Good thing I saw this thread, cause I was about to ask the same noob question .

But anyways, I haven't recieved my water temp gauge yet, and I just got a koyo rad. Curious what changes did you guys see in temp's when comparing the stock rad. w/ an aftermarket rad.?

Also, who runs their fans all the time?

 

/\ WTF?

 

BTW: Anyone ever see temperature *drop* after coming off high rev operations or even stable 4-5000 rpm operation?

E.g.: At 180F, cruising. Downshift to 3rd, take it to 8000, then back off. Afterwards I see it drop to 170F then go back up. I suspect either the increased speeds during the 3rd gear period are temporarily providing more heat transfer at the rad, or probably more accurately, the increased water-pump speed has something to do with it.

 

I guess that sitting in traffic is not "normal driving conditions" as defined by RB. If you are cruising at 70mph, on a 70 degree day, your water temps should stay around 180.

Clayne, My water temp gauges (VDO and stock) don't move quickly enough to change temps given your parameters.

SoCaLove, I run my fans after the car reaches 180, if I am driving in stop and go traffic. There is no need to use them on the freeway.

 

There's three things that affect how much the coolant is cooled: How hard the engine is being pushed, how much airflow through the radiator and how quickly the pump is circulating the coolant. Different combinations of these can combine to raise coolant temp or lower it and it will vary for most every car.

I've seen many cars that actually cool more when raised just past idle since the coolant is circulated more quickly, or it may do just the opposite. Depends on water pump capacity, radiator efficiency, thermostat, fan switch etc.

I find the quickest way to cool the FD off is to run at the highest speed with RPM around 2000. That means chugging it around in 5th at a constant speed.

As for temps this past weekend I did 80mph for 250 miles each way with the car loaded down as well as pulling the tire trailer/tools; outside temp about 70 degrees. Car ran at 185F all the way there and back while averaging 18mpg Once the hot 100+ degree Texas summer gets here I would expect it to run closer to 195+F at those speeds and load unless the splitter is in place.

 

Damon, you are forgetting surface area. Bigger radiators and oil coolers add surface area for better cooling.

 

Actually efficiency is what counts. Surface area alone doesn't necessarily help. "Radiator efficiency" encompasses anything having to do with the coolant /radiator/ducting IMO.

I'm speaking of a given situation though, I don't change radiator and oil cooler size while tooling down the road

 

Oil temp shouldn't be rotary specific as it only reflects the capabilities of the oil.

240F is a maximum I've heard and used.

Coolant? Well if your car has the stock fan control system the fans don't even turn on until 227F right? With the parking lights they come on at 207F or so.

 

That's why I debated with you to mount it in the TS outlet housing!

LA trip looks like a possibility soon, BTW.

 

But don't forget the faster you circulate the coolant, the less heat transfer that actually occurs (to a point). This will result in lower temperature figures for the *coolant medium*. As you already know, this is why correlation against oil temps is important.

 

The first part of what you said is not true, the second part contradicts the first part I believe.

If you move the coolant through the rad very fast the heat transfer will actually increase since the average temp of the radiator. This means the delta T, the difference in temp between the air and rad/coolant will be greater, promoting heat transfer.

Heat transfer = mass flow rate* delta T* specific heat

Notice as the mass flow rate increases you'll transfer more heat.

 

That is not necessarily true. Why do you think they put "turbulators" in radiators? To expose more of the actual coolant medium to the heat transfer *area*.

If we pump it through the radiator and water jackets at twice the rate this is not going to equate to twice the cooling efficiency. No way. The only way to increase DT is to expose more of the medium to transfer area - which in the case of a cooling system, requires more of the coolant to come in contact with the transfer area. It's not going to do this if it's hauling *** through the system.

I guess one could say that a turbulator's purpose is more so to create turbulence/swirl rather than "slow down", but I would think the latter is implicit anyways.

DT varies with flow rate, but is not a result of flow rate. Which is why it is seperate in the equation.

Not if your DT is dropping due to less actual coolant volume exposed to transfer area.

 

when i see 117c which is about when the stock guage starts to move i start short shifting

 

Actually I see what you were saying Jeff. Yes, if everything is constant, then increasing flow rate should result in more heat transfer.

I guess I was trying to say that increasing flow rate will result in other variables, which impact DT, to no longer be constant.

 

Clayne, I mounted my sender in the radiator hose about 4" from the T-stat housing. It should give me the exact same readings as if it were in the housing itself, after the t-stat.

Let me know when you are coming thru SLO. I would like to see your car, and BS for a while.

I wonder if anyone actually makes a water pump that flow so fast that it pushes water thru the radiator too quickly to cool properly.

 

*sorry for the double post*

 

sorry to dig up a dinosaur here guys, but i'm getting scared... my water temps (as the temperature here has gone through the roof and humidity too) have gone from a cumfy cozy 90-95C on my PFC up to a scaring me 100-104C in traffic. is 104C too hot to be safe? i see people saying 114C and 117C before they worry... i'm getting my Koyo installed this Monday and will have the cooling system flushed at the same time. am i going to notice a big difference in temps with the koyo than with the stocker? is there any way to tell if my water pump is bad? i just had a brand new OEM thermosensor put in about 3 months ago so i know thats good.

 

Do you have a front mount IC? Do you have the bellypan? Did you change the fan settings in the PFC or still set to default (99C)? How old is the t-stat?

The water pump either works or it doesn't.

 

hahaha, I just searched for this thread to recheck temp levels after driving today...and I see you are at the bottom :p

Me and pugg live next to each other. It was about 90-95 here today, slightly humid. I was seeing 96C and that is my highest in a while so that is why I was searching. Seems I was still in my state of paranoia. pugg57 seems to be getting close to the limits though.

 

Remember, the stock ecu doesn't even turn the fans on to the "low" speed setting until 105C. You guy are still being too paranoid....

 

honestly, I am more paranoid about a hose going...maybe one that got missed or somehow lacerated/damged/fubar when installing my mods and the swaps of the rebuilt twins.

 

does anyone have an answer to my question? what can i safely run... and will the Koyo drop my temps pretty well? judging from runbergs comment (105 is where the stock ECU triggers the fans, i shouldn't be too worried... when i hit 110C i'm stopping and popping the hood, i don't care where/when that is. hopefully that Koyo will make a world of difference.

 

The koyo should help a good bit. I think your smart to either stop/pop hood or do the damonb - 2000 rpm cruise at 110 or so. I see it hit that when I'm doing spirited mountian cruises (uphill).

 

You didn't answer any of mine.....

If you see over 112C, you need to start taking measures to reduce temps. There is nothing wrong with 104C, but it may or may not indicate a problem with your cooling system. Hence my questions.

I seriously doubt the Koyo will make a noticeable difference over stock in street driving.

 

now for my own question. Sometimes I'll see the PFC spike a high temperature hold at 110 or so while the constant is only at 92. Anyone else experience this type of spike? I cant figure it out and decide if I should mind the high number or go off the constant. It seems to sometimes spike high at startup (if the car is warm) then drop rapidly to happy zone (80-90).