Benefits & Disadvantages of various temp thermostats on engine performance

I'm going to try to define the question well enough that it fits the "high-end" discussion parameters for this forum.

Last week I failed emissions testing, my hydrocarbons were twice the allowable limit of 220. I think I have it were it will pass now thanks to some idle timing adjustments and putting the stock thermostat back in.

But that's not my main point....this whole thing got me thinking about ideal engine operating temperatures and what you give up at each temperature.

So what are the ideal temperatures you want to see in an engine? LT1's are reverse cooled of course, so the heads see the coolant first and are thus cooler with the 180 stat than a typical Gen I with a stock 195er.

So then, a 160 stat in an LT1 would put those temperatures even lower. Any adverse effects on oil temperatures?

A hotter combustion chamber produces a more complete burn, right? (to a point, of course, too hot produces preignition). Yet a hotter overall operating temperature increases heat soak and increases air intake temps, reducing the total HP potential of the intake charge. A cooler chamber can tolerate more timing advance, but if the burn is incomplete, is there any advantage? Is there any justification for splitting the difference, say, 170?

I'd like to see some in depth disscussion here. What's preferrable, what produces more power, what produces better longevity, etc. etc.?

------------------
1996 Trans Am WS6, A4, GTP Stage I heads, CC 304 cam (210/220 .500/.510 114LS), Comp 1.6 ratio Pro Magnum roller rockers, FLP long-tube headers, Flowtech cutout, Dynomax Ultraflow muffler PN# 17227, BMR rubber/poly tubular LCAs, Lakewood adj. PHR, LT1 Edit for OBDII, LT4KM, 52mm TB.
Member of MTFBA (Middle Tennessee F-Body Association) (http://www.mtfba.com)
10/27/01: 13.22@106 w/2.1 60ft and lots of KR.

I'm pretty curious on that subject myself...which is part of the reason I haven't gotten a lower temp one.

ttt

<font face="Verdana, Arial" size="2">Originally posted by Chris 96 WS6:
I'm going to try to define the question well enough that it fits the "high-end" discussion parameters for this forum.

Last week I failed emissions testing, my hydrocarbons were twice the allowable limit of 220. I think I have it were it will pass now thanks to some idle timing adjustments and putting the stock thermostat back in.

But that's not my main point....this whole thing got me thinking about ideal engine operating temperatures and what you give up at each temperature.

So what are the ideal temperatures you want to see in an engine? LT1's are reverse cooled of course, so the heads see the coolant first and are thus cooler with the 180 stat than a typical Gen I with a stock 195er.

So then, a 160 stat in an LT1 would put those temperatures even lower. Any adverse effects on oil temperatures?

A hotter combustion chamber produces a more complete burn, right? (to a point, of course, too hot produces preignition). Yet a hotter overall operating temperature increases heat soak and increases air intake temps, reducing the total HP potential of the intake charge. A cooler chamber can tolerate more timing advance, but if the burn is incomplete, is there any advantage? Is there any justification for splitting the difference, say, 170?

I'd like to see some in depth disscussion here. What's preferrable, what produces more power, what produces better longevity, etc. etc.?

</font>

Chris, this is an excellent question. I'm doing my typical run through the forum as there are some threads I've neglected for lack of time. I'll answer this question sometime this week. I'd like to get some of my notes and show you some of the differences we've seen in many of our tests, so I'd like to put down some hard numbers. Alot of theory too. http://web.camaross.com/bb/smile.gif

Take care,
Chuck

That would be great Chuck! I've always wanted to see some hard numbers on the thermostat issue.

