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Planning to get one of those Koyo rads later this year but was thinking of upgrading the thermostat "while I'm there"...

This seems like a good deal from Crucial, on sale now for $45 shipped and the guy there (Jeremy) makes a decent case for using them. Check it...

http://www.crucialracing.com/products/coolsafe.php

"A high performance radiator will lower the coolant temperature at the exit of the radiator as it is a larger heat sink and can dissipate more heat. The stock thermostat, which opens at 172 degrees, is located at the entry of the engine block immediately after the coolant exits the radiator. When installing a more efficient radiator before the stock thermostat, the stock thermostat is actually slower to open than normal because the coolant passing through the bleed hole is colder than normal. If you suddenly go to high boost, the thermostat will not react until the coolant flow and temperatures get high enough at the radiator discharge to open the thermostat allowing for significant coolant flow. As Subaru engine coolant temperature sensors are located on the top of the engine block, coolant temperature is measured as it leaves the engine, not at the thermostat, so coolant exiting the engine under high load could be 40 - 60 degrees warmer than the 172 degree stock thermostat temperature and heat-induced detonation can occur. When your Engine management system senses detonation, ignition timing is retarded and your engine loses power..."

What do you guys think?

Also, can you point me to were this goes and what I'd have to take apart to replace my OEM one?

Many thanks!

~Adam

If you plan on tracking it, then no. The radiator will not be able to cool enough regardless of the T-Stat. For a DD car then probably yes. It might help some.

All you do is pull the hose at the bottom of the radiator and you got the T-stat. To be honest I would stick with the stock one. OEM one is the exact degree temperature for the engine to run efficiently. The -10 to 20 degree difference can be noticeable.

I've run a Crucial T-stat for 2-3 years now. There is no noticeable difference (it's only 12*F) in driveability, mileage, heater function, anything.

It's easy to install - folow the lower rad hose to the block, and there it is.

The bonus over an OEM is that it will fail OPEN, not closed. Unfortunately I had 2 of these fail (open) with no assignable cause. Jeremy is great though, and I had replacements ASAP (he fronted the replacements too so I wasn't out of commision) -Great customer service.

The last one I put in has lasted the 2-3 years I mentioned - I think they had a bad Lot, which I and a couple others had trouble with.

I also run a Redline Water Wetter mix and slightly more H2O than stock (like 1/2 pint of WW and a 70/30 mix)

_Chad

tmarcel wrote:If you plan on tracking it, then no. The radiator will not be able to cool enough regardless of the T-Stat. For a DD car then probably yes. It might help some.

Marcel, could you clarify this distinction for me a bit more? I am planning to track the car...


Thanks for the input folks - I may spring for this. I like that if it fails it fails open...

Cheers,
AW

My understanding was that OEM thermostats were also designed to fail open, which is one thing that made them superior to many third-party ones. Is that not true?

According to crucial.....or internet folklore that's not the case, but I'd probably tend to agree that OEM's fail open.

Either way, I'd still run OEM. In a city driving environment, your coolant temps will stay between 180-200 deg F based upon cycling of the fans.

Unless the AC/defrost is used, then the temp will drop to that of the t-stat. This also could apply to highway driving.

Without knowing where the ECU starts triming fuel for startup enrichment, I'd be a little cautious in running the engine cooler. 10-12 deg F may not be a big deal, but then again it may.

Just my 2 cents

Interesting. So the thermostat would cause the engine to run cooler at start - what about larger rad? Is the Koyo rad mod something to beware of as well?

AW

Adam,

The radiator works in a similar fashion as an intercooler. You get to the point where it gets overworked (heat). That was my point. Bump up to a more efficient radiator and that will do a better a job than a bandaid t-stat. If you can beat the snot out of it between 170-190f and not go any further it'll be good to go.

Yeah, I get it. I'm getting the rad so I don't need the trick t-stat. Cool. $45 bucks more I can use on something else...(this really is a sickness).

Thanks mang,

AW