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<< Lancair Builders' Mail List >>
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Gentlemen of the list,
I have been watching the exchange of expert opinions on the list concerning
engine performance. Hence, I am hoping some of you can shed some light on a
problem our IVP has been experiencing since day one:
PROBLEM:
During climb we are pulling 31" MP and 2500 RPM right up to FL230. Cruise
can easily be established at this setting at FL230 or below netting us
266KTAS. Above FL230 the MP and RPM fall off to 28.5" MP and 2350 RPM.
No amount of throttle can correct this.
However cabin pressurization stays at 4.5 to 5.0 PSI indicating the torbos
are still providing pressurization. Speed drops from cruise at FL230 of 266
KTAS using 31" MP and 2500 RPM to cruise at FL 250 of 248 - 253 KTAS with the
bled off power setting referenced above of 28.5 " and 2350 RPM.
CORRECTIVE ACTION:
In order to resolve this we have taken the plane to Magnum Engines in Dayton
OH and they performed a compression differential check, verified all the
hoses are in place and tightened down with no leaks and verified the
wastegate was closing all the way. They turned up the oil pressure slightly
but otherwise could find nothing substantial wrong.
After leaving their facility the engine performed exactly the same, still
dropping RPM at altitudes above FL230.
ENGINE DATA:
The engine is a TSIO-550 "B Model" with 90 flight hours since new.
On takeoff at sea level it develops a full 38" MP and 2750 RPM.
It has been upgraded by Magnum Engines which I understand involves a new
camshaft, ceramic coating cyl etc and other performace tweaks. It also has
had the entire fuel injection re-built by TCM as it sat for 8 years and
requird all new seals etc.
It also has GAMI Injectors.
It runs very smooth and well within CHT (360) EGT (1580) and TIT (1650)
ranges and burns a respectable 18 - 20 GPH depending on the power setting
used.
QUESTIONS:
1) Does anyone out there have a "B Model" TSIO 550 so I can compare numbers?
2) Any ideas what could be the problem and where I should start at finding a
soultion?
3) Tony Durizzi reports that his "E Model" TSIO-550 does NOT experience any
of these problems...has some design change been made in the mater engines
which would account for this?
ANY IDEAS GANG?
Thanks
Dave Riggs
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LML website: http://www.olsusa.com/Users/Mkaye/maillist.html
LML Builders' Bookstore: http://www.buildersbooks.com/lancair
Please send your photos and drawings to marvkaye@olsusa.com.
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