Thermostat

[Demps]

Does anyone make a lower temp thermostat for our cars anymore? I have lower ones from Ron/Randy Woods' SLP & AO. My new to me car runs significantly warmer with what I'm guessing is a stock thermostat.

Ted

[A26B]

Ted,
No one that I know of if Randy doesn't make them anymore. I would recommend you drill one 1/8" hole in the flange of the 185f thermostat. Makes a difference.

[HAWAIIZR-1]

Originally Posted by A26B

Ted,
No one that I know of if Randy doesn't make them anymore. I would recommend you drill one 1/8" hole in the flange of the 185f thermostat. Makes a difference.

Ted,
Sorry to barge in on your thread. Thanks for this question and this is good timing since I'm getting ready to replace my radiator, coolant, hoses, etc. My other Z had the Randy 160 and I know he no longer makes them. I have a question for Jerry though.

Jerry,
I saw your great thermostat info on your website and found I have a couple AC Delco thermostats I bought years back. Do you know who made those and any known issue with them. Do you still recommend the 1/8" hole even if I'm upgrading to a Fluidyne radiator?

Thanks,
Craig


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[A26B]

Originally Posted by HAWAIIZR-1

...............
Jerry,
I saw your great thermostat info on your website and found I have a couple AC Delco thermostats I bought years back. Do you know who made those and any known issue with them. Do you still recommend the 1/8" hole even if I'm upgrading to a Fluidyne radiator?

Thanks,
Craig

Craig, the hole drilling concept originated with Lingenfelter. I first did it to my 185f thermostat (3 holes) AFTER I installed a Ron Davis radiator. Summer driving was exactly what is expected from a 185f t-stat, abt 190f. Winter driving was about 165f.

Since then I have recommended it to quite a few others. 3 holes seems to be too many for colder climates when driven year around. For South Texas & gulf coast area I think it would be fine.

Several guys have drilled holes in t-stats & found the stock radiator adequate afterwards. This points to the thermostat as being the flow restriction that causes stock radiators to blow if the bypass is blocked. Drilling holes reduces the back pressure & allows more coolant to flow through the radiator. There is a point of diminishing return though, that occurs when there is not enough coolant retention time in the radiator for heat transfer. There is not any fixed answer as flow rate, ambient temperature & air speed are all variables in the equation.

Even though Ted is on the Gulf Coast, I recommended 1 hole to Ted because he's a young, nimble, top gun, fighter flyin' stud & can drill another hole if he wants some more cooling.

[Dynomite]

Originally Posted by A26B

Craig, the hole drilling concept originated with Lingenfelter. I first did it to my 185f thermostat (3 holes) AFTER I installed a Ron Davis radiator. Summer driving was exactly what is expected from a 185f t-stat, abt 190f. Winter driving was about 165f.

Since then I have recommended it to quite a few others. 3 holes seems to be too many for colder climates when driven year around. For South Texas & gulf coast area I think it would be fine.

Several guys have drilled holes in t-stats & found the stock radiator adequate afterwards. This points to the thermostat as being the flow restriction that causes stock radiators to blow if the bypass is blocked. Drilling holes reduces the back pressure & allows more coolant to flow through the radiator. There is a point of diminishing return though, that occurs when there is not enough coolant retention time in the radiator for heat transfer. There is not any fixed answer as flow rate, ambient temperature & air speed are all variables in the equation.

Even though Ted is on the Gulf Coast, I recommended 1 hole to Ted because he's a young, nimble, top gun, fighter flyin' stud & can drill another hole if he wants some more cooling.

Assuming the 165 deg thermostat and 180 deg thermostat have the same opening (full open) the 165 deg thermostat would not offer greater cooling once the coolant temperature reaches 180 deg as both thermostats are then fully open.

On the other hand......At coolant temperatures below 180 deg, if you start drilling holes such that the thermostat flow area is increased when fully open the 180 deg thermostat will start closing at cooler temperatures and the more holes you drill the more the thermostat will close to maintain 180 deg.

