LT5 Cooling and Radiators

[QB93Z]

Originally Posted by Billy Mild

Can a stock clean radiator provide enough cooling for the LT5? It seems that the aftermarket units really help it cool the way it should have from the factory.

Your question has many answers depending on several factors. Is the C4/LT5 modified in any way that would affect power output or normal operation? What type of driving are you doing? Is the exhaust system modified? Do you ever go faster than the speed limit? Do you use the C4/LT5 for off road driving or racing?

I believe that a stock C4/LT5 with a stock radiator and fans that has no debris in the air flow path will operate in the normal temperature range.

If you make any modifications that increase power, you will have to modify the cooling capability to keep up. Or, as a minimum you will have to ensure that the air flow through the radiator is not reduced by debris.

Jim

[Dynomite]

Here in Central Valley CA predicted 107 deg today with 100 deg every day through July 14 (then 109 deg on July 15). Will get lots of Engine Coolant System Testing done using Ron Davis Radiators next couple weeks in what I would call extreme Ambient Temperatures

Got Engine Coolant temperatures up to 220 deg F yesterday in 100 deg ambient racing around (No Traffic) and in traffic (idling in traffic and 100 mph on Test Road) and at higher rpms without paying attention to what I call (conservation of Engine Coolant Temperatures). Engine Coolant Temperatures quickly dropped over 15 deg once I collected myself and this with AC Full On (fan speed 10). The Engine Coolant Temperatures actually dropped a bit just idling in traffic after I was done fooling around

You may think 220 deg F is HOT but in a Stock Radiator Fan System, the Radiator Fans would not even come on yet (My Radiator Fans were ON with Haibeck Chip and 180 deg Thermostat)

If you are NOT looking at Digital Engine Coolant Temperatures using the HVAC System, the Temperature Gauge needle is a tad under half or at half at Engine Coolant Temperatures around 200 deg F and a tad over half at Engine Coolant Temperatures around 220 deg F. Each Engine Coolant Temperature Gauge will be just a tad different.

HVAC Display Digital Engine Coolant Temperatures in Deg C.......
Push/hold up and down buttons each side of Fan Speed Center Button until you get 00.
Then push Fan Speed Control Button UP to right of Fan Speed Center Button until you get to 16.
Then Push Center Fan Speed Button to Read Engine Coolant Temperatures in Deg C.

Approximate C to F
85 C is 185 F
93 C is 200 F
100 C is 212 F
104 C is 220 F
110 C is 230 F
120 C HOT.....do not operate at 250 deg F (TURN AC OFF).

Also...no one has mentioned except HIB (who uses water coolant and a water wetter only) that if you do not use antifreeze mixture your coolant System could boil over at 212 deg F (a bit higher Engine Coolant Temperatures with a good radiator cap which maintains 15 psi Coolant Pressures). NOT GOOD

In regard to Loosing Coolant vice Heating Coolant to HOT temperatures. It has been said that as long as you do not loose the Coolant and the Water Pump is NOT Airlocked (like concern for low oil level in oil pan but as long as you have oil pressure) you will NOT destroy the LT5 Engine

[Billy Mild]

Originally Posted by QB93Z

Your question has many answers depending on several factors. Is the C4/LT5 modified in any way that would affect power output or normal operation? What type of driving are you doing? Is the exhaust system modified? Do you ever go faster than the speed limit? Do you use the C4/LT5 for off road driving or racing?

I believe that a stock C4/LT5 with a stock radiator and fans that has no debris in the air flow path will operate in the normal temperature range.

If you make any modifications that increase power, you will have to modify the cooling capability to keep up. Or, as a minimum you will have to ensure that the air flow through the radiator is not reduced by debris.

Jim

I would think simple mods like airlid mod, or a full exhaust would only help the engine run a bit cooler. I might be wrong though.

[Dynomite]

Originally Posted by Billy Mild

I would think simple mods like airlid mod, or a full exhaust would only help the engine run a bit cooler. I might be wrong though.

I see no difference in Coolant Temperatures with Stock Exhaust or Full Offroad SW Headers/Exhaust (I have one of each both with Ron Davis Radiators). I think the engine compartment gets hotter with Headers. That theory could result in more HOT Air around the engine and escaping under the car.

Regarding Thermostats........Just as a comparison, I have checked several Stock Thermostats which ALL seem to open at 170 deg F as compared with Marc Haibeck's and Jerry's 180 deg F Thermostats which open AT 180 deg F. Some run 160/165 deg F Thermostats which once the Thermostat is fully open would not make a difference on the stabilized Coolant Temperatures no matter which Thermostat you used (A Cooler Thermostat would make a difference on how fast you get to that stabilized Coolant Temperature). This assumes the Full Open Thermostats are all of the same Coolant Flow Restriction/Flow Rate.

Jerry has the special rubber thermostat gaskets sold separately in case the thermostat gasket gets messed up during installation of thermostat.

I think we need more experiments with Radiator Cooling fan flow rates. We all have experienced trash blocking the radiators and the higher Coolant Temperature Results. We all have also experienced the effects of vehicle cruise speed on Engine Coolant Temperatures as compared to Engine Coolant Temperatures idling in traffic.

[dredgeguy]

23 years of sucking up debris into the stock radiator. Replaced it with a DeWitt, Jerry's hoses and new 180 degree thermostat and should be good for another 23 years.

[FU]

Did you do the 3 1/8 inch holes in the thermostat mod ?

[dredgeguy]

Originally Posted by FU

Did you do the 3 1/8 inch holes in the thermostat mod ?

Lots of discussions about it and went back and forth on this issue. Ended up doing a single 1/8 inch hole

[WARP TEN]

Originally Posted by QB93Z

Your question has many answers depending on several factors. Is the C4/LT5 modified in any way that would affect power output or normal operation? What type of driving are you doing? Is the exhaust system modified? Do you ever go faster than the speed limit? Do you use the C4/LT5 for off road driving or racing?

I believe that a stock C4/LT5 with a stock radiator and fans that has no debris in the air flow path will operate in the normal temperature range.

If you make any modifications that increase power, you will have to modify the cooling capability to keep up. Or, as a minimum you will have to ensure that the air flow through the radiator is not reduced by debris.

Jim

Certainly true about having a clean radiator, but even with mods I have not had any overheating issues. I have Marc's 510 HP package which includes his chip that modifies cooling so that both fans come on at 205 degrees. When I first bought the car and again when we did the engine, we checked the radiator for debris and found none. In the two years I have had the modifications, including some mighty hot days (not many this year!), I have never seen coolant temperatures in excess of 208 degrees. Early on I added a debris screen just in case. So a clean stock radiator with both fans coming on at 205 seems to provide adequate cooling for mine even for a slightly modified engine. --Bob

[secondchance]

Originally Posted by FU

Did you do the 3 1/8 inch holes in the thermostat mod ?

Frank,

I tried 3 1/8" holes 2 years ago. During the winter coolant temp refused to go above 153 degrees F. I was concerned with inability to boil off water build up in oil. Went to one 1/8" hole and recommended the same to Charlie.

[FU]

Originally Posted by secondchance

Frank,

I tried 3 1/8" holes 2 years ago. During the winter coolant temp refused to go above 153 degrees F. I was concerned with inability to boil off water build up in oil. Went to one 1/8" hole and recommended the same to Charlie.

Interesting , 153 degrees F is no good for a winter driver. What degree thermostat did you use to get up to 153 f ?