Lowering coolant temps on the track

[99redgst]

Here is a little data I collected this morning after a 30min drive. I parked the car, left it idleing and measured temps with my laser thermometer. This is what I found

Exh mani: 800-900F
Turbine housing 900F
O2 housing 650F
Waterpipe at lower radiator end 195F
Waterpipe directly behind turbine housing 350-375F
Waterpipe at WP end 225F

So my theory that the waterpipe is being heated is definatly correct. I would have a hard time beliving that this is not increasing coolant temps before it gets to the WP. Also keep in mind that the temps were measured after cruising conditions with a few pulls here and there. Under track conditions it has to be much higher.

 

[Ludachris]

Here is a little data I collected this morning after a 30min drive. I parked the car, left it idleing and measured temps with my laser thermometer. This is what I found

Exh mani: 800-900F
Turbine housing 900F
O2 housing 650F
Waterpipe at lower radiator end 195F
Waterpipe directly behind turbine housing 350-375F
Waterpipe at WP end 225F

So my theory that the waterpipe is being heated is definatly correct. I would have a hard time beliving that this is not increasing coolant temps before it gets to the WP. Also keep in mind that the temps were measured after cruising conditions with a few pulls here and there. Under track conditions it has to be much higher.

I can appreciate your theory but I really question how much heat is actually transferring to the coolant as it quickly passes through that small area of the water pipe that is hotter. I'm not saying doing this mod will not improve cooling, I just don't know that it would make that much difference. Please do go through with it though. I'm interested in seeing the results and I'm all for being innovative.

It would be really nice if you did the hood vent mod first, did some testing, then did your water pipe mod afterward so that we can see how much it improves cooling temps beyond the basic mods that have been proven already. This way those of us who have done all the other stuff can see if it's worth the big expense and extra work.

 

[Ludachris]

Wouldn't it be cool if we could mount a camera in our engine bay with thermal imaging to see how hot air flows through our radiator? We'd be able to see where it goes or if it just sits there... if only I had a boat load of cash!

 

[99redgst]

It would be nice to do some testing like that. However I will only be attending two more lapping days this year, once in Sept and one in Oct. I would like to do everything possable to lower the temps before going back, not looking forward to running another day of high temps. The track is the only place I have encountered this problem so it would really be the only place to test it. If there is enough interest in this I could wait and just do the hood vent to help out the dsm community.

 

[99redgst]

If I do go back to the track with the waterpipe still in place, I will take my thermometer with me and see how hot it gets there.

 

[stealthTT]

Here is a little data I collected this morning after a 30min drive. I parked the car, left it idleing and measured temps with my laser thermometer. This is what I found

Exh mani: 800-900F
Turbine housing 900F
O2 housing 650F
Waterpipe at lower radiator end 195F
Waterpipe directly behind turbine housing 350-375F
Waterpipe at WP end 225F

So my theory that the waterpipe is being heated is definatly correct. I would have a hard time beliving that this is not increasing coolant temps before it gets to the WP. Also keep in mind that the temps were measured after cruising conditions with a few pulls here and there. Under track conditions it has to be much higher.

Infrared thermometers are great for measuring real high temps without contact, but they can easily lead you to the wrong conclusion. Several things can happen to the radiation that interacts with a surface. It can be reflected by the surface, like light on a mirror. It can be absorbed by the surface, in which case it causes a change in the temparature of the surface. In some cases the radiation can also be transmitted through the surface.

When taking a temperature reading, we may be seeing not only radiation that has been absorbed and is being emitted (that which tells us something about its temperature), but also radiation that is being transmitted through the target or reflected by it. Neither the transmitted or reflected radiation tells us anything about the target temperature.

Aluminum is highly reflective of infrared. It can have an emissivity approaching .05 which means that only about 5% of what the infrared thermometer reads is associated with the temperature of the object. Conversely black electric tape has an emissivity of about .95 meaning about 95% of what the infrared thermometer reads is the temperature of the object.

I would guess that when you measured the water pipe you were also seeing a reflection of the exhaust parts. To come close to accurately measuring it you need to find a way to lower the amount of reflected radiation. You can attach a low reflective surface to the aluminum, allow the heat to transfer to that item, and then read the temperature of your test surface. Black electrical tape happens to work pretty well and the 3M stuff will stand up to very high temps.

If you want to test what I'm telling you, drag the brakes on your car to get them hot. Shoot the shiny part of the rotor. Keep in mind what could be reflected by the angle of your thermometer. Try different angles to reflect off the wheel or your body. Then shoot the outside edge or another rusty part and you'll see it's much warmer. Then put a piece of electric tape on the shiny part of the rotor, wait a minute for it to heat, and shoot just the tape. It'll show up much hotter than the shiny exposed part of rotor right next to it.

You must also be careful of your field of view. Infrared thermometers display the average temperature in a circle of view. So you have to be carefull that you are measuring only what you want to. I've seen guys aim a cheap infrared thermometer at an item 100 feet away and proclaim it's an accurate reading, just because the lazer dot was only on the object. Wrong! You just measured the object, the wall behind it, and the tank of hot water next to it.