I know my car seems to run faster when its cooler but I'd also like to know why http://web.camaross.com/bb/smile.gif

------------------
Jason
93 TA, M6

The lower thermostat thing has always been a puzzle to me. I've heard too many differnt things about it. For one someone once told me that if you want your engine to run cooler you put a higher temp thermostat in it like if your car has a 180 stock you run a 190 and it will run cooler. That makes absoulutly no sense to me but the logic behind that was that since the thermostat won't open as soon the coolant in the radiator gets more time to cool thus doing a better job of lowering combustions temps. That seems logical to me, for some reason I can't agree with it, even though i've heard many people say it's true. To me it just makes more sense that if you had a colder thermostat like 170 instead of 180 that your thermostat would open sooner and recirculate quiker to keep a lower temp. I'm still not sure which one is correct yet. As far as you failing for hydrocarbons... The thermostat is really going to have more of an effect on nox, because nox forms at high temperatures. Hydrocarbons is the result of unburned gasoline, which could mean a few different things. Too rich mixtures too lean mixtures, bad catylitic converter, bad ignition system, etc etc. I wouldn't suspect engine operating temperature as an issue unless your normal coolant temp was never getting hot enough for your vehicle to go in close loop which would in turn make your car run rich, which may also make people believe that lower coolant temps make their car faster when in fact it's only because their car is running richer since it never reached close loop. I'm just trying to think of an explanation, not sure if this is true.

Thanks Chuck, look forward to reading your comments.

I've heard of the 160 not allowing the oil to get hot enough to boil out water, leading to bearing damage in the long term, but I think the guy swapped it back out before anything adverse happened. I don't think that's the norm, but its certainly something we've never heard a definitive answer on.

The ultimate goal would be to get the engine nice and hot but maintain a cold intake air charge. There is definitely a balance, and I remember watching NASCAR Winston Cup last year and Larry McReynolds commenting on the ideal temps they like to see for coolant and engine oil. Whatever those temps are (don't remember exactly what he said), would be the goals, and I wonder which temp thermo gets you closer to those values?

I like the LS1's approach... composite intake= cooler intake= more power.

If I could get my engine to run at about 195 degrees, yet keep the intake manifold cool, and the inlet air temperatures down, I'm in good shape.

Alas, the aftermarket hasn't jumped on this yet.

------------------
John
'71 Camaro
350, 4 bolt, 212/218@.050", Edelbrock RPM heads, 3.42 posi, blah blah blah

I wanted to bring this back to the top in the hopes that Chuck would post his comments.

<font face="Verdana, Arial" size="2">Originally posted by Chris 96 WS6:
I've heard of the 160 not allowing the oil to get hot enough to boil out water, leading to bearing damage in the long term, but I think the guy swapped it back out before anything adverse happened.</font>

hmmm... you have a point about the water not boiling out. since the water and oil don't combine, the water would retain its own vapor pressure (boiling point) separate from the oil.

If the water's from a coolant leak, I dont' think you'd be able to evaporate it out anyway... the coolant has already raised the boiling point beyond even stock thermostat temps. Besides, at that point you've got worse things to worry about. http://web.camaross.com/bb/smile.gif

If the water's from condensation inside the crank case and engine, yeah you may be able to validate that. But I'd be aweful curious to see the accumulation rate of moisture in a daily driven engine vs the oil-changing frequency.

Anyone have some numbers to post regarding % water content in oil they recently had analyzed? (say after 3000 miles or so)?

If you neglete oil changes, accumlation may be an issue, but again, you'd have worse things to worry about damaging your engine if you try to pull a Mobil 1 "reccomended" 15,000 mile oil change. http://web.camaross.com/bb/smile.gif

I'd bet the dirt and metal would kill you faster than the water contect.

BTW, this may be a good theoretical discussion, but my baby's been running a 160* stat for 30,000 miles (of 107,000 total) and still runs like a champ. I've seen the gains on my 70 mile commute each day, and wouldn't go back to stock unless Chuck SWORE it'll blow up my engine at 150,000. (the goal is to run this baby to 200,000 miles without a rebuild http://web.camaross.com/bb/wink.gif).

<font face="Verdana, Arial" size="2">Originally posted by Steve in Seattle:
hmmm... you have a point about the water not boiling out. since the water and oil don't combine, the water would retain its own vapor pressure (boiling point) separate from the oil.

If the water's from a coolant leak, I dont' think you'd be able to evaporate it out anyway... the coolant has already raised the boiling point beyond even stock thermostat temps. Besides, at that point you've got worse things to worry about. http://web.camaross.com/bb/smile.gif

If the water's from condensation inside the crank case and engine, yeah you may be able to validate that. But I'd be aweful curious to see the accumulation rate of moisture in a daily driven engine vs the oil-changing frequency.

