Technical ZZ4 operating temperature

Don't have to google. It's a pretty simple one. The temps the OP stated in his opening post are not a problem. I don't get the point you are trying to make. If an engine runs within an acceptable temperature range (for that particular type of engine), there is no need for undue concern. You could tailor your responses to help the guy out. I'm sure he would appreciate it, especially from someone with your experience and expertice..............

 

Your right, the OP's temp's are just fine. Oh, and thanks for the advice.

 

Thanks everyone!

 

I had a ZZ4 engine in a C-10 truck 20 yrs ago.. It ran 180 - 210 F depending on time of year and a/c use here in the desert. The truck pulled my car trailers very well

 

You can google this subject and find whatever answer to support whatever you think.
Folks on other boards will say it’s a little too hot. Others will say it’s fine.
You’ll even see new vette guys using a 160 stat in higher performance applications but the timing is changed a good bit. Cars still run 220, the stat just opens up a lot sooner.
I’m going off work experience

now my 500 in my bus runs 180-185. If it’s 10 degrees or 100 degrees.
The info I read on these engines is they tend to run hotter. 210-220. I’m looking into that and plan to try to bump the temp up.
Will confirm with a contactless thermometer

 

While I have nothing to add to the conversation, it has got me thinking.

If the cooling system is designed to maintain a consistent operating temperature, wouldn't a rise in operating temps indicate a problem that needs fixing?

Stuck in traffic, temp gauge starts to rise up. Options are pray traffic starts moving? Hit the heater control and the fan as you roll down the windows and shut the Ac off? Put the car in neutral and bump the revs?

Just saying, maybe the argument isn't what temp the thermostat opens, or what temps the engine should run at, but rather why is it rising up as a guy is stuck in traffic?

 

I'm going to try to explain "somewhat" my rationale on why higher temps are not good for nostalgic engines. I know there are many people on here who have no idea how their new computer cars work.
I'm not an expert, but I think a little helpful explantion will shed some light here.

In a modern 210 degree operating system, the computer employs a couple of "knock" sensors which are screwed mechanically into the engines block (or lifter valley). They sense knocking long before its audible to the human ear. As the engine is running, the computer advances the timing.......until it hears the beginings of a knock. It advances the timing "continuously" in all driving modes. It does this to get the umteenth of gasoline efficiency/emission reduction.
As soon as it hears the beginning of the knock, it backs off the timing a few degrees and then starts advancing it to the point of knock.....then retards slightly and advances again. Over and over and over.
While its doing this it is also monitoring lots of other inputs from different types of sensors. The O2 sensor in the exhaust pipe is monitoring (logically enuff) the amount of oxygen exiting the engine. That tells it if the engine is running rich or lean.....or just right.
By knowing rich/lean, the computer additionally supplies more or less fuel which also helps keep the engine temp under control.
The point here is that the engine does reach the point of spark knocking, and it does over and over......
but the computer is there to pull the timing back and adjust the fuel input and even turn fans on and off.

You don't have that protection in old school engines operating without computer controls. So when your engine is operating at 210 and the temp begins to rise for some reason, you have nothing to protect it. You also have less room for the engine to absorb additional heat and still be ok.

One other thing that is seldom pointed out is that various engines have "hot spots" within them, where coolant is subject to boiling. Generally its near the exhaust valves in the heads.....especially if two exhaust valves are adjacent to one another. Look at the 400 Chevy and the difficulties they had with siamesed cylinders. So while a temp gauge may read one thing, certain areas within the engine may be much hotter locally. Even with lower operating temps this can be a problem, but I'd hate to try running an old 400 at 210 degrees. Also remember that the temp rating of a thermometer is where it "starts" to open, not where its fully open.

Anyway, I hope this helps some people to understand the difference between newer vehicle operating temps and older (non-computer) vehicles, and thus my viewpoint on the subject.

Edit added below:

Lucky13agogo said this:
I've got a LS1 in an off topic car that's designed to run hotter than anything else I've had. The first few times I sat in traffic and saw the temp climbing over 220 I started to get a bit worried, until I learned the factory set the low fan to kick on at 226 and the high fan at 238!

