nobrakes

Packaging problems re: moving overflow tank up much higher. There's a collision avoidance light, a spare tire, etc. but perhaps we can figure out a protected spot. Car owner says he's going to look at an F-body radiator set up later today.

MSURacing

iTrader: (1)

You need a bigger radiator than that!!!!!

Go look up C&R or Be Cool and get an aftermarket radiator. Those types of radiators are only good, on a SHO for 350HP with serious airflow. You need to get a good 4 core radiator. They can custom make them to your size, so that will be no problem.

nobrakes

I thought we'd need a bigger radiator when we went to the LS1 from the SHO, but the car owner wanted to try the one he had. It cooled the Ford well. He likes to run stock parts due to cost and ease of replacement.

I was thinking of a police package radiator like from a 9C1 Caprice or pursuit camaro or maybe even the new Impala V-8.

How does one determine proper radiator sizing. And Katech runs no thermostat, correct?

andereck

This is just for you:

Document ID# 684885
2003 Chevrolet Corvette

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Cooling System Description and Operation
Cooling Fan Control
The engine cooling fan system consists of two electrical cooling fans and three fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage and ignition 1 voltage from the underhood electrical center. The ground path is provided at G102.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan 3 relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan 3 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 3 relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).

Engine Coolant Indicator(s)
COOLANT OVER TEMP
The IPC illuminates the COOLANT OVER TEMP indicator in the message center when the following occurs:

The PCM detects that the engine coolant temperature exceeds 124°C (256°F). The IPC receives a class 2 message from the PCM indicating the high coolant temperature.
The IPC will also illuminate the CHECK GAGES indicator and a chime sounds when this condition exists.
Cooling System
The cooling system's function is to maintain an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system is designed to remove approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the system cools slowly or not at all. This allows the engine to warm quickly.

Cooling Cycle
Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. Some coolant will then be pumped from the water pump, to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost.

Coolant is also pumped through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders where it absorbs heat.

The coolant is then forced through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.

Coolant is also directed to the throttle body. There it circulates through passages in the casting. During initial start up, the coolant assists in warming the throttle body. During normal operating temperatures, the coolant assists in keeping the throttle body cool.

From the cylinder heads, the coolant is then forced to the thermostat. The flow of coolant will either be stopped at the thermostat until the engine is warmed, or it will flow through the thermostat and into the radiator where it is cooled and the coolant cycle is completed.

Operation of the cooling system requires proper functioning of all cooling system components. The cooling system consists of the following components:

Coolant
The engine coolant is a solution made up of a 50-50 mixture of DEX-COOL and clean drinkable water. The coolant solution carries excess heat away from the engine to the radiator, where the heat is dissipated to the atmosphere.

Radiator
The radiator is a heat exchanger. It consists of a core and two tanks. The aluminum core is a crossflow tube and fin design. This is a series of tubes that extend side to side from the inlet tank to the outlet tank. Fins are placed around the outside of the tubes to improve heat transfer from the coolant to the atmosphere. The inlet and outlet tanks are molded with a high temperature, nylon reinforced plastic. A high temperature rubber gasket seals the tank flange edge. The tanks are clamped to the core with clinch tabs. The tabs are part of the aluminum header at each end of the core. The radiator also has a drain **** which is located in the bottom of the left hand tank. The drain **** includes the drain **** and drain **** seal.

The radiator removes heat from the coolant passing through it. The fins on the core absorb heat from the coolant passing through the tubes. As air passes between the fins, it absorbs heat and cools the coolant.

During vehicle use, the coolant heats and expands. The coolant that is displaced by this expansion flows into the surge tank. As the coolant circulates, air is allowed to exit. This is an advantage to the cooling system. Coolant without bubbles absorbs heat much better than coolant with bubbles.

Pressure Cap
The pressure cap is a cap that seals and pressurizes the cooling system. It contains a blow off or pressure valve and a vacuum or atmospheric valve. The pressure valve is held against its seat by a spring of predetermined strength, which protects the radiator by relieving pressure if it exceeds 15 psi. The vacuum valve is held against its seat by a spring, which permits opening of the valve to relieve vacuum created in the cooling system as it cools off. The vacuum, if not relieved, might cause the radiator to collapse.

