Let's see what I remember:
Flight model seems accurate (although I flew a 350). Feels heavy like the real airplane. Only thing missing is my left arm constantly hurting from having to force the airplane one-handed through takeoffs and landings.
Both models (350 and 310) are turbocharged and losing manifold pressure in the climb happens in the real world as well. You need to increase the throttle as you climb to maintain manifold pressure, not adjust the mixture. I take it you're climbing at full power? In the real airplane we'd reduce the manifold pressure to a climb setting at 1,000 feet. Otherwise you risk burning up the engines. We'd also set the mixture at 1,000 AGL to a certain fuel flow (18gph in the 350... don't know what to set in a 310... maybe 16gph would do) and leave it there until cruise, where we'd set it to a certain value of EGT. We adjusted the throttle as altitude increased because the engine wouldn't be able to maintain a desired manifold pressure due to reduced air density at higher altitudes. There's a very technical description I've included on how the system works a paragraph below this, but if you're interested in getting back to flying, I'll share a few power settings with you that'll work just fine in the sim (set the mixture as you like, but you only need to adjust it at 1,000, then again at cruise, don't touch those settings until you touch down): Takeoff: Climb (>1,000 AGL) Cruise:
MAP: Full MAP: 38" MAP: 30"
Prop: Max RPM Prop: 2400 RPM Prop: 2300 RPM
Mixture: Rich Mixture: 16-18 gph fuel flow Mixture: EGT 75 Rich of Peak Temp or 1525, whichever less Here's How the Turbocharger Works:
In the Navajo engine, the turbocharger is controlled by two controllers: 1) Differential Pressure Controller, and 2) Air Density Controller. The differential pressure controller controls the turbocharger wastegate (which controls the speed of the turbocharger) at low to medium power settings. It does this by maintaining a certain pressure in the area between the turbocharger and the throttle plate (known as "Upper Deck Pressure") that is greater than the pressure between the throttle plate and engine inlet (known as "Manifold Pressure" or MAP). The throttle plate provides a restriction that makes this differential pressure possible.
So, when you open the throttle, it moves the throttle plate to a more open position. That removes the restriction from the upper deck, which causes the differential pressure controller make up for the reduced pressure by speeding up the turbocharger to increase upper deck pressure until it is back to 6.0-6.5 inHg higher than the MAP. This works great until you go to full throttle.
At full throttle, the restriction from the throttle plate is gone, and it's impossible to maintain the higher upper deck pressure differential. At this point, the differential pressure controller could speed up the turbocharger so much that it can produce enough pressure to overboost and damage the engine. This is where the air density controller steps in.
The air density controller measures the actual density of the air exiting the turbocharger, and once the density reaches a certain value, it stops the turbocharger from going any faster, which allows the engine to produce only as much power as it can at a given altitude. This happens on takeoff, and to a certain extent climb. Of course, that's provided that you're at a high enough altitude to require full throttle to maintain your climb MAP setting. At this point, you won't be able to maintain a higher power setting. Perhaps you can adjust the mixture at this point, but I've never flown a Navajo high enough to need to so I wouldn't know much about that.
Hope that was somewhat helpful. Good flying!