My engine coolant temperature guage has been getting a bit high on the track, so last time I was there I datalogged the coolant temp using Cipher. During the 25-minute run session, my coolant temps reached about 240 degrees Fahrenheit (116 C), and finally peaked at 246 F (119 C), before the run session ended. The ambient temperature was about 92 F.

I am running a stock radiator, stillen oil cooler, with the following mods: plenum, headers, high-flow cats, and fujitsubo exhaust. I drive it pretty hard, either on the gas or the brake most of the time, much of it WOT and high RPMs.

I plan to install the Koyo R-Core radiator to hopefully keep the engine cooler. If anyone has any additional advice or input, I'd appreciate it.

Here is the graph of coolant temp over time (the scale goes from 90 C to 119 C):

 

i don't have any suggestions other then what you are doing. however I would like to hear back from ya when you get that radiator put in and and log some temps.

edit: would suggest therm also

 

Running a mix of 100% water + water wetter definitely helped with my temps as well. Distilled water cools better than coolant.

 

That is the most stupid statement I have seen on these forums in a while. Distilled water DOES NOT cool better than Coolant. Distilled water BOILS like any other water. The coolant is what prevents it from boiling and keeps the temps down. Do it this guys way, you will overheat your car real fast.

I would recommend just some good coolant, 50/50 mix, water wetter, and use some Amsoil (which does help keep the engine cooler over other oils).

 

coolant isnt there too cool, it raises boiling point, lowers freezing point, and prevents corrosion to the metals in the motor.
im interested to know what my car gets up to after 100 miles of racing/enthusiastic driving on mountain roads

 

Might want to rethink that.

Water has better heat transfer properties than any glycol based coolant. As a result, straight water does cool better than antifreeze. As long as the water is kept under pressure in a sealed radiator system, the boiling point will be elevated enough that boiling isn't an issue.

Glycol based coolants raise the boiling point and lower the freeze point. They also provide lubrication for your cooling system. They do not however transfer heat as well as water. Hence water cools better.

http://www.peakantifreeze.com/tech/tech_c.html

From the fourth paragraph......."Water is an excellent conductor of heat. Glycols are not as good of heat conductors as water. As the concentration of glycol increases, the heat transfer ability of the mixture decreases."

So basically the less coolant you have in your car, the better heat transfer and therefore faster cooling.

 

Then go ahead put water in your radiator by itself in your car. Don't come back to me when your car overheats and blows a head gasket real fast on the track.

 

For correct info please see link: http://www.centuryperformance.com/coolingsys.asp

Copy and Paste a few items:

Most liquids have a specific "boiling point", which is the temperature at which the liquid begins to change to a gas. If pressure is applied to the liquid, it must become hotter before it can boil. Pure water in a cooling system will boil (at sea level) at 212° F. At higher altitudes, atmospheric pressure is less than at sea level. Example: Water at 5,280 feet will boil at a mere 203° F. A cooling system that is under 15 pounds of pressure however, will now allow the water to reach nearly 250° F before it can boil. Even at this temperature the water is able to circulate through the engine, cooling parts that are at a much higher temperature without the water boiling. As long as the coolant remains in liquid form it can do it's job and transfer heat to the radiator so it can be dissipated. Coolant that is boiling cannot transfer as much heat and engine overheating is likely to occur if the coolant turns to a gaseous state. Steam adjacent to a hot surface, such as a combustion wall, can actually act as an insulator - thus preventing any heat transfer to the coolant.
Pressurization of the system is achieved by a special radiator filler neck and radiator pressure cap. The filler neck has an upper and lower sealing seat with an overflow tube connection between them. The lower seat is engaged by the pressure controlling valve on the cap and the upper seat (in an open system) is engaged by a spring metal diaphragm in the cap. The radiator pressure cap features a spring pressure relief valve which closes off the lower sealing seat in the filler neck. This pressure relief valve allows pressure to build up to a specified level, the permits excess pressure to escape through the overflow tube when it exceeds the range of the pressure valve spring. This valve protects the cooling system from damage from excessive pressure. This pressure relief system also includes a vacuum relief valve that allows air (in an open system) to enter as coolant contracts. This prevents the radiator hoses and tanks from collapsing from the partial vacuum that would be created if air was unable to enter.

 

Even though some time ago water alone was used for many years in automotive cooling systems, the fact that it only has a 32 F° freezing point, a 212° F boiling point, it evaporates easily, creates rust and corrosion, and leaves mineral deposits has made it less than optimal as the sole coolant. It is much more efficient to utilize a chemical added the the water to improve the efficiency of the coolant. This chemical is commonly called "Anti-Freeze", but the more accurate name is ethylene glycol (EG). In recent years (EG) has been replaced by propylene glycol (PG). This is a much less dangerous chemical.
Since antifreeze as a 50-50 mix with water elevates the boiling point to 227° F, and lowers the freezing point to -27° F, it should also be called anti-boil. Good quality antifreeze contains water pump lubricants to help maintain the efficiency of the pump, rust inhibitors to keep unwanted deposits from forming, and acid neutralizers to help protect the inside of the radiator, heater core, and hoses from corrosion.

Of course, antifreeze does not last forever, so it is recommended that the coolant be changed at least every two years or 24,000 miles. However, many vehicle owners allow do not follow this service interval and allow their cooling systems to become rusty, dirty, or clogged with mineral deposits. This causes water pump and hose failures, poor performance, overheating, and other component failures. To eliminate these problems it is best to have your vehicle's cooling system flushed in a professional shop that flushes and filters the coolant in your engine using equipment that is not only effective, but environmentally safe. The old way of simply using a flush kit with a water hose is illegal in many states and districts, and should not be attempted if you give a care about your family and the environment around you.

