Here's how you resolve this never ending over blown issue. Leave the DIC on ODOMETER and drive the car. The temps are fine.

If you've turned your Vette into a drag racer and need to hot lap it without the heat induced timing reduction, then you may want to do all kinds of aftermarket mods to keep it cooler. But for 99% of the street drivers, just drive the car and quit worrying about the temps.

 

05 MN6 Z51 (oil cooler) & OE T-Stat

Water 196-200
Oil 210-214

 

IF you are going to leave it stock. But, if you want more HP, run it a little cooler. As stated before, the PCM pulls timing with elevated ECT and AIT's. This pulls power. In addition, higher ECT's mean the heads are hotter, which can cause detonation, and the PCM will initiate KR, pulling even more timing and power.

 

1000% false. Water evaporates long before boiling temps. At 180 degrees water is gone in a matter of minutes from the oil. When you boil water on the stove do you see the steam long before the boiling point? How does water evaporate after it rains then without 216 degrees on the ground?

The big advantage to the 160 degree stat is that engine temps both IAT and coolant temps pull timing when they get too hot. The IAT sits in the MAF which is mounted on top of the upper radiator hose. It can pull 12 degrees timing. 20-30hp.

 

Sorry Uber - I'm with TommyD and Spin on this one.

 

Okay, someone explain to me how a 160 degree thermostat alone keeps the car cooler once the coolant temperature reaches 160 degrees, and the thermostat opens up.

Eventually the engine reaches what we engineers like to call steay state? You still have the same amount of heat being produced by the engine, and the same amount of water being circulated by the water pump and the same amount of air across the radiator. It will take longer to get to that steady state temperature, but it will get there. Thermodynamics is a funny thing.

 

It's valid for drag racers and others who use a short occasional blast of power. If they can get their engine cooled down to 160 between runs, there is a short term benefit.

If the cooling load keeps the coolant temps over 180 or so with a wide open 160F thermostat, then as you say there is no real advantqage.

 

 

You guys are missing one point. The radiator has sufficient heat rejection capability to cool the coolant below the stock thermostats closing point, with sufficient air flow via forward motion or fan speed. When the coolant is below the closing point flow stops as does additional cooling. But with a lower temp thermostat it will keep cooling until either the radiator can't reject anymore heat or the thermostat closes.

Eg: My Z06, with a 160 thermostat, running 25% coolant, 75% water, and one bottle of water wetter, will run about 165 to 170 ECT when cruising at 65 to 75 MPH, in 80 to 90* heat. With a stock thermostat it was in the 190's. Stop and go driving produces more heat, and gives less airflow through the radiator and the ECT goes up, very rarely into the low 200's.

 

Newbie here, I searched for "oil cooler" and didn't think I should post in a C3 forum ... so ... bought my first Vette a couple of months ago ('07 Z51 auto with shift paddles) and took it to the track for a one day open tracking event. In ambient temps of 90* the oil temp hit 300*, tranny 265* and water 220*. So I had to pull off early each session ... and in general keep revs below 6000 -- which I haven't had to do in any of my previous daily driver/track cars (Toyota, BMW, Porsche). My understanding is that the Z51 comes with an oil cooler so what more should I do? (I'm most worried about the oil temp but the tranny seemed to not want to change from 5th to 6th near redline so it may also need cooling attention). Advice or pointers to another post would be very welcome. Thanks.

 

Going with a lower thermostat will not help either as the stock one was wide open under your operating conditions. Running an automatic wasn't helping as you were dumping more heat into the coolant due to the losses in an automatic. Not sure why you had to keep the revs down although it really doesn't help to push them all the way to red line as the cars probably perform best shifting in the 6K range. Once you got to those temps you should have been at steady state and been able to complete your sessions although I am not familiar with the automatic performance as all my C6 time has been in 6 speeds.

The Z51 doesn't have an engine oil cooler. It has a power steering cooler and for the manual tranny it has a transmission cooler. You can run the car reliably for several years this way but it is nice to get the temps down a few degrees (I ran my 97 for 3 seasons at those temps before putting in a Ron Davis Racing Radiator). Going to an Engine Oil Cooler will help but a larger radiator will really help. You can keep the stock thermostat as the larger radiator with engine oil cooler should drop temps down to 200 coolant, 230 to 250 oil and I am not sure about transmission as I haven't had any experience with the automatic.

Once you get used to it a C6 Z51 should give you far more pleasure than the other cars you mentioned as you blow by them at the track.

Bill

 

.... My car runs 15 to 20 degs cooler under all conditions except stuck in traffic or barely moving! I don't care about all the engineering theory, fluid dynamics, blah.. blah.. blah! All I know is that it ran around 195 to 210 BEFORE I installed a 160 stat. Now it's 180 to 185 most of the time! It also cools down much faster after it getting warm in traffic and I get moving again!. It drops right back to about 180 in a a minute or two. I want someone to tell me they actually installed a 160 stat and NOW there car doesn't run cooler on average. If you don't believe it will run cooler invest 20 bucks and 1/2 hour and then tell me it doesn't run cooler! There is VERY noticeable difference in performance when running at 185 versus 200 + degs. I don't really care why it works.. I only care that it DOES WORK..........

 

Actually, it does have an engine oil cooler.

 

 

Okay, I am man enough to admit the fatal error in this post. Thermostats are not on/off, they modulate to a setpoint. Cooling system never really reaches "steady state". As the coolant temp goes up the 'stat opens up to allow more flow, higher coolant circulation and more air means more cooling and 'stat begins to close modulating around the setpoint. 160 degree setpoint should run 20 degrees cooler (approximately) than a 180 degree setpoint.

 

Thanks for all the feedback fellas. I was just curious. My blown Cobra has a 195* t-stat and never goes above 200 or so and I figured the Vette couldn't possibly run hotter naturally aspirated so I never understood why it seemed like they ran so much warmer, but after you guys quoting your temps it sounds like they run pretty close. Thanks!

 

The A6 does not.

 

Much of the talk is from those who have not actually installed a 160 stat. If those had actually done it, they would duplicate your observations.

 

Just to add, my C6 when stock ran 210-220 when sitting in traffic. Got as high as 230 at the track. Ran about 190 when cruising. These are coolant temps. Put my 160 t-stat in, no tune and the car still hit 210-220 when sitting but would go as low as 170 while cruising. With the tune, my fan is at 90-100% quite often (can hear it all the time), I've seen as high as 200 so far this summer at idle with the air con running. This is in hot, humid Florida weather. It's around 165 while driving, 190 while sitting without a/c on.

 

Not true. You don't have to boil the water to get rid of it. 180 degree water will evaporate very easily. Anyway, oil temps run several degrees hotter than water temps. Much of the time, over 212 degrees. Any water in the oil will be long gone after achieving operating temps. And that includes a 160 t-stat.