Anyone have some numbers to post regarding % water content in oil they recently had analyzed? (say after 3000 miles or so)?

If you neglete oil changes, accumlation may be an issue, but again, you'd have worse things to worry about damaging your engine if you try to pull a Mobil 1 "reccomended" 15,000 mile oil change. http://web.camaross.com/bb/smile.gif

I'd bet the dirt and metal would kill you faster than the water contect.

BTW, this may be a good theoretical discussion, but my baby's been running a 160* stat for 30,000 miles (of 107,000 total) and still runs like a champ. I've seen the gains on my 70 mile commute each day, and wouldn't go back to stock unless Chuck SWORE it'll blow up my engine at 150,000. (the goal is to run this baby to 200,000 miles without a rebuild http://web.camaross.com/bb/wink.gif).</font>

Oil gets a lot hotter than the coolant.

Rich Krause

------------------
'95 Z-28 383 with Vortech, NX kit, etc.
"1FASTZ28"

The primary questions I'd like to see answered are these:

1) Does a 160 stat in an LT1 allow proper combustion chamber temps to be reached? e.g. there is such a thing as too cool a chamber.

2) Ideal oil temp is somewhere around 210-220, right? What is the 160's effect on this.

If I were running a 160 in a gen I small block my concerns would be somewhat different. Since the heads receive the coolant last in a traditional small block, I'd be less concerned about chamber temps and even more concerned about insufficient oil temps. I ran a 180 in my old '85 Camaro and thought it was more than sufficient...I don't think I'd run a 160 in a Gen I.

My understanding of the oil/coolant temp relationship is that oil is typically ~30*F higher than the coolant in the engine.

A 160*stat, running coolant at ~170*F would corrospond with engine oil being at ~200*F. (which is below the pure boiling point of water, not that it matters if you change your oil http://web.camaross.com/bb/smile.gif).

Considering the mutigrade oils avilable, I'm not so sure you'll see any difference between 15*F change. Especially since its only at cruising temps that anything's affected. stop and go driving has the engine temps get to the same level eventually (the 165 to 180 zone is the only difference).

<font face="Verdana, Arial" size="2">Originally posted by Mr. Horsepower:
Chris, this is an excellent question. I'm doing my typical run through the forum as there are some threads I've neglected for lack of time. I'll answer this question sometime this week. I'd like to get some of my notes and show you some of the differences we've seen in many of our tests, so I'd like to put down some hard numbers. Alot of theory too. http://web.camaross.com/bb/smile.gif

Take care,
Chuck



</font>

Chuck, can't wait. Then we can just post a link to this post under that huge discussion (argument? http://web.camaross.com/bb/wink.gif ) going on in LT1 tech. Thanks for lending the knowledge.

Still waiting eagerly for Chucks input http://web.camaross.com/bb/smile.gif

Here is the deal with engine temps. First of all, water will vaporize at any point above freezing. You don't have to have the water boil out of the oil, it will do it anyway. Your engine oil is formulated to take this into account and prevent the buildup of acids caused by oil-water contamination within its normal usage life. Afterall, how hot does the oil get in your lawnmower?

I don't think the moisture in the oil should be the biggest concern here.

The biggest concern sould be on cylinder wear. It has been proven time and time again that too cold of a thermostat will cause stock engine failure. This is due to the stock engine pistons and rings being designed to run with a 195 or 180 theromstat (depending on what came stock). Someone I knew put a 160 stat into his 94 Z and now wonders why he has serious blow-by just a year later. The damage comes from the piston's and cylinder wall's abaility to transfer heat and the difference between the two materials. If you put a 160 stat into a stock (lower ended) engine, you will scoar the cylinder walls. This happens because the pistons are not expanding to their "designed" size and this, in turn, puts more stress on the piston rings. You can rebuild your engine using better materials for the pistons and rings and run tighter clearances that will last longer under a 160 stat if you choose. It just depends on how much it is worth to you. I don't think the minute gains you get from using a 160 stat are worth it.