This is because many cheap infrared thermometers will have a field of view as poor as 6:1. This means at only 6 inches away you're measuring the average temperature in a 1 inch diameter. At just 6 feet away, the field of view is now 1 foot in diameter. 60 feet away equals a horrendous 10 feet of field of view. Those thermometers are basically worthless unless you can get within inches of the object. My Sentry ST650 (~$100) specs at about 12:1 and measures a spot 2 inches in diameter at 24 inches or 2 feet. My Mikron M7815 thermal imaging camera (~$30,000!) measures a 320x240 array (76,800 individual points) at 70:1.

http://www.professionalequipment.com/category.asp?keyphrase=infrared-thermometer
http://www.mikroninfrared.com/Default.htm

One last item to consider is that even though the piping could be really hot, the amount of transfer to the coolant is going to be significantly less. Metal conducts heat really well. Because it's dense, the molecules collide and transfer their energy very easily. Fluids are less dense and so the molecules have less of a chance of colliding. Water has a thermal conductivity of about .6. Aluminum is rated about 230. Stainless steel is about 15. Copper is about 400. Air is about .025.

But this is only one component of the transfer. The ability for a material to heat up or cool down must also be taken into account. This is called thermal capacitance. Air can change quite rapidly with a small amount of energy. Water needs huge amounts of energy to raise in temperature. This is why water is used as a coolant. It has the ability to absorb and release a tremendous amount of energy.

I would speculate that since you have no way for the hot underhood heat to evacuate from your engine bay, your radiator does not have good air flow through it. Therefore the discharge temperatures are high because your radiator is rendered inaffective. I would follow what everyone else learned the hard way. Put a vent in the hood like the RRE/Carbontrix vent. If that doesn't fix it completely or you want to "fix it once and be done with it", shroud the air flow so it has to flow through the intercooler and radiator.

 

[99redgst]

I have a Raytek MT6 which has a field of view of 10:1. http://support.fluke.com/raytek-sales/Download/Asset/MT6BroEngRevA.pdf

Excellent post. I will be putting a vent on. I guess I wait and see what that does on the track before going through with this. The thing that made me come up with this theory is that I have had several people tell me thier operating temps went up by 10-15F after going to a larger turbo. With nothing else changed on the car it seemed like logical sense that the turbine housing that is sitting closer to the waterpipe was the culprit. Also remember that I have a second reason for wanting to do this, lowering intake air temps. Do you think that the lower radiator hose that is pretty much touching the CAI pipe is having an effect on the intake temps? Here is a pic of my intake setup:

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You can't blame a guy for thinking outside the box and trying to find new ways to resolve an issue.

 

[aaronmatusz]

StealthTT:
That was amazing! Thank you very much for that info, I'd like to get an infrared thermometer and know how to use it too!

Also I agree that airflow is the biggest thing to get right on your cars. After that is under control, it wouldn't hurt to heatwrap or shield some of the sensitive gear near the turbo (the alternator is a good example)...and that water pump pipe is easy to wrap, so just do that first.

 

[underradar92]

Why not also try one of these crossflow radiators. http://www.colemanracing.com/catalog/index.php?cPath=40_257 They are more efficient, cheaper, (you could sell your used bolt in type, and probably be money ahead) and the 27.5" wide one should fit. It would make plumbing neater also.

I've been looking into this sort of setup also, partly to move the upper radiator hose out of the way of a sealed extractor box. Total elimination of radiant heat to the radiator, plus true negative pressure behind the rad.

There is also one with a built in oil cooler.

 

[asian312]

We actually applaud you for thinking outside the box. Like many have said in this thread, anything that helps combat overheating for our cars is always welcome.

I think one of the main reason for the increase temps with larger turbo setups has to due with the tune and the increase in HP. Looking forward on your findings with the hood vent.

 

[99redgst]

I paid a lot less than that for my Koyo. I could have the AN fittings welded on the Koyo and still wouldnt have spent as much as that radiator. I don't think the radiator is the issue. If I didn't already have the Koyo and wanted to reroute my radiator hoses I would consider it, but I see no need to change at this point.

 

[underradar92]

I paid a lot less than that for my Koyo. I could have the AN fittings welded on the Koyo and still wouldnt have spent as much as that radiator. I don't think the radiator is the issue. If I didn't already have the Koyo and wanted to reroute my radiator hoses I would consider it, but I see no need to change at this point.

Cool enough (pun?) just an idea.

Which 2 track days? Is the F-body in Oct. one of them?

 

[99redgst]

They are both in Shawano. At USAIR http://www.usainternationalraceway.com/trackmap.php

I help work the event so I am there all day. You have to work every other hour, when your not working you can spend as much time on the track as you want. You also get a reduced rate. If not working the event it is 65 for 4, 15 minute sessions. It is a karting track so it is slower tighter course, but it has a lot of elevation change which makes it fun.

