Chapter 23 Oil Cooler

The plans oil cooler mounting locations are mounted to the firewall at the top of the cowl or on the bottom cowl.   I opted for the top since the exhaust area is lower pressure than the NACA inlet on the bottom side of the aircraft.  The pad mount alternator will get cool air.  Also, when parked the top opening will allow convection air to pass through and cool the auxiliary case engine area.

The oil cooler will be mounted in the top of the cowl position above the pad mount alternator.  This will allow access to change the oil filter.  The bolts holding the tank vent manifold will screw into nutplates on the oil cooler mount.   The plans specify to mount the cooler 1.5" below the lip at a 10 degree angle.

I used 2024 1 x 1.5 Angle and .75 x .75 Angle stock.  Floating nut plates receive the bolts through the firewall and vent manifold block.

Above the engine mount, the .75 x .75 angle stock rests and can be secured with an Adel clamp.

45 degree steel fittings will be installed.   The outboard mount needs to be fabricated and installed.  Box tape and scrap foam will be used as a form for the duct.

 

Test fitting with the center bottom brace resting on the motor mount.

View from underneath.  Top cowl oil door hinge is to close to the outboard flange of the cooler.

Tilting the cooler a little more improves clearance with the oil door hinge.

Shortened the center bottom brace, installed nutplates and attached an Adel clamp.

Lower inboard bracket with nutplates is installed.  Attached to motor mount with an adele clamp.

Top center brace is drilled and attached.

The nutplates are to small for the jig so didn't get the holes perfect.  Fixed them with a Dremel.

Borla fuel pressure regulator is mounted to the bottom bracket. I decided this location had several advantages over other locations.

Inboard view of fuel regulator.

Test fitting reveals the oil dipstick clears (barely), but a benefit is when changing oil, a the line can be disconnected to drain the cooler into the oil dipstick tube using a small funnel.  The duct also was very close to the oil door hinge on the top cowl.  The glass duct construction required multiple layup/cure/trim iterations.  Would have been easier without the engine mounted.

Inboard view of the regulator/oil cooler/duct and bracket bolted to the fuel tank vent manifold.

Last night I ordered Aeroquip 466 hose assemblies (almost $1K) with stainless steel fittings:

AN4- Straight - Straight (fuel pressure sensor hose) 14"

AN4- Str-Str (oil pressure sensor hose) 7"

AN6-Str-90 (fuel reg to FW) 20"

AN6- Str-Str (fuel reg to fuel manifold) 13"

AN6- Str-90 (fuel manifold to FW) 32"

AN8- Str-Str (oil cooler return to engine)  18"

AN8- Str-Str (engine oil out to cooler in)  30" 

Fuel regulator mounted to oil cooler bracket.

One line was a little to short so I added a 45 degree M-F adapter.  The dipstick clears the AN8 oil line.

A better view of the outside lower angle support using an Adel clamp and an L bracket.

Fuel lines routed to the pressure regulator.  The return line feeds off the bottom of the regulator and goes to the firewall bulkhead connector.