Cossie

My car had a koyo installed recently

After long distances or after 25-30 mins track sessions(with cool down lap) I will have water temps of between high 80s to low 90s C. When I pull in and idle, water temp stays the same.

When I turn off the car and watch the water temp, it would rise to 110ish. I would then have to either start the car or move it around to cool it down more.

Even with the fan on but engine off, it would still rise.

So much for a 'good thick core'



Anyone else has such a problem?

Oh, I run 10psi of boost...

suprfast

i too have noticed that i get a little heat soak(from my belief) while waiting in traffic, idling, low speeds. i noticed that when on the freeway my defi reads about 170F. i have nothing to compare this to as i installed the gauge at the same time as the radiator. if i had to do it again i would install the gauge first and might go with the fluidyne just for soak problems. again, i cant confirm that my radiator is actually heat soaking as i dont ahve anything to comare it to. just feels like it gets hotter than what i like it to. when the fans are on(pulled AC relay) my temp never reads over 85C or 190F. that sounds great to me though. this is even cruising around town senslessly for hours(i get bored and just love to drive her)
kris

ttb

i have a koyo and if the temp starts rising because of idling or stop and go traffic, turning on the A/C always brings it down to high 80 C. so i don't think my koyo gets heat soak, but maybe i dont push it as hard as you on the track. now the IC...once the temp goes up there's no way I can get them to go down.....

ttb

>> Even with the fan on but engine off, it would still rise.

i don't think you can avoid this. my understanding is w/o the engine on the coolant is just sitting there, not circulating, so even with the fan running can it be that helpful? where is the sensor located? if the sensor isn't where the fan is the temp will just rise/remain the same.

red 7

mine has always done that ever since i put the power fc in, watching the commander of course, its been about 2 years of PFC and only about 6 months of koyo and it still does the same after i turn the car off then turn ign switch to on after a few min and its around 110 c

I thinks its pretty normal cause your engine isnt on turning the water pump to circulate the water through the radiator no matter what size it is. the water is in the engine just soakin up the heat.

if im wrong someone let me know cause mine has always been like this

sometimes i just let the fans run for a few then crank the engine to circulate the cooler water in the radiator and then shut it off after i check again the temp goes back down

neevosh

When the car shuts off, coolant stops circulating. If you guys are worried about heatsoak, pop the hood after you shut the car off to let the heat escape. There's not much else you can do.

skunks

do you pop your hood like neevosh said?

rynberg

Any car heatsoaks after shut off, it's just more of an issue with the FD because of cramped engine bay, twin furnaces, etc.

The best thing to do is to simply lower the temps as much as you can before shutting down. Popping the hood would help also. I never shut the car off with the temp above 190 F. Even doing that, I have recorded peaks (with the Defi link series) as high as 220 F after shut down. I don't think it's something to really worry about, but I wouldn't shut off the car with temps above 200 F either.

cover8

well for those of you who have not have heat transfer in college...the problem with the thicker exchangers (intercoolers too) is the pressure drop across the heat exchange surface. Ideally you would want a thin film with greater length/width surface area to minimize the pressure drop of the cooling fluid (air)...thicker exchangers need great cooling fluid flow (air) so the all of the exchange surfaces are contacted. (the catch phrase is "thin film")

A good example of this phenomenom is looking at evaporation...take some petroluem ether or acetone (for those of you that dont have a meth lab) and fill two bottle caps....take on bottle cap and spill the contents on the counter and spread it out...compare the rate of evaporation to the other bottle cap that was not dumped. This reveals the importance of immediate surface area contact with the cooling fluid. The volatiles that you spilled on the counter will evaporate far quicker than the solvent in the bottle cap. The functioning mass transfer surface area is far greater for the spilled solvent that the solvent in the bottle cap.

This can be explained mathematically...

q = -kA

where q= conductive heat flow

k = thermal conductivity (different value for different materials)

A = cross sectional area (key words: "cross sectional" not "total area")

adam c

iTrader: (2)

There is something you can do. I did the fan mod on my car. It keeps the fans running for 10 minutes after the car shuts off. It significantly lowers the under hood temperatures. Check it out:

http://www.scuderiaciriani.com/rx7/fan_mod.html

Garrett

First make sure both fans are coming on line. My car used to skyrocket up to 116 C with the car off. I found out that one of my fans wasn't coming on. I couldn't believe I didn't notice my fan not working. Every time I would look it seemed and felt as if they were both coming online but because the intercooler was in the way I couldn't see that it didn't function.

During all this I learned ways to reduce my temps. Leave your hood open and the ac on (with the engine off) for around 10 minutes. On the other hand you could do the fan mod or you could use a turbo timer if you have one and time it for 10 minutes (that's what I did). If you have a PFC or some kind of engine management, program your high fans to come on at around 87 C and you want have any problems. I did that and don't think much about replacing my radiator or watching my temps as compulsively as I did before.

garrett

yzf-r1

iTrader: (1)

great post cover

the problem is, there isn't enough room in an FD for a thin exchanger with a very large surface area

so far my PWR seems to be working great

cover8

Agreed...although there is a drawback...the q=-kA equation is reversible...so it is important to realize that heat transfer rate can heat-up as fast as it cools down.

