Simviation Forums

i flew the bonanza p35 from nanaimo.ca to olympia.usa. no particular problems. i flew below the legal altitude but the plane is leveled at a constant speed. engine:75%, propeller 88%. mixture 59%, fuel pump activated. here are the numbers that bother me. fuel PSI low around 20, and CHT (what ever that is) close to 500 F. i'm flying with no possible damage to engine but can these numbers be improve.here is a screenshot:


thanks for any informations.

When working with recipricating aircraft engines you have three temperatures of particular concern

1. CHT = Cylinder Head Temperature 500 is a little on the warm side... you would want to see a CHT in a Bonanza of somewhere in the neighborhood of the 350s - 400s tops

2. Oil Temp - easy, just keep it under the red line

4. EGT = Exhaust Gas Temperature, this is the temperature of the Exhaust gasses as they leave the exhaust valve. in a real bonanza you might want to see an EGT of about 1400 degrees to about 1450 tops.

controlling these temperatures should be a fairly easy thing

one thing you can do is open up the cowl flaps, this will allow for greater air flow through the engine compartment. While these are normally closed in cruise flight (or cracked open slightly) they should be fully opened during takeoff, climb or any ground operations to allow for maximum cooling.

another option is the mixture control. A full rich mixture control will typically yield a cooler burning fire, enriching the mixture should produce an almost immediate reduction in CHT and EGT across the board. The leaner you go with the mixture... the hotter the temps will be across the board to a point

lower the nose and climb at a faster airspeed (slower vertical speed) this will allow more cooling air to pass through the engine compartment and help keep temperatures to more nominal levels.

try these things out on your next flight, im sure you will see a difference.

also try running the following power settings for your Bonanza

Takeoff - Prop lever full, Power lever full (assuming its not turbo charged)

Climb - reduce power to 25" manifold pressure, then reduce prop RPM to 2500 RPM to attain "25/25 squared engine"

cruise, 19" manifold pressure with a prop RPM of around 2300 - 2400 RPM

on final approach, set the prop RPM to full and fly it on down to landing.

let me know if this helps control those temps

i think i will have to print this, so much info. thank you very much.

I modified the air-file on that Bonanza, specifically for CHT management..

Just lean until fuel-flow peaks..

Sounds like an oxymoron? 

Just lean until fuel-flow peaks..

Sounds like an oxymoron?

Just lean until fuel-flow peaks..

Sounds like an oxymoron?

thanks again for the infos. i printed it and will keep it at hand the next time i fly. BTW, i'm using the % because that's the info appearing when i put the arrow or hand on the VC panel, and using a french language FSX. to this day i never knew what cowl flaps were used for, now i know, thank you. i have no clue about 19"  or 21" of MP. is there a gauge giving that info? i will be more aware of the leaning process.

i have no clue about 19"  or 21" of MP. is there a gauge giving that info?

It's the big gauge named  'MAN PRESSURE' .. (manifold pressure) 

OK i just did a little hop and the opening of cowl flaps did a good job in keeping the CHT in lower 400 F. and the manifold gauge give info in inches so i got it. still a lot of work to do, but i'm going somewhere. thanks again.