Over time leaks can develop in the cooling system. If these leaks are not corrected you will lose excessive coolant which can cause overheating and engine damage. Although many leaks can be fixed as easily as tightening a hose clamp, in many cases you may still need to replace hoses, the water pump, various gaskets, or even radiator or heater core repair or replacement. Some chemical additives call "stop leaks" or "sealers" have been developed to stop some minor leaks from inside the cooling system. Most chemical sealers are derived from solutions which contain thousands of small particles that upon coming in contact with the leak will collect in sufficient quantity to where they clot up and stop the leak. These chemical sealers should only be used as a short term fix in certain circumstances, but can be quite effective. Just remember to only use them in moderation. Excessive use can cause other problems and they do not seal all leaks.

 

You're both right. Water does cool better but it's boiling point is much lower. Even with raised pressure you can reach the limit. Worse while the average temp might be below the boiling point, the temp at the cylinder heads is going to be much hotter and trapped vapor at that point can lead to detonation and engine damage.

I would recommend running the ForgedPerformance upgraded fans/shroud along with that Koyo radiator. With that added cooling, you can consider a pure glycol based coolant like Evans NPG+ that eliminates water vapor related issues. It does not conduct heat as well as water, but due to high thermal transfer associated with nucleate boiling, it can manage higher heat levels in a manner that is safer for your engine. You can reference more technical information at the evans web site : http://www.evanscooling.com/html/npgPls.htm

 

where is your a/f? do you measure egts? maybe you are a wee bit lean?

do you have the stock bumper?

 

I have the Evans and FP upgraded fans. I drove the car for a 30min session 90% of the time over 4.5K shiftting @ 7K. It would rise to about 246 and stay there if driven above 4K. On my cool down lap it dropped down to 190 in about 3 turns and stay there till i pitted. This is with two big turbos.

 

I think what you posted supports my claim. Water under 15lbs of pressure doesn't boil until 250 degrees. If you are running your engine at that temp, then you are asking for trouble anyway. At any temp above 250 I agree with you 100%. So you are right.

However..At the temp range I try to run my race/track cars 190 - 220 water does transfer heat better than glycol based coolant and therefore my cars will run cooler on straight water.

Based on that I still assert that the OPs statement is not the "most stupid statement" as you have posted and perhaps you should apologize for that.

 

This statement is definitely uncalled for especially when it is based on ignorance.

This is only 1/2 true. Coolant does prevent boiling by raising the boiling temp but does NOT keep the temp down. If that were they case why do you bother mixing it with water at all?


Pure water has 2x the heat transfer capability as a 50/50 mix however it has 2 drawbacks. First it is highly corrosive to metals and second it has a high surface tension. What a high surface tension does is causes local boiling. As you have mentioned, actually quoted boiling water has horrible heat transfer properties. In other words hot spots in the engine can cause boilover even though the whole system is not "overheated". The solution to that is a product like water wetter that inhibits corrosion as well as coolant and lowers the surface tension of water. Joeygill response was actually much smarter than yours

The only reason I can see running some coolant is if you are in a place where the temperature drops below freezing as watter wetter or the like does nothing to lower the freezing point.

oh btw distilled water has less impurities and therefore less corrosion properties than tap water so that would make sense as well.

my $.02

 

Opinions are like *******s, everyone has one and it stinks

Anyways, say what you will...but you may want to know that SCCA mandates that all their race cars run ZERO coolant. They only allow WATER + Water Wetter (or similar substances). Albeit this is for safety reasons, however if water boils in the radiator like you say it would, then I guess all race cars are run on boilling water.

This is an excerpt from a NASA rule book:-
7.9 Engine Coolant
The only engine coolant used in the radiator shall be water, though surfactants such as Redline “Water Wetter” or Neo Synthetics “Keep Cool” are allowed. The intent of this rule is to avoid slick track conditions produced by spilled antifreeze, not to limit water additives.

You can read the full rule book here http://www.nasaproracing.com/rules/SE-R-Cup.pdf if you so please.

Oh and by your explanation, my radiator water should have been boilling when I was running the track on a humid 95F+ day with just water + water wetter.

 

I feel sorry for your Z. Either you're reporting information you've heard from someone who has no idea what they're are talking about...or you yourself don't understand certain heat transfer properties.

Coolant's main advantage is in climates which experience "winter-ish" temperatures. But you live in the south, so...I guess it still wouldnt be much of an advantage to you?

 

No sir, read the article I posted. I wasn't wrong on what I said.

Coolant does not only help with winter temps. lol.

I have raced for 10+ years, I know a few who had water in their cars, they limped home after 2 laps.

 

if you're at the track, and there is no chance of rain, remove all the black plastic shrouding by the wiper blades.

ie:



i noticed a 10 degrees cooler water temps after i did that.

also you could add a vented hood (or get one of my vents i'm making) and that will help the airflow from the back of the radiator.

are you running the stock undertray? whats your front bumper like? oem?

 

The reason why you noticed a drop in temp, is because you removed the rear seal around the hood itself. What I did on my G, was cut a hole in the middle of the windshield at that seal and pushed it apart by about 3-4 inches so it had a hole that allowed the heat to escape. This help a lot.

 

I am not disagreeing just asking.....

With respect to removing the engine seal I have heard from a couple of Z drivers that this helps cooling. However my experience in other cars is that it doesn't help (in the case of my FBody it actually hurt) due to the base of the windshield being a low pressure area. I tied yarn to my Trans Am (at the back of the hood) when I pulled the seal and it actually was sucked (or pushed) inside the engine bay by the low pressure instead of being blown out.

Many race/drag cars (including NASCAR) actually pull air from that area for the intake.

Is there a difference in the Z design that allows this to work?