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Heater bypass and vapor locks. Links?

Denok

Denok

Active Member
Patron
My plane suffers from pretty serious vapor locks on the ground in hot weather which makes my engine temp rise rapidly and dramatically. I always need to hurry to get in the air because oil temp will jump past 200 deg.
One of the first thing I will do is to install a shroud around my fuel pump and check fuel lines. That will certainly help a lot.
One thing that sure doesn't help is the heater bypass box which, when closed, dumps a very large amount of heat behind the rear baffle, very close to the fuel pump. Has anyone made a mod to take this unwanted heat somewhere else, away from the accessories gearbox area. Pictures would be great.
IO-360 B1B on 100LL, dual Pmags with automotive plugs on A curve advanced 3 deg for low mass prop.
Thanks
 
I've had the same thoughts, no problem here with my fuel temps due to a different fuel system design, but I believe this is at least part of my oil temperature problem. My heater bypass blows almost directly at my oil cooler outlet, which will produce a higher localized pressure there and slow airflow through the cooler, and I am going to make some type of ducting to direct that heater bypass downward to the cowl exit instead.
 
The RV-10 cabin heat boxes are mounted on the firewall just aft of the fuel pump. The result is you have very hot heat muff air bouncing off the closed valves right back at the fuel pump.

I did two things:
- I added an overhanging flap of this stuff:http://www.aircraftspruce.com/catalog/avpages/forbes5.php?clickkey=3041841
The Koolmat is has two holes cut out to mount between the firewall and the cabin heat boxes, with a flap that extends up and then over the front of the cabin heat boxes. The result is the hot heat muff air now is directed down to the cowl exit, not at the engine.
- On the RV-10 at least there is far more cabin heat than needed - ever. I made an air orifice out of .032" aluminum cut to the diameter of the SCAT hose, and drilled a 3/4" hole in the middle. The orifice goes on the engine baffle SCAT hose flange. I have it held onto the flange with aluminum tape. The SCAT hose slides over it. The result is less air stolen off the engine just to be dump on a hot day, and still far more heat than I will ever use.

Carl
 
I entirely remove my heater box and route the scat tubing from baffle to heat selector.

The additional air circulation in the cabin is nice and in the other position it offers blast air to the mechanical fuel pump.

Give it a try!

;) CJ
 
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