I see the fan I want and that will fit in my application comes with a sensor which screws in to the block and turns the fan on at 210f. Why is this so high if the thermostat is in the 180 -190 range? I assume they know what is best but I also see varations which can let you set the temp at which the fan comes on. Is this ok or should I look for one which cnaa be set to a lower temp? Thanks again

 

Hi Mr. Lear!

I have just a few thoughts - and maybe a few questions. First what engine are we talking about cooling here, and what radiator set up do you have? And, is this a two fan set-up where one comes on at a higher temp or when the "air" is turned on?

Different engines cool differently and some run better hotter or cooler. My thinking is, first, you are only talking about 20 to 30 degrees difference. And the block is always going to be hotter because it has more mass than where ever your thermostate is located (that is if the fan sensor is mounted at the END of the coolant flow - I'm assiming it might be going into the temp gauge sending unit spot) But more than that, it's a balance between the fan operation and the coolant flow. You want to have the coolant flowing freely through the radiator (ie thermostat open all the way) when the fan is working. And, as much as we hate to admit it, the fan is a suppliment to the flow of air caused by vehicle motion (and of course when stopped). So with certain configurations, your electric fan may not run at all until you pull up to a light or get into stop and go. And in those cases, it will feel the rise in heat in the block (or intake manifold depending on your engine) at the sending unit before it feels it at the thermostat (and the thermostat has the few seconds to react).

Not sure if I expailned that right - could be wrong, but I think you will be fine.

J!

In this case, unless you want your engine to run and stay cooler (like 160, or mine at 140), you should be just fine.

 

Just about all engines are far more efficiently at higher temps.

Chances are, your fan will only come on when you're sitting in traffic. It probably won't come on running down the road at all unless you're tied to a heavy trailer towing it up a hill.......THEN you'll probably be "under fanned" with ANY electric. They don't have many electrics that will work for towing applications.....

I have a question now for you J

Why in the world would you have any engine running at 140 degrees? (unless it's a marine engine, raw (salt) water cooled) Running at that temp you don't even remove all the water vapor from the oil. Oil temp should never be allowed to run below about 180* just to keep all the moisture out....


Regards,


Rick

 

Hi Rick!

Good question - been asked many times and answered a few but I'll pass on the theory.

First, I have an oil filter that removes 98% of the water from the oil. When I change it I can actually ring it out and see it - along with the carbon, metal flakes (I'm still breaking in) most of the dirt. My oil is CRYSTAL CLEAR even with 3000 miles on it - can't hardly see it on the dipstick! And believe it or not, I'm running the oil through an oil COOLER before it enteres the engine as well!

(Rick = ).

That oil is also a primary coolant in the engine and I have incorporated systems to use it as such, and provide better lubrication. I have a HV oil pump to allow the oil filter to be hooked up in tandem with the cooler and engine supply so the oil is clean when it goes into the pan, then pumped up and drawn through the oil cooler and into the engine. The filter filters all the oil continuously. No bypass. No oil pan sludge. Just good, fresh, cool, clean, moisture free, oil.


The lubricating system in an engine and the "primary cooling" system in an engne are much more efficient when managed as seperate systems (ever do any flying or work on airplane engines). Thus oil temperature and coolant temperature are very different animals, bu tin normal configurations are interresultant). One system functions to draw heat off the engine mass (cast iron block, heads, etc.) the other has a dual role of lubrication and drawing heat off INTERNAL MOVING parts.

And controlled oil temperatures on parts that depend on oil for cooling - bearings, rings, lifters, etc provides better friction control, lower parts, temps and less wear.

I run it that way, and a little richer, to save on oil breakdown and engine wear. Plus, with the big engine (FE390PI) I am having to be careful during my break in of that temp climbing through the roof after freeway driving then doing stop and go. I'll probably bump it up to 160 at 5000 miles. It normally only runs at thermostat temp (140) on the freeway anyway. My focus is on oil breakdown and the subsequent engine wear (especially at start-up, and when stressed - up big hills, towing or loaded), and preventing that wear.

It runs fantastic! Mileage is horrible, but alot of that is the 750cfm Edelbrock out on the top, and the lead foot installed on the drivers right side.

IOW, I'm willing to sacrifice "efficiency" (ie. mileage) for "protection."

Ok, Rick, now you can shoot me!

J!

 

Well..... I'll keep my pistol holstered!! No shooting on this end!!!


There's nothing wrong with experimentation! You are doing oil analysis I presume?

The only thing I could say ...is the cost of the fuel you put in your engine might far outweigh any longevity you get from running it that way......

What do you mean by "horrible" mileage?

Let's say for example, you were to get 18 mpg for 200,000 miles. (not unlikely considering most engines will go that far if taken care of reasonably)

200,000 miles would result in about 11,000 gallons burned (@18mpg)

Now let's assume you do things that make your oil crystal clear, 140* F temp etc etc....BUT you only get 9MPG...well....you're going to burn 11,000 ( 11 THOUSAND) MORE GALLONS!

at even $2/gallon that's 22,000+ dollars (more)


Now I just used those numbers for comparison. Maybe horrible mileage to you doesn't mean the same as it does to me.

