confab

What I see is vast differences in wear between lubricants in the top chart.. And, since 25C is about 80F, and that is not coolant temp but cylinder wall temp, that's effectively ice cold.

For the SAE 30, it then shows effectively a flat bar up to 329 degrees F.

IOW, No more wear at one extreme than at the other.. It's a wash, and there isn't a significant difference in the center of its range, either.. Which is about 200F.

So, minimal wear and essentially flat readings from about room temperature up to the temp of a deep fryer, and way, way above operating temps.

The other chart, OTOH, shows wear in the multiple thousandths till we get to a coolant temp of about 115F ish.. This wear continues and does not vanish till we get about 200F.

Where, I guess it vanishes completely?

Something else, how many modern engines have you guys tore down VS years ago? Remember the "Cylinder Ridge" and how horrible it used to be? Notice how it is just not real bad now, even when the mileage is much, much higher. You just wipe it off with the cutter in a couple swipes and it's gone!

This is because the materials have improved drastically during our lifetimes, and it isn't just limited to the composition and nickle content in the engine block or the advances in lubrication technology. The "Ridge" is a little empirical evidence that we've all noticed, but I'm sure the racers here have the specifics.

IOW: I don't really know for a fact that tests from years ago are even relevant now?



This has been a great thread, btw! I love to learn new things.

confab

PS: The bottom chart, 30SAE, Converted to F, There's no real difference in wear from 122F (Even Low for Boat Coolant Temps, Overall) to about 284F.

Tom400CFI

with all of this...especially the bold. We have engines now days with well over 100k miles on 'em, and you can still see the cross hatch on the cylinders.

Those graphs are something and I appreciate that they were posted, for sure....but for me, the raise more questions than they answer.


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confab

Agree.. Not trying to throw shade at anyone.

This has been a great thread because of the data.

Always in it learn something new!

Purple92

Fundamentally - I agree with you guys - as I said in my first post - while I typically like to see engines running in the 180 ish range - I'm more concerned with oil temp than with coolant temp. I run a 15W-50 in the engines that see primarily track usage - and I try to keep under 3,000 RPM until I get 180 degree oil. (In my particular situation - I have 180+ coolant tempos WAY before I have 140 degree engine oil). I run the higher viscosity oil for the improved film thickness, but I realize that when that oil is cool - it's just not able to do it's thing like it can when it gets "warm"... That's a tradeoff I'm willing to make.

I've watched a VERY experienced dyno operator breaking in an engine (my engine) on a dyno - once he gets oil temp into the 170+ range - he starts bringing the revs up and applying some sporadic load to the engine to try to get the rings seated. He won't rev the motor till it has oil temp and he typically makes the coolant temp 180 degrees or so (you can do that on an engine dyno).... Watching that process taught me something....

Personally - while I do think the consistency of the iron used for the block is far better today than it was 70 years ago - I think the big difference in wear we typically see is due to the quality of the oil being MUCH better, and it doing it's job Much better !!! I've dug into late model engines that had 100K miles on them, and with decent oil (Mobil 1 - changed every 3K - 5K) the valvetrain still looked nearly new. I think with the oils that were around in the 1960's - 1970's and 1980's that would not be the case.

Two other things I will say - 1) while I said earlier that the consistency of the iron today is significantly better than the old days - if you look at an advertisement for the aftermarket Blocks (Dart - World Products) - they claim to use a much "harder" cast iron. They say it's tougher and wears better. I expect that the OEM's don't use it because a) it's more expensive, 2) it wears cutting tools faster, 3) they don't need the strength. 2) Oil temp seems to be very proportional to Engine RPM - what I've read is that one of the big contributors to engine oil temps is the heat caused by the valve springs getting compressed and extending again. In fact if you look at some pretty high dollar race motors - you will see an oil pressure line heading to the valve cover where a oil line system it squirts oil directly on the valve springs. Just sayin'....

Tom400CFI

I totally agree. I've got diesel engines at work that have 10,000 hours on them, still have crosshatch on the cylinders and no meaningful ridge at the top of the bore. I don't think the iron is any better than the "old days"....the oil is way better.



I don't follow. Not relative to coolant temps, anyway.

dclafleur

I'd like to point out that at lower temperatures you generally have lower emissions as well.

Like all these discussions there's more to it than low=good or high=good. Most of it comes down to Goals vs acceptable compromises.