Now once fully open at over 180 deg, the more holes you drill the greater the flow and the greater the cooling at coolant temperatures over 180 deg. Same goes for a 165 deg thermostat once the temperature reaches 165 deg with the thermostat fully open at greater temperatures....the more holes the greater the flow over the wide open condition.

There has been some suggestions to drill 1/8 inch holes in the thermostat flange to allow better cooling.
Just tested several 180 deg F Thermostats for opening temperatures and found the Stants 180 deg Thermostat will start opening at 175 deg F with complete opening at 185 deg F. Marc suggested at one time the older Stants will deteriorate (Decrease in FUll Open Area) by up to 15% as they age. A thermostat with over 50k miles generally opens 5 degrees later and opens about 85%. The Stants tested would be fully open with a flow area of approximately .785 square inches at 185 deg F.

Thermostat opening at 175 deg F....................................Thermostat opening at 185 deg F (Full Open)


A 1/8 inch diameter hole in the flange will offer additional flow area of .0123 square inches. Which one such hole will increase the total flow area by .016 or 1.6% (three 1/8 inch diameter holes would increase the flow area by 4.7%). This thinking does not address the change in coefficient of Discharge of such small holes.

Now compared to the normal aging of the thermostat of 15% over several years of use one would be much better off installing a NEW Stant Thermostat gaining 15% flow area as compared to drilling three 1/8 inch holes in an older Stant Thermostat only gaining 4.7% flow area.

See item #7 The 180 deg versus the 160 deg thermostat or no thermostat

Given the LT5 runs Hotter idling at a stop sign than at 2,000 rpm as cited in Item #5 in the link above a much better focus regarding engine Heating would be engine RPM (which relates directly to pressure on the coolant flow through the Stant Thermostat) and not the Stant Thermostat (Old or New).

[HAWAIIZR-1]

Originally Posted by A26B

Craig, the hole drilling concept originated with Lingenfelter. I first did it to my 185f thermostat (3 holes) AFTER I installed a Ron Davis radiator. Summer driving was exactly what is expected from a 185f t-stat, abt 190f. Winter driving was about 165f.



Since then I have recommended it to quite a few others. 3 holes seems to be too many for colder climates when driven year around. For South Texas & gulf coast area I think it would be fine.



Several guys have drilled holes in t-stats & found the stock radiator adequate afterwards. This points to the thermostat as being the flow restriction that causes stock radiators to blow if the bypass is blocked. Drilling holes reduces the back pressure & allows more coolant to flow through the radiator. There is a point of diminishing return though, that occurs when there is not enough coolant retention time in the radiator for heat transfer. There is not any fixed answer as flow rate, ambient temperature & air speed are all variables in the equation.



Even though Ted is on the Gulf Coast, I recommended 1 hole to Ted because he's a young, nimble, top gun, fighter flyin' stud & can drill another hole if he wants some more cooling.

Thanks for your expertise Jerry. I have GM 10135637 or AC Delco 131-51. I will drill a single 1/8" hole as recommended. From some info I found the thermostat I have is a 180 degree? I don't know how it compares to Stant, but it is made in the USA so I like that. Thanks again for your thoughts.



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[A26B]

Originally Posted by HAWAIIZR-1

Thanks for your expertise Jerry. I have GM 10135637 or AC Delco 131-51. I will drill a single 1/8" hole as recommended. From some info I found the thermostat I have is a 180 degree? I don't know how it compares to Stant, but it is made in the USA so I like that. Thanks again for your thoughts.

Anytime Craig. I believe the OEM thermostat was Stant.
BTW, you posted such great photos, I just used one to modify for my post.

[Demps]

Originally Posted by A26B

Even though Ted is on the Gulf Coast, I recommended 1 hole to Ted because he's a young, nimble, top gun, fighter flyin' stud & can drill another hole if he wants some more cooling.

Thanks for the info. That was my next step. I think I may go at 2x holes & count it done.

As for young, not anymore but I'm still getting to fly.

Ted

[A26B]

Miss seeing you, Caroline & those babies. I think we will be in Destin during June. Maybe??

[Demps]

Just let us know. Steaks on the Dempseys.

Ted