So it appears that the high temp thermostats do allow even higher temps to occur. Think what this does to the oil in the engine which is also fighting to give up its heat. Its going to have a very difficult time exchanging heat at these higher temps.

 

Running temp depends on a lot of things.
Temperature, humidity, how hard the engine is working, condition of the system, power adders, how heat exits, coolant, cap………
The stat opens up at a given temp but not fully open until higher.
I’ve got 2 older rides I’m driving. Both have new radiators made by the same company, pumps, hoses and t-stat all in working condition.
The 500 inch motor nuns 185 constant.
The 350 runs 200-215. It rises at a stop light about 10 -15 degrees. Both are mechanical fan and no shroud.
The 350 fan is about 6 inches away from the radiator, the 500’s fan about 2.
The 350 needs a shroud.
rising when stopped is normal but if excessive indicates not enough air flow when stopped.
210 isn’t hot with proper coolant and cap for a SBC for hot summer driving. Even with a 180 stat.
I’ve seen em run cooler. Usually in trucks with larger under hood room and radiators.
The vette and Camaro 350s I’ve been around, including 70-80s carburetor engines tend to run hotter. If 210 was bad, they wouldn’t have survived.
Newer ones run hotter, last longer with longer oil change intervals.
Technology sure has come a long way

 

I posted the GM spec sheet for the ZZ4 above but apparently you didn't bother to look at it. So I'll post the direct excerpt from it so you can see for yourself what the ENGINEERS at GM recommend. Google can be a wonderful thing even for those with engineering degrees as well as those without one. I think its somewhat humbling when a person realizes "the more I learn the more I realize how much I don't know". Thats why I use Google and the Hamb ......to learn.

 

Yep. A 180 stat.
200-210 sounds about right for summer driving.

 

Not to be argumentative, just in the spirit of good discussion and expanding our collective knowledge here, but I don't perceive Motor Trend as an unfailable gospel of mechanical engineering; or the Engine Masters guys as the ultimate arbiters of horsepower truths. I couldn't watch the video of the dyno testing because it's behind a paywall, but I assume they ran multiple dyno pulls on an engine and the only variable was the thermostat opening temp. Correct me if my assumption was wrong. Tell me, did they also measure incoming air temp? The loss in h.p. was about 2.2%, which is a pretty small percentage and could be the difference seen in any 2 dyno pulls really. Were these averages of multiple pulls, or the best results of multiple pulls?

In any case, if the results are accurate, and higher coolant temps do result in a slight h.p. loss, what accounts for that loss? Just another assumption here, but I assume the change in power is a result of a change in intake charge temperature, right? A cooler intake charge is more dense, carrying more potential energy. If this isn't the answer, what is?

And to get back to the discussion, how does this affect wear rates? Tribologists have broken down the mechanics of wear into 3 modes, Abrasive, Adhesive, and Corrosive. Which of the 3 is aggravated by higher operating temps? Abrasive wear is caused by particulate contamination (could be 2 body or 3 body contact); adhesive wear is the transfer of metal from one surface to another, caused by contact between moving parts resulting in micro welding due to high hear from friction and tearing of metal as it transfers from one surface to another; and corrosive wear includes not just corrosion from acidic compounds, but erosion, like from cavitation.

Elevated temps could result in decreased lube oil viscosity, and decreased film strength, potentially allowing 2 closely separated parts to make contact, resulting in adhesive wear. And particles that break off from the adhesions can migrate to other parts causing 3-body abrasive wear somewhere else. So if the change in temp is sufficient to cause excessive thinning of the oil this could lead to wear. That is true. But is a change from 180* to 210* enough of a change to cause excessive viscosity loss in the oil? That is the question.

On the other hand, as pointed out earlier, cooler operating temps can lead to accumulation of condensation in the oil, which leads to the formation of acids and corrosive compounds in the oil, leading to corrosive wear.

