

You just don't see many working seaplanes that are turbocharged. Now, if you were starting out at 5000 msl....maybe.

I was really, really impressed with the IO 550. I tell people it's the engine that Continental always wanted to build......And, it runs lean of peak beautifully.

MTV

Great feedback. This site is great.

Follow on question: if the budget were to include second generation 206’s, where would you rank the IO and TIO-540’s with the Continental’s?

Thanks

aqua wrote:Great feedback. This site is great.

Follow on question: if the budget were to include second generation 206’s, where would you rank the IO and TIO-540’s with the Continental’s?

Thanks

I have a fair amount of time in Lycoming and Continental powered 206s. All turbocharged.

The Lycoming is a cleaned up 2006 model with wheel pants and such. We cruise at about 160 knots on 20 gph at 18000ft on oxygen. This results in impressive XC performance. Has decent range too.

I fly a 1971 model on reconnaissance missions. It has a turbocharged Continental. It’s a few hundred pounds lighter, but far less decked out.

If I were to choose between the two, it would definitely be the older one.

aqua wrote:Great feedback. This site is great.

Follow on question: if the budget were to include second generation 206’s, where would you rank the IO and TIO-540’s with the Continental’s?

Thanks

The H model 206s are all fairly heavy. The Lycoming engine is part of that, Lycomings are heavier than comparable power Continentals. But, the late 206s we’re also pretty “dressed up” with “Executive” type interiors, etc. I don’t know how much of that weight you could reverse, but surely some by going to a utility interior.

MTV

Does anyone have a tsio 520 stc for the 185? I know there are a couple of one-off stcs for individual planes.

Another consideration is that there is a longer TBO on the io550s, I believe it’s 200 hours more.

Any 206 is fine, if you get a turbo be prepared to swap it out for a 550. We ran turbos extensively at the former company I worked at, when I started my own company (after they went out of business) I knew to stay well away from Turbos to not go broke.
A 520 will do just fine at lower altitudes especially with a tuned exhaust, keep the prop to a 80 inch and it will not be to loud with no loss in take of performance. The 550 requires a larger prop for best take of performance , That is only approved on floats. with the same prop a ported 520 may just take of as short or shorter than the 550 but once airborne the 550 is a significant improvement.
So here it goes 520 is by far the most cost effective, ours usually go TBO.
550s are great all around performers use a bit more fuel (extra power extra fuel simple) you may need to take care of cylinders a bit more.
Turbo 520s ( the 310 HP later models) are awesome performance at altitude about the same fuel consumption as the 550 and will bleed you dry on maintenance.
All will greatly benefit from Whip Tips for a flatter faster climb speed that keeps the temps down and cruises level at higher weights.
That is the first thing I do on any 206 it pays for itself.

I've been coping with a CHT temp issue with a IO520A Engine for almost a year now. I bought it last August and the first thing I did was put a JPI 830 in it. I was amazed and shocked to see CHT's at 400-420+ on a full rich, full throttle (24.5-25 GPH), full MP @ 100-110 MPH climb.

Usually see 14.5-15 GPH In cruse and it's not much better 7500'-8500' cruise power settings I use, 2350 RPM, MP 21-22 and ROP (1400 DEG EGT) I'll see 360-400 CHT's @ 50-75 ROP will get me 150 MPH true. I can't even think about shutting the Cowl flaps. I know, I know Go faster burn more fuel and cylinders or go slower and burn less fuel and Cyl's.

I've been dabbling with LOP operations lately and seeing significantly lower CHT's 340-355 and much slower speeds 120-130 TAS. I'll lean to peak then continue leaning about 50-75 Deg. I'll see about 11 GPH, I still can't close the Cowl Flaps at those settings. It's a bit discouraging watching 172's pass you

Side notes, I've had the fuel settings adjusted by a reputable shop and didn't make a difference. I've got Power flow exhaust coming tomorrow Should be on by next week. Considering a top overhaul with ported, polished and flow balanced Cyls. Ly-Con says that will help some with the EGT's and increase power.

Yikes, 25GPH full throttle fuel flow is way too low. No wonder your CHT’s are so high. If memory serves me correctly it should be around 31GPH, your 550 flight manual supplement should say. Also, after setting your LOP cruise mixture increase throttle/MP a few inches to make up for the lost power, yes you will increase fuel flow but it will still be less that rich of peak.

Yikes, if you read my post I was very detailed with my settings. I'm operating a non-turbo IO 520 not a 550. Fuel settings for the 520 are 24.5-25 GPH. Not 31 for a 550

Glidergeek wrote:Yikes, if you read my post I was very detailed with my settings. I'm operating a non-turbo IO 520 not a 550. Fuel settings for the 520 are 24.5-25 GPH. Not 31 for a 550

I'm running an IO-520F (normally aspirated). FF at full throttle is set to around 30 gph, which is (intentionally) higher than the manual. #5 is still much hotter than the rest of the cylinders, and I have to run the boost pump to keep the #5 CHT below 420 on departure. I go lean of peak as soon as I get to cruise, and then I can keep #5 under 380 with cowl flaps part open.

