I just installed a 160 degree thermostat in my 91 formula 5.7L. It seems to work fine but the guy at the auto parts store said that stock for that car is 194 degree. This is a pretty big difference. What, if any is the downside for installing 160 degrees?

I want to go fast but I dont want to significantly shorten the life of my engine.

 

may be too cold for a computer controlled engine. it will run richer because the computer is trying to get it to 190° but can't which will lead to worse mileage and carbon fouling. I would run a 180°, no lower.

 

Thats kind of what I was thinking. I guess the advantage of a lower thermostat is that the engine runs colder and will be better for racing. These thermostats are only 5 or 10 $ and relatively easy to put in. I could install a 180 degree now and keep the 160 deg just for the nights I was going to the drags. I wonder if it would be worth the extra hassle?

 

Your car will never go into closed loop again.

 

Sorry, I don't know what you mean. Please explain?

 

Better stick with the 180 degreet thermosat. It'll run much better. because with the 160 you will have too many problems especially if you daily drive it. If you want you should check out the old posts to see about this. Later man.

 

i dont know fuel injection all that well so someone else can elaborate on this. when the engine is warming, the computer is in open loop which means it does not take into account every reading from every sensor to adjust fuel/air ratio which is not very efficient but it gets the engine warmer quicker. once the set temp is met, the computer goes into closed loop and begins taking readings from all sensors to get you a 14.7:1 air/fuel ratio.

 

160 will work fine. Don't worry about going into "closed loop." Your car still will. You only have to have coolant temp above 70*F and the O2 sensor in it's heat range (which has nothing to do with the thermostat). Closed loop is where the ECM uses the readings from the O2 sensor to trim the fuel curve for ideal A/F mix.

Anywho.... I used to run 160s in my TPI cars to help keep underhood temps down. The TPI has a LOT of big, long, metal intake parts that can transfer heat into the incoming air, costing you power. I also used to bypass the TB coolant lines and relocate the MAT (Manifold Air Temp) sensor over into the filter box. These three mods together would make the engine's power far more consistent as the engine heated up.

In theory, running cool costs you power since you spend a larger portion of the energy released in combustion heating up the relatively cooler engine around it. It's thermal efficiency, I beleive it's called, goes down slightly. But reality is that keeping the intake cooler and the incoming air nice and dense seems to have a much greater effect on power.

Downside was that the heater was kinda weak on cold winter days. In theory, running that cool can cause the oil to tend to sludge-up on you more quickly, but I never experienced a problem and always changed it every 3K anyway.

 

I have had a 160 in my L98 for a year and a half now and haven't fouled any plugs yet,but it does run rich.Up here beyond the Chedder curtain my car runs between 155 and 160 on the highway and rarely runs above 190 sitting still when it's hot out.

 

After doing a search and reading everything I could about 160 degree vs 180 deg stats on this website I have decided to install a 180 degree one. I will probably drive around with the 160 deg until the weekend just since its already in and I would like to see how it runs though. Just seems like there is really no advantage to stick with the 160 degree, while theres some disadvantage (mainly fuel economy). Thanks for the responses.

 

Even though you have decided on a 180* stat, I'd just like to say I've had my 160* stat in my car for two years now and I have had no problems. My car runs noticebly better at 160* then at 190 and above temperatures. No, I have no problems going into closed loop and my gas milage is unchanged. For the price, one of the best things I've ever done.

Chris

 

160 wont hurt a thing. have had one in for almost 2 years..summer and winter..never a problem

 

i use a 160 in everything i've owned the last few years and the only problems i've ran into are not enough heat when it's below 0 out (not much of a problem really), and moisture in the oil when using an oil cooling and running it in the winter time. i've done alot of testing with it and found closed loop will come in along with most of the major computer functions (the essentials) working just fine. my LG4 ran a best of 30mpg, my LB9 ran a best of 28mpg, and my LT1 28 mpg best. these were just my camaro's i've ran with it. there is more to just installing it or it won't do it's proper job. with the lower temp thermostat you'll find it running richer than normal if you don't move the timing advance up a couple to few degree's. on a dyno the 160 has shown to be the best because it keeps the air intake temperature down as well as oil temperatures if you run an oil cooler. fuel temperature will also stay lower at the fuel rail, but these numbers are only better i've found when the ambient temperature is 50 F and over otherwise the 180 to 195 will be way higher producing power. unfortunatly not all of the features of the prom will come into effect, but your major functions will work and that's what's important. there's alot to chosing a t-stat, but chose based on what you think will work good, and maybe do some testing. as vader would probably agree, without testing you can't learn which is why he agree's cooler thermostat is better, but he preferr's the 180 for the extra functions it allow's the ecm to perform. both work great and the power difference is minimal so it's up to you of course.