I think both scenarios are the extreme's, 2 ditches on either side of the road, so to speak. On one side we have an engine that operates too cold leading to condensation buildup and sludge and deposits and corrosive wear; and on the opposite side of the road we have engines that operate too hot leading to thinning of the oil and contact between moving parts. But is this really an issue at temps between 180* to 210*, or slightly on either side of those temps? I tend to think not. I think if an engine gets fully up to 180* and maintains that temp for probably 15 to 20 minutes or so, the oil temp will be higher than the coolant, and should be hot enough to volatize any condensation that formed when it was last shut off. And even if an engine hits 210*, or even up to 220*, a decent quality modern API licensed oil should maintain sufficient film strength to keep moving parts fully separated. But that does bring to mind the conversation the other day about using low viscosity oils, like 0W-20 & 5W-20, which theoretically would be more likely to allow contact under extreme high temps. So something to think about there.

Anyways, just my thoughts on the subject.

Just for my own amusement I put together this viscosity comparison graph using info from tech data sheets of common engine oils on the market. The data sheets are available online if you search. I left brand names off as that's really not important, just the typical viscosity characteristics of various SAE viscosity grades. Visual aids always help me grasp concepts better. 100C = 212F, so the oil temp ranges we're interested in with this discussion would be on either side of the 100C line.

 

I've put the 180 deg. thermostat in almost all the Chevrolet engines I have built. Pretty much the standard for 1st gen. SBC. I modify them by drilling six evenly spaced 1/8" diameter holes in the flange. Also played with water restrictors in some circle track stuff but that's another animal.

 

I see "knock" mentioned several times. Does increasing water temp from 180* to 210* increase the probability of "knock", or detonation.

 

There are optimal temperature ranges for both water and oil for achieving maximum power output. The difference between 180 and 210 deg. in water temp. is negligible for most applications. Certainly atmospheric conditions play a role as well. Engine oil temperature plays a significant role in engine cooling as well as the effectiveness of the oil additive package in the oil. Bob the guy has a fantastic website established if you want to learn more about engine oil or other lubricants.

https://bobistheoilguy.com/forums/

 

Or you can ask me......

 

Ya get even more different answers with oil temps.
The 20-30 over water temp answer
the needs to exceed 212 answer
The 220-230 is perfect.
Race guys running 240-260
NASCAR oil temp gauges that registered well over 300
The Porsches I worked on, the oil cooling fans came on at 230 the oil temp thermostats were in the 190 range.
Interesting subjects.

 

Seems that would depend how close to detonation you already are given your ignition timing, type of fuel, AIT, design of the combustion chamber etc.

 

The hotter the oil runs, the faster it will oxidize. The Arrhenius Rule says that for every 10*C increase in temperature the rate of oxidation doubles. Oxidation is the main reason why oil needs to be changed, reduce the rate of oxidation and you extend the life of the oil. And vice-versa. 230*F is the common upper limit for normal service life of the oil. You can run it up to 300* if you only need it to last for 1 race. At some point thermal cracking of the oil happens, that's not good.

 

Again, not being contrary, but how would an increase in coolant temp affect those things? Will the combustion temps change considerably with a change in coolant temp from 180* to 210*? Enough to affect detonation level?

I'm sorry, I know some people see these discussions as nothing more than mental masturbation; I see them as opportunities to learn. I certainly don't know everything, I try to learn something every day.

 

Yep. Race engine oil changes are generally cycles, races/heats or passes, not miles.
I’d like to see before and after oil results from a 500 mile NASCAR race

 

I know what you mean. I feel the exact same way despite some opinions formed by others. We are fortunate to have the collective knowledge of the HAMB especially the real world experiences. People who have genuinely been there and done that. There's always going to be someone smarter or more experienced than us. The trick is to gain their respect so they will share what they know. Unfortunately some people are so convinced they know something they will not absorb a different perspective for fear that they might be wrong.

I think your first question should be the other way around. That is how do those things affect to cooling temperature.

To answer your last two questions I would say no for that small of a coolant temp. change. I would say (and others may not) that the combustion temperatures are more greatly influenced by compression ratio, camshaft timing events, ignition timing, type of fuel, AIT, design of the combustion chamber, even the types of materials used in certain components and their ability to transfer heat. The coolant and oiling system has to be able to cope with that part of the chemical reaction (Combustion) which is converted into heat energy and to maintain reasonable operating temperatures of the various engine components.

Time for lunch and back to my carburetors. I'll check back tonight for more discussion if you like.