Really it boils (pun intended) down to an energy balance...if you create more BTUs then you remove you will accumulate and soak.

jimlab

One thing I didn't see anyone mention is that it's not the Koyo radiator that's at fault for the elevated temperatures after shut-off.

The coolant temperature sensor is not on the radiator... it's on the filler neck of the water pump. The heat of the engine is going to cause coolant temperature in the engine, water pump, and filler neck to rise after shut-off, no matter how large or small your radiator is.

If you're concerned about temperature, you need to find a way to keep engine coolant flowing after shut-down (an electric water pump, for example) and a way to move air through the radiator when the car isn't in motion (a switch to turn on your fans), if they're not coming on automatically.

spurvo

Heat soak is due to turbo housings. With the temp gauge at thermostatic minimum, the ONLY engine part that is much hotter than this are the turbo housings. I measured it with a thermo couple. Even during normal part throttle cruising, these get to up to 500C!! When you shut off, the heat (literally wiggling iron atoms) has to go somewhere, and that somewhere is into the engine block. With the coolant stopped, there is nothing to transfer the heat to, so the block temp just rises, and the coolant with it. That's why the gauge reads higher (I know, duh!!). Even turning on the fans after shutting off does no good, as there is no way for the coolant to circulate through this nice heat sink. The only way I've found to cool the turbo and eliminate heat soak is to cycle the temp. You idle it and watch the temp go from 177F (thermostatic minimum) to about 205, then kick on the fans and bring it back down to 177F. Do this three times, shutting off after the third. I've seen turbo temps go from 450 C to 300C or so. Heat soak goes from a 33F rise (177 to 210F) to about a 3F rise (just peeks at 180 )

I want to put an auxillary cooler in my front end that takes the coolant from the turbo, runs it throgh the cooler, then inserts it right after the thermostat (but still on the low pressure side of the water pump). Probably needs an electric pump. Which would fail. And boil the coolant out of my engine. Causing an engine fire. Making my pretty silver paint... darker.

Ooohh, I know! Pull the turbos!! hee...

Shinobi-X

I'm running the stock radiator, and when I turn on the fans, the car stays at a steady 180F.

SleepR1

Cool running motors around here. My new street ported KDR 13B REW with J-spec twins, GReddy Type 24 V-spec FMIC, Koyo, GReddy Airinx runs 85 C (185 F) during the Indiana winter months! Highest I've seen thus far is 86 C (186.8 F). The water temps are read from the Power FC Commander. The Power FC kicks the rad fans on at low speed at 86 C (186.8 F), high speed at 87 C (188.6 F). I have my first track event March 22 with the new motor, J-spec twins, FMIC, intake, and rad setup; I'll be interested to see how the water temps fair with hard use at Putnam Park Road Course www.putnampark.com

israel

iTrader: (3)

and who in kansas city doesn't have one of those?

the electric waterpump sounds interesting, i know it's been discussed on the forum before. does anyone run/know about
this ?

spurvo you said an electric pump would fail? please elaborate? or were you just thinking?

f***!! pizza burning, damn informative threads!

jimlab

http://www.flatlanderracing.com/meziereimport.html

The only problem is that once you eliminate the water pump, you have to find a new place to hang your alternator.

spurvo

Just pretending to think I always liked the fact that a failing mechanically driven water pump gives some warning (noise and peeing) before failure. I just caaaan't imaaaagine the possibility of an add on electrical part failing in an FD. Never happens, right?

jimlab

The Meziere electric pumps are rated at 2,500+ hours of service. I have a Meziere on my engine...

yzf-r1

iTrader: (1)

I need to adjust the brightness on my computer

DamonB

I have the stock radiator but installed shrouds around the radiator mouth. My temp gauge (in tb coolant line) won't budge over 180F (thermostat temp) unless the outside temp is above about 50 degrees. Highest I have been able to get it on the highway is still under 200F. My Miata thermoswitch will kick the fans on high at 205 (only when sitting) and the motor cools NOW; the fans typically run under a minute. Anything under 200 is a very cool running motor IMO.

I am still interested to see what happens during our nice hot Texas summers though.

spurvo

Damn thing looks like a silver heart transplant.... oh, right

I'm all for the electric, though service life of 3 years is a little short for me if it was the ONLY pump I had. My thought had been to run an auxillary system to provide extra cooling for the turbos under long term part throttle applications. I fully recognize that typically the thermostat cycling at freeway speeds provides adequate cooling, but I STILL want that turbo as cool a possible, in a perfect world. Anyways...

Three years was two hours driving per day (weekend jaunts amortized into daily average) per week for 52 weeks divided into minimum service rating listed above. Again, not like anything electrical on an FD might fail.... just because!

Hey, do you ever let novice junkies come by and drool on your shiney bits? You know, so I can bore you with the details of my travails with NW Differential. Feel free to tell me to eat me (huh?)!

jimlab

You had a problem with NW Differential?

Sorry, I don't have any shiny bits. They're all being stored at other people's shops.