 

160 SUCKS in the winter....i had one, Swapped that out for a 180, Much betta, still 195 is the best for heat.....If next years winter proves to ICE again I will swap back in the 195 for the winter.

 

Well now Ive got doubt again, lol. It stays pretty warm here in Houston for most of the year, and yes 91 formy does have and external oil cooler. I drove a little last night with the 160 deg in there and I definetley noticed lower temperatures on the temp gauge. I dont know how to read the stupid gauge I guess. There are 10 equal divisions between 100 and 220. does that mean each line is 12 degrees? It was running on about 4 to 5 lines over 100, so that would be 148 to 160 deg I guess. Anyway it seemed a little sluggish at first (possible AF mixture too rich) but when I jumped on it a little I got significant tire barking with a shift into second, which I usually get, but his was a little louder. I really didn't drive it enough to tell. Im need to take her out for a drive this weekend, then decide. Fortunately these stats are pretty cheap. I hope Idon't have the same problem deciding on an exaust system.

 

Man I wish they made a dual purpose stat for all-weather conditions that would be way cool wouldn't have to worry about which temp thermo to use jsut toggle a swithc and wala! Just wanted to put my 2 cents in> I guess it depends on where you live too some places are very hot in the summer and very cold in the winter. And some places like me (cali) pretty much stay average all year round. Oh well just wanted to put my 2cents in. Later man. I think TPIS sells a 170 stat also. You can try that and see how well it works also.

 

Less heat=longer engine life

 

i agree with you oray, but not a dual purpose. with this being the year 2002, why can't they make an electronic thermostat to control the flow amount and a way to adjust when it opens? i'm suprised it hasn't been produced yet, but it's the one thing i feel cars need engineered for them.

 

Must be nice to get that kind of gas mileage.
With my 160 I was getting 14mpg. my foot's not that heavy.
I'm currently on a mileage run with the 195. Trying to figure out why my mileage is so poor.

 

This couldn't be further from the truth. Our engines were designed around the 195' thermostat. By running cooler, you are in effect running looser bearing tolerances and looser piston fit by running things cooler. Why do you think you're not supposed to drive hard on an engine when it's cold. Well by running a cooler stat, you are in effct doing the same thing just on a smaller scale.

 

Less temp doesn't equal longer engine life--unless you are overheating. If you are runing electric fans with the stock temp switch or a mechanical fan clutch you will still run the same temp around town. If you don't have enough air flowing through the radiator to cool the engine, it will heat up until the fan kicks in--regardless of the thermostat used

 

First and foremost decide what kind of driving you are going to do. If is strictly high speed highway, I would use a 170, or 180 stat. If you do general driving in minor stop and go the 160 will be fine and the car will be in closed loop. The AVERAGE temp that the motor will run at will be higher than 160 anyway. Also the block learn ability of the ECM will relearn fuel delivery parameters to some degree. Remember that the fans will not kick on until a much higher temp. The only drawback is that heater operation will be marginal at best. If you want to check for closed loop install ALDL jumper into test position while engine has warmed to where it would normally run in your type of driving. OPEN loop will cause the MIL lamp to flash 2 times a second, CLOSED loop it will blink at a one second rate. This is the field service mode . I guarantee that you will go to closed loop as soon as that temp guage is about a needle width off the stop. DO NOT put in the jumper before you start the engine-IMPORTANT. I have tried the 160 and wanted a little more heat here in Pennsy. A better setup is to use a 180 stat and use a lower temp aux fan sensor. You can get one from JET for about 45 bucks. Mine turns on the fans at 205, off at 185. I believe that a more consistent temp is better for the engine overall. Danno, 89IROC, 5.7

 

Go and read the Tech Article on the Home Page......Electric Cooling Fans & Mods... Good Article, and it will answer your question....after that..... you decide.

