Aftermarket thermostats

[dragoontwo]

Originally Posted by Ashikabi

I believe your question is directed at OP, not me. He claimed thermostat opens fully at 95 but coolant temp is 92 on the track. I think something is wrong here because that simply shouldn't be possible for the thermostat to not even fully open on the track. Almost sounds like he's looking at intake air temp or something.

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I should have been more clear. The opening question was for you.

[Ashikabi]

Originally Posted by dragoontwo

I should have been more clear. The opening question was for you.

I don't know where in the loop the temp is taken but it will certainly matter. Coolant entering the core will vary significantly from that exiting the core

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[JIM THEO]

I changed my OEM thermostat with a Sard 82C (exact same part with NTCL 82C thermostat) mainly because I found that this car reaches easily 102-103C with steady throttle, stationary at 2500-3000rpms!

What I realized is that it increases slightly fuel consumption, gives some room before water AND oil temp rises (for example in mountainous roads you can thrash it here and there with no overheating problems), and probably helps in knock behavior.
In addition, the winter I should adjust the temperature higher, from the interior temperature control, to achieve the same heat.

Forgot to add, Mishimoto is different technology than our NTCL thermostat plus it's reliability issues!

[Compelica]

Originally Posted by Ashikabi

I don't know where in the loop the temp is taken but it will certainly matter. Coolant entering the core will vary significantly from that exiting the core

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The coolant temp was taken from the stock sensor via OBD2.

I watched my track day recording again - it did log a higher coolant temp at 93C when my oil temps were on 120C. Have to admit that I'm a track novice and I probably could have gotten the car pushed harder for sure.

Originally Posted by JIM THEO

I changed my OEM thermostat with a Sard 82C (exact same part with NTCL 82C thermostat) mainly because I found that this car reaches easily 102-103C with steady throttle, stationary at 2500-3000rpms!

What I realized is that it increases slightly fuel consumption, gives some room before water AND oil temp rises (for example in mountainous roads you can thrash it here and there with no overheating problems), and probably helps in knock behavior.
In addition, the winter I should adjust the temperature higher, from the interior temperature control, to achieve the same heat.

Forgot to add, Mishimoto is different technology than our NTCL thermostat plus it's reliability issues!

Thanks for the feedback. Here where I'm from it's a tropical climate all year round so we don't use the heaters. Referring to your 102-103C temps, I believe you are referring to oil temperature? Do you have any record of peak coolant and oil temperatures pre and post-OEM thermostat?

Also - NTCL also sells their thermostats directly under their own brand too, at least good that there's an option.

[Compelica]

Some tidbits of info on a low thermostat on our FA20s by Andre from HP Academy:

"First of all, in terms of the thermostat temperature or the cooling fan. Yes the engine will be more prone to knock or detonation as I've kind of touched on. When the engine's operating temperature is higher. It's all about that combustion temperature. So the trend that we're seeing a lot with a lot of late model cars now is to run a very hot thermostat, perhaps as high as 92 to 95°C, you'll have to convert that into Fahrenheit sorry, my brain doesn't work in imperial.

But that's to aid fuel economy. However that hotter operating temperature does definitely make our engine more knock prone and on engines that are already knock prone, it can make our job tuning the engine a little bit more difficult. This is something I found on our Toyota 86 with the FA20 engine, the stock thermostat on hat is 92° and I dropped that down to an 82° thermostat and found that I did get an improvement in the engine's ability to take timing. One thing, without trying to get too involved with this, one thing that you do want to watch is it's all well and good if your operating temperature on the dyno is perahps 80 or 82°. If however like I see with our Toyota 86, the engine temperature creeps up to 95 or even 100° out on the racetrack, that's the situation we really need to be tuning for and being careful of so you do need to be aware of how the engine coolant temperature may affect the car once it's off the dyno."

https://www.hpacademy.com/previous-w...link-g4-vipec/

[JIM THEO]

Originally Posted by Compelica

Referring to your 102-103C temps, I believe you are referring to oil temperature? Do you have any record of peak coolant and oil temperatures pre and post-OEM thermostat?

