New thermostat on the market for the WRX

[AZScoobie]

I tested a new Tstat by Crucial racing systems. Its rated at 160 degrees F. Its the new "fail safe" design where if the unit fails it will fail open and not closed. This would prevent overheating on failure.

How I tested the Tstat on my WRX at the time running around 325whp on the dyno dynamics: I sat and idled until I reached temp stabilized. With the stock Tstat this was around 88-89C as reported by delta dash. I then ran through the first 3 gears at WOT and pulled over while running data logs with delta dash. I forgot my dang Delta dash Key today so I cant post these logs. But here are the start and ending temps:


STock Tstat:
start of test 88C at idle.
End of test 102C with a rise 20 seconds later to 105C.
Time back to 88C was 3 minutes at idle.
Steady state cruise on highway 85C

Crucial Tstat:
Start of test 82C
End of test 85C A rise to 87C after 20 seconds.
Time back to 82C was 1.5 minutes.
Steady state cruise on highway 76C

My car as a PWR radiator, Samco Radiator hoses and a 50/50 mix of coolant and water. Stock fans.


Bottom line... The Crucial runs cooler all the time (duh) and has a much faster time back to the idle temp or near the Tstat's actual temp. The ECU in the Wrx and in my Type RA ECU considers the engine warm at 70C. Steady state cruise at 76C is close.. In 40-50 degree temps.. I worry that cars that are in very cold weather might run to cold and get enrichment and or no heat out of the cabin vents... AVCS on my car will not work under 71C... On my car at 80mph in 40 degree weather there is not much heat out of the vents with the Tstat. If I boost it up 10 seconds later heat pours out of the cabin vents and then later drops off. Other drawbacks would be a longer warm up time. I let me Temp gauge rise to normal before any boost or real throttle input. That can take a few miles or at least 10 full minutes of idle now.

East coast people might want to change back to stock for the winter. Not a big deal. People in hot climates dont even think about not buying this. Road racers especially...

Here is the blurb on the Tstat:

This thermostat is designed to keep your engine cooler and provide safety in case of failure.
The stock WRX thermostat doesn't open and allow coolant to flow until 172°.
This Crucial Racing Systems thermostat opens 12°'s cooler, at 160°. Cooler engines make more power.
When any other thermostat fails it locks in the closed position, preventing coolant from flowing to the engine.
The CoolSafe Thermostat locks in the open position in the event of failure. This could save your engine.
These thermostats are all individually tested and are covered by a lifetime guarantee.

Just for the record I dont agree with this blurb about cooler engines make more power. Thats not exactly true.. A cooler engine is less prone to detonate. A hotter engine normally runs cleaner and is more effecient. A cooler engine will probably last longer and it will certainly raise the detonation threashold of the engine. A leaner AFR can probably be run and or more boost. High HP WRX's can get over 105C on long pulls. A single Dyno pull on a 400whp WRX will have a rise of 15-20 degrees. I have been told by Subaru mechanics that the heads warp around 115C... Thats getting to close for my comfort. The WRX uses an Oil cooler that uses the coolant water to remove heat from the oil. I dont have an oil temp gauge but I will bet that oil temps would be much lower with the stat during racing... A big plus on a WRX.

Here is the address to order one:

http://www.infinite-performance.com/...6&PRID=1428414

As always.. I dont sell these and cannot get you one. The only place I know of to get these is through this shop or through Crucial direct and crucial does not have a website that I am aware of. I was told about them from another board member and called Crucial direct. That board member had Crucial's number and I have since lost it. If someone gives me the number I will post it or you can post it. Yes, I paid for mine....


Cya

Clark

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[Unabomber]

Thanks for the great review. However, I think you are missing a key ingredient that may lead many astray. A lower temperature thermostat combined with a stock computer isn't a great idea unless you utilize proper engine management to account for the temperature reduction.

[AZScoobie]

The stock computer has fuel and timing offsets for water temp. It tunes itself. I have the rom files in front of me and during testing watched the ECU's rom file with Flash 2k and my WB AFR meter. As noted the only concern is cold weather cruise where it might be possible to drop below 71C where the ECu actually adds enrichment and thinks you are in warm up.

Clark

[Unabomber]

This really stinks! I do believe your views and do not discredit them. However, according to page 4 of this Subaur .pdf document it will cause issues with the fuel injection. Sadly, many mods can have + and - issues with differing viewpoints. Who knows........

[cronic]

Clark great info.. Will this be a worth while mod for people on the stock radiator?

D-

[AZScoobie]

I must be blind. I dont see anything in that document about your statements.

Clark

[Unabomber]

Page 4 left hand side between Fuel Injection Logic and Learning Control.

[Unabomber]

While thinking this through based on SOA's info, I did think of something. It "says" that coolant temp is a correction factor. It doesn't state at what degree it is a correction factor. Many internet searches in the last few minutes pretty much say colder is "bad" because an ECU will be tricked into thinking you are still at start up and make you run too rich. If 82-87C (your experienced range) is above the ECU's correction threshold, then no adverse problems should be seen.

[Bolster]

I have this T-Stat on a shelf in the garage. I'm waiting to do it when I put on the VF22, Inlet hose, and 70mm APS CAI. All of those together should make for a fun tune.

