Cooling Question
 

Ok, last year I installed a Fluidyne rad to keep temps down particularly when in traffic w A/C on. Worked great have however, with ambient temps below 60, it was difficult to maintain operating temps on motor. At cruise, coolant temps would drop into the 150-160 range. Which is not desired if you want Closed Loop operation w Learn Control. So I finally bought a stock therm from Jerry's and had it installed. turns out the thermo coming OUT of the motor had 5 holes drilled in it. The stock thermo was installed w 0 holes.
The result is that coolant temps increase now unless motor is turning above 12-1300 rpm. That includes at highway cruise. So I know I don't need 5 holes in thermo, but I'd like to avoid doing this again. How many holes should I put in stock thermo so that fans can maintain steady operating temps?
I should add that I have under drive pulleys and temps creep up they don't shoot up.

Re: Cooling Question
 

I'm running dual core Dewitt so may behave a bit different. Having clarified, I drilled one 1/8" hole on the thermostat. During 90 to 95 degree day, long idle with AC on takes coolant temp to 213-215. During the last winter, steady state 60-70 mph cruise stabilized coolant temp was 185-187. Hot day, 195-200 degrees at 60-70 degrees.

Re: Cooling Question
 

Do u know what temps ur fans come on at?

Re: Cooling Question
 

I have the Dewitt's radiator with a Ron woods 160 thermostat and one drilled hole. I have the fans on early mod and the Dewitt's spal fans. In wintertime the car randomly exceeds 1/2 band on the gauge. I would say no more than 2 Dom as 5 is almost a bypass

Re: Cooling Question
 

My motor is a mini stroker - 4" bore x 3.75" stroke - 378, with .425 intake cams and secondaries removed. I'm running Marc's chip with secondary fan coming on at 205, I think.

Re: Cooling Question
 

Ok, one other question. What diameter for the holes?

Re: Cooling Question
 

One 1/8".

Re: Cooling Question
 

Ok guys.......just a little experience with thermostats (180 deg), Dewitts, Fluidyne, Ron Davis ALuminum Radiators, Fans, and Water Pumps for ZR-1s

1. Fans turn on at 205 deg F and OFF at 200 deg F (Haibeck Chip)
2. I use 180 deg Thermostats.
3. Ron Davis, Dewitt, and Fluidyne multi core Aluminum Radiators.

My experience in all ambient temperatures.

A. In sixth gear running 65 mph (less than 2,000 rpm) the Coolant always gets a bit over 200 deg F. On Hot days the coolant will get a bit over 213 deg F.
The key is the Water Pump is not pushing enough flow through the fully open thermostat to cool the engine to a Temperature where the Thermostat takes over (180 deg F).

B. If I shift to 5th gear at 65 mph (more than 2,000 rpm) the coolant temperature drops to Thermostat control (180 deg F) on cool days and drops to near 200 deg F on Hot days.

The Summary is simple.....

The Thermostat is fully open at all coolant temperatures over 180 deg F (no need to use cooler thermostat unless you want to run at temperatures below 180 deg F).


The Water Pump does not provide enough flow to cool the engine at rpms less than 2,000 rpm. This is not an issue at ambient environmental temperatures on cool days. This is a problem on HOT days. The Aluminum Multi Core Radiators DO provide better Heat Dissipation and offer cooler Coolant at ALL Temperatures for which the 180 deg F Thermostat Controls the Flow (above 180 deg F Coolant temperatures the Thermostat is fully open). The Cooling effects then being dependent on Water Pump Flow Rate and Air Flow Rate through the Radiator.

Having the Fans come on at 205 deg F DOES provide for COOLER Coolant in the radiator once sufficient coolant flow rate is provided above 2,000 rpm. Using Aluminum Multi Core Radiators ALSO provides for COOLER Coolant Temperatures in conjunction with the Air Flow provided by Fans and Vehicle Speed. The Heat Removal Rate from the Radiator is greater as the Air Flow Increases and as the Aluminum exposed to that Air Movement increases.

It DOES make a difference if you are moving at speed in conjunction with Fans PULLING Air Flow as the additional Air Pressure Up Front does add to the TOTAL AIR FLOW through the Radiator at any ambient environmental temperatures.

Using 180 deg Thermostats insures that the engine will not run cooler than that temperature since the Thermostat is in control and controls the Coolant flow rate through the engine at all Coolant Temperatures less than 180 deg F.

Thermostats, Fans, Water Pump, and Radiators

Re: Cooling Question
 

YUP!:thumbsup:

Cooling Question
 

Dynamite is correct. All those extra holes in the thermo could delay opening a little. Prob wouldn't notice. A good thermo has a bleed hole. All you need is one hole and install it at the top to bleed any trapped air. 180 is the way to go. And it will help some to have a fan come on at 185-190 but coolant flow is more important. With ac the fans should be running anyway, but idle in hotter temps is still going to stress the system. Too cool a thermo will result in the engine staying in "choke mode" in colder weather.


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