I have a 180* thermostat in my '86 IROC. I installed a new radiator (the old one blew up) and a dual-fan setup from an '89 IROC. I also utilize two fan temperature switches to automatically turn on/off the fans.

I took my car out a few weeks ago and the gauge didn't even reach the line between 100* and 220*. I drove it for at least 30 minutes. I made sure that I disabled both fans before I took it out, too (I have a switch to manually disengage the fans completely).

Now, something doesn't seem correct here. I know that it was cold when I took my car out (35* maybe), but the engine should at least warm up a little bit. I'm thinking of putting a 195* thermostat back in to see if it helps. I drag race my car in the summer, so I'd like to improve performance by running it a little cooler than stock, but I also don't want to be tearing up my engine and gas mileage in the process... I get about 12-15 mpg right now. What's an adequate temperature? I also have a switch to manually engage the fans, bypassing the automatic fan control. I only use that when I drag race.

 

If you really need to monitor the temp accurately, you need a 'real' guage. The stock guage isn't real accurate. An aftermarket mechanical temp guage should do the trick.

 

a 180 should worked year round with out running fans..
when its cold outside it takes my car at least 7 to 10 miinutes to fully heat up to around 220 with a 195 stat.

your mpg is pretty low.

 

im running a 195 stat, with a 3 row alum radiator and stock pump and everything, i rarely go over 200, i have my fans hooked to a toggle switch and turn them on at 180 and it usually stays right there, as mentioned get a mechanical gauge, my stock gauge was waaay off...

 

What you are seeing is correct with a 180 stat. I had exactly the same results when I fooled with different stats. The guage is not exactly linear and it's that way by design. With a 195 and normal 40mph and up driving when warmed up fully it should run on that line bet 100 and 220. Most GM vehicles are designed to run at a reference point on the guage. The blazers run on the first line just like the rock, my daughters cavalier actually has 195 on it's line. They do this to give the driver a reference and it helps to pick up problems BEFORE they become major. I checked mine with a laser and when the guage is on that first line it is at about 197 degrees.

 

Right, I knew about the non-linear design of the gauge. Now we know that my gauge seems to be working properly. Therefore, what is a decent temperature for the *engine* to run at, for the best performance and gas mileage? Not thermostat temp, but engine temp -- I think I can configure my auto fan switches to "hold" a certain engine temperature if I figure out what that optimum temperature is.

 

Your minimum is going to be the stat temperature. I would say, try to keep the temp around 185 with the fans--at that temp the thermostat should be fully open. Consistent temps will help make your car more consistent. To find the best temp for your car, will take some trial and error. Mine seems to like 180, yours may not.

 

195 will be the temp where you will get the best mileage and driveability overall. 1989 Iroc zz-4 block, 24mpg highway in OD

 

my 88' loves the 180 i have in it right now. i'm getting 18+ mpg in the city with lots of "spirited" driving :sillylol:

 

so, if I'm reading this right, the temp gauge is supposed to be on the line between the 100 and the 220 (160 if the gauge was linear)?

Damn, then my car problem is elsewhere...

 

I think that factory Water temp guage actually measures HEAD temp. which technically should be the same thing since the water in the head is the same temp as...

or is it? My 89RS factory guage reads under 100* mark almost ALWAYS. but my aftermarket ultra lite guage tells me over 195* in normal day driving.

 

as it commonly known around here, factory gauges are very inaccurate. so king's case is a good case of just that.

 

The coolant in the head should be at its warmest point before it goes back into the radiator. The only better spot for it is in the intake right before the stat, exactly where GM put the ECM temp sensor.

 

yea you want the temp to be around 180-190.... you want the heads to be hot with a nice cool charge of air coming in the intake.

 

I'm surprised that this thread is still active a month after I posted my initial question .

Based upon what I've read here, I bought a 195* thermostat that I'm going to put back in the Camaro. I have access to one of those laser pointer thermometers -- where would be the best place to aim it to see if my stock gauge is reading the wrong temperature? I thought about the radiator hoses, but I would think that the rubber hose would act as an insulator and not give a true reading.

 

This was a good thread.
I often thought whether putting in that 160 stat was the right thing to do? My problem was that during the hot summer drives (with A/C going) the needle on the gauge was almost redlining. With the 160, it doesn't do it but I'm not driving in very hot weather the last few years.
So my question is: in your experiences, is my mileage suffering with the 160 stat?
Running too cold? I'm thinking for year-round driving, hot/cold?
I do get terrible mileage even when I light foot it. (It's an 82 LG4, carb.)

Pacer

 

Keep in mind that the thermostat temp is the minimum temp for the engine....if you have an overheat problem, you are running 230+ temp and you have a 195 thermostat that is working. Switching to a 160 thermostat isn't going to help. At 200+ degrees a 160/170/180/195 thermostat is going to be wide open, all flowing the same amount. The cooling system must have the capacity to maintain that lower temp for it to do any good. As far as mileage, toss in a 180 thermostat and see what happens. No way to tell if the 160 thermostat is affecting mileage without a comparison.