I dont think some of you quite know what the thermostat does so ill try to explain in a way yall can understand. The thermostat opens and closes to block or allow fresh coolant to recirculate through the system. Putting a lower thermostat opening point will absolutely nothing for an otherwise stock motor which almost 100% of us have, so it will yeild you no benefits. Second, it will cause your Nox emissions to go up which tends to happen when your air/fuel mixture runs rich. Also, by lowering the the thermostat opening point you motor will run cooler, but as a side effect it will run richer which in turn hurts performance, which is what you want in the first place correct ? Anywho, as for the open loop mode, your coolant temp. sensor will tell the pcm what temp. its at so it can go into closed loop, which uses the o2(oxygen sensors).

 

You are correct but you quoted me and I'm referencing a ECM Reflash to take advantage of the cooler temps by leaning it out and allowing more timing advance there for limiting the increase in NOX . By no means do I advise anyone to run a lower temp T-stat with out telling the ECM what your doing .

 

Im sorry man, i didnt mean to imply that you were wrong or anything, but quoted the first reply that i saw, and you were the lucky one. But for now, i dont think our motors are having problems with overheating or would benefit much from a lower operating tempature as long as its in between 180-195, i see no reason for any concerns to change your thermostat

 

Late model motors, expecially stock, don't see the benefits of a cooler stat like older motors did. You might see a slight increase in power and the sacrifice of gas mileage. If you want to lower, 180* is about the lowest. I ran a 170* in my truck for years and recently went back to a 195* and gained back 1.5MPG and truck actually runs cooler on the guage. I'm running elect fans on it also (96 5.7) with a 180* temp switch. I like the current stat much better, even performance wise verses the cooler stat.

 

But for now, i dont think our motors are having problems with overheating or would benefit much from a lower operating tempature as long as its in between 180-195, i see no reason for any concerns to change your thermostat[/quote]

You need to drive here in Arizona....

The recent trip to the Grand Canyon with the HHR group, showed me engine temperatures of 228. Some of the California people indicated they witnessed 235 coming acrossed the desert.

My temperatures happened in the climb from the desert area to the mountains...which was a period of about an hour. Once reaching the destination temp.'s went back to a "normal" for Arizona of 205.

While I agree with the discussion on thermostats, I believe GM under engineered the radiator by about 1 quart, especially for the hotter areas of the country.

 

On the same trip Snoopy is talking about, I only checked mine a couple of times and it got up to around 205-210. Once we got done with the up hill driving it stayed around 197-200. It is back to reading around 189-193 on a normal day of 115 outside air temp.

 

Unlike most traditional engines, the 2.4L VVT motor will probably not benefit from a lower temp thermostat. From our dyno testing results, the HHR makes more power at hotter temps. It likes to run at 204-210 and puts out good power there. We hit upwards of 230 on several runs.

There was some chatter recently about the HHR running "lean" with aftermarket intakes. Let me assure you that this is NOT the case. All our A/F ratio charts show that the HHR's ECU continually richens up the mixture to compensate for any change in the intake. This is part of the reason the CGS made so much power. Our dyno tech said that if we could lean it out more we would see an even bigger increase in power as the ECU is still running rich (as it does stock).

Next step: engine management mods. It will be pricey, and require you to have a laptop, but you will be able to plug in and make all your own changes, record them to the black box, and download run info for comparisons later - all right through the stock GM port.

This will be an option different from sending your ECU in to be reflashed. Instead, you can do it all right in the car with your laptop!

 

Right on, Mike....

A GM engineer told me exactly the same in regard to ECU management of additional air flow, within certain restrictions.

Oh, and the "excess" engine temp.'s is not acceptable for the time periods that were indicated. He is personally disappointed with this engines cooling ability. The cooling system was NOT designed for the extreme loads experienced.

 

Snoop...
As stated in other threads (and witnessed by myself 1st hand with several vehicles)... the 'water wetter' products (coolant additives) work very well. I've used the RedLine version for several years on several vehicles (including my motorcycle) with outstanding results!!! Just wanted to restate this as an option for the concerned individuals running in the hotter parts of the country.
On a different note- I'd be willing to bet your ride wouldn't get over 200* with the additive in place. Not bad for an $8 investment.

 

What Scoop said. These products break down the surface tension of the coolant, allowing more heat to transfer from the engine block to the coolant, and thus be circulated and dissipated. There are several brands on the market, NAPA carries them as well as most auot parts stores. For those in hotter climes, it might be a good investment - just open and pour.