[Ninjaneer]

OK, sorry to bump an old thread for my first post, but I have some experience designing oil cooler systems for cars, so I thought I'd offer some thoughts for those wanting to put their own cooler together. I'm looking into buying an FR-S, so I was researching oil cooler kits and came across this thread.

First, some general thoughts... Personally I've had good experience with Mocal parts for just about any oil cooler application. They make good quality coolers, hose, fittings, and sandwich plates. The main US distributor of Mocal parts in the US is BAT, Inc. I believe they also sell direct to consumer. You have to be careful with a lot of the universal kits you see being sold on ebay and around the internet. Many times you'll find the cooler quality sucks, and the hoses and sandwich plate will leak. Stick with a quality supplier like Mocal, Earl's, or Setrab. Those 3 use what's called a pressed plate core design, which uses a series of plates with internal "turbulators" to maximize heat transfer. The much cheaper, "fin tube" coolers are no where near as efficient, and have a higher pressure drop. All of the kits I've seen on the market for the BRZ/FR-S appear to be the pressed-plate type, which you would expect given the high cost of the kits.

Cooler Core:
Mocal has 2 different widths of coolers, a 115mm matrix core and 235 matrix core, with different row sizes within those. The 115 core is a good compact size for tight areas and for applications in high airflow areas and/or where extensive cooling isn't needed. I use a 13 row 115 matrix core for an MR2 Spyder application mounted in the side air vent, and it provides adequate cooling for everything but heavily boosted engines. Perrin appears to use a 235 matrix, 16 row Mocal cooler (Correction, it's a 13 row). That is a good all around size for most applications. You could get away with a 13 row most likely, looking at oil temp numbers I've seen on the board. I wouldn't go any higher than 16 row unless you are running some monster HP. As far as inlet size, 4 cylinder engines with short oil line runs can get by with 8AN, but I use 10AN as my standard.

Hose and fittings:
I personally only use stainless braided hose and aluminum swivel fittings, rather than the "push-on" style rubber hose and fittings. I've heard of and personally witnessed too many cases of the rubber hose fittings popping off and spraying oil everywhere. The rubber hose also ruptures and is damaged more easily. The cost of stainless hose and fittings is a little higher, but worth it for peace of mind and for looks IMO. If you do use rubber hose and fittings, make sure you use oetiker clamps on the fittings. You might have to find someone with a pair of Oetiker pliers to borrow, which aren't cheap.The one thing you have to be careful with about stainless braided hose, is it will saw through other hoses or wire over time due to vibration, so you have to make sure any part of the hose that comes in contact with wires or other hoses is covered in sheathing. The main challenge with stainless hose will be assembling the hoses and fittings. The anodized aluminum fittings will scratch and mar using steel tools. I have a special aluminum vise and aluminum wrench to assemble my hoses to keep them looking nice.

Sandwich plate:
Mocal makes the best sandwich plate I've found. They make a thermostatic plate that keeps you from excessively cooling during warm up or cold temps. Don't even think about putting together a kit without a thermostatic plate or some sort of external thermostat. You'll be running cold oil and might never get to proper oil temp in some cases. With the FRS/BRZ, you'll need a spacer to provide the needed clearance over the "cup". Mocal sells a BRZ/FR-S specific plate that includes a 25mm spacer. Expensive, but good quality. For plate fittings, use 1/2" BSP to 10AN fittings and 1/2" Dowty seals.

Mounting location/bracket:
Mocal has a universal bracket which may or may not work for the FR-S/BRZ. I'd recommend some kind of damping between the bracket and cooler if possible to keep down vibration. The Mocal bracket has damping pads included. Some sort of custom bracket might be a better approach for the FR-S/BRZ. I like Perrin's approach of mounting the cooler on risers behind the front grill. Simple approach, and great air flow (better cooling).

I've already gotten too long winded, but later I can post up part numbers for the above parts I would recommend if anyone is thinking about putting together their own cooler kit. Using Mocal parts I would guess you could put together a high-quality DIY kit with stainless hoses for less that $500. Using rubber hose and a smaller core could probably get you under $400.