MPPalmer(at)aol.com
Guest
|
 Posted: Thu Jun 26, 2008 9:48 am Post subject: Hot oil cooler ideas from Phoenix |
 |
|
Location, location, location. I've moved our oil cooler inlet for better cooling. Per some aircraft we saw at OSH while building, I thought I was being "cool" by putting the intake for our cooler on the pilot side bottom of the cowl. The thinking was that the prop would spin air into the cooler (left side of lower cowl) and that, being on the bottom, the cooler would get more ram air on climb out, when you need it most. (And on the other hand, it would automatically "close off" in level flight, due to the boundary layer increasing in cruise, bypassing the scoop. I have since moved the NACA to the copilot side. MUCH better.
First, our cowl scoop (carbureted Glasair II) blocked any air rotation from the prop. In essence, I think I had a dead zone on the pilot side of the lower cowl. Second, there is no ram effect with a NACA. I have a NACA for engine intake air and it's remarkable, but those things don't see any ram pressure at all! (Probably by design.) I do not see any increase in MP from a climb attitude to a screaming dive. I still like the bottom location of the NACA for the closing, boundary layer feature (if any). i.e. lower cooling drag in cruise.
In our hot Phoenix summers, we will see one needle width short of redline on climb out (guessing about 230 degrees). That's on a tricked out 320 (170 HP?) with a SW oil cooler. It quickly comes down to vernatherm temp 180 - 190 on leveling out. (We run WOT, 2400 rpm, LOP. LOP helps a lot.) Interestingly, when we slow to 15 inches for pattern, the oil temp will come back up to almost red line! A combination of lower differential air pressure across the cooler due to the slow airspeed and the oil not moving through the cooler at reduced engine speed.
Things to check: Is the oil cooler flowing correctly internally? (Was it new or used?) Pacific Oil Coolers can clean them. They claim flushing with solvent doesn't really do it.
I've seen temp changes when I change the static oil pressure. There's a balance between having oil flow too fast / too slow through the cooler. Try increasing / decreasing your oil pressure to see where you are.
Are your oil lines okay? If rubber, any broken flaps inside the hose? I switched to Aeroquip 601. Indefinite life, much more flexible and very smooth wall.
Getting air OUT of the cooler is as important as getting air in. Is there an unrestricted path from the output of the cooler to the bottom of the cowl? Is the cooler in a low pressure area? If you're side mounted, I'd run a giant SCAT tube to the bottom of the cowl to see if that helps the air flow out the cooler. Or move the cooler down to the bottom of the cowl, where air can come in from a bottom mounted NACA directly into the cooler and quickly exit out to the lip of the lower cowl scoop.
Ted Setzer took us for a ride in the factory III years ago at a summer airshow here. Red line all the time on the oil temp. Ted remarked that there were better locations for a cooler than the stock factory right side of the cowl. Not being a III driver, I don't know where they exit that air, but I've seen some funky reverse NACA's (bumps out into the airflow) at OSH on some III's as they try to ameliorate the problem.
I helped a guy with a tricked out Glasair I, 200 HP+ engine who has the right side mounted cooler. He lives in Ogden, UT and says he gets very hot on climb out too. I made a fiberglas plenum to direct air from his inlet to the cooler. I don't remember if I made a similar plenum to direct the air out the side louvers. Unfortunately, his Whirlwind prop blades delaminated and he hasn't flown since my mods.
Hope this helps,
Mike Palmer <><
**************
Gas prices getting you down? Search AOL Autos for fuel-efficient used cars.
(http://autos.aol.com/used?ncid=aolaut00050000000007) [quote][b]
| | - The Matronics Glasair-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Glasair-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
