Result: Excessive engine wear
no affect on cooling. Thermostat doesn't help cooling (heat transfer) it only helps warming up which you need, absolutely must have rapid warming up.

200*F coolant is ideal. 202-212*F actually is ideal. Do not run below 188*F coolant temp in any combustion engine that you care about unless the oil is fully warmed already to 210-215*F and the engine has been built with looser piston-to-wall clearance to account for the colder coolant temps with hot oil, like we do on boat engines running cold lake water 165*F no issues 212*F oil with properly set piston to wall.

I Recommend: use a stock balancer, get rid of under drive.
Consider running higher quality fans. Ensure voltage at the fan is fully alternator voltage above 12.8v to 13.2v (14v would be good- upgrade the wires and quality grounds)
Use as much water as possible, water is superior to any anti-freeze solution. Do not full rad with ONLY anti-freeze, more water is ideal if you don't freeze it.
Investigate the duct work and shroud. Look for holes between fan and radiator. Even a tiny hole makes a big difference.
Look carefully at the ducting for ideas. Look for debris and spacing issue.
Consider insulating the exhaust system with ceramic coatings, heat shields, or exhaust wrap. This will cool the engine bay down allowing the radiator to move more heat per unit time.
I do not recommend a vent, such as hood or fender style venting. This should not be done.

Summary: Focus on bringing down the temp around the radiator, improving airflow, increasing insulation around the engine, upgrade the wires and fans, avoid underdrive pulleys, use as much water as possible.

 

Not sure why you wouldn't recommend a vented bonnet? It allows more heat out engine side and improves pressure ratio to the benefit of flow through rads. My oil and coolant temps dropped ~30f with vented hood, no other change.

Now drag wise, that's a different story but I don't think many really care about that aspect.

 

+1 on what @Kingtal0n said. You want to make sure as much air as possible is passing through the radiator and not around it. A vented hood (bonnet) might help, but it is masking the underlying issue here. Swap out the UD pulley and seal up the radiator shroud and I bet OP's issues are resolved.

Also, make sure your oil temp is up to normal op temp before you start hammering on the pedal. It takes a good 10min of easy driving before mine gets to ~160°F. Its amazing how much smoother my Z06 is once it is up to proper temp...engine and transmission.

 

Excessive or unnecessary venting creates an energy leak. It will reduce economy and efficiency. It could lead to excessive carbon deposits and uneven distribution of heating air along the intake pathways, create unwanted disparities of heating the engine bay, and other potential issues. Automotive manufacturers go to great lengths to fully insulate the engine to prevent energy loss and reduced economy, and they intent to rapidly, fully warm intake air completely to avoid distribution issues leading to carbon deposits, poor vaporization of fuel at low speed, and low velocity and lost organization of intake airflow at low speeds.

I'm not saying venting doesn't have it's place. But a street car isn't one of them.

 

It does play a significant part in the system if it's a 25% UD. If you're running Propylene Glycol, instead of Ethylene Glycol, youll notice a huge effect whan coupled with a 25% UD, in extreme heat. I learned the hard way. 240° coolant temps at 70 mph freeway speeds IS significant. Been there, done that. Learn from my mistakes....

 

Yeah that was kind of my point. For oem design, sub optimal. For aftermarket mash-up on a c6 z06 a vented bonnet does work to drop oil and coolant temps....

 

Didn't see that it was 25%. That's a lot smaller. Mines a 10% running on just water and water wetter with a fully sealed shroud. Runs fairly well in Az summer heat

 

It depends how the vehicle is used. The guy mentioned alot of slow speed driving, that is when the excessive cooling/carbon and low velocity air is an issue.

With respect to economy, kind of like a grill. If you have a grill overheating then open the lid, let the heat out, that is like a car at WOT losing heat rapidly, very poor BSFC lots of wasted fuel but it keeps the engine safe.

On the other hand, grill is 350*F trying to cook some meat at the right temp, leave the grill lid closed. If you open the lid while cooking at the ideal temperature, then it will require more fuel (gas) to keep the same temperature.

So, cruising along, losing heat with the grill lid open, if the vehicle spends a lot of time doing that it is throwing away fuel, money, energy, and it may contribute to carbon coatings.
On the other hand, like you say- lots of WOT, big power inefficiency, trash the heat, bring down the temps.