------------------
1987 Trans Am GTA WS6
5.7L SuperRam
4L60-E Trans
3.73 SRD

1987 Pontiac Fiero
3800 Series II SFI
4T60-E Trans
3.33 Final Drive

1988 Pontiac Grand Am
3300 MFI
4T60 Trans

1966 Plymouth Belvedere II
318 Semi-Hemi 2bbl
Torqueflite 727 Trans

http://dtcc.cz28.com

[This message has been edited by MadMax350 (edited February 12, 2002).]

I found a fascinating article from 1933 on just this subject. They were testing v-12 aircraft engines, but many of the same priciples as well as conclusions are applicable here.

Its perhaps more interesting as a historical reference than for anything practical to this disscussion.

http://naca.larc.nasa.gov/reports/1933/naca-tn-476/index.cgi?page0001.gif

i know on my 98 LS1 i get a water like sludge on the oil fill cap between oil changes. I was using Mobil 1, then went to Valvoline Synpower, then to regular Valvoline....I run a 170 T-stat and my guess is that its too cold and the oil does not get up the proper operating temps.

oil looks fine when I drain it, its just on the top end it is kinda sludgy water mixed oil. concerns me but the car runs fine still

First time to post in this room, but here goes...

In a pure physics world, you would want to have the heads and cylinder walls at their hottest. Combusion process is a change of state of the gas/air mixture. Some of that change of state is in the form of heat, the other, in the form of the mechanical energy. If less of the total energy goes to heat, more will go towards the mechanical. A lower head and wall temperature will absorb more heat and thus have less energy for the mechanical force.

That is why aluminum heads will make less power than cast iron. Whoa you said, that is not what all the experts say. Well, the reason aluminum heads make more power is because they can run higher compression and more ignition(because they run cooler and less detonation).

So in the real world, a cooler running engine will be able to run higher compression, and more ignition advance with lower octane gas. But... run the same engine at higher temp and with higher octane gas and it SHOULD make more power. But then you have the problem with intake air density getting lower due to the higher temp. It all a balancing act.

So the solution is to run hot as hell head and block, cool as ice intake, 110 octane gas, and as much ignition advance as the engine will take. I have always thought of casting an intake with cooling lines running around and use the A/C compressor to run the intake at supercool temps.

But to answer your question... I dont know the ideal temp. Surely someone has done some dyno work with these ideas put into practice.

My 2 cents... Ken

------------------
FOR SALE
96 Z28 6spd
Usual mods (thermo, SLP cold air, pulleys, airfoil, borla cat back, hypertech, SLP LW Flywheel, clutch, pressureplate)

13.4@104MPH

Pretty interesting.I know the busch north car that I used to work on would like to run best about 200-210 but they could be tough to keep their on a short track in traffic in the middle of the summer.But I recently saw a show with Warren Johnson,He likes his huge compression prostock Moters in the 140 range.I missed most of the show.I was flipping through the channels and that got my attention but I missed the theory behind it.

Best educated guess,Busch car low compression,needs the Higher temp for a complete burn compared to High compression of a prostock moter that makes plenty of combustion chamber heat.

As far as premature wear of cylinder wall sealing in an lt1 with a 160 stat.I dont know?Good theory but We have been puting hyper pistons in standerd small blocks for a while with the same stats and alot less compression (8.5-9 street moter).

I figure the factory engieneers set the lt1's up with emmissions in mind Thefore the defenetilly wanted decent combustion chamber temps.The aluminum heads soke up the heat and the reverse flow also keeps them cooler.

Theory is great but actuall dyno time comparison is wear it is at.
Does it come down to increased longevity vs. More power?

I have used 160 and 180 stats in my lt1's.I beleive alot of it comes down to fan control.Try running a 160 stat with stock fan settings,not much diference in overall average temp. especially when in traffic.

