Cooler Thermostats?

[andymoraitis]

I'm looking for some feedback from you guys on changing out my thermostat on my GSX. I'm currently running a 16G on the stock fuel setup and have the boost dialed to 16 psi (tuned by Buschur). My EGT's run fine at cruise (1350) and I never peg the needle under full boost. My goals aren't to turn the car into a monster, but run as much boost as possible, safely, on the stock fuel system. The next group of mods will be a 255 fuel pump and a 2.5" downpipe. Per Dave Buschur, he says that this alone should be good for 18 psi without concern.

Anyway, I remember that on our mid 90's Mustang Cobras, we would use cooler thermostats, or remove them entirely, to make the car run richer. If I were to install a 140 or 160 thermo in my 2G, would I be able to add a little more insurance by making the car more rich? Again, I'm not looking to crank the boost to 20 with just a fuel pump, but provide a safer environment to run 18 on an upgraded pump. For those of you who would recommend bigger injectors and an AFC, keep in mind that an AFC isn't something I want to get into for this car.

Sorry this was so long, but please let me know your thoughts when you have a chance.

 

[Project ES]

From what I've researched on cooler thermostats, theyre not good for dsm's. I've come under the impression that our motors and equipment are set up to run efficiently up around 180* or 190*. I could be wrong though, Hopefully someone else will post some useful information here for ya if im wrong. Im running a 180* in mine and my car seems like it never completely warms up in this cold weather. But then again I only start mine up and run it for a half hour or so. Its closed up in the garage all winter though. Prob not the greatest idea but I've been told u can pinch the fuel return line a lil bit to increase pressure under the stock fpr, I havent done this but ive heard from a few local dsm'rs that it works. Try at your own risk!!!

 

[andymoraitis]

I've heard the same thing before especially with respect to the N/T cars. Like I mentioned, I don't want to do something like this as a band-aid, I'm just wondering if it will help keep things richened up a bit as added insurance. Logically it should, but what do I know? Thanks for the reply!

 

[16g-95gsx]

You definately dont want to remove the thermostat entirely at all. In all honesty the stock 2g 180* thermostat is fine. There is absolutely no reason to change it at all, especially on a setup like yours where the radiator is recieving full airflow. If you wish to increase your cooling abilities, try a higher pressure radiator cap, water wetter, and straight distilled water as coolant.

By using a 255lph HP without any form of a fuel pressure regulator your idle and cruise conditions will suffer some, especially idle, and also on/off throttle conditions. Your top end fueling will however gain. 450cc injectors really dont allow for much fueling at all, imagine 90% IDC, and you are looking at 97.2lph, not much fueling at all. The 2g stock fuel pump at 15psi, on 12.5v according to RRE was flow tested to 99.68lph, this means that on 12.5v and 15psi of boost pressure, it could support the stock injectors at 90% IDC. Now using that value of 99.68lph, which would be the flow rate as mentioned at 15psi on the pump at 12.5v, crunching some numbers gives us a airflow rate of 27.82lb/min assuming a 10:1 AF ratio and .76 as the specific gravity of pump gas. A small 16g on 18psi of boost Id imagine is at least 31lb/min or so, they generally flow around 35lb/min or so at sea level on around 21.5psi from my own personal experience, meaning that, you definately wouldnt be able to support a 10:1 AF on that pump at 12.5v, and 31lb/min which is my guess of what youd be flowing at that point. If the AF was changed to 11:1, you still only have support for 30.6lb/min, which is again less than the airflow Id expect to see you run on 18psi on any decent setup, and also this is assuming 15psi of boost, 18psi of boost would lessen the output of the fuel pump.

Now, RRE rates the 2g rewired pump at 14v and 15psi at 131.23lph, much more than the unrewired pump. Crunching this number, brings us to, 36.6 lb/min of airflow at 10:1 AF, this would be on 15psi, so it would be slightly less at 18psi, however it still would alot a decent window if you are only aiming for 18psi. Basically, if you crunch the numbers, you can see that if you rewired your stock pump, you could most likely get away with the 18psi without even upgrading it, assuming the voltage was anywhere close to 14v, and you kept the boost that low. Now an upgraded fuel pump is always a nice thing, and upgrading to a 190lph would bring you to 145.11lph even in its unrewired 12.5v state at 15psi, meaning that it should be able to support that flow value without an issue, however its up to you.

What I can see, is that again, using RRE's data, you can see that the 450's, at 90% IDC (which is all Id ever want them to even peak to, no point in letting it go further) on the stock base pressure, will only allow 97.2lph, and about 27lb/min of airflow assuming 10:1 AF, 11:1 alotting 29.8lb/min, which could possibly net you some possible knock due to skewed timing maps on an Safc if you use one. So injectors IMO are the worst of your fueling and the weak link in your fueling system, as you can see by the numbers I just spit out for ya. For a small 16g, true 550's would be good, however Id say just go ahead and get 650's, just in case you do ever want to upgrade down the road.

 

[L2RTSiAWD]

On my car I have some cooling issues because of the huge FMIC I have combined with hot temps here in AZ.

What worked for me is drilliing a small hole in a stock thermostat and I wired a fan switch so I can turn the fans on manually for those really hot days.

I have thought about an aluminum radiator to see if it would cool enough to not use the fan switch but I haven't seen anything real that shows me a 375 dollar radiator is alot better than some wire and a 2 dollar switch.