What the engine masters test shows is that anyone who tells you there isn't more power to be made at lower operating temperatures is generally wrong.

confab

Never thought about that... lol.


30 would probably throw a diesel for a loop in cold weather.

Tom400CFI

It's a diesel. Don't you just keep it running 24 hours a day?? It burns less fuel than starting it!

I totally Well said.

84 4+3

I've heard some interesting stories from the battle of the bulge... something with people having to build fires to heat the oil pans on tanks enough to start. Granted those were gas iirc but imagine a diesel in the same situation.

krackenvette

I am more concerned with oil and transmission temperature. So, I run my engine fans at 185sh. My oil temp here in SC runs around 210 to 220. I have a B&M stacked transmission cooler running in conjunction with BeCool radiator with internal transmission cooler. I have seen highest temperature of 180 using laser temp tester on oil on dipstick. I have a 2800 stall and 3.75 gears..
I make good power, so I am not concerned about a little more or less. I am looking at longevity on parts cooled via engine radiators system.

Purple92

The reason I mentioned the cast iron that is used by the aftermarket block producers was to try to better drive home the point that the cast iron alloys used by the OEM's is not the strongest stuff around (meaning that the reduced wear we see these days is not due to "harder" cast iron wearing less - but from the oil protecting it better).

The comment about the valve springs being a major driver to engine oil temp was primarily to help illustrate what I was saying earlier - that I am more concerned about oil temp than water temp, and that while engine oil and coolant temp influence each other - you can raise oil temp pretty easily with some high RPM running - which won't necessarily do much to coolant temp.

Pretty impressive about a 10,000 hour industrial diesel that still has little or no ridge on the top of the bore... If that were a pass car engine - that would probably be somewhere on the order of 400,000 miles. And if I understand correctly most Industrial diesels operate at a much higher percentage of their full power output than most auto engines do, so the loads that the rings place on the cylinder walls are significantly higher...

Tom400CFI

too.



I guess it depends on the application. This engine was a snow cat engine; 330hp Mercedes OM926. It is making full power for 50% of it's life, and then no power, or exhaust braking, for the other 50% or it's life. Up, down...up, down....18 hours a day (night). But I agree, I was totally impressed with the cylinder wall condition on when I looked inside.


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GREGGPENN

Back during my build, I used the following chart to determine MAXIMUM coolant temp. Minimum temp can be a function of other things...like winter temp and/or percentage use in the winter time.





I remember a similar thread years ago. One of the other factors was getting the block hot enough to "evaporate" any condensation in the crankcase....meaning the lower you run an engine, the more likely you'll end up with condensation/moisture in [with] your oil.

For my (383 L98) setup, I chose 170 as my target temp....which forced me to try a 160-stat. I ran it for a couple of years but it must have been faulty. I ended up with 130-135 deg temps in the winter...which, of course, was too cold for adequate cabin heat. When I replaced it, I went with a 180-stat but haven't had pinging like the chart would imply (with my 8.5 dynamic CR and 91-93 octane local fuels)

Seems I also remember arguments (from CFI-EFI? and others) about heat-loss being less at higher temps...which represented more retention of power. IOW, people didn't necessarily agree colder was better. Contrary to the link posted at the top of the second page (which was around the time of the other debate [to which I refer] I seem to remember another site proving why cooler DID create more power. The existence of to conflicting articles likely spawned that previous debate. Sorry, I can't find the counterpoint article/link to provide.

Purple92

Interesting chart !!!

I know some thermostats are designed to always bypass a little bit of coolant - it keeps air pockets from building up, and tends to create less thermal shock when the thermostat does finally open (particularly if owners do not understand that you should drive relatively easy for the first few miles to get things warmed up)... BUT - the amount of coolant some systems bypass around the thermostat is pretty significant... I have a 454 in a 1 ton pick-up, and in 70 degree weather running the engine for 5 min will barely get the coolant gage to move. It typically takes about 5 miles of driving to get coolant even close to 180 deg. I'm guessing that on that truck - when dead cold - about a cup of coolant is heading into the radiator every 15 - 20 sec....

I would have been interested to see if putting some cardboard in front of part of the rad in very cold weather with the 160 t'stat would have significantly increased the coolant temp...

