Think I have a problem

[Dream to fly]

Today I took the plane up to 5000 ft and was practicing slow flight.  All was good until I transitioned to cruise and noticed that when I opened the cowl induction door I didn't see a manifold pressure increase.  when I landed I proved the cable and the door are functioning correctly and the engine is running fine.  Could it just be that the temps were right around 90 and it was not cool enough to see on the old mechanical gauge?   Or should I be looking further?

[RLCarter]

What shape is the seal in? Mine is brand new and only see 1/2" change at best (7500ft)

Edited July 9, 2017 by RLCarter

[Yetti]

It's a small change for sure....  and a very imperceptible change in the sound of the engine. Since you are used to listening to the engine and if you pay attention you should hear it.  Most people probably do not.

[Browncbr1]

Were you WOT?  I think you only get the increase if wot.  At 10k, I get about 1" with it open

[TonyK]

I have only seen 1/2 - 1" of MP change using it from 7500' - 12,500' depending on throttle and prop settings.  I'm not sure it's worth it.

[Bob_Belville]

I see 1.0-1.1" MAP (and I have a Challenger Air Filter which should be more efficient than the old Brackett filter)

1" of MAP above 9,000', which is about 5% more power, is definitely worth it. 

(Tony I am not sure that I understand how mixture or prop position makes a difference in this situation.)

[Browncbr1]

The extra 1" at 10k improves TAS by about 5-7 kts on my stock F near gross weight and adds about .5 gph.  Worth it for me.   

I just recently started to figure out how to use it without causing intake turbulence.  On mine, I need to pull throttle back until dropping some map, then increase just to get it back, then open ram air.  I was doing the opposite prior and it caused a little rough uneven Gami spread or something.   Now that I figured out how to use it while keeping my engine smooth, I really like it.     Still have a Bracket filter.