STI Thermostat

[Jelwin]

Probably asked and answered before, but can an STi thermostat be a direct replacement for the OEM item for the EZ30? Do I need to change any sensors or anything? Needing a cool change, because my cooling system needs flushing and thermostat needs replacing, due to overheating issues

Edit: this was due to me reading the Perrin article back a few years where he said he put an STi thermo in but i cant remember/find the finer details of what he actually did and needed.

[teK--]

No point running higher pressure cap without upgrading rest of cooling system. It will do more harm than good.

[kleinerbastler]

I think he means the thermostat and not the radiator cap- but no idea if it will fit.

[teK--]

Sorry I misread. Not sure what STI cap is rated at but I found when running slightly lower temp thermostat fuel efficiency is down (I do a lot of short trips). Had no choice of temp it was what Subie Dealer sold me as OEM replacement.

[kleinerbastler]

@Jelwin
I found the lines from Perrin http://blog.perrinperformance.com/perrin-h6-build-up/
"...One of the things we discovered with the first build is the engine runs pretty hot. An oil cooler was added this time around to ensure the oil stayed nice and cool, and maybe help keep coolant temps in control. Of course this adds even more oil to each fill, and makes the oil changes about the same a big diesel truck! Like we said, the engine runs hot, hotter than the 4 cylinders by about 5-10C. So next up is a radiator. A Koyo radiator was purchased, and modified with 2 entry points for the H6 engine. We also added the STI thermostat, which is 5degrees C cooler. All this should help control temps for any situation..."
So probably it will fit.

I used the "live help" from Perrin, but the person there had only "unknowledge" about the things and couldn´t give me a 100% answer.

[MH3.0R]

I am running one of these:

http://www.tuspeed.com/grimmspeed-subaru-160-degree-thermostat-p-1498.html

OEMs have to meet emission standards part of which is the startup / engine warm up cycle, and I think that is why STI only drop the thermostat by 5 degrees compared to non STI versions. The aftermarket and forums that I have read all subscribe to the lower temp thermostats. For my driving pattern it has worked as I have a long hwy stretch initially, then city start/stop cycle. I did note that in the winter months, the car took about another 1 to 2 kms to get up to operating temps (water temp via ECUdatascan). but thereafter sat reliably at 82 to 83 degrees until I hit the start/stop cycle, then back up to the 88 to 92 degree range.
Summer or Winter, very similar readings for the water temps. I have not modified the radiator (stock), but I do have a Trasco Oil Filter which is all Aluminium with fins for extra cooling and high quality filtering. I got this from Ivan at:

http://x3emotorsports.com/cart/index.php?main_page=product_info&cPath=34_131&products_id=277

He also supplies my Redline Oil and the replacement filters over the last 3+ years.

[senator]

Guys you can also source Sards racing thermostats from Phat GT, I think they come in variable temps to suit your applications.

I’ve got one fitted in my GT (71ºc), I pretty sure you can get them for the H6’s.

Phat GT also sourced an aftermarket water pump with a solid impeller for smoother and quicker flow.

[Jelwin]

Huge help guys thanks a lot!

[MH3.0R]

GTs and 3.0R have the same thermostats in terms of size and fitment from my recollection.

But Radiator and Oil caps, well they are completely different! Go figure!