 

another small advantage to PROM burning is you can set your fan turn on temps in the chip. So you don't have to buy a fan switch, or deal with getting to it, which is usually worse than spark plugs.

 

originally posted by Ed
This couldn't be further from the truth. Our engines were designed around the 195' thermostat. By running cooler, you are in effect running looser bearing tolerances and looser piston fit by running things cooler. Why do you think you're not supposed to drive hard on an engine when it's cold. Well by running a cooler stat, you are in effct doing the same thing just on a smaller scale.



I can't believe what I'm hearing!
First off you are contradicting yourself by saying you should run a 195 degree stat,but also saying you should burn a chip to turn the fans on earlier to cool the temperature down.

Friction=heat=wear,Less friction=less heat=less wear,show me I'm wrong!

 

First these are my opinions not meaning to contradict or argue with anyone. Our cars weren't designed around the 195° thermostat... they were designed to operate at 195° "normal operating temp". (Actually 100°C @ 1000 RPM... which equals 194°F).

This would be great and acceptable BUT the 195° stat won't keep our operations in that range and neither will our cooling fans considering a single fan in the mid 80's kicks in at 234°. The 195° stat was GM's shoddy and inexpensive attempt to reduce emissions...... to heck with engine wear. As a matter of fact a little premature engine wear would be great for GM service departments.

A cold engine will damage parts... a hot engine will damage parts. A cooler running engine will produce a bit more power, or the illusion of it because of fuel enrichment and air density, a warmer engine will be more consistent. Our engines work best at or around "normal op temp".

The entire reason for dropping stat and fan temps is to KEEP them in normal op temp range instead of them shooting off the end of the scale as they do.

Most of us can agree the 195 stat is too hot unless you live on the North Pole or South Pole so this is where the debate begins. IMHO your stat choice should be made purely based on your CLIMATE and COMFORT. Your comfort and your engines comfort.

The reason we get so many opinions is because we all live in different climates with different situations. So be it. GM chose the 195 as a "one size fits all" and it just doesn't.

We all tend to think our stats "control" our engines and it's the other way around. Our engines control our stats and our stats affect our engine operating temperature range.

Consider the temp rating on a stat is the opening temp. It isn't fully open until app. 20° higher than the rating and the opening temp is also +/- 3° margin of error.

Choose the stat that will keep your feet warm in the winter and your engine as close to "normal operating temp" the majority of the time.

 

This is an easy one.

Look. As the engine warms up, the metal expands. This closes up the piston to bore and bearing tolerances. You know how when you build an engine you measure things like bore, ring gap, bearings, etc. Well those specs are all based around the intended use of the engine. For example, a nitrous or SC motor usually runs a larger ring gap to accomadate the additional heat form the extreme combustion. Or also why forged piston motors don't make good drivers because the pistons have a higher thermal expansion constant, thus on a cold start the pistons are looser in the bore than a cast piston motor. This is undesireable because all that moving around is what causes wear. And also allows more blow by since they are not fitting the bore. Blow by not only costs power / efficiency but also contaminates the oil w/ combustion by-products / fuel.

Your fundamental flaw is thinking that the higher engine temps are causing more friction. That couldn't be further form the truth. As i stated in the forged vs. cast piston debate above, it's extra movement in the bore / bearing that causes wear. The pistons and crank / rods, etc don't have any friction or metal to metal contact. They ride on a film of oil, CONSTANTLY. Now if the bearing tolerance isn't right, the oil won't be able to maintain the film thickness, and contact can occur. That causes immediate severe wear, and will only keep getting worse fast. Why do you think once you hear a rod / crank knock you're not too far from loosing the motor. Once the rod is moving far enough to knock, the oil film gets squished out everytime it hits. Thats also why race motors run heavy epxensive oils. It's all blueprinted down to the oil temps the car is going to run so they know how well the oil can support the gap.

Instead of just spouting 8th grade physical science concepts like friction makes heat , why don't YOU try to prove ME wrong, maybe with some applied examples and demonstrated knowledge of the concept of an engine as a system.

 

Correct me if I am wrong. Has anyone measured OIL temp with the different stats. Seems to me that would be the REAL test. The temp of the coolant is not respective of actual block temp. My 89 IROC varies so much that I am not sure :lala: I really do not think that stat temp really matters all that much. What I feel is really important is stability(consistent temp). Maybe I will try to measure oil temp. ANOTHER project. Danno

 

What about a 170??? Wouldnt that be best of both worlds?? Good heat in winter and still stays cool in summer.