 

[talonTSIDriver]

I will be adding a hood vent on my 2g very soon. I experienced temps over 220 after a few laps (at the Shawano lapping day), and probably should have pulled off the track, but when catching a Z06, i just could not get myself to pull of the track until I passed him.

 

[schemauer]

My personal (very unscientifically proven) opinion is that the coolant is moving so quickly through that coolant pipe that bypassing won't make much difference. I wrapped this pipe with a heat relfective material on my car and noticed no difference in coolant temps. However, I have no way of measuring if - or how much - this may have decreased the outisde temp of that pipe.

A couple of data points on the overheating issue.

On my '95 Eclipse GSX I had an overheating issue on the track. The car still has AC and also a FMIC. The biggest difference in coolant temps came when I made some changes in the front end of the car (ducting) to make sure that any air that entered the front of the car had to pass through the radiator. This involved blocking off the area below the FMIC where air could escape. Also closing off the small gaps on each side of the radiator. Even blocking the small gap between the top of the radiator and the frame just ahead of it. I'd do this before anything else. As mentioned above, wrapping that coolant pipe on this car made no difference.

My Archer Talon track car has the stock radiator, only one rad fan and an upgrade SMIC. This car never runs hot - even on very hot days at the track. I see a max of about 220 deg water temps. The coolant pipe is not wrapped. There are some plastic ducting panels that were added to the car by the builder to direct all air through the rad. The hottest the car ever ran was at that small track in Shawano. Just not enough airflow at those slower speeds to keep anything cool.

 

[underradar92]

FWIW, you could add another small fitting to the lower tank and route a heater hose in that way, and not have to deal with foggy windows on cooler evenings, when turbo cars run their best.

 

[stealthTT]

As others said:

-do think outside the box, but remember or learn intermediate physics and fluid dynamics

-increased temps are due to more hp and therefore more heat in the engine to reject with the coolant

-fmic causes a big pressure drop at the front of the radiator reducing the pressure differential

-you need to either increase the pressure on the front side by ducting or reduce the pressure by venting

-venting typically creates less drag, so I prefer to start there

Also, the radiator pipe will add very little heat to the moving air in the intercooler piping. Air has a thermal conductivity of about .025. You'd need a HUGE temperature differential and area of contact to make any significant change.

 

[Ludachris]

Once again, we love seeing people think outside the box around here. We need more innovation!

I think the intake temps will be more affected by trapped underhood heat than the heat coming from the lower coolant hose, but even then it's minimal. You can always wrap the intake pipe with reflective heat wrap/tape. That's what I'm going to do at some point - along with all of my I/C piping.

And as others said, the increased operating temps from a bigger turbo is mainly due to increased horsepower and the engine having more stress put on it.

 

[99redgst]

Well, I am going to start with the vent and some sort of ducting for the radiator. I think I am also going to get one of those turbo wrap kits. They claim they reduce spool time, I am interested to see if that statement holds any water. If I can reduce my spool any more I will be ecstatic. I recently put on a cylone intake manifold that reduced my spool by 300-400rpms, so if I could gain more that would be great. Even if it just contains some of the heat it will be worth it though. I'll probably also heat wrap the O2 housing and down pipe. As well as use some reflective barrier on the lower IC pipe and intake pipe.

 

[Evan K.]

At what point are you spooling now?

 

[99redgst]

I get 20psi by 4k on a PTE 50trim(nonBB) with FP2s and a stock 6bolt and cyclone intake. I used to hit 20psi at 4400-4500rpms with the stock 1g intake mani before I installed the cyclone.

 

[nightspeed87]

My car used to run a little hot even in just regular street driving.
I know anything over 206 pulls 1deg timing, I would love to see my temps stay
between 185-200 under all conditions... Logger showed it get up to max of 210 ( spirited street driving.)
But it was about 95 degs that day ( FL for you. )
I have a 180deg thermo, stock radiator and hoses, one stock fan
metal sbr heatshield ( placed on top of the stock heatshield.) temps are ok but get a little
to high when i start to get on it a lot. Mainly radiating heat under hood and that is why this thread has interested me in doing hood venting.
Also 99redgst, do you have your coolant fan wired to run full blast all the time?
Mines comes in with the ign, and has helped reduced temp due to not allowing
things to heat soak as fast from the get go. And the ducting under the fmic
and shrouds to the radiator helped a good deal also. I run straight distilled water with water wetter,
no coolant. I plan on getting a koyo soon.

Off subject, but did you port your cyclone?

 

[99redgst]

I have the Spals wired so they will both turn on full speed when the AC button is turned on, otherwise they turn on at 200 by themselves. This is acctually an issue I no longer have to worry about. I am parting out my dsm. I will be getting a 3rd gen RX7 and swapping in a LS1, that will be the new track car. On a side note, no I did not port the cyclone. Both the cyclone and Koyo w/spals are up for sale if you are interested in either.

 

[Pro3racer]

RX7 w/ LS1, FTW!!! I may actually continue researching this idea, the only thing I would have to figure out is my coolant return line.