One of the mods I did on older model EFIs was to install a lower temperature thermostat to change the loop point of the ECU.. denser mixture, cooler running, a smidge of HP
I haven't seen this mod discussed or listed yet , so I am assuming the ECOTEC engine won't play with this mod :confused:

I did that on my Mustang. I'm pretty sure it can be done on the Ecotec. I haven't looked around for lower temperature thermostats for 2.4 yet so I don't know if anyone makes them. :confused: It's not that high on my to do list yet. :lol:

I did that on my 94 Suburban. Usually it's done to keep the engine cooler to prevent detonation after other mods (my Suburban had a B&M supercharger). You have to make sure to select a thermostat temperature above point where the computer goes to closed loop operation. Otherwise it will run open-loop, which results in a very rich mixture with terrible gas mileage and black exhaust. On the Suburban, the stock thermostat was 195 degrees, I used a 180 degree thermostat. The open loop to closed loop point occured at 160 degrees. If the computer is reprogrammed for a much lower temp thermostat, then you can go lower than the closed/open shift point but that is much more involved than a simple thermostat change.

Steve

If you install a lower temp T-stat you will need to let the ECM know that . So you can turn the fans on early and take some fuel out .




Thanks
Matt
www.tunetimeperformance.com

SO Matt if I had one of your retuned ECMs would I need to put a lower T-Stat in ? would the retuning take some of the fuel out?

Our Tune is flashed the way you want it . We can tune for the lower t-stat . or we can just have the fans com on early and not change the t-stat . It's your choice . We will change things biased on what you want out of it .


Thanks
Matt
www.tunetimeperformance.com

I know that "power stats" are popular as a performance mod but there is a downside that I'm witness to very often. Lower operating temps bring lower oil temps as well. In most street driven vehicles this can cause the oil to become contaminated with moisture that doesn't get "burned off" from normal higher oil temps. In the past few months I have seen several vehicles with hydraulic lifter problems and other oil related problems that were directly related to low temperatures. In my humble opinion, the engineers who design these powertrains know what they are doing, for what ever small gain a person might see from lower temperatures a "payback" in the form of more frequent service would result......or possible mechanical problems. Ol' Smokey Yunick knew 'way back when that more consistant horsepower and efficiency is possible with a bit higher temperatures than most people were running at the time. Smokey wasn't dumb. I'll leave my factory thermostat in place, thank you.

I do agree with you to a degree. We will do what ever is asked of us as far as a tune , but on my personal HHR 2.4 I have just lowered the fan turn on temps to keep it more consistent. I will say that with a 180 t-stat you will gain some ponies with very little risk. Is it worth it ??? It's up to you . If every thing is cooler I.E. coolant/trans temp / oil, by as much as 10 degree's then you should see less ware any more then that will not benefit you .

What would the risks be of lowering the temp to 180?
Is it best donw electronically or with a thermostat?

You cant do it electronically. You can lower the fan turn on temps . if you change T-stat you have to lower fan temps and take some fuel out .

You cant do it electronically. You can lower the fan turn on temps . if you change T-stat you have to lower fan temps and take some fuel out .

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).

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!!! :thumb: 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.

To Scoot and SoCal....

Thanks for that info. I had been considering that additive because of "Songman" and someone elses discussion on other threads.

I am however, very concerned about warranty issues, because of the Owners Book and TSB discussions related to radiator/cooling additives. A discussion with a friend, who is a service advisor at a dealership (not mine), said IF GM deems any malfunction a result of the additive, a normal radiator/pump repair would be in excess of $1000.

I still may try it, however. Again, risk and reward.

The display of engine temp.'s is why, on a previous discussion, I raised questions in regard to the relationship between engine temp.'s and trans. temps. It would be my belief that if those "extreme" temps. in the engine have some relationship to the trans., it would cause premature trans failure (probably just after warranty expires).

Again, thanks for the info.

CJ, I saw it on one of the internet websites that I "Googled", for info on Royal Purple. You might try that, if you have not.

To Scoot and SoCal....
I am however, very concerned about warranty issues...
Agreed... however, I can't honestly think a dealer would give you static over pouring in an $8 bottle of additive. ESPECIALLY when your vehicle is operating in excess of 200+*!!!:eek:!!!- but guess it depends on the dealer.
Honestly, there's 2 ways to avoid this problem... #1- they'd never know because the 12oz.'s of color added (the RedLine product is HOT PINK) would blend in with the DexCool and be unnoticable, #2- drain and refill prior to service. ~Then again, if your having cooling problems, it may have already 'auto-drained' itself.

