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280Z-LS3

Advice on radiator and fan for LS3 swap

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Any of you guys have issues with the radiator overcooling? I'm running the Champion radiator with a drilled (4 small holes the size of the jiggle pin hole) 180 degree stat and FAL Hurricane fan. During the summer it would get to 205-210 if sitting in traffic and ambient temps were 85+: not ideal but I could live with it because as soon as you get going over 30mph the temps go down to 175 and hold. 

The problem now is that the ambient temps are getting in the lower 60's at night and while cruising, the coolant temps are getting down to 140-150 unless I close the valve to the heater core. 

Anybody else have this issue? 

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Posted (edited)
14 hours ago, calZ said:

Why do you have holes drilled in the thermostat?

Standard practice for the last few LS swaps I've done to help maximize cooling with less than ideal radiator setups. When not using a heater core (more full race oriented), the absence of the additional coolant volume becomes apparent pretty quickly at low speeds. Drilling holes is the step between a stock t-stat or just running a disc to slightly restrict the flow.  

This setup has an unshrouded fan. 5/8" coolant hoses to a Vintage Air heater/defrost unit. Originally I just had the t-stat housing looped but adding the heater core dropped coolant temps 10-15 degrees when sitting in traffic (blower motor off). Inside the car is a sauna, but the motor is happier.

20200816_191801.jpg

Edited by SH4DY

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I think the reason for running hot in traffic is the lack of fan shround, air is not being pulled through a large portion of radiator.  Then while moving temps go down indicating rad has good air flow.  Get a C7 Corvette fan assembly, that maybe the easiest solution.

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Posted (edited)

SBC 350 carbed 240z

 

Arizona Z Car aluminum radiator + shroud + 3000 cfm Volvo fan + 185 Degrees On/170 off  thermal switch + 70 amp fan relay + no thermostat = 185 deg indicated temperature during long idles in California central valley heat (100 to 110 deg).

 

Volvo fan is two speed, but is wired to run on high speed at all times.

 

Other: high volume water pump

 

Works.  185 deg all day

Edited by Miles

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You guys are missing what I'm saying - the cooling system is cooling too well. It's getting too cold. I'm not worried about the temps during stop and go traffic - I'm more concerned about the coolant temps not getting above 150 on a cool night. 

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No, they understand. They're trying to solve the actual problem rather than the one you've created. 

 

The only way you can make your car cool less is to reduce cooling capacity. So you can put in a smaller radiator that won't keep up when it's warm, or you can put in a thermostat that works like it's supposed to when it's cold and then work to make sure the engine stays cool when it's hot out.

 

If your problem is that the engine doesn't start cooling itself at a low enough temp, then put a lower temp thermostat in so it opens earlier. That's essentially what you've done with the holes, except there's no off switch for holes. Or, leave it at a stock temp thermostat and either upgrade your radiator or do better with fans/ducting to increase your airflow. 

 

Is 210 even too hot? I've never done an LS swap, but everything I've seen/read says that stock ECUs don't even turn the fan on until well over 200. 210 in a worst case scenario sounds perfectly within the stock specs. 

 

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Too cold?

 

  • Remove thermostat and install a flow restrictor.  Try Moroso flow restrictor. Start with the mid size (blue) restrictor.
  • Install a thermal switch that turns on fan at a higher temperature. Or turn your fan off with a switch.

With the components I listed in my earlier post, once my engine temp a reaches steady state of 185 deg (center of temp gauge) on cold 65 deg days or hot 110 deg days the needle just stays dead center.

 

You just need to tweak things a bit.

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On 10/2/2020 at 12:45 PM, SH4DY said:

You guys are missing what I'm saying - the cooling system is cooling too well. It's getting too cold. I'm not worried about the temps during stop and go traffic - I'm more concerned about the coolant temps not getting above 150 on a cool night. 

ummmmm why not run a PWM brushless fan and adjust accordingly... Running to cold, reduce the fan speed. to hot, increase the fan speed. 

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17 hours ago, DonH said:

ummmmm why not run a PWM brushless fan and adjust accordingly... Running to cold, reduce the fan speed. to hot, increase the fan speed. 

Fan is off and it's that cold. Has nothing to do with the fan. 

Stopping the coolant from flowing through the heater core via the heater controls seems to keep it in the 160-170 range which I'm OK with. 

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47 minutes ago, SH4DY said:

Fan is off and it's that cold. Has nothing to do with the fan. 

Stopping the coolant from flowing through the heater core via the heater controls seems to keep it in the 160-170 range which I'm OK with. 

 

This is interesting. Please remove the thermostat, take the car for a drive  and report back what the temperature is.

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Modern engines are designed to run at higher temps.  The piston to bore and bearing clearances to machined for an anticipated temperature range and resulting degree of expansion as the metal warms up.  From what I understand accelerated engine wear can occur from constantly running the motor too cold.  Something to think about...

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Use a standard thermostat (no holes drilled in it) and try it. It has to run at the same or higher temperature than the thermostat rating (assuming that the temperature rating of the thermostat is accurate). Marlan Davis recommended a 160 degree high-flow thermostat (Summitt Racing part no. SUM-365-160) to me in the article they did relating to a question I sent in to Hot Rod Magazine on a cooling issue with my car. See the article at the link below.

 

https://www.hotrod.com/articles/stop-hot-day-overheating-on-500hp-ls-engine/

 

Mike Mileski

Tucson, AZ

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I'm  using a 3 core Champion and Taurus  2 speed fan with only high wired to a Dodge minivan PWM controller, stock thermostat and 4 corner  steam vents in the heads, stays at 200 under all conditions. LS engines need flow through the heater hoses or a small bypass in the thermostat, removing the small rivet is enough, hope this helps. 

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