160F Thermostat vs Higher

[Dominic]

On my 2002 Camaro and previous 2000 Firebird V6 (all iron pushrod 3800) I've run 160F thermostats. I have consistently had faster 1/4 mile times by 0.4-0.6sec running lower coolant temps than higher. The stock thermostat in these cars is 195F.

Oh, I also get better highway fuel economy with the 160F.

Do any of you run a particularly high or low thermostat in your race cars for any reasons? I have many people telling me that "160F is too cold" but I don't have any problems to speak of.

 

[MGBV8]

http://www.carnut.com/ramblin/_cool3.html

 

[Gurkha]

190F is too high for my taste, my diesel MB engine came with 172F T-Stat which would make my engine run at 194F making me extremely uncomfortable, also during stop and go in summer, the performance would go down significantly. I changed it with a 161F T stat and now the car runs at 176F steady, no matter how hot outside, also keeps the engine performance far better as well as the oil condition stays quite well even at extended drain.

I would say this high T stat only came due to EPA's regulations, sadly, this also leads to higher ring land temps as well as under the hood temps as well as shearing the oil, in long run, heat is and will always remain a killer, no matter what.

 

[Patman]

I don't believe 0.4 to 0.6 better just from a thermostat. That's a difference of about 30-40hp, which is simply not possible from that.

I've been drag racing since 1991, with various cars, and never saw any tangible performance benefit from going to a colder thermostat. And I've never seen the ET drop by 0.6 just from a colder coolant temp. I would often let the car sit for a couple of hours in order to get the coolant temp down around 120-130F, and it never runs 6 tenths better. With the supercharged cars I've owned it might run 3 tenths better, but with normally aspirated cars the difference wasn't that much (a tenth or two at most) And keep in mind, that was with a much lower coolant temp than you'll see with a 160 thermo. You'll typically see running temps of about 175-180 when you've got a 160 thermo.

 

[1 FMF]

190F thermostat, no problems here. On the LS1/2/6, the only problem I can see with a 190F thermostat is in stop/go driving in hot weather. Radiator fans are electric and don't come on till coolant hits 226F and higher, unless you reprogram. By then it's too hot and you're reacting to an overheat instead of preventing. With an aluminum motor, it sheds heat well so a 190F isn't that hot. You should really be looking at oil temp as well, colder oil = thicker oil = less economy. This past summer with a 190F thermo and manually switching on the fans, I run 220-240F oil temp with 5w-40 oil. Now with weather 40-70F I see 190-210F oil temps unless I romp on it. I have run a 160F thermostat, never noticed a problem but I never did a comparison to really find out. I don't believe you get better fuel economy with a 160, not in PA and certainly not this time of year. This is all for a stock motor. Now if you are running a turbo or blower or did work to bump up compression or are lapping the car at high rpm's for long periods of time then yes a colder thermo would be in order, along with a radiator upgrade and fan reprogram. I would first look at a better/larger radiator and airflow to maintain temp (rather than running colder to prevent overheating) as that's primarily where the problem is. Had a 1999 ss and those years had a 180F thermo as oem, which I think is a better choice than the 190F especially for warm weather driving.

Best reason I can think of you getting faster 1/4 mile on lower thermostat is it was allowing the motor to run full timing and not see any knock retard which is common with today's crappy ethanol'd pump gas. Full timing on cooler thermo = more power compared to better efficiency at hotter coolant temps but with less ignition timing. Run a 180 or 190F thermo and a higher octane fuel, bet you run your fastest time.

gurkha: diesel ignition is based on heat in the cylinder, how do you figure a lower thermostat/coolant temps = better performance?

2002 camaro ss, 34k miles, M6, stock except for k&n filter and ngk iridium plugs,
this is 3rd pull out of 5, oil temp at 220F, coolant about 200F (less than 210 mark on gauge).
I was running vp 100 octane unleaded, so I know I was getting full timing. Also running mobil 5w-40 oil, pennzoil synchromesh in M6, and redline 75w90 in rear. I also made an effort to drive car on highway just before the dyno to get drivetrain hot. I was looking for maximum #'s.

 

[Ryan00TJ]

I run a 160T stat in my LS1 from Spring till Fall. Actually just recently swapped back in the 195. I reprogrammed my fans to come on at lower temps and it does make a difference in coolant temps w the 160 during the hot summer and after hotlapping at the track compared to stock fans w the 190stat. I change out the 160 during the winter as the motor runs pretty cold with the 160. Takes too long to get to operating temp. With the 195 it's just about right and runs a little cooler than the stock setup.

I went with the 160 after adding higher compression 10.8-1 heads and noticing the motor running noticeably warmer than at the stock 10.0-1 setup.

 

[Dominic]

That's pretty interesting. I have a 180 and a 195, so I might switch back to my 180F for the PA winter just to keep the heat in the motor - she is running very cool with the 160F and the cold air up here.

I used to live in FL, and the 160F kept the motor around 175-185 on the highway.

 

[mechtech]

When you are racing, both thermostats are open, anyway.
Street efficiency is much better with a warmer thermostat.

 

[edvanp]

I have the 3800 Series II SuperCharged engine and I've run the 160 & 180 degree T-Stats. I found the 160 to be too cold for year round use, especially here in Michigan. The 180 works fine for me.