 

[16g-95gsx]

The stock radiator fan is set to come on at conditions above 210*F if I am not mistaken, meaning that until then your car just continues to warm up at idle. Ideally it should stay around 190*, but we all know that not to be the case always. For climates like yours Id definately advise the fan switch, where it will automaticlally run both fans at full blast (which doesnt happen until really hot conditions). That should drop temps a good 6* or so from my experience. Like I said, with this guy, it sounds to me as if he has no FMIC, so airflow to the radiator shouldnt be an issue at all, and if he wants very nice cooling all he should likely need to do is just what I had told him. In your case, if you like AC especially, an aluminum radiator would greatly help you out. In addition if you do have a FMIC, be sure NOT to remove the radiator shroud, but rather modify it if need be, and still leave it installed. Air will always go around any piece it can, it likes to take the path of least resistance, so dont give it a window, force it to go through the radiator.

 

[L2RTSiAWD]

In your case, if you like AC especially, an aluminum radiator would greatly help you out. In addition if you do have a FMIC, be sure NOT to remove the radiator shroud, but rather modify it if need be, and still leave it installed. Air will always go around any piece it can, it likes to take the path of least resistance, so dont give it a window, force it to go through the radiator.

Well I do have it setup to run both fans full blast, my AC has been broken but I planned on getting it fixed before this summer. Maybe I will get a new radiator as well.

 

[andymoraitis]

Thanks for the great answers gentlemen. I do appreciate the concise and accurate feedback!

 

[DSMu4ia]

Mitsubishi has a OEM 180*F thermo that works good in our cars. Unless your cooling system is up to the task however, your engine will never run at 180*F.

My advice to you is to wire the stock fans, or get a set of Spals. Wire them up to your liking.

I myself run the main passenger side fan on high 100% of the time, the drivers side spal fan is on a switch, and I turn it on whenever I remember.

 

[ari2gdsm]

On my car iam currently running a 160* thermostat. I just recently installed it. I thought that the car would run a little cooler all the time. On the highway my temp. runs about 150-160. the thing is that when im at a drive thru. My temp runs up to 200-210. after that I start seeing vapor come out of the hood. (keep in mind i installed a radiator, coolant hoses, 160 therm., 50/50 mix)which makes me turn off the car or just get out of the line as soon as possible. Well i figured out my problem. on the highway there is more air (duh) and the thermostat is staying open which allows the coolant to stay colder. At the drive thru the thermostat stays open all the time because there is no air getting to the radiator. So what happens is the thermostats open and the fluid is constanly resirculating around the motor and the radiator. Because the thermostats open, the fans do not get a chance to properly cool down the fluid as it passes thru the radiator core. its sort of like running no thermostat at all. only on the highway. youre best bet is to run a 180* thermostat so that it does hold some coolant in the radiator and you can get some type of cooling to the motor.

 

[leet]

Well I do have it setup to run both fans full blast, my AC has been broken but I planned on getting it fixed before this summer. Maybe I will get a new radiator as well.

John, get yourself a sheet of very thin metal. Cut up and form a shroud that will go from your FMIC to your radiator. That way the air has nowhere to go but through. It will be a bit of work, but the returns should be worth it.

As stated above, don't give that air any way to go around the radiator.

 

[DSMu4ia]

The problem with non-OEM thermostats is exactly as you describe. The cheap 160^F things you find at Pepboys, are not meant for performance use. They physically don't flow enough coolant to make them worthwhile. You can try to drill holes in them to make them better, but even then, a 180*F Mitsu one will work better.

BTW, The standard DSM ECU code will retard timing when it's under or over certain degree's.

I believe on a 2g, this is <184*F and >212*F. I'm sure the 1g is fairly similar.

 

[rdrkt]

There is a couple of issues with running a cooler thermostat. On a stock ecu car the fuel maps really aren’t designed to see drastically cooler than stock coolant temps while cruising.

Step one is to get some control over your fans whether it be with a manual switch like L2RTSiAWD uses or through ecu control. You definitely want to be able to monitor your exact coolant temps and turn your fans on around 170-180 and then get a Tstat to match that. If your fans aren’t coming on till 200 degrees coolant temp or greater you are going to run into cooling issues no matter what tstat you have in there.

 

[16g-95gsx]

Above 206* and 1* is pulled on a 2g
Above 224* and 2* is pulled on a 2g
Dunno bout below a threshhold though, but with 171*F coolant temps with a quick look at one of my logs here, I see 16* of timing on stock timing maps, so if there is it cant be at 171* or higher .

 

[Defiant]

On my car iam currently running a 160* thermostat. I just recently installed it. I thought that the car would run a little cooler all the time.

Thermostats aren't for cooling engines: radiators do that. The thermostat's job is to keep an engine warm. A 160° thermostat opens and allows full-flow at a temperature much below a DSM's operating temp. You'll be much better-off to go back to the stock spec thermostat.

 

[mntalon_05]

I believe there's something on the 1000faq website about this. If the coolant temp is too low, the ecu won't come out of it's "warm up" map if I remember correctly.

 

[98TalonTSi]

If the car does not come up to proper operating temps, then fuel efficiency will suffer.

 

[andymoraitis]

There is a couple of issues with running a cooler thermostat. On a stock ecu car the fuel maps really aren’t designed to see drastically cooler than stock coolant temps while cruising.

Step one is to get some control over your fans whether it be with a manual switch like L2RTSiAWD uses or through ecu control. You definitely want to be able to monitor your exact coolant temps and turn your fans on around 170-180 and then get a Tstat to match that. If your fans aren’t coming on till 200 degrees coolant temp or greater you are going to run into cooling issues no matter what tstat you have in there.

Interestingly enough, this is what I neglected to mention that we did on our Cobras. We used to wire the cooling fan to come on at ignition and the water temps would be amazingly low. Doh! I should have been thinking "fan" instead of "thermostat the whole time. Live and learn! Thanks for the reminder