Summer Cool Down For Quick Turns

[Txbyker]

I had a quick turn around the other day.  Outside temp 95.  On the ground for less than an hour.  Taxi'd out, on climb out, oil temp over 200, CHT over 400.  What do you guys do to cool off your engines when you know you have a quick turnaround?

Russ

[gsxrpilot]

Take off... shallow climb... get to cool air.

[gsengle]

I leave my oil filler door open to help cooling while I'm parked unless it's too windy....


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[kmyfm20s]

I have been taking off the last 5 weeks in 105+ temps. The hottest day was 117!  Fuel boost pump on to keep the EGT's and CHT's under control. When my hottest EGT get down to 1225 I turn off the fuel pump. Climb at 140 KIAS. This will keep the CHT's under 400 on the hottest day.

[Fly Boomer]

Okay, I'll be the goat:  What does the aux pump have to do with EGT and CHT?

[201er]

If there's a breeze, park facing the wind with the cowl flaps open.

[Txbyker]

Just now, 201er said:

If there's a breeze, park facing the wind with the cowl flaps open.

I will need a sawzall, ha just kidding, no cowl flaps.  But thats a good point, the fbo's always have one idea about where they want you but good to override them and park as you say.

Russ

[kmyfm20s]

27 minutes ago, Fly Boomer said:

Okay, I'll be the goat:  What does the aux pump have to do with EGT and CHT?

Boost fuel pressure and FF. In the R models you have the benefit of the extra fuel being recirculated back to the tanks. This helps keep the fuel cool and prevent it from vaporizing.

To add to my original post your sea level take off FF should be around 29.6 gph to also maintain proper cooling.

[kmyfm20s]

I was able to pull up a flight when I took off on a 118 degree that day. My CHT redline I have on my Savvy analysis is set a 380 for reference. I climb from -40 MSL to 8500' MSL.  You can see where I turned off the boost pump twice. I thought my mechanical pump when out but was fine after I leveled off and the air temp cooled.

Chart with Feul preassure and outside air temp

 

Oil temperature and FF

[1964-M20E]

Open cowl flaps on approach to dump more heat coming in.

 

 

[TonyK]

The F1 teams use battery operated leaf blowers to cool the brakes and engine when they are in the pit boxes.  How about one with at tail of skeet tube into the cowling?  If you had the weight to spare some of them might give you 40 minutes of 180mph airflow.

[Jeff_S]

Call me a cynic, but I really question the idea of leaving the low boost pump on for the IO-550 unless there is a problem with the engine driven pump. If you have adequate fuel flow at full throttle and mixture rich, pumping even more fuel is going to reduce your power and seems like a waste...not to mention potentially wearing out the auxiliary pump.

The IO-550 is designed to run with cylinder temps in the 400s, and while I wouldn't want to keep them there for long, I don't see it as especially dangerous in a climb. Keep your speed up and get to cooler air seems like the best approach to me. Even on a hot day, if your temps are still too high in cruise, maybe time to check your baffles too.

Oh, and keep a little more oil in the sump than you otherwise do. I generally let it drift down to about 5 quarts on the dipstick and it's happy there, but in summer temps I'll keep it at 6 just to keep more cooling circulation. 

[gsengle]

Call me a cynic, but I really question the idea of leaving the low boost pump on for the IO-550 unless there is a problem with the engine driven pump. If you have adequate fuel flow at full throttle and mixture rich, pumping even more fuel is going to reduce your power and seems like a waste...not to mention potentially wearing out the auxiliary pump.
The IO-550 is designed to run with cylinder temps in the 400s, and while I wouldn't want to keep them there for long, I don't see it as especially dangerous in a climb. Keep your speed up and get to cooler air seems like the best approach to me. Even on a hot day, if your temps are still too high in cruise, maybe time to check your baffles too.
Oh, and keep a little more oil in the sump than you otherwise do. I generally let it drift down to about 5 quarts on the dipstick and it's happy there, but in summer temps I'll keep it at 6 just to keep more cooling circulation. 

The pump shouldn't enrichen the mixture any, probably just increases the amount of fuel that comes back, and the extra circulation keeps the fuel in the lines from getting too warm.


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[carusoam]

Seems to be a two part question...

1) good engine cooling for the ground portion

2) good cooling on departure and climb out...

On the ground, I go out of the way to point into the wind, leave the oil door open...

Probably doesn't do much but keep the top of the cowl from baking the paint off...

+1 with shallow climb @120KIAs, blue box mixture technique...

Best regards,

-a-

[Jeff_S]

8 hours ago, gsengle said:

 

The pump shouldn't enrichen the mixture any, probably just increases the amount of fuel that comes back, and the extra circulation keeps the fuel in the lines from getting too warm.


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Maybe, maybe not. I know there have been two occasions where in my boneheadedness, I forgot to turn off the fuel pump after starting up. I kept asking myself why the engine was running so rough as I taxied out to run-up, so there was definitely a lot more fuel going into the injection system than normal. And once you have fuel circulating in the lines (which presumably you do, if you are flying up into the sky) then the fuel from the gas tanks is almost certainly not going to be too warm. And if you look at the Savvy charts above, while it's clear that having the fuel pump on did affect the EGTs (which it would, since the mixture was incredibly rich) it doesn't have much effect on the CHTs, and that's what really matters.

Admittedly, we don't hit the 100's very often here in Atlanta, but we get plenty of 90+ degree days. I still maintain that keeping the best airflow over the engine and making sure your baffles are in good shape is the most effective way to control temps overall.  But that's just me...we are all free to operate our engines however we choose! (And this pertains only to our M20Rs that don't have cowl flaps.)

[M20F]

Lowering pitch is really the best and simplest solution.  Dialing RPM back a bit can help as well.  

[kmyfm20s]

11 hours ago, gsengle said:

 

The pump shouldn't enrichen the mixture any, probably just increases the amount of fuel that comes back, and the extra circulation keeps the fuel in the lines from getting too warm.


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I have been flying in extreme heat for years and used to burn up cylinders all the time in a C182 that I had with an IO-550 STC. Learning how to keep cylinders cool has become kinda a hobby and has saved me lots of money. I have yet to replace a boost pump from wear but I'm sure it's a possility. I have replaced several cylinders in the past from heat.

A good engine monitor will tell you otherwise about a boost pump not enrichening the mixture. The data below show 3 step downs in fuel pressure on my climb from below sea level to 8500' with never leveling off. The first step if from simply turning off the boost pump when my EGT's are cool enough. The mixture is still  firewalled at this point. The second step is starting to lean the mixture.  This day it was only 106 degrees out.