RedHot85Vette

I read in a book by John Loughmiller, "C4 Corvette Buyers Guide: A Reference for the Purchase and Maintenance of the 4th Generation Corvette", where he speaks about the sequence of events that occur when you start your car what has an L98, that the ECM looks for 160 Degrees Coolant Temperature before entering Closed Loop. John Loughmiller is a verifiable expert on the C4. He also states that installing a 160 Thermostat is a waste of time. What is the verifiable, officially documented, preferably by GM... TRUTH?

Just to note, the Chilton's Manual has a diagram that states that the Factory ECM, Stock, turns the cooling fans on at 239 degrees. My belief is that high temp is related to an emissions standard. There is also a Bypass Coolant Sensor between spark plugs 6 & 8 which also is preset to turn the fans on at 239 degrees. You can change that sensor to a different temperature range, 200 On / 185 Off, for Example. There are other ranges. You can find them cheap on ebay.

I prefer the 195 myself in that I do mostly driving around town and local, and I want to ensure the best oil flow for the sake of internal engine wear, give me the best fuel mileage (that I don't really care about), and reduce the risk of sludge formation. I have my fan come on at 200. I have a 3 core aluminum racing radiator. a clean cooling system with Hyperlube installed. I have a new 17 lb radiator cap. All my sensors are up to date. My hoses brand new ( and I'm either getting a better water pump, or an electric one, although I"m not sure what to do about the missing water pump pulley... new belt? maybe?... dunno). I disabled the heater core valve and associated vacuum line, so that it is open all the time and that coolant is ever flowing through the system everywhere. I did a throttle body bypass but I'm not sure that's such a good idea just now). My smog pump, gone (my AC system is next, I live upstate NY... there's maybe 2 days a year where AC might be nice... I'll gain lots more room in my engine compartment, so it will be easier to work on things, and there will be more air flowing around the un-cluttered engine bay helping to keep things cool... I'll lose lotsa weight, less weight/more speed... I rather take the top off and enjoy the breeze), My timing is at TDC and needs adjustment,which I will set to the Book spec, 6 BTDC. I have some work to do on my car before I adjust the timing properly. But as it stands, my car drives like a hot rod rocket, and my engine runs happy and cool.

John

bjankuski

The 1985 vette actually enters closed loop at 104.5 degrees, so even though John is a C4 expert he is not a tuning expert. The data shown is for a 1985 stock auto vette.

RedHot85Vette

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Thanks for this quick response and data. I really appreciate your input. Gotta have the correct data in order to get things right with your engine. I have another question about Closed Loop, and the 1985 MAT (Not to be confused with an IAT). I'll post it separately since this post is about coolant temperature.

Tom400CFI

...more.

Engine Masters just did another test, exploring the engine temp vs power more carefully. They positioned a air flow meter on the mouth of the carb, temp sensors in the room, the plenum, one in a runner, and EGT, and obviously the coolant temp sensor. Engine was a 598 CID, Brodix 365 oval port heads, Brodix single plane, solid roller...

First pull; 79* room temp, 135* coolant temp, 43* plenum air temp, 68* runner air temp...790 tq, 854 hp.
Second pull; 78* room temp, 200* coolant temp, 42* plenum air temp, 71* runner air temp...774 tq, 836 hp
Third pull (heated intake w/hair driers); 89* room temp, 135* coolant temp, 260* plenum surface temp (start of pull, 220* end of pull -air temp during pull=66*), 230* runner surface temp (start of pull, 204* end of pull -air temp during pull = 88*)...784 tq, 857 hp
Fourth pull (Iced intake); 79* room temp, 135* coolant temp, 34* plenum surface temp (44* air temp), 230* runner surface temp (44* air temp)...806 tq, 862 hp
Fifth pull (Iced intake/heated carb); 78* room temp, 135* coolant temp, 47* plenum air temp, 54* runner air temp...796 tq, 856 hp

In this test, they theorized that the colder coolant temp creates a cooler combustion chamber temp, lowering "ambient" pressure in the chamber, allowing better cylinder filling. Note that in the first two tests, the only change was the coolant temp and tq changed by 16 lbs, hp by 18 numbers.
Also, with a wet manifold, Engine Masters' attributed the hp to the temp of the fuel, more than air/intake temp. They noted that the air flow readings were higher on the runs where the fuel temps were lower.


None of this took advantage of timing changes allowed by head/combustion chamber temps. Timing remained unchanged throughout the test.


And, more real data for you to digest.

krackenvette

One thing to think of is oil temperature too. it does play into HP also.