 

my 160 SUCKED(was in the car when I got it) NO HEAT
had a 195 in the black car, that had heat, put a 180 in the convert, that heat is OK.....170 would half *** suck. ESP on cold days

 

GM sells a 170 thermostat too...

Personally, I think the "our cars were designed to run...." arguement is a line of BS. Just because GM put a 195 in our cars from the factory doesn't mean it's right. GM has done lots of things that were later found out to be not quite right.

I do agree that running a 160 degree thermostat on a new engine is bad because you're not giving the engine adequate temperature to properly seal your rings. However, I think on higher mileage engines, a cooler thermostat is better because less heat does in fact equate to less wear. Perfect example along the same lines would be when I was running my 305 with over 200,000 ... I used R45TS plugs (hotter plugs) and I was constantly burning oil out the exhaust. I switched back to R43TS (cooler plugs) and it quit burning oil.

Also, some chips require a 160 thermostat due to timing figures programmed into the chip. Hotter temperature are a perfect condition for knock and the colder thermostats lower temps and reduce the condition for knock, preventing knock especially at higher RPMs.

I also agree with Danno in that it would be more oil temp rather than coolant temp that will have the most effect on the piston rings ... but on a new engine, cooland temp has an effect as well but not so much on a higher mileage engine. It all has to do with current wear on the engine based on the age and mileage of the engine.

 

.[QUOTE]Instead of just spouting 8th grade physical science concepts like friction makes heat , why don't YOU try to prove ME wrong, maybe with some applied examples and demonstrated knowledge of the concept of an engine as a system.


Gee Ed,that really hurt!
I agree with what your saying,but doesn't more heat=more expansion?And if that is true,then how far can a bearing expand before it starts to wear?

 

 

WOW! You can just smell the love in here . To answer your original question, I have run a 160* in my car for the past two years in Utah without a problem. I also have performed the TB bypass. It gets pretty cold here in the winter and the heater doesn't work nearly as well when the temps dip into the teens. Aside from that, I'll stick with my 160* and remote fan switch. That set-up keep her cool at the track. Go with the 160*.

Lates,
JD

 

Nobody is saying that you can't run a 160 thermostat. In fact, to the average person you'd never know the difference. Of course his question was are there any adverse effects, of which there are MANY.

The inverse, are there any positive effects, is no, there aren't really. Any performance 'gains' could be had just as easily (and more correctly) through proper tuning. As for not overheating, that's simply a function of the health of the cooling system and proper operation of the fans. If you are having temperature control problems, look into things like improper water to antifreeze ration, loose hose clamps, blocked radiator (internally or externally), BAD RADIATOR CAP (#1 culprit that everybody overlooks), dead water pump, etc. A 160 stat alone isn't going to do much if anything for an overheating problem.

 

Someone had recently theorized the following....having a 190* or 180* stat opposed to a 160 may actually help cooling.

If the stat opens at 160, it will probably always stay open. Hence, the coolant doesn't get to cool down for very long inside of the radiator.

With a 180* (or 195* as in my 83 Bronco) the 'stat closes more frequently and the coolant sets in the radiatior....cooling down!

And you know what, it's helped my over all temperature stay lower in my Bronco. The camaro is next!

I had a 160* stat in my Bronco and it was consistently running 210 in traffic!!! Now I very rarely get much more than 200* and it's usually around 185 to 195!!

 

Way back to the top of this thread: Larry, being in Katy, Texas your thermostat solution is easy. Drop in a 180, see if your car runs in a comfortable heat zone. If it's still too high spend five more bucks and sport for a 170. Your dilema will be solved.

Otherwise I see two trains of thought going on here. Dropping the stat for performance sake and dropping it for overheating problems. For performance you might as well chalk it up right next to a TB airfoil......... ain't gonna' happen. Or I should say there are better ways to make more noticable gains without the risk.

For overheating: Ed I agree with you under "normal" and "average" conditions and situations however some of us exist in abnormal or adverse conditions. You can take a perfectly tuned, properly set up car and boil it over say in Phoenix, AZ. I no longer live in this extreme condition but I did have to deal with it. A 160 is almost a necessity just to get by. I would venture to say a 160 in Phoenix is like a 180 anywhere else. And your coolant temps will well exceed 225 not even counting trying to use your A/C.

