After fitting a 6MT gearbox to my '98 GT, the oil temperature rises too high at trackdays. After 5 laps (around 1:12 each), the oil reaches 120-125 degc (outside air temperature 25 degc). At this point I return to the depot to let it cool down.

There is almost no space left below the intercooler and down through the gearbox tunnel, as the 6MT occupies the whole area.

Is the increased oil temperature caused by high intake temperatures? Can I improve the situation by adding an oil cooler kit, or is the only option a FMIC?

I feel sorry for the car when the oil temperature rises this high

 

Are you still on the OE TMIC? If so I'd measure the inlet temps as I bet they are skyrocketing. FMIC or bigger TMIC may help. Oil cooler is fixing a symptom but not the cause IMO. This could work but is a PITA to change the oil...

F

 

Still on the OE TMIC.

I think I'll have to drop any trackday activity until a larger FMIC is installed, I didn't expect it to be so noticeable. I guess David@API Engines can supply a new one if my engine goes <POP>, but I think that'll have to wait a year or two

Any FMIC recommendations? £300-£400 price range.

 

STi7/8 or Hybrid FMIC
F

 

I was asked when I fitted my 6 speed if I had a top or front mount intercooler. As air flows under the car, it causes a vunturi(?) effect, ie helping to pull air down through the intercooler from the top of the engine. Due to the increased size of the 6 speed, this effect is lost, hence higher temps. Lucky for me I already had a FMIC fitted.
Hope this helps

Nathan

 

Hybrid FMIC, without a doubt. Top piece of kit, and best value for money. Talk to Harvey (harveysmith1@btopenworld.com) and he'll sort you out.

Cheers,
Paulo

 

Is the gearbox/drivetrain tunnel in later cars with 6MT wider than in the classic GT? If not, how do Subaru solve the cooling issue?

 

FMIC or a chargecooler will address any charge air temperature problems but you still have the problem of having blocked the air path out of the engine bay with a bigger transmission. Also, FMIC will probably affect radiator performance to some degree.

With FMIC, you could try removing the bonnet vent covers and raising the rear edge of the bonnet to encourage air flow through the engine bay.

J.