But if running cold, makes the mileage terrible but makes the engine last longer .....it's probably not worth it.......you can buy more than a few engines for 22,000 (unless you're talking about tricked racing or aircraft engines......


Most engines today if run reasonably and the oil is changed at about 5000-7500 miles will safely go 200,000 miles with very little other maintenance.


I'm not really criticizing what you're doing as much as I'm wondering if the benefit is worth the cost......(in fuel, and other effort)

For example, there's a lot of discussion on start-up wear and arguments on whether pre-oilers help....Maybe they're great on a Merlin or an Allison but they're just not worth the trouble on a SBF/SBC because the engines will go 200,000 miles without them....AND I don't want the thing any longer than that!!

You mentioned aircraft engines. I have one of those sitting in my Stinson out in the hanger out back. It's got an oil cooler on it (no Vernitherm) So I have to cover part of the cooler to get the oil to at least 180* in the wintertime.....otherwise it gets a LOT of water vapor in it....

Oil cooling is pretty important in an air cooled engine. Liquid cooled engines are not as critical since water is so much better at transferring heat than oil.....Oil is not a very good heat transfer medium(by comparison)

Most newer cars run pretty hot by older standards....hence the 15lb radiator caps etc...

 

I noticed a very noticable diffrence in performance when switching to a 180 t stat from a 160. One reason older engines are run cooler is the older verticle flow radiators couldn't hold up to a 15 psi cap because of the large upper tank. Engine temp definatly affects combustion. If your fuel is not being burned properly you are advancing cylinder wear. the engine oil today is designed to run at a cetain temp. so I dont see an advantage to running an engine at such a low temp.

 

My suggestion is to just try the fan with the supplied control thermostat. If it doesn't come on when you want it to change the t-stat. (You might check with the manufacturer and see if they have different t-stats)


You still flying a Lear?


Regards,


Rick

 

Ron Frances wire has a fan controler that you can adjust for turn on and tur n off.They also have a sender that hooks to one of the water pump bolts.Thats what I am running with a 160 thermostate,stock rad,351 winsor,c6 and trans cooler.The truck runs 180 all day.If I get in heavy trafic it will go to 220 then cools back to 180 when I get moving.

 

Yes yes, yes,,,,,,,,I know, you are right in theory! I'm not sure I'll buy the double the mileage with a 20 to 40 dgF increase, but I know it will increase at least 4 to 5 MPG more - like I said, don't care at this point about mileage, but probably will later. I'd be pressed to put 4000 miles a year on the thing anyway at this point. So even though your math is right, the overall cost comparison is not quite accurate in my case, especially when you compute in labor costs for engine repair, rebuilding and replacement.

Unfortunately, I end up getting into this conversation every time I say I've got that 140 dgF thermostat in the truck. Everyone just goes crazy. You'd think I was burning down the house or something.

I'm not trying to be clippy and appreciate your advice - it's good advice, but for now I have my reasons for doing this this way, unconventional yes, and right or wrong I don't have the patience to keep trying to explain and justify this particular design, and the theory and engineering that went into it. I don't propose that others do it either, it was just a simple statement.

This is a brand new engine. After the break in and the engine temp fluctuations stabilize out and the cooling and oil systems are proven reliable, I'll certainly consider warming the optemp up a bit. For now I want the safety margin and extra protection. And I will run my oil cooler, though, for the reasons I mentioned, and the way it's scrubbed I'm sure it will be fine and perform as I designed it to. Oil temp and engine operating temp are two entirely different beasts. Normally the oil temp in a car is dictated by the engine operating (coolant) temp. I have the ability to cool my oil independently.

This isn't a radial engine being flown at altitude with less atmospheric pressure and much higher relative humidity, where much more water per unit of air (to the point of carburetor icing) is sucked into the engine and needs to be boiled out by high oil temps.

I do pre oil BTW, kind of - have a seperate starter switch from the ignition and give it a few seconds of turn before turning on the key. With a BBF engine (sbf/SBC???????) with a compression ratio of almost 10.8 to 1, I consider pre oiling and improved lubrication protection/thermal exchange to be of paramount importance - Mileage at this point is not a major concern.

If I was that worried about just mileage, I would have bought a 4 cylinder Toyota, not a big old heavy metal truck, and built it around a big high performance engine with 750 cfm of carburation on it....ya think? Forests and trees guys, forests and trees. We all have our thing I guess.

That Stinson sounds fun - I learned to fly in the T-28 (has an oil cooler door on the cowl controlled manually in the cockpit)...dont remember the temp to open the door at - that was 31 years ago.

J!

 

yes still flying a lear (31a) also have flown a stinson (more fun than the lear0