Regardless of oil or water temp you still want the intake charge cool as posible.Does keeping the water/eng temp down help control that? In my opinion yes and no.Lets say you are at the drag strip in the middle of the summer The car starts out cold.You go through the staging lanes shuting it on and off.You get to the line .temp is about 170.You run 13.8 or so at 100.Now you hot lap the car temps at the line are in the 200-215 range best guess you run 13.85 to 13.95 at 99 or so.Is it heat soak of the intake or overall temp that efected your et?I say heat soak.On the next pass Ice the inake for 15 minetes or so.You still are at the same operating temp once you stage the car.Do you find that lost .05-.1.I bet you do.

------------------
95 Formula Solid Roller 9 Inch 4.10 H.D. Locker,6 speed

94 Hardtop Heads up Drag car


94 Formula A4 Stock
120,000 miles 13.82

I know this one's been dead for a long time, but I really would like to hear Chuck's comments on this.

I feel neglected http://web.camaross.com/bb/tongue.gif
http://web.camaross.com/bb/biggrin.gif

It would be nice to hear Chuck's comments on a lot of things but I havent heard from him for months...

http://web.camaross.com/bb/frown.gif

<font face="Verdana, Arial" size="2">For one someone once told me that if you want your engine to run cooler you put a higher temp thermostat in it like if your car has a 180 stock you run a 190 and it will run cooler.</font>

Somewhere along the line, common sense and logic need to rear their ugly heads. http://web.camaross.com/bb/smile.gif

<font face="Verdana, Arial" size="2">If I could get my engine to run at about 195 degrees, yet keep the intake manifold cool, and the inlet air temperatures down, I'm in good shape.</font>

<font face="Verdana, Arial" size="2">It all a balancing act.</font>

<font face="Verdana, Arial" size="2">Does it come down to increased longevity vs. More power?</font>

http://web.camaross.com/bb/smile.gif

<font face="Verdana, Arial" size="2">Oil gets alot hotter than the coolant.</font>

OK, how hot is ideal? Through tests, the ideal WATER temp to keep engine component wear to a minimun, without sacrificing efficiency is 175-180* Ironically, more cooling of critical areas of the engine is done with the oil, not the water. I didn't answer the oil temp directly, did I? http://web.camaross.com/bb/smile.gif

<font face="Verdana, Arial" size="2">Does a 160 stat in an LT1 allow proper combustion chamber temps to be reached?</font>

I did say water temp above, NOT thermostat. If you need to install a 160* thermo, you have a weak link(s) elsewhere.

<font face="Verdana, Arial" size="2">Ideal oil temp is somewhere around 210-220, right?</font>

I believe you are a hair low to pretty close.


------------------
I'll be back



[This message has been edited by arnie (edited July 07, 2002).]

ttt

Man, talk about ressurecting the dead.:(
My sincerist of apologies to everyone who waited for an answer from me on this. Feel like I've let some of you guys down....

This must have been right before my ISP nightmare... but anyways. I WILL type out something coherent on this subject tomorrow although I covered quite a bit of the thermal efficiency issues in the "How much compression" thread here the other day. May want to check that out in the meantime.
My day starts early.

Take care,
Chuck Riddeck
Progressive Race Engine Development

Originally posted by Mr. Horsepower
Man, talk about ressurecting the dead.:(
My sincerist of apologies to everyone who waited for an answer from me on this. Feel like I've let some of you guys down....

This must have been right before my ISP nightmare... but anyways. I WILL type out something coherent on this subject tomorrow although I covered quite a bit of the thermal efficiency issues in the "How much compression" thread here the other day. May want to check that out in the meantime.
My day starts early.

Take care,
Chuck Riddeck
Progressive Race Engine Development
Sorry :( not my intention to make you feel bad. But I would really like to hear your view on this and apreciate the time you take to talk to everyone:) .

The theory of a 160 thermo being bad doesnt seem to hold up well at all. In an otherwise completely stock 97 I run a 160, and its been in for 20,000 of the 50K total miles on the car. the needle never comes more than halfway past the very first mark unless idleing when its hot, and it runs better than the usuall stock LT1.