The pressure cap allows pressure in the cooling system to build up. As the pressure builds, the boiling point of the coolant goes up as well. Therefore, the coolant can be safely run at a temperature much higher than the boiling point of the coolant at atmospheric pressure. The hotter the coolant is, the faster the heat moves from the radiator to the cooler, passing air. The pressure in the cooling system can get too high, however. When the pressure exceeds the strength of the spring, it raises the pressure valve so that the excess pressure can escape. As the engine cools down, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum causes the vacuum valve to open, allowing outside air into the cooling system. This equalizes the pressure in the cooling system with atmospheric pressure, preventing the radiator from collapsing.

continued......

andereck

Surge Tank
The surge tank is a plastic tank with a pressure cap mounted to it. The tank is mounted at a point higher than all other coolant passages. The surge tank provides an air space in the cooling system. The air space allows the coolant to expand and contract. The surge tank also provides a coolant fill point and a central air bleed location.

During vehicle use, the coolant heats and expands. The coolant that is displaced by this expansion flows into the surge tank. As the coolant circulates, air is allowed to exit. This is an advantage to the cooling system. Coolant without bubbles absorbs heat much better than coolant with bubbles.

Air Baffles and Seals
The cooling system uses deflectors, air baffles and air seals to increase system cooling. Deflectors are installed under the vehicle to redirect airflow beneath the vehicle to flow through the radiator and increase cooling. Air baffles are also used to direct airflow into the radiator and increase cooling. Air seals prevent air from bypassing the radiator and A/C condenser. Air seals also prevent recirculation of the air for better hot weather cooling and A/C condenser performance.

Water Pump
The water pump is a centrifugal vane impeller type pump. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades or vanes. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by one or more sealed bearings. These sealed bearings never need to be lubricated. With a sealed bearing, grease cannot leak out, and dirt and water cannot get in.

The purpose of the water pump is to circulate coolant throughout the cooling system. The water pump is driven by the crankshaft via the drive belt.

Thermostat
The thermostat is a coolant flow control component. It's purpose is to regulate the operating temperature of the engine. It utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a piston. When the element is heated, it expands and exerts pressure against a rubber diaphragm. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.

When the coolant temperature is below 91°C (195°F), the thermostat valve remains closed. This prevents circulation of the coolant to the radiator and allows the engine to warm up quickly. After the coolant temperature reaches 91°C (195°F), the thermostat valve will open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. The thermostat also provides a restriction in the cooling system, even after it has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.
Transmission Oil Cooler
The transmission oil cooler is a heat exchanger. It is located inside the right side end tank of the radiator. The transmission fluid temperature is regulated by the temperature of the engine coolant that surrounds the oil cooler as the transmission fluid passes down through the cooler.

The transmission oil pump, pumps the fluid through the transmission oil cooler feed line to the oil cooler. The fluid then flows down through the cooler while the engine coolant absorbs heat from the fluid. The fluid is then pumped through the transmission oil cooler return line, to the transmission.

Coolant Heater
The optional engine coolant heater (RPO K05) is rated at 400 watts and supplies 1365 btu/hr. The engine coolant heater operates using 110-volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather -29°C (-20°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.


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Document ID# 684885
2003 Chevrolet Corvette


So you know more than the people that built the car, and me as well.

white2001s10

iTrader: (4)

I'm going to definately have to go with YES on that one.
That's one piece of writing that will not be going into my library or list of credible sources.
It's obviously full of inaccuracies and omissions.
Must I point them all out?

It's actually kind of hilarious to read.... "up until 195*F the tstat stays closed" leads you to believe that it's alternately opening and closing instead of reaching an equalibrium.... uhmm sort of like the pressure in the entire system is constantly trying to do as well.

It never even mentions the existance of the bypass valve, passage, or function for that matter.