It depends why the temps are high in the first place. I've never needed a vent even at 1200rwhp the fuel is sufficiently to cool the engine with the right oil cooler, fuel choice is a part of the solution, as alcohol fuels will help engine maintain low IAT and low cylinder temps, while the right oil cooler is instrumental to maintain block temps. Radiator cooling and hood venting solutions are... really a last resort. Like if you can't fit the right coolers, fans, radiator system, for some reason. Lack of fabrication skills I guess. I can always seem to manage but not everybody has a full fab shop and 3-phase tig handy, easier just to cut a hole somewhere. For me, the name of the game is control. Control theory to control temps, pressures, surface contacts, vibration/energy, etc... and a hole anywhere is loss of control. I never like to lose control. Maybe a vent with a switch to close it would be okay.

 

What no one is mentioning is the fact he has a 160 stat. That means that it's always open, effectively the same as no stat at all. Instead of working the way it's supposed to (opening and closing to regulate flow of water into and out of the radiator) it's open all the time and water doesn't have time to exchange heat in the radiator.

A 160 used to be called a "winter" stat because outside temps in very cold climates wouldn't allow the engine to get up to temp. A 195 was called a "summer" stat because the water needed more time in the radiator to shed heat.

Back to basics.

 

Engineering inevitably speeds up the water pump impeller to increase coolant flow when an overheating issue is experienced, reducing the time the coolant spends in any one location. As Kingtalon stated, a thermostat controls how fast an engine warms up. It controls the minimum heat the engine coolant will experience. I don't know where your location is, but in Michigan, we never had a "Winter" thermostat, or "Summer" thermostat. If we ever decided to have such an unconventional setup, the figures you list for each season would be exactly opposite what you're saying. In cold weather, I'd much prefer a 195° stat over a 160°!!! The 160° would be more popular in the Summer......

 

You've got it exactly backwards, which is very common. In your version, as is happening for the op, the start would open once and never close. In the winter it would take a very long time to open and the hot engine would then be filled with very cold water, potentially enough of a difference to make a crack. Talk to any good radiator shop and they'll agree.

 

No, I don't, and no, they wont. I had a friend who ran a good radiator shop for over 30 years. But I don't need to talk to him. I've had physics classes which support my opinion. Impeller speeds are always increased to improve high coolant temps. That is fact. If you think the coolant flows thru the engine too fast, and doesn't have time to pick up any heat, next time your cold outside on a windy day, you can remove your coat to warm up. The wind will now blow by so fast, it won't have time to pick up any heat, so you'll warm right up. If the radiator size is sufficiently sized and matched to proper impeller speeds, it will easily spend sufficient time in the radiator to dissipate heat. UD balancers contribute to higher coolant temps. But, the coolant now spends more time in the radiator, because the pump spins slower, so that can't be. OK. BTW, GM engineers created a brutal test for the LS7 when they developed it. They alternated feeding the water pump approx 32° temp coolant, then fed it 200°+ coolant, back and forth approximately 100 times, and nothing cracked. It takes a LOT to crack an aluminum casting, otherwise off road vehicles like dirt bikes, 4 wheelers, etc., would crack engine castings as soon as they went through a deep puddle, or small body of shallow water. I'll agree to disagree.....

 

Ooo I love this kind of myth, or misunderstood at least. This is a tough one to visualize, no shame.

The cooling system is a closed loop. If the water spends less time in the radiator then it also spends less time in the engine, the difference between the two temps becomes less but overall the cooling ability of the radiator is unchanged, same surface area and ambient temp, heat is removed at some rate from the entire system at once since it is a closed loop. Unlike lake water cooling for boat engines using lake water, where the system is OPEN loop and fresh cool water always tries to enter the engine, must be pre-warmed or it can crack a block or cause issue with cylinder galling, ring wear, whatever.


If we remove the thermostat completely then water will be the same temp in the engine as it is in the radiator, with only a minor difference between them, all the time, does that make sense? In other words- IF we flow constantly very fast water through the entire cooling system then by action of their exchange rate they will have the same or similar temperatures, only slightly warmer in the engine where the heat is added.

This is what started the sort of myth of 'water doesn't spent long enough in the ...._______". Imagine we removed the thermostat from an engine, but we set our fans to turn on at say 200*F. Now, the radiator must reach nearly 200*F to warm the engine to 200*F, since the water entering the engine needs to be 200*F for our fans to turn on and to keep the engine near 200*F. That means the water entering the radiator needs to be warmer than 200*F since the radiator will cool the water some, maybe a couple degrees. We wind up with an unfortunate side effect of fast constant water flow when cold- the radiator is taking forever to bring the engine up to operating temperature, and the heat lost constantly by the radiator during this warm-up period is lost energy, lost efficiency, lost economy, and excessive warming up time which leads to excessive engine wear and tear. Not good. We must use a thermostat.