[CynicX]

Originally posted by AZScoobie
When any other thermostat fails it locks in the closed position, preventing coolant from flowing to the engine.

i'm a bit confused....i've had 1 stat fail in my daytona, 2 in work vans, 1 in a older tahoe and the only problem that accured is the engine would not get to operating temp and i wouldnt get heat in the cabin cuz they all locked in the open position.....i'm failing to see how this new stat is a break through in thermostat technology.....

[CynicX]

unless i was just lucky and there is a chance they coulda got stuck closed and the new stat prevents that chance....if that case i'll shut up....

[vile]

most thermostat default to the close position when it fails(why, i have no idea).....but this is by no mean a break through technology, as it's been on the market before...beside, i don't think clark mentioned anything about it being new out there, i think he was just pointing out a fact/feature

unabomber, luv ur faq, but clark's review on product are very thorough and is always a good read......but hey, we always need someone to keep us honest right? hehe

btw, do the maintance faq, i'm tired of those threads in the maintance

[Unabomber]

I have no doubt about the review. The results he posted were stunning to me. I do have an issue as to wether this is something everyone should do or if the stock ECU will hate the lower temps. I plan on poking around to see if I can find the answer and hopefully AZScoobie will come up with some more supporting info as well. It's "tests" like this that I really enjoy!

FYI, I am all over the Maintenance forum right now. Oil and coolant were done and next up is spark plugs. Thanks!

[hotrod]

Good review Clark. I also have one of those. I have used the fail open designs for some time and was glad to see this come out for the subaru. A fail closed thermostat (which is the most common design) can kill an engine during a major over heat episode.

Living where I do, I will be using the coolant /thermostat change system I always have. In the late spring when the record low temps get near freezing, I change to a summer coolant blend 15% antifreeze, and some water wetter, and switch to a cooler thermostat. I'll be installing my Crucial Racing 160 here in a few weeks probably.

As far as the ECU, IIRC Jan shim posted quite some time ago that the key temp is 68 deg C, that the ECU goes into cold mixture rich mode.

According to the manual #8 pg CO-4, the car considers any temp over 76 -80 deg C as normal operating temp. (thats the stock thermostat open temp). At 95 deg C it kicks on the electic radiator fans to cool things down. Clarks temps are much closer to the overtemp fan turn on signal than they are to the low normal thermostat open temp. I doubt there is an issue especially in warm weather.

Keep in mind he has an upgraded radiator, with the stock radiator it will be even worse.

If I can find an affordable lap top by then, I will do some logging on the street and at the strip with the Crucial Racing Coolsafe 160 thermostat and a stock radiator. Here at altitude it will be a good test because the lower air density causes the radiator to not cool as well as it does at sea level.

Larry

[mlambert]

How much and where to buy?

[hotrod]

There are several vendors. They sell for about $75.

Oakos Automotive has them and Dave has been very good about ontime delivery to me for stuff I bought from him
www.oakos.com

Clark has a link up above for
infinite-performance, But I've never done business with them.

Larry

[4evryng]

Speedmonkee is a NASIOC vendor and also sells the Crucial Thermostat for $75.

It's not on their website. PM Jeremey for pricing and shipping. They are in SoCal.

[Unabomber]

Jan shim's temp article

60 degrees C seems to the point where the engine is warm. I hope to find some more supporting posts later today. Work calls....

[hotrod]

Unabomber:

Thanks for chashing Jan Shim's post down, for some reason I couldn't find it, when I wanted to. That is the one I was thinking about, so the key temp is 60 deg C, not 68 deg C.

The 60 deg C (140 deg F) threshold is well below what the engine would run with the Coolsafe thermostat in it. That makes me feel better, I might even put it in a couple weeks earlier now.

I know making the change to water wetter and a lower % of antifreeze helped reduce my tendency to detonate, this thermostat should ( I hope) give me a little more room for some more boost.

Larry

[Unabomber]

Sure thing. I just wanted to be sure that switching to a cooler thermostat didn't have any ill effects since I did read that coolant temps can effect things. Since according to Jan shim and AZScoobie there doesn't appear to be, I think it's a safe mod that will keep your engine running cooler. It may not give more HP, but I think it's a good reliability mod. AZScoobie also has a big honking PWR radiator too, so this probably accounts for some of the cooling effeciency as well. I wonder what a cooler thermostat will do with an OEM radiator?

SARD, ARC, and Nippon also make lower temp thermostats for those with interest.

[AZScoobie]

Back when That post was writen we did not have the Rom file for the ECU. Now that I do I can confirm that 71C is the cross over point where the ECU considers the engine to be warm.

The statement about Temp correction only supports what I originally said. AFR is adjusted based on coolant temp...

Clark

[Unabomber]

Cool, 71 is lower than the temps you were seeing, so this is additional confirmation that this is a good/safe mod. Thanks for your review and follow on input!

for Clark!

[AZScoobie]

Except for my theory that it could drop below 71 in cold weather I think most will be ok... If you road race or drag race with a high power Subaru this would be worthwhile.. If you have a lower powered or stock car there is probably no point.

Cya

Clark

[Javier]

So the assumption being that with the stock radiator temps will probably be a little higher... Would this realisticly then be ok for us East-coast guys even in the winter?

[AZScoobie]

Someone on the east coast with a Stock radiator will have to test it.

Clark