Also - NTCL also sells their thermostats directly under their own brand too, at least good that there's an option.

No, I am reffering to coolant temp when you keep the throttle steady at 2500-3000rpms!
This is from the factory for emissions control as it heats up the engine for better combustion.

It was scary when I first saw it and no one could tell me why this happened to a brand new MY18 BRZ.
In the end I found it is normal and all cars of this platform do it, I have recorded it but I am in the office now.
Since I fitted the new thermostat no more coolant temps above 95-96C.

This NTCL thermostat is also factory fitted to a Forester according to my Subaru mechanic, I don't know what generation/model, and cheaper than Sard/NTCL!

[tomm.brz]

it seema impossible to me that you reach over 100C on coolant just on cruising, unless other bad issues like extremely poor fuel that brings your AM to 0.1 and you re still knocking and the pulled timing overheat the engine
This time i d really need to see it to believe it

[JIM THEO]

Originally Posted by tomm.brz

it seema impossible to me that you reach over 100C on coolant just on cruising, unless other bad issues like extremely poor fuel that brings your AM to 0.1 and you re still knocking and the pulled timing overheat the engine
This time i d really need to see it to believe it

Not cruising, stationary, as when you pass emission tests! IAM was max...

[JIM THEO]

This is a picture I found in my office computer where temp was at ~100C (lift off throttle).
102C was the max temp I recorder with Techstream, not continuous, it was between 95C - 102C when stationary at 3000rpms
https://ibb.co/2sW707C

[tomm.brz]

ah ok! stationary, so where is the oddity? if you dont provide an airflow, radiators are very poor devices
just mod the tune to kick in fans earlier and your problem is disappeared without changing the thermostat...

My car stationary doesnt go over 89C even with 40C ambient in summer waiting at the McDrive for 20 minutes in queue

[JIM THEO]

Originally Posted by tomm.brz

ah ok! stationary, so where is the oddity? if you dont provide an airflow, radiators are very poor devices
just mod the tune to kick in fans earlier and your problem is disappeared without changing the thermostat...

My car stationary doesnt go over 89C even with 40C ambient in summer waiting at the McDrive for 20 minutes in queue

Not at idle, keep the throttle for some mins at 3000rpms and you'll see 100C or above

[tomm.brz]

Originally Posted by JIM THEO

Not at idle, keep the throttle for some mins at 3000rpms and you'll see 100C or above

i d still see 89C even if a do a 2 minutes launch control @ 4000 rpm with boost and -20 of timing because at 88-89C both of my fans kick in while stationary withouth the need of an aftermarket thermostat

[JIM THEO]

Originally Posted by tomm.brz

i d still see 89C even if a do a 2 minutes launch control @ 4000 rpm with boost and -20 of timing because at 88-89C both of my fans kick in while stationary withouth the need of an aftermarket thermostat

I do have the fans adjusted to lower temps but this just gives an extra margin before temp rises, how your fans cool the engine while thermostat is closed?

An example: https://datazap.me/u/jim-theo/log-16...=0-29-30-31-45

[nikitopo]

Originally Posted by Compelica

I'm toying with the idea of getting an aftermarket thermostat. Based on opinion the stock radiator has significant thermal capacity left to sink more heat, but most don't advocate changing the thermostat given reliability concerns. However all things considered, I wanted to address two particular potential benefits with the lower coolant temp on my setup:

1. Oil cooling. I'm on the Forester water to oil exchanger and having a larger coolant to oil temperature delta will further reduce oil temperatures.
2. Knock resistance - lower coolant and oil temps would influence cylinder head and bore temps, reducing the tendency to knock. This opens up further tuning potential.

There's several choices of thermostats available for our cars:

1. SARD 68C/82C
2. Mishimoto 76C
3. Billion 65C/72C/82C
4. NTCL 82C

I have a Cosworth thermostat 76C (not the one from Mishimoto). The coolant temperature sits at around 80C-82C depending how hard I drive. Oil temperature is also a few degrees lower even without an oil cooler. These are non-idle temperatures where the heat exchanger can work.