I see the majority run the stock 186 stat , but does that change if I am running an iron block? I would think a lower stat would be needed since it retains more heat. Yes no? Should I stick with the 186 stat ?

 

a thermostat will lower starting temp. i dont think that will make a huge different.

 

With an iron block, I would use a 160 degree stat'.

This is my personal opinion, but I wouldn't run anything lower than a 180 degree stat' on an aluminum block, as I've read they make a bit more power at warmer temps.

 

Don't know here ya heard that. 160* on my LS1 and it loves it. Just because the Tstat is rated at 160* doesn't mean thats where it runs. Right about 180* here which is about perfect for me.

 

http://www.hardcorels1.com/vbulletin...read.php?t=375

https://ls1tech.com/forums/generatio...hermostat.html (post #10 is very informative)

From Chevytalk.com

"In EVERY aluminum head engine I have ever had, temperature is critical to getting them to work. I set cast iron engines to 180 deg/F, and, aluminum head engines to 192/195 deg/F. Anything cooler with the aluminum heads, power/performance suffers significantly."

Just because your car seems to run "fine", doesn't mean that setup is ideal.

 

Thanks for the link. I've argued with people for quite a while concerning coolant temps that are too low.

 

I'm sorry, that's a load of ****. You can think what your want I truly don't care. Seems to run fine? The car is a heads, cam, intake car. While street and dyno tuning we were able to make quite a bit more power without knock by swapping the tstat out and lowering the fan turn on speed. Also when doing pulls that start at 195*/200* coolent temps the where ending closer to 225*, no thanks. I'm not just listening to internet bullshit here guy.

 

I’m gonna add my $0.02 because I’ve done the swap.

My car (when it had the 2.73 rear) achieved 30 MPG on a nice long highway drive. I figured it was a rarity as I get 22-26 average around town.

Then I did the swap to a 160 degree thermostat and had the fans set to come on at 160 degrees. They certainly do run a lot more now (I’m glad I did the truck alternator upgrade). Using a TechII, I see my real running engine temperature runs 180 to 185 which I like.

The car runs better. It’s smoother and seems to react quicker. It’s driveability has certainly improved. I’m glad I did the change, I would do it again in a heartbeat and would recommend it to others. Before the swap, there had been some instances of knock. Afterwards, knock is a rarity.

On the highway, it now managed to achieve 28 MPG. I don’t know if this is because of the lower temperature or my lead foot.

As far as "boiling out the water from the oil" or anything else like that, I think my oil is pretty good. I’d think that if I had water in my oil, my thermostat and fan on temperatures would be the least of my problems.

My milage has taken another hit with the new 3.42 gears I have but WOW what a difference in performance! After all, we wouldn’t have these cars if we were concerned about fuel economy. My Monte hit a whopping 8 MPG or something. And my long gone 5.0 GMC Savana managed an astonishing 11 MPG.