The car has ran a best of 13.51 @ 104.3 on a 2.1 60 ft, on a dead stock car 9 i dont considder the thermo really a mod since you can do the same thing by lettign a car with a 180 thermo sit and cool off) When i race I let the car sit for a hour between runs, start it and let it idle until the needle gets to right off the first tick (about 160-170 prolly) Usually runs 1-2 mph slower when at full temp

From an engineering standpoint, it's simply a matter of thermal efficiency vs. volumetric efficiency.
Generally speaking in non technical terms, the hotter an engine's coolant temperature is, the lower it's volumetric efficiency.

This is an example of what I'm talking about: It is output from a test engine, all oil temps were the same for each test (thermostatically controlled). The intake was also cast aluminum for this engine which displays a better comparison for the LTx guys than a test with some composite or thermoplastic design.

With 95ºC coolant temperature:

85.3% VE at 3000 rpm
104.5% VE at 6000 rpm
98.8% VE at 7200 rpm

A minimum BSFC of 263 g/KWH at 3000 rpm

273.48 lb ft at 3000 rpm
313.39 lb ft at 6000 rpm
389.83 Bhp at 7200 rpm

With 105ºC coolant temperature:

83.8% VE at 3000 rpm
103.6% VE at 6000 rpm
95.7% VE at 7200 rpm

A minimum BSFC of 261 g/KWH again at 3000 rpm

270.24 lb ft at 3000 rpm
304.4 lb ft at 6000 rpm
388.89 Bhp at 7200 rpm

In each test, the spark was adjusted for MBT.

This is just a snippet from the whole test but it makes the point. I can post more of this type of testing for those interested. Take from it what you will... leave the rest. Considering the fact that it took me about an hour to dig this out of my files, I feel like posting more but I think that little bit gives a good understanding of what's going on.:)

Chuck Riddeck
Progressive Race Engine Development

Go to bed Chuck :D Its 4am here and you're making me think waaay to hard...

But since you're here anyways... ;)

How signifigant is the change in BSFC from 263 to 261? I mean it doesnt sound like much, less than 1%. It almost seems like the potential gains in fuel economy would neglegable in comparison to the loss in VE (almost 3% @6K).

Originally posted by Mr. Horsepower
From an engineering standpoint, it's simply a matter of thermal efficiency vs. volumetric efficiency.
Generally speaking in non technical terms, the hotter an engine's coolant temperature is, the lower it's volumetric efficiency.
Chuck Riddeck
Progressive Race Engine Development

Chuck, while I do not have a disagreement with you regarding what you stated, I respectfully disagree in the direction and emphasis given to the answer of what is an ideal water temp.

While pro drag racers know that a cooler engine is a quicker engine, way down their list of priorities is engine wear in this case. For those of us that actually put street miles on their cars, lower water temps and the resultant increase in engine wear, is a concern that should be a priority. Chuck, much like knowing that narrow valve seat/valve contact widths generate better flow. But for those of us that don't plan on valve touchup at 500 mile intervals, that little extra torque gain is more than negated by the sacrifice in longevity/durability of the valve job.

Arnie, where have you seen A motor fail due to the addition of a 160 degree thermostat? There is probably 100,000 LT1 and LS1 cars runnign around everyday with them, and no one has voiced a serious concern about them. The only guys who Ive seen hurt motors with a 160 in them were ones that sucked bolts into the intake, nitrous motors, turbo motors that went lean in a cylinder. I just dont see any basis to saying a 160 degree thermostat can hurt a motor.

Im runnign one, adn this motor is arguably the strongest runnign stock LT1 Ive seen.

I've been running a 160 for 3 years and have no problems with it. It's @123,000 miles and still purrs like a kitten and makes plenty o' power. At one point, when my front ground effect wasn't on yet, but I have the 2"lower air deflector on, my car would not run above 140, and again had no problems making power. Of course, 93's are known to be exceptions to the rule when it comes to 4th gens...:D

The point about the oil temps being controlled dosen't address the issue that the cooler thermostat may never let the impurities "cook" out of the oil until it reaches full operating temperature Actually, I shouldn't say never, but it would seem that the process would take longer or might not even happen at all if the engine was run for short periods all the time.

