Subaru cooling improved

[rvator4twa]

I have flown my RV-6A Subaru H-4 since March 2011 but when the heat came last summer, my cooling was insufficient. I have increased my cooling by upsizing the rads from 44 frontal inches each to 72 by having custom radiators made by Eddie at Techweld, Paducah, KY. Our St. Louis heat wave showed 112 OAT when I took off last week and climbed to 3000 AGL before leveling to keep coolant at 220. When tested at 95-100 OAT I climbed to 8000 before leveling with coolant not exceeding 207. For those still trying, custom rads. may be the answer. You can see my photos at kitlog.com/my kitlog/builders/ron burnett.

[rv6ejguy]

112 OAT, yikes! You've got a pretty good handle on the cooling now if you can fly in those temps. Good job getting this solved Ron.

[Tandem46]

Originally Posted by rvator4twa

You can see my photos at kitlog.com/my kitlog/builders/ron burnett.

This works better: http://www.mykitlog.com/RonBurnett

[David-aviator]

Good work, Ron. You have had more success than I did with cooling. Perhaps if I had stuck with the H4 instead of going to the H6, it would have worked out better.

[rvator4twa]

Without your help and guidance, I never would have got this project in the air. Thank you.

[DanH]

Originally Posted by rvator4twa

I have increased my cooling by upsizing the rads from 44 frontal inches each to 72 by having custom radiators made by Eddie at Techweld, Paducah, KY. Our St. Louis heat wave showed 112 OAT when I took off last week and climbed to 3000 AGL before leveling to keep coolant at 220. When tested at 95-100 OAT I climbed to 8000 before leveling with coolant not exceeding 207.

Ron, how do those temperatures compare to the original radiator setup?

The original installation appears to have had simple boxes between cowl intakes and the heat exchangers. Were they sealed to the cowl somehow?

[rvator4twa]

Dan,

The origuinal rads had me leveling off at 500 to 1000 (if lucky) agl to keep the coolant below 230 with OAT temps about 90. Multiple flights were out of the question in summertime. Now I am looking to install a controllable butterfly shutter on one of the rads to keep cooling temps higher, especially at cruise.

Ron Burnett

[pierre smith]

Originally Posted by DanH

Ron, how do those temperatures compare to the original radiator setup?

The original installation appears to have had simple boxes between cowl intakes and the heat exchangers. Were they sealed to the cowl somehow?

Dan, a friend of mine also had a 4 cylinder Subaru on his -7 and yes, there are two square boxes attached to the coolers and no rubber material to the front of the cowl.

During a BFR flight I administered, it always ran over 230 deg or more and 35 MPH slower than the IO-360 he now has in it.

Best,

[simpkinsona]

Sealing the radiator boxes is critical for these engines. Mine still has the small radiators but with good seals to the cowling. The oil cooler had one of the seals slip allowing an air leak, oil temps were 10 degrees higher relative to coolant temps until I fixed the seal. Too bad the company didn't stick with the H4. If they had stuck with it and given realistic performance figures, they would have sold many more. My RV-9a has the performance of an O-320 fixed pitch.

-Andy

[rv6ejguy]

Originally Posted by simpkinsona

Sealing the radiator boxes is critical for these engines. Mine still has the small radiators but with good seals to the cowling. The oil cooler had one of the seals slip allowing an air leak, oil temps were 10 degrees higher relative to coolant temps until I fixed the seal. Too bad the company didn't stick with the H4. If they had stuck with it and given realistic performance figures, they would have sold many more. My RV-9a has the performance of an O-320 fixed pitch.

-Andy

I agree, sealing is very important and most of the problems started when the H6 came along. They are very heavy for an RV6-9. A good H4 will true 150-160 knots and does not weigh much more than the Lyc C/S.