Manifold Pressure at Cruise

[Green Hornet]

I recently flew from the SF bay area to St George, UT. At 13,500 ft, cruise my manifold pressure was at 18in with 2300 RPM. I was at 135KTs airspeed with a tailwind 154 KTs ground speed.
The manifold pressure just stayed at 18 for the 3 hours. I hear, read & have had about 22in / 2200RPM in the past. I just got a new muffler system.
Does this sound OK that the manfold pressure is lower or is this a problem?

[MauleWacko]

[Green Hornet]

I never saw 22" @ 13,500 I think there is a math to alt vs press.

How about the sound with your new exhaust system vs the old one. CHT EGT etc??

The sound is quieter even though I have noise reduction head set. I did take off the head set at one point and it did appear to be a smooth running engine. But I am always amazed at the great job the noise cancellation does. The CHT and EGT are lower but I was at 13.5K alt and it was much colder ambient than I normally run at sea level @ 25 degrees C ambient kind of typical California temp. I'll have to get back to you with some comparisons to what I know from the past. It is difficult to say on the first cross country at altitude. For the time being I will be in Utah for some time but I'll try to keep track of the data at these different temps and altitude.
I had the throttle wide open so it was getting plenty of air so I am thinking 18in is fine but I was just wondering what others have seen at that altitude.

[diebroke]

You must have left the turbo charger sitting on the bench.

18 at 13.5 is about right.

You get a hangar OK?

Snowed 4-5" on the benches of SLC today. Still trying to get south to Skyranch.

Gary

[Green Hornet]

You must have left the turbo charger sitting on the bench.

18 at 13.5 is about right.

You get a hangar OK?

Snowed 4-5" on the benches of SLC today. Still trying to get south to Skyranch.

Gary

Hey Gary,
No I left a message for Jesse but he has not called back yet. I flew back to CA. on SWA today to get the wife, car and stuff. We should be heading to St George on Thursday/ Friday. I met a bunch of guys who were from SLC who were staying in St George until the weather improves. I was disappointed in 1L8 as far as the hangar story. I'll explain when I see you. For now I am tied down at St George with a lot of others. The hangar opportunities don't look good but I'll keep trying.
CYA
Bill

[maules.com]

Sea level MP is 29.92 though there is usually a loss of .5" for induction drag.
The normal loss is approx 1" per 1000msl
Actual barometric pressure at 13500msl is 17.94" so with a .5" induction drag, you would have 17.44 on a standard day, thus we can deduce that you were in a high pressure area and your engine is producing the appropriate power.
With a good engine you can only achieve 22" at about 8000msl.

[Green Hornet]

Sea level MP is 29.92 though there is usually a loss of .5" for induction drag.
The normal loss is approx 1" per 1000msl
Actual barometric pressure at 13500msl is 17.94" so with a .5" induction drag, you would have 17.44 on a standard day, thus we can deduce that you were in a high pressure area and your engine is producing the appropriate power.
With a good engine you can only achieve 22" at about 8000msl.

Thanks Jeremy

I read some long, really long, discussion about the subject that left me scratching my head. You set my mind at ease and taught me what I wanted to know in a short paragraph, You da man
Cheers Mate
Bill