My .02

Originally posted by 95 Z-28 LT1
The point about the oil temps being controlled dosen't address the issue that the cooler thermostat may never let the impurities "cook" out of the oil until it reaches full operating temperature

The only impurity I'm aware of that would "cook" out of the oil would be water. That being the case the water would still be boiled off eventually. Just because the oil in the sump is cooler than 212ºF doesnt mean thats the case for all the oil in the motor. For instance I'm sure the oil on the cylinder walls is much wamer than the oil at the bottom of the pan.


Actually, I shouldn't say never, but it would seem that the process would take longer or might not even happen at all if the engine was run for short periods all the time.

Yes, but this is the case no matter what thermostat you run.

Originally posted by LTOne4Fun
Im runnign one, adn this motor is arguably the strongest runnign stock LT1 Ive seen.

How strong your engine runs has nothin' to do with it. HOWEVER, if guys are runnin' with the lower temp thermo. for over 50 thou, it (the test) must apply to engines in use longer than most keep theirs in original form. Maybe the ones responsible for the test sold rebuilt engines!

I installed a 160 thermo in my 95 lt1 at 12,000 miles. I currently have 104,000 miles on my engine with no problems. The engine uses 0 oil between changes and I could even still see the crosshatching in the bores when I swapped heads 1,000 miles ago. If the 160 thermostat increases engine wear, I don't think it is that significant. I think it is more important to run a good engine oil with frequent changes.

Rich

I thought I'd add some of my experiences w/ the LT1 thermostats. I have 3, 160 degree motorad(sp?) thermostats. In Indiana in the winter, it is not unusual for my coolant temp not to get over 155 degrees (22 mile trip to work) w/ two of the 160's. In the winter, i now run a 180 degree thermostat and i have 185 degrees of coolant tempurature. these temps are taken via a scanner at the water pump. Last winter i ran a 160 all winter and with the oil not getting hot enough, i got a brown, thick oil residue coating on the internal engine parts re: rockers, valve springs, retainers, valve stems. This past weekend, I decided to place the 3, 160 degree thermos and 3, 180 thermos in a pot of water w/ a digital thermometer. I watched when the thermostats started to open, when they fully opened and when they closed. All were different, one 180 would not open fully (210 degrees)and others went from closed to fully open in 10 degrees. one of the 160's didn't open till 180 degrees. The 160 i ran last winter opened at 152 degrees!! The other right at 160 (winter coolant tempt w/ that one on a cold day, 164 degrees) one of the 180's did not open till 195 degrees. They all seemed to close at different temps although close to when they started to open. Very inconsistant performances. Other than the brown coating , I've noticed no performance difference re: fuel economy, however we know full tempt coolant (over 170 degrees)and oil (190) probably benefits engine performance and protection. IMHE

Originally posted by arnie
Chuck, while I do not have a disagreement with you regarding what you stated, I respectfully disagree in the direction and emphasis given to the answer of what is an ideal water temp.

While pro drag racers know that a cooler engine is a quicker engine, way down their list of priorities is engine wear in this case. For those of us that actually put street miles on their cars, lower water temps and the resultant increase in engine wear, is a concern that should be a priority. Chuck, much like knowing that narrow valve seat/valve contact widths generate better flow. But for those of us that don't plan on valve touchup at 500 mile intervals, that little extra torque gain is more than negated by the sacrifice in longevity/durability of the valve job.

"Ideal" means different things to different people. For a drag racer it means one thing... for an engineer designing an emissions compliant powerplant it means another... to an engine builder building an endurance racer where fuel economy is of importance it is another. So, there is no "ideal" water and oil temp for every situation. That is the point.
If you want hard numbers then these should be general guidelines to follow when maximum output is the goal with no regards to fuel efficiency..... keep the water temp at approximately 170ºF and oil temps at approx. 210ºF. How's that? Very educational.

Good luck,
Chuck Riddeck

Originally posted by Mr. Horsepower
So, there is no "ideal" water and oil temp for every situation.


Oh, I agree.

Originally posted by Mr. Horsepower That is the point.

OK. :)