What I experienced was, for lack of any other description, a temperature rise phenomenon whereas once your temperature started to rise and got momentum nothing you do or your cooling fans do is going to stop it from going off the end of the scale. What I also noticed is that by dropping the stat this rise took longer and was not as severe. It can and did make the difference of whether you were pulled over on the side of the interstate with steam coming out.

Engine heat is one thing and it is good (my opinion) engine overheat is another and that is not good. Your stat has to be matched to your environment.

 

Ok I have had all the thermostats. The 180 is the best all around. I have read in a camaro high perderamce manual that if you have emissions then run a 180 or higher or you will the emissions system. Also the 160 on a daily driver is really overkill on a stock engine. Also if you have a electric fan then it really dosent do much cehck the tech articals. Just to let you know, you wont really gain that much power from either.

 

I've run a 160* thermostat in both my cars, and I'm not fond of them. I thought I would need them here in Florida with the heat and humidity, but the truth is, if your cooling system is operating properly, heat shouldn't be a problem. I've been running a 160* stat with 85% distilled water/15% anti-freeze and a bottle of Water Wetter. I can't get the cars to run over 160* here in Florida, and they feel sluggish. These engines don't really wake up until 180*-185*. I'm getting rid of them and going to 180* stats. If you're overheating, I'd look for another culprit.

My $0.02

 

Ok genius, explain why in my engine the hot plug fouls easier and the cold plug stays cleaner in more fouling conditions?

You've been asking for this "applied examples and demonstrated knowledge". Well, there it is ... and yes, now you're going to try spouting off some other line of BS of something you've "read" or "heard" to try and back up your statement but don't waste your time.

I think you should take your own advice and try some "applied examples and demonstrated knowledge" instead of spouting off what you've read or heard somewhere.

Simple fact of the matter is more heat=quicker breakdown of oil=greater possibility of metal to metal contact.

 

Just go right on telling yourself that if it makes you feel better and justifies (in your mind) switching to a 180* tstat.

 

Hmmm.... this thread is about to make the Israeli/Palestinian conflict look MINOR.............so I just throw in one more pointless comment before all hell breaks loose.

No disrespect 86TPI but I think Scram is right. They wake up about 180/185 because they are approaching normal operating temp 194°

Let's try this another way. Put in whichever dang stat it takes to keep your engine at 194° as much of the time as possible.

Now I'm sure that will be the last word.............. right...........LOL.

C'mon lets talk VW's

 

Wow, this question sure generated a lot of comments. I have read all of them and learned some stuff. I put the 180 back in instead of the 160. After all the comments I thought this would be the best. The car is running great and I cant wait to put on an exhaust system. Maybe that will generate another good conversation.

Later Larry

 

I have the 180deg in my car, and I love it. greatfor highway and in town.

 

*Ed rant mode on*

Ok.

First mistake, assuming that GM actually designed the engine tolerances for 195 degrees. The clearance specs havent changed over the years, but the intended operating temps have. In fact the 195 doesnt even apply to electric fan cars, they dont turn on the fan in traffic until after 220 degrees. Like Mike said, it was 100% emissions reduction related. Hot isnt necessarily good. I forget the 'ideal' oil temperature, but 160 is too cold. I think its around 200 or 210 is ideal. Thats too hot for tranny fluid though. The operating temp of both my TA's (240-220 depending on fan on-fan off conditions) is really too hot for the oil too. GM was just off their rocker IMO. Tranny fluid would work better at 160-170. Generally the engine will make more power at less than the oil temp, 180-190 is probably closer to ideal. So now you have a complete mix+match of temperatures. What to do? Well, how about sticking with what just about everyone has been doing for more years than I can count and run a 180 stat and make your engine run close to that temp wise?

Second mistake, oil at high temperatures is thinner and if its too high wont leave the proper film on the parts and will cause excessive wear. So really, at 160 the oil isnt at an ideal temp but its taking care of any excess clearances you think are there from the lower temperature. I'd rather have it a little colder than a little hotter.

"The pistons and crank / rods, etc don't have any friction or metal to metal contact. They ride on a film of oil, CONSTANTLY."