It suggests the system was designed to remove 1/3 of combustion heat, when in reality (without a tstat as restriction) it is actually capable of removing almost twice that much heat.

I get the impression this document was either "dumbed down" or simply written by a moron.


Now I'm going to suggest something very simple and hopefully reasonable to you. That is instead of taking everything from this document (or from the internet for that matter) as fact, do some of your own testing to see the results and how things are working.

I think that you'll find that there are many restrictions and sources of friction in the block, gaskets and heads (besides the tstat) that will contribute to the small pressure difference between the block and radiator.

The tstat is actually between the radiator and the input to the waterpump on an LS1 (not the other way around), so the increased pressure of the system is pretty even except localized at the input side of the pump.

I also think you'll see a very dramatic drop in engine coolant temperature when running without a tstat. Testing different points in the system with thermocouple wires is a simple way to test. Pressure transducers are a little harder to come by, but still very do-able.

I promise you that testing this will show you a lot more than internet searches.

MrDude_1

iTrader: (4)

rather then argue, i'll just go back and answer your question with a path to a solution.

the problem:
under load, the engine overheats, but cools quickly..

we can safely assume that its having trouble removing the heat. right now we're also assuming the water pump is working correctly, and that the coolent level is correct.

there are two simple things i can think of that could cause this problem. the pump cavitating, or the radiator being to small.

because the cost of a new radiator would be a bit much just to test, first thing i would do would be to temporarily install a stock thermostat. this will tell us if there is indeed a cavitation problem from no thermostat... if your car heats up to temp, and stays there... then you know where to look.
if it does the same thing, your heat exchanger (radiator) is just too small.

for a cheap replacement, try a radiator from a 4thgen camaro, or a late thirdgen camaro. they're alum/plastic. the thirdgen one is more upright, and has a slightly thicker and better core.
edit:
if you prefer a all alum radiator over a plastic tank one (i would in a offroad enviroment) Be-Cool does have a nice selection of cheap universal radiators.. they're built pretty tough, and cool great.... plus theres no plastic tanks to crack. if they ever do get damaged, you can repair them too...


as a side note... coming out of the top of the heads is a air bleed that must go into the radiator end tank or the inlet of the water pump. if you're not using it (alot of people assume its just there to feed the throttlebody to keep it warm) then you will have air trapped in your engine with no path for escape, and you'll have cooling problems. i only skimmed the thread since there were people bitching back and forth, so if you already mentioned it, sorry, i must have missed it.

MSURacing

iTrader: (1)

So final conclusion, get a better radiator.

Quote:
Originally Posted by andereck
Document ID# 684885
2003 Chevrolet Corvette
So you know more than the people that built the car, and me as well.
.

Oh, and you really need to run about 50 of these engines on the dyno to even think to catch up to me. So, good luck with that!!!

johnpate01

iTrader: (3)

I think that you all need to grow up and stop bickering like 2 old women. There have been some interesting theories presented. But, I am not one to say that there is only one conclusive answer to the overheating problem. There are probably several possible fixes. Start changing parts one at a time like Mr_Dude suggests until your engine doesn't overheat anymore. When you find out what it is, let us know.

SILVERZZ28

iTrader: (3)

If you pull the thermo make sure you block off the heater passage like mentioned

mrdragster1970

.

Didn't we just do this??
My stuff always runs cooler with NO therm. Wide open, no restrictor.

.

kistlerjm9

iTrader: (24)

thermodynamics here are the key, for a simple test just install a radiator pressure tester to the rad, with a stock 180 thermostat you will get about 14 pounds of pressure... with the therm removed and blocked off bypass wouldnt you know you get about 14 pounds of pressure... general conclusion is get a bigger rad

SS02G

What about the effects of thermocycling anyone consider that yet?
Just asking i didn't feel like reading every post.

lt170chevelle

iTrader: (2)

on an added note..summit racing has all aluminum universal radiators for dirt cheap..in many sizes and orientations..ok..breaks over..ding ding!!