Honestly, though... people RACE with ONLY this in their rad's!!! *Most* do not contain silica, which would wreak havoc on aluminum pumps and/or brass gaskets, therefore I really don't see how the additive could be the cause of any significant problems. On that point- couldn't the dealer argue that using any engine oil other than the recommended grade be the cause of engine failure (e.g. synthetics)?
I could go on and on with analogies, but... you get the point. I guess it really comes down to the dealer/service department your dealing with... *should* their ever be a problem.
Go out and buy some 'quality' additive!!! Just my :2cents: Very reasonably priced mod with OUTSTANDING results!!
F.Y.I. ... I was (very) hesitent to put it in my motorcycle back in '95... but did (in '96) and haven't looked back since! Put it in every vehicle I've owned since...
:thumb:

O'k...you convinced me !!!!

Reading through this thread I've noticed people reporting higher than "normal" temps. I'm assuming these where the temps the DIC displayed. What did the analog gauge say? I ask because I've noticed my digital temp on the DIC go from 194 to 210 waiting for a green light but, the analog gauge doesn't move. I'm wondering just how accurate is the digital readout.

Based on previous DIC experience (no puns here), I would put more faith in the digital than the "analog".

My analog displayed just a bit over the half way point at the time I got the 228 readings on the DIC (BTW ..dash gages are indicators, according to GM, not gauges....because of of previous law suit).

I was on GC run with the wifes HHR (HHR DLYT), we encounted high temps several times on the way to Williams on Friday evening and on the way home. We saw temps of 235+ causing us to run without the A/C on to keep the temp from rising any higher. I was using both gauges, the analog gauge went 3/4s of the way up, prompting me to check the digital gauge. The DIC showed temps of 235+ the outside temp was over 110 f at the time and we were pulling some long grades at 80MPH, after slowing to around 70MPH, reducing engine RPM the temp started to drop. Snoopy and I discussed using cooling adittives while and the GC, I just completed building a 71 SS Chevelle big block car that I installed A/C on. It was having a couple of cooling issues, I flushed the system even though coolant was only a couple of months old, refilled with fresh coolant, water and Water Wetter, noticed about a 15 f drop in operating temps even with higher outside temps than before. I have a bottle of Water Wetter I think I'm going put it in the HHR. I agree Snoop, I think GM under estimated the cooling system and question if GM tested the HHR under extreme condition. It concerns me seeing such high running temps.

Snoopy
Have you notice any high temps on yours the last few days? Seems like with the hotter outside temps mine is running a little hotter. But I am not sure if that also has to due with the fact at work has to sit outside in the sun.

When I first stated reading this thread I was not to worried, but after the CG run and this last week, I am stating to wonder about it all.

Yeah D...

I noticed "in traffic" engine temps of 215-217 when the ambient rises to about 108-110. Temps seem acceptable at 190-200 when the ambient is below 105. On the freeway near the "stack" I had an ambient of 117 and my engine temp went to 217 in pretty heavy, well moving traffic.

I guess I'm one of the lucky ones... I did a surveillance job this week and was sitting in my HHR for 9 hours, sitting in one spot with it running and the a/c going, outside temp of 104 and my temp gauge never went above the halfway mark and my DIC never read over 203....

CBL

I guess I'm one of the lucky ones... I did a surveillance job this week and was sitting in my HHR for 9 hours, sitting in one spot with it running and the a/c going, outside temp of 104 and my temp gauge never went above the halfway mark and my DIC never read over 203....

Just out of curiousity isn't that hard on the engine just idling it there for 9 hours at a pop? What does that do to your MPG?

yep, i'm sure it's not good on it, when I started my DIC was at 31.2... at the end of the day is was at 17.3. By the time I got to my folks house for the night (30 miles highway) it was back up to 25.3

I did a lot of sitting/idleing last summer in my Silverado extended cab and it's still running strong. I run Royal Purple oil in the engines so I would think that probably helps some. I was honestly surprised that the temp didn't go overboard though. I was working with another investigator and he was in a Dodge Stratus and he did not have any temp problems either.

Normally when the weather is not so warm I just park and roll down or crack a window or two. But when the temps are up it's just unbearable to sit there for long periods without the engine and a/c running.

CBL