I guess I'm missing something. A Lycoming IO540 develops 250hp at sea level, standard day with 29"MP. Yet, Service Instruction 1257g says the TIO-540 C1A on the Aztec produces 250hp at sea level, standard day with 33" MP. What gives? Max MP at sea level 30c should be 36MP (Service Instruction 1187J). Not happening. Also, shouldn't the density controller increase max MP with altitude to the rated max of 39"MP at 18k. Mine doesn't.
Lycoming Will the real MP for rated HP please stand up.
- Thread starter mgdimarco
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- Timothy
There are plenty of variables in play. The difference between 29in and 33in is the turbo. This is in the name of the engine.
You also did not mention RPM, this plays a factor in the HP developed.
Did you compare compression ratios?
I am sure there is more.
As for 39in for the max, if that is actually the spec, then you have a problem. From my experience with turbos, it will be one of a few things:
1. stuck wastegate (it cannot close completely)
2. leak in the system
3. bad turbo
Good luck,
Tim
You also did not mention RPM, this plays a factor in the HP developed.
Did you compare compression ratios?
I am sure there is more.
As for 39in for the max, if that is actually the spec, then you have a problem. From my experience with turbos, it will be one of a few things:
1. stuck wastegate (it cannot close completely)
2. leak in the system
3. bad turbo
Good luck,
Tim
39" at 18,000 is the spec hot day. The chart shows 36" at sea level hot day (presumably ISA +20c based on other charts) rising to 39" at critical altitude of 18,000. Then MP drops as altitude increases (obviously). Same chart showing 33" to 36" std day. My point being the engine sits at 33" cold day, hot day, sea level or 13,000 as max MP. Density controller issues? Engines just came out of overhaul.
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