I'm sure the answer is somewhere on this forum, I'm just not smart/patient enough to find it; Posting a question for the hive mind --
Dataset:
Two RV-7's, Airplane 1 & 2, both with IO-360-A1B6 Angle Valve, SilverHawk RSA-5 fuel injection/Avstar fuel injection, Dual Plasma III Ignitions @ 20°BTDC.
Airplane 1 had a SW 8406R "7-Row" oil cooler, fed by a 3" SCEET duct from the #4 Cylinder back baffle, aluminum box duct transition to oil cooler.
Airplane 2 has a SW 10599R "9-Row" oil cooler, fed by a 3" SCEET duct from the #4 Cylinder back baffle, custom fiberglass transition/plenum from duct to oil cooler face.
The oil temps for equivalent power settings, DA and TAS***, and CHT's are essentially the same between each aircraft ... ~185°F
Why is this the case?
In my pea-brain, I would have expected the 10599R to reject about 30% more heat than the 8406R, the OT should run about 10% or so cooler.
Unfortunately, Airplane 1 was lost, and no more data from that aircraft is available -- so I am left chasing variables for Airplane 2. Going to a larger duct and/or SW 10611R is interesting and would probably solve the problem - but overkill IMHO and hiding the real root cause of the loss of efficiency.
***Here's one additional data point -- Airplane 1 was painted, and would yield a 180KTAS+ cruise at test power settings, Airplane 2 is bare metal, rough fiberglass and cruises at 172KTAS with test power settings. Could the difference in TAS be driving this temperature delta?
Cheers!
Dataset:
Two RV-7's, Airplane 1 & 2, both with IO-360-A1B6 Angle Valve, SilverHawk RSA-5 fuel injection/Avstar fuel injection, Dual Plasma III Ignitions @ 20°BTDC.
Airplane 1 had a SW 8406R "7-Row" oil cooler, fed by a 3" SCEET duct from the #4 Cylinder back baffle, aluminum box duct transition to oil cooler.
Airplane 2 has a SW 10599R "9-Row" oil cooler, fed by a 3" SCEET duct from the #4 Cylinder back baffle, custom fiberglass transition/plenum from duct to oil cooler face.
The oil temps for equivalent power settings, DA and TAS***, and CHT's are essentially the same between each aircraft ... ~185°F
Why is this the case?
In my pea-brain, I would have expected the 10599R to reject about 30% more heat than the 8406R, the OT should run about 10% or so cooler.
Unfortunately, Airplane 1 was lost, and no more data from that aircraft is available -- so I am left chasing variables for Airplane 2. Going to a larger duct and/or SW 10611R is interesting and would probably solve the problem - but overkill IMHO and hiding the real root cause of the loss of efficiency.
***Here's one additional data point -- Airplane 1 was painted, and would yield a 180KTAS+ cruise at test power settings, Airplane 2 is bare metal, rough fiberglass and cruises at 172KTAS with test power settings. Could the difference in TAS be driving this temperature delta?
Cheers!