Check this out.

http://performanceunlimited.com/illu...ermostats.html

It's gota nice graph of engine temp vs wear as well as a great write up.

 

I think a 17x thermostat would be better than a 160. I forgot who sells them.
Also, I have been told by a tuner that the LSx motors make the best power in the low to mid 190° range. These motors are designed to run in the 220°, and that is the only way GM could get the HP and pass EPA laws. I try to run mine in the mid 180's, but that's because I have a supercharger sitting on top of the motor. I would try just setting the fans first. IF that doesn't work, then go with a thermostat change.
Also, be sure to clean all the leaves and crap out of the A/C condensor and radiator. There corvettes are bottom feeders, and pick up the crap off the road like a hoover vacuum cleaner.

 

Well they say 180 is the best coolant temp

 

Vinci sells a 170, but it is always bypassing fluid so it doesn't heat up enough for cooler weather. Not sure if anyone else does, but would like to hear if someone else knows.

 

Take that thermostat out and you will see that you wont get any heat

 

You'll get heat-it'll just take longer.

 

Don't bet on it.

This time of year in the upper midwest, with no (or stuck open) tstat, you'd be lucky to maintain 120* coolant temps.

Been there done that. Stuck Tstat in the winter = no heat!

 

It look like all things being equal the 160* runs at highway speeds around 15* cooler than a 185*.

Correct me if I'm wrong, but I beleive the fans cut off after 35 MPH whatever the engine temp is. Reprograming the fans only helps at less than 35MPH.

 

From the Service Manual .....

The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).

The only time speed is a factor is when the fans are running in LOW speed to pull air through the A/C condensor.

 

Fans run when preset temp is acheived at any speed.

Thanks

 

That is true.

 

 

 

After reading through this and several other threads, it seems to me that a 170 thermostat would be a good compromise for us folks up north who drive the cars in cooler weather part of the year.

 

When I went looking at cooling my 1999 coupe down a bit, I did some reading. Probably a mistake - an engineer reading - but since I work on computer systems and not mechanical systems, it seemed a little education was in order. I'll try to recite this from memory - surely someone will correct my numerical mis-recollections.

The shop manual stated, somewhere, that the engine enters closed loop at 167* water temperature. Since you need closed loop to pass smog in the People's Republik of Kah-lee-fohr-nyah (phonetic Arnold...), it was important that the engine at least achieve 167*.

Next bit of reading indicated that the Hypertech 165* thermostat started opening at 165*, but wouldn't be fully open until somewhere close to 180*. Okay. I changed it out.

The fans are programmed cooler - can't recall just what they are set at, but 205 on, 190 off sounds right. My concern was for city driving. On a hot day in Los Angeles or the Bay Area, it wasn't uncommon to see 235 or so. I'm a geezer, so above 220 worries me a little.

With the 165* Hypertech stat and the fan settings as stated, the city temps dropped into the two-teens and low 220s. Don't remember seeing over about 220* on a 100*+ summer day. But just dropping the fan settings had already helped in that regard - summer range was 215-225 after setting the fans down.

So under normal driving, on the freeways, I usually see 180-190 on other than the hottest days, and in the high 190s to low 200s (about 205* max) on those days when the temps are over 100* and I'm on the open freeway here in the rural part of the state. Winter, it runs 178* or just over. In closed loop by over 10*, and close to the optimal 185* from an earlier post.

It's a compromise. Since daytime temps can swing by 80* or more over the course of the year, I have to go for my biggest concern - the hot days.

The remarks about the cooling system determining the actual temp is spot-on. It also explains the car running hotter on a 110* day than on a 35* day. I've really seen this with the old 428CJ in the Shelby. It's all I can do to keep it below 230* in the summer, even with a four row core (max from the factory in 1969 was a three row). A 160* stat has minimal effect - just takes longer to get to 230*.

Short version - I like my 165* stat. Can't prove any performance change, but I'm set enough in my ways to think that the 190* to 220* range is a better place for my engine to be than the 220* to 240* range. On average, with a stat that STARTS opening at 165*, I see probably 185* (accounting for the number of hot days vs. the number of cold days). The oil temp runs just under 200* on a gentle drive, and in the two-teens when moving a bit more briskly. Trans runs in the low 190s on flat land, and 200-220 under more spirited driving on in the mountains. My transmission shop doesn't like high trans temps, so we fought to get into the 200-220 range as a typical max.

As an aside, the thing that did most for the trans temps was not the cooler stat. I installed a 3/8" tunnel plate with ceramic coating, to keep my wife from complaining about the rather warm console on hot days, and it is positioned between the exhaust system and the cooler lines. Normally, the lines are perhaps 2-3" above the exhaust, and get the heat that is thrown off. The tunnel plate dropped the trans temps by about 10-15 degrees in the summer, depending on what I'm doing with the car.

Lots of good info in this thread, but it has been discussed a lot. Any mod is "garbage" to someone. Too many variables. I'm considering a 6-speed convertible as a replacement for my A4 coupe, and won't set it up the same. But if someone gives you a 165* stat, my opinion is that it isn't a bad thing.

Oh, regarding stuck thermostats in Chicago, I lived in Naperville some years back (western suburbs), and had the stat on my pickup stick open. Never got over about 70-80* engine temperature, and no heat/defrost until I changed it. Being from Los Angeles originally, this was novel. But it was dead of winter, didn't get out of the teens that week. Man, was that cold!

Happy New Year, everyone! This forum is such a kick, and source of good information - I can't help but wish everyone a great year!

 

I think a new kind of thermostat is in order. Assuming a cooling system capable of perfect cooling capacity, the thermostat should stay closed to something like stock temps so that OIL temps can be allowed to rise quickly to 210 degrees. Once that happens, the thermostat should open and remain open BELOW it's opening point and not close again until, let's say 140 degrees.

A thermostat that works like the fans, but at high ON (open) temp and a very low OFF (close) temp. Any electrically controlled "thermostats" out there? Something that can get the coolant (and thus oil) up to temp quickly and then allow the coolant to cool way down....(but not the oil temp which should stay high based on usage).

edit: of course the ECU should be tuned for this, etc.