This is really funny Ed. I guess thats why engines never wear out? Pistons get scuff marks almost immediately after firing it up, I dont care how much oil you put in the cylinder, how much you prime the setup and how recently they were coated with any sort of break in lube, they are gonna make contact and get wear. Thats why theres clearance between the head and piston, for the flip-flop at the top when the piston swaps from rubbing on the right side to rubbing on the left, or vice-versa depending on how you look at it. Theres tons of friction going on in there. The crank and rods have all sorts of friction going on too, I've seen way too many nuts messing with needle roller bearings in the crank/rod and cam area to reduce friction. Metal-metal contact is inevitable, the oil is there to minimize the heat and hence wear.

*Ed rant mode off*

In all seriousness, a 160 stat isnt going to hurt much. My car spent the better part of its life on synthetic and a 160 stat, and when I had the heads off to mess with them, the cross-hatching was very evident and all the way up the cylinder with almost no wear at all. That was at 100k miles. It also went into closed loop just fine, and even the EGR works but doesnt go to 100% instead it runs around 70% but I dont care. Theres some minor issues of things that are set in the ECM to work at higher than 160, but really you shouldnt worry about it too much. Gas mileage will suffer slightly, but the car might be faster. It might be slower too, kinda depends on how its tuned. Ideally, a 180 would probably be the best choice for most cars and most people. Theres of course some exceptions like living where the temps are normally 120 degrees outside to begin with, or maybe normally -20, thats something you have to decide on. I'd guess where you are 180 is your best bet compromise from most standpoints.

 

One thing that I think may have been overlooked is that how much does coolant temp reflect the actual operating temp of the block. This is where I think an oil temp guage would be useful when trying different stats. Once combustion occurs is the cylinder wall temp actually reflective of the coolant temp. Obviously there is some relationship, but how much. I would be willing to bet that the actual internal engine temp probably would not vary more than a few degrees with a 160 or 195 stat. The coolant temp can be pulled down pretty fast by the action of the radiator, but is it really reflective of internal engine temp? I ran a 160 for a couple of months and found that my fuel economy did drop noticeably, on the order of about 10%. In my humble opinion I think that trying to maintain a fairly constant temp is probably more important than whether it is 170 or 180. I run a 180 now and with the heater off the average operating temp is pretty close to what was indicated by the guage with 195. The only time I see it stay a little lower is when I get a chance to cruise on the highway. So much for my 2 cents. Danno

 

Well, I've run them both, and I can tell you that in both the Z28 with a 420 HP 383 in it, and the Vette with the L82 in it, they both feel sleepy and sluggish with the 160* in them while the coolant temp can't get over 160*. But being that you are so clearly more qualified than anyone else in the whole wide world to determine the proper Tstat for my car, I'll just go pull my Tstats out and follow your advice. And maybe you should give the engineers at GM a call, they apparently need your help because they are just too stupid.:hail: Maybe you should check your cooling system and fix what's wrong with it instead of your Bubba fix of shoving a lower tstat in it.

PS, you can shove your flags up your...and I don't need to "justify" anything. I have no need of your approval.

 

I have no idea. Maybe you were doing more short trip driving when you had the hotter plugs in. I assure you that your understanding of spark plug heat range is so flawed that i won't even argue with you on this one. Everyone in this thread w/ a brain knows how spark plug heat ranges work, i am done arguing with people who don't know what they are talking about. I don't have time to explain how engines work anymore.

 

One nice thing about the whole Tstat debate is that they are easy to change!

If anybody feels that a 160* would work better for them, spend 10 minutes and swap it out. Use it for the duration of an oil change or something and see how it does.

Much of this is trial and error anyhow, especially when you're mixing and matching parts and such. I mean with cooling you've got to consider many things like terrain, ambient temperature, driving styles, elevation, any modifications done to the car, condition of the engine and so on.

I've had a perfect cooling system before but a lemon of an engine that would always overheat---no matter what.

The most important thing is to not get so involved with your opinions that you're more worried about being right than getting it right.

Ignorance is bliss and I'm pretty damn happy!:lala:

 

Thank you madmax.

I guess I can cancel my appointment with Frasier now.I really thought I was losing my mind!!!!!!!!!!!!




Graduating to the 9th grade!!!!!