“Loafing” a TSIO-520

[AA5Bman]

For those of you that have actually run some of the bigger turbo’ed engines, is there anything wrong with loafing them along at something like 20”/2300?

I have a NA Cessna 205. I love the bird and the only thing I’d upgrade to is a turbocharged 206 for the hot, high, and heavy performance. In my NA 205 (260hp IO-470), I’ll routinely cruise along at 10,000, getting something like 20” of MP, 2300 RPM, burning 11gph and going 130 knots which I’m pretty happy with.

In thinking about upgrading, I’ve talked to some turbo 206 (pre-restart) owners who have told me that you need to run the TSIO-520 hard, for instance, one owner reported that their typical scenario was to fly 12,500 at 28-30” MP, 2450 RPM, burning 18 gallons per hour ROP and going 146 knots.

I figure that the 205 and 206 are basically identical airframes. At the same weights, going the same speeds, they should have pretty much the same fuel burns. Is there any reason you couldn’t cruise in the 206 just like I cruise in my 205? Pull the MP back to 20” and loaf along burning 11ish gallons per hour and going 130 knots? The extra 7 gallons per hour doesn’t seem worth the difference in speed.

Will running at significantly reduced power settings hurt the bigger turbo’ed engines? Seems like a dumb question, but maybe I’m missing something.

 

[Rgbeard]

My Turbo Lance has manufacturer-approved economy-cruise power settings down to 55%. The numbers at various altitudes are on my sunvisor for easy-reference.

At 55%, the settings are around 22” and as low as 2,200 RPM. It’s listed at around 12 or 13gal/hr if my memory is correct. I would not intentionally run lower at cruise.

By choice, I choose 65% for cruise, which is 25” at 2,300, 16gal/hr. I have used 55% on rare occasions, such as a short hop over to the airport 10 miles away.

There is an approved power setting of 75% and 81%. I see little reward for the higher power and fuel.

Edit: just to clarify, it’s a Lycoming, but I am not sure this makes much difference.

 

[N1120A]

Higher speeds and fuel flows (usually) mean better cooling, especially on engines that aren't necessarily set up to run LOP.

I know mechanics who insist that running full throttle, even over red line, can't hurt the engine, so long as it is cooling properly, and will in fact cause the engine to work better.

 

[Grum.Man]

As long as CHT and EGT are within normal operating range there shouldn't be anything wrong with it.

 

[Lance F]

I run two TSIO520NBs on my 414. If you’re concerned about fuel flow, fly LOP regardless of the power setting. I did a couple of long trips this week. Due to winds aloft I flew west at FL180 and east at FL210. My power settings were 31.5” and 2350 rpm. Fuel flow per engine was 15.0 at FL180 and 14.7 at FL210. This gave TAS of 196 at 180 and 200 at 210. Should I have wanted to the engines would have been happy at fuel flows down to 14 with some loss of airspeed. Lower power settings would give even lower fuel flows. These are very versatile engines. I’ve experienced nothing that would indicate they have to be run “hard”.

 

[Checkout_my_Six]

I run my TSIO-520 LOP and loaf it from time to time....like was said make sure your TIT and CHTs are in order and all is fine. TIT needs to be 1,650 F or less and CHTs should be 380 or less.

Today I ran over to the next airport over to wash it....ran at 24 and 2,500 and 14 gph LOP. CHTs were 340 or less....probably running 155-160 kts.