How much of a difference do you notice w/boost pump on?

If your engine is set to 25 gph max, you need to get with a shop that knows IO-520s in Cessnas.....yours is set waaay too low, and that's the reason you're seeing high CHTs.

Seriously, the factory FFs are waaay too low, crank them up to over 30 gph, and you'll see a reduction in CHTs. Every shop in Alaska I ever dealt with knew how to set fuel flows, and before we did so, we consulted with the factory. Why in hell they haven't changed their "guidance" I have no idea, but you're asking for cylinder problems running those FFs.

MTV

MTV thanks, I'm seeing this trend in replies.

I had the tornado alley turbo STC installed last summer on a 185 setup as an amphibian. This is the same people who run GAMI. The two companies are colocated at Ada, OK. Most of what they sell is for the Bonanza, but the original STC was for the 185. I highly recommend their “advanced pilot seminar” (online) to get their take on normally aspirated and turbo operations both ROP and LOP. This is based on years of experience and on the engine test stand operations at GAMI.

Personally, I love it. They support this for either the 520 or the 550. I have the 520 and it was retrofit. This is a fairly extensive modification. It does add about 70 pounds in front of the firewall, and I added ballast to the tailspring to balance it out to the same CG as before the modification. I normally fly with two people, 50 pounds in the extended baggage, and then whatever else we might need for a the mission (camping, biking etc.).

I am not flying this plane commercially. But I live near the mountains. Before installing the STC, the engine has all the limits discussed in the thread. With the STC, peak MAP is increased to 32” and peak FF to 35 GPH and it climbs at 1000 fpm at 90 KIAS to 15000 (I have not taken it higher yet). Service ceiling is raised to 24,000. That 32” is ~ 320 HP. There is a benefit in takeoff performance at any altitude.

My typical takeoff is 32”, 2850 and then bring the prop back to 2700 for noise abatement to the maximum continuous power setting. You can run it like that continually for real and the engine stays cool at the higher fuel flows. Once at the desired altitude, nose over and accelerate to the target cruise speed, prop back to 2500, then lean back to 13.1~15.1 (LOP) for cruise. During a descent, you can just pull back the throttle and below a MP the EGT and TIT will spike, at which point you screw in the mixture about two twists to enrich and you can fly that to the landing and shutdown without the 4 minute wait. (With this procedure, the engine stays warm in the descent even with the cowl flaps open.) If you enrich and carry power into the landing, the 4 minute cool down is recommended. That can be done during any low power operation, including (water) taxi. They have recommended operations online which is aimed at the operation of the STC for the bonanza which goes into more details. The operations for the 185 with the STC and the bonanza with the STC are not 100% the same (no boost pump required in 185 climbs, at least for my model year (1977)), but they are substantially similar. You can check out the bonanza channels for feedback on the bonanza STC. People love it. There were two other 185s getting the STC overlapping when I did this last year, so there are other people out there with this setup, but far more people get this for the Bonanza.

Since this is a modification of a normally aspirated engine, there is very little ground boost and the tip speed at peak TIT is much lower than in most TSIO engines. While there is a stated TIT limit, it is not a materials limit and there is no danger of turbine blade damage from the blade tips stretching and making impact inside of the housing.

I do not have the basis for recommending this for commercial float plane operations. That is not what I do. But the TN STC amphibian will walk away from the stock normally aspirated tailwheel at around 10,000. I normally climb to 15,000 when I am going long distance and it trues out at ~150 KTAS at 14.1 LOP at 15,000 (118 KIAS). That is about the same FF as the normally aspirated 24/2400 configuration at sea level, and a few knots faster.

You can still run things ROP using the same configurations as before the STC, but also using much higher continuous power settings. If I am doing commercial maneuvers, I will leave the mixture forward and use the throttle to control power. If I am going travelling, I will climb to altitude then bring back the prop and the mixture to LOP to control power as described above.

For me, the plane is now readily comfortable for either bumming around the PNW and BC at 1000’ or jumping over the Rockies at 15,000+ and 150 KTAS* (carrying mountain high oxygen).

For my missions, that is a great outcome.

PS: if you want a much more in depth look at this STC for a 185 tailwheel with an IO 550, search for “the fastest 185 in the west”.

Looks like this thread was brought back from the dead, but my .02:

I ended up with the TSIO-520, and I'm very pleased with it for MY mission profile which includes about 10% back country and 90% cross country. Primarily, I appreciate it for it's performance margin. If you run ROP and stick to modern guidance on CHT, it will basically operate at the same FF and performance as the TIO-540. In fact, I use that POH for fuel flow starting points. I'm a knuckle dragger that runs ROP.

I cruise at high power most of the time, 2500 and 30", my mixture knob is full forward all the time. Typically 25gph in cruise.

On a hot day, climb above 10,000ft MSL can be as low as 300fpm and I often have to cruise with the cowl flaps partially open to keep #5 below 390.

I'm installing a relocated oil cooler as soon as my mechanic has time, I'm hoping that will alleviate #5 being so much hotter. I've personally inspected the baffles, and the seals have been redone. Besides looking into the max fuel flow, I'm not sure what else to do.