... Any thermostat
Now, lets look at a 160*F thermostat example. The thermostat stays closed until the water at the engine inlet can reach nearly 160*F or so. There is a range like with a wastegate where it 'cracks open' not fully open so we can't say for sure 160*F- maybe its 158 to 162 range or something. Anyways.

Around the cracking open point of the thermostat cold water from the radiator can flow into the water pump region- a region specifically designed to mingle hot engine water with cold radiator water just before it flows into the engine. At first, the water entering the thermostat may be 80*F or so, while the engine is ~166*F in this example, cracking open thermostat to let in 80*F water which will mix with 166*F water and bring the temp down back to 158*F where the thermostat will close tightly again. The fans, lets say are set to 200*F, they stay off the entire time. We initially recognize that it only takes a little tiny bit of 80*F water to bring the 170*F~ water back to 160*F while the engine is warming up, the rad can stay cool for quite a while, while the engine is warmed up rapidly to the thermostated setting.

However. The fans never kicked on, right? Because the water entering the radiator at the setting point is still much less than the fan turn on temp.
So, when do the fans kick on?
Lets say 200*F fan turn on, 190*F fans off. This is like my gasoline daily driver turbo set point (actually 196*F on 188*F off)
It matters where we measure, I use near the head exit point to the radiator, water coming out of the engine, not going INTO the engine which is much cooler.
Anyways- so lets look at this situation.
How did we raise the temperature of the engine to 196 or 200*F? We let the water coming in become near 170-180*F something like that. Which means the thermostat is open, staying open. Not closing. When the fans kick on at 200*F, the thermostat is open. The fans turn off at 190*F, the thermostat is still open. It will not shut until 160*F or less, right? So, basically, it does nothing. Its almost exactly like having no thermostat at all.

Lets look at another example, this time 185*F thermostat. I set my fans to 205*F and off at 195*F.
The fans come on at 205*F- thermostat is open, water is free flowing through radiator and engine.
The fans turn off at 195*F- thermostat is open, water is free flowing through the radiator and engine.
Again, its like the thermostat isn't even there. The thermostat does nothing to cool the engine. All it can do is rapidly warm the engine to it's pre-set temp and then meter water gradually at that temp until the whole closed loop system can be fully warmed to some minimum temp where the thermostat remains open the entire time.

What if we set our fans *off* temp below the thermostat closure temp? Ah- this is a tiny secret from clutch fan days where the fan always runs. Then the fans will continue to run, even when water has stopped flowing into the engine because the thermostat closed already. That means the fans will run constantly while the radiator becomes cooler and cooler because water is stopped inside due to closed thermostat, assuming we have strong enough fans and a nice radiator design. If we had a clutch fan, the thermostat setting becomes the fan setting for the water leaving the engine. We can take advantage of this situation in racing events where we desire cold water from the radiator to be available but the electric fans must be activated manually on a switch to run like a clutch fan constantly and the thermostat closure point must be high enough to maintain engine efficiency for the type of racing. For example if I plan vehicle on a road course for 20 minutes, I would prefer to start with a cold radiator, not a fully warmed radiator with the thermostat hanging open. So I bypass the 200*F setting with a fan manual switch and bring the engine temp down to 185*F where my thermostat closes (no less than 185*F though). and now the engine sips colder and colder water maintaining 185*F while the radiator drops gradually 175 165 155 145 135 whatever it can reach. Then, the event begins and I flip my switch off, the fan turns off, if I want to conserve the energy of the fan (less voltage drain, fan is off, free up some battery). The engine is still 185*F thermostat closed, and it will remain 185*F until the water entering the engine finally begins to exceed 185*F at which point the water outlet temp of the engine will climb and eventually turn on the my fans again at the appropriate 200*F setting for on.

 

I tried to say the same thing, in less words. You are correct, of course. If there is one area people misunderstand about stats, it is this: Many think it's like a switch. With a 160° stat, they think it's wide open at 160°, totally closed at 159°. They do not function like a switch. A 160° stat is barely open at 160°, and probably not fully open until 170°-173°. Stats control (try to!) the minimum coolant temps ONLY. Coolant temps above the stats minimum opening, in this case, 160°, are controlled by the cooling SYSTEM, NOT the stat.......

 

I wasn't expecting that much of information i do realy make this post on fire
I really appreciate every reply by the way im in Saudi Arabia where summer temp reaches 122 day time and 104 to 95 at night any how but some friends car won't affected by these temp cuz they have stock cars or not major modifications
Mine is TT with 1000hp
I have 2 11'' spal fans that is controlled by SSR (soild state relay) my kit is almost like pro speed if u don't mind just look at the picture and tell me if i have something wrong im running stock water pump and 160 stat