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Trying to educate and understand

Fenderbean

Well Known Member
Turbos and lean of peak, I didn't think turbos would prevent lean of peak. Is this a correct train of thought? This particular conversation was around an IO-540 with turbos on an airplane that traditionally has the Cont 550 with turbos. I guess the 550 you can do this with turbos vs the IO?
 
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Turbos can run great LOP. Having balanced fuel injection, no induction leaks and an engine monitor (for each cylinder) is the key. Turbos can also be on carbureted engines not just injected engines, which are designated IO (Injected, horizontally Opposed). Carbureted engine don’t normally run LOP as well as IO engines.

I had a P210N for 5 years. It has a TSIO-520 engine (T for turbo charged). My normal cruise numbers were 30’ MP, 2500 RPM and 30*-40* LOP ON 16 gph with hottest CHT around 380. I’d see 185 ktas at 17,500. It ran great and I miss it to this day!
 
looking into something that has a 540 twin turbo on it, seems to be a thirsty combo from what I was told. 22-24 gph. I couldnt understand if that was throttled back 65-75% or fuel throttle. The conversation was comparing it to a twin turbo 550, lean of peak was around 16 gph. I understand the 550 is better on gas but thats a bid difference.
 
The P210N fuel flow at full throttle was 36 GPH. Running 22-24 GPH with a twin turbo 540 is probably 80*-100* ROP.
 
I flew Navajos for a while. Nothing fancy, old instruments, but decent airplanes. Turbo angle valve TIO-540 rated at 350hp running ROP at 65% (31", 2200rpm) burned 17gph each. This was about 100° ROP.

We'd flight plan 300lbs/hr climb and 200lbs/hr cruise and that seemed slightly generous. That's for two engines too
 
This is to help me decide on a project that comes with a 540 with twin turbos is why im asking. Its on a lancair but the motor has an hour of run time and I just didnt want crazy fuel burn on something that just hauls 4 people and not pressurized. Someone gave me some information that I think may have been a bit biased with 550s
That being said could this information be from a high altitude prospective? I not sure the exact numbers but these type of motors lose 40+% of there power at 15-20k alt
 
Just Google:

Lycoming DOCUMENT PART NO. 60297-23P for TIO-540 Parallel Valve

or

Lycoming DOCUMENT PART NO. 60297-23A for TIO-540 Angle Valve
 
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Turbos don't like enormously high EGT's feeding the turbine side - so stay ROP or LOP - but not AT peak.
 
Another question for the masses, why don't more convert to water cooled cylinders? Seems like a nicer way to go with lycomings? I see the advantages but what are the disadvantages? Besides the ridiculous cost, thanks!
 
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