thermostat

[dskopek]

This whole thread can start as many questions as it can answer!! Most motors will make peak hosepower with a cool engine (160-180 deg F) and hot oil (210-225 deg F) This is seen all the time in dyno tests where the temps are more controlled then in a car. When you get to a street driven car I have to agree that you need to run about 180 deg water temp for everyday use and don't run a high flow thermostat. What you will find is again in most motors is the water flow is aready as fast as you want it to go and still get thermal transfer from the engine block to the water. If you move the water too fast the water temp will be lower coming out of the motor but the block temp and head temps will be up and so will the oil temp.

[95SleeperAcheiva]

Years back I ran a '92 Z-34 and if she was around 135deg coolant temp she was faster. This was on track temps of 95-110F. I tried a stock t-stat, then upgraded to a 180, she went faster. As I would experiment and let her sit and cool She ran faster yet. I modified a mustang stat of 110 deg and ran faster yet. I don't think it was too much to do with actual block/coolant temp as it did in allowing the intake or maybe motor in general to heat up and super heat the incoming air, and making it less dense. I watched my data records and noted a drop in engine temps along with the drop in ambient air temps, ya, denser air=more power. I confirmed this when I ran an air/water intercooler pumping ice water through it on natural aspiration engine and cut .7-1 full sec off my time! Remember this was USVI drag strip in the summer right on the ocean. So maybe in a street application you won't gain power untuned, but for single passes, it keeps the air cooler.

[reborngarcia]

OK i am going to add to this i live in Florida and it gets hot and sticky here. last time i was at the track at night i was still running over the 200 mark when i was staging after seating for a good 30 mins. my 2 cents is what if you run no t-stat in the car. it will still get up to temp??? and is it really that big of a deal if i do this? or can i run just water in the whole system with some water wetter.

[robertisaar]

no stat can still get up to 250*F, it just takes longer to get to the rated stat temps, but once it's there, it's more or less the same. and when there is airflow(either by some strong fans or lots of wind whipping through the radiator as you're driving, the temp won't be regulated at all, your coolant temp will be dependant on the amount of HP(and therefore heat) your engine is producing at the time and the amount of airflow going through the radiator.

[prophiseer]

Sorry to drag it up - but choosing a thermostat should really been a per application deal - unless you're dealing with an OEM motor. Reason being, everyone drives differently . . . as well, not everyone lives in the same climate . . .

Personally - I'm running a 175 for a few reasons. One, the collector on the front header sits less than 0.25" from the thermostat housing. There's an air gap, but it aint much . . . I was concerned with the coolant temps in this one specific area, especially if the motor is idling for long periods of time. Two; I live in a climate where our summers are absolutlely ridiculous between the ambient heat and the humidity, even with a stock motor, I was fighting to maintain temps I was happy with (I prefer the system to average 200F), and even more tired of the PCM constantly cycling the fans every couple of seconds. Three, our traffic lights here were designed by morons. It's not unusual to sit at one light for 3-5min, finally get the green, and the next light a few hundred yars ahead just turned yellow . . . get to the next light and wait another 3-5min. Unless you hit the highway or backroads, it's hard to get enough moving distance to let natural airflow cool things down.

Anyhow, my current setup tends to operate between 200F-210F (based on PCM's data) . . . she only pulls down cooler if I get it going for long stretches on the highway or the backroads. I haven't noticed any issues with oil contaimination, nor any reduction in fuel efficiency (through extended periods of highway driving) . . . hell, if nothing else, I average 34mpg on the highway as it is

But - such are my circustances for my situation . . . individual results may vary

[carbon]

Just have to throw it in because I haven't seen it yet reading through this thread...

FACT: A thermostat sets the lowest temp the engine will operate at after warm up, it has no effect on the maximum temperature. You cannot correct an over heating issue with a cooler thermostat. Only fans and/or a larger capacity cooling system can control high temps.

[geoffinbc]

Thats is very true.

[TechRod]

LOL


Couldn't miss the opportunity

[Daguse5853Z]

higher engine temps reduce emissions. this is a well documented fact. engines run better around 180 then they do 195 (performance wise). 120 is way too cold for anything. there is a upper and lower extreme to the spectrum. 195+ being the upper for emissions and 120 being the way low end for performance (using 120 as a example bc i saw it earlier in the thread). the reason 180* thermostats arent listed for newer cars is bc it's illegal for emissions. If you have a parts guy that knows his shit he can just cross over the demensions of your t-stat and find a good replacement IF he doesnt know his engine history. I would not worry at all about putting a 180* t-stat in my car. Put a 180* t-stat in, tune for it and enjoy the benefits.

[Daguse5853Z]

moisture in the crankcase isn't under pressure at certain stages through the oiling system.

So letting a car reach 212* will vaporize crankcase moisture, I never thought about it but it makes a lot of sense. So the fans should not turn on until 225*?

by the time the coolant reaches 180 or 195* you would think that the substance the coolant is taking heat away from would be well over the vapor point of water or condensation (the engine block is hotter then the coolant). Thats like saying the boiling water is just as hot as the flame that heats the pot. We all know that our stoves gets ALOT hotter then the water that it's boiling.