High Performance thermostats?

Discussion in 'Street/strip 400/430/455' started by rkammer, Apr 3, 2021.

  1. Nailhead in a 1967

    Nailhead in a 1967 Kell-Mnown Wember

    He was online yesterday, but it looks he doesn't really care......

    ThermostatPaul.jpg
     
  2. sean Buick 76

    sean Buick 76 Buick Nut

    or maybe he was busy and didn’t have time to respond?
     
    Max Damage likes this.
  3. sean Buick 76

    sean Buick 76 Buick Nut

    https://flowkoolerwaterpumps.com/products/robertshaw-330-160-degree-thermostat

    Why Robertshaw? Because we make a hi flow pump and its unique three port construction or "balanced sleeve" design equalizes the system pressures above and below the thermostat’s moving valve. Therefore the thermostat is pressure balanced and will respond to system temperatures only. No other thermostat does this.

    Other Features of a Robert Shaw Thermostat:

    1) Stress-free construction. Robertshaw makes the thermostat's strut assembly from brass, not stainless steel, because brass can be bradded to the housing with heat instead of sledge hammer-like stress. This technique permits two brads per strut. Other manufacturers forcefully attach the struts to the housing with intense, metal-weakening pressure on the struts, binding each strut in only one spot.

    2) The Power Pill®. This is the heart of a Robertshaw thermostat. It detects minute changes in the temperature of the coolant, and quickly activates a precision-engineered stem or piston to open and close the thermostat valve.

    3) One-piece bypass poppet. With other thermostats, the bypass valve stem is welded on. The weld tends to fail under stress. To eliminate this problem, Robertshaw manufactures the entire copper cup and bypass stem from a single piece of metal.

    4) Short-stroke piston. In conventional thermostats, the piston must make a large stroke to open the thermostat far enough for adequate coolant flow. But the long stroke compromises durability. Robertshaw engineers achieved a shorter stroke with a uniquely-designed flange and poppet. This design increases the longevity of the thermostat, yet still allows adequate coolant circulation.

    5) Contoured strut. Making the strut assembly from brass instead of steel provides another benefit: brass, being more malleable than steel, can be precisely formed to maximize coolant flow.

    6) Uniform quality. Robertshaw builds all thermostats to OEM standards -- so your replacement thermostat is identical to those used in new Fords, Chryslers, and other cars.

    The Power Pill
    At the heart of a Robertshaw thermostat is the power pill. Its job: to detect minute changes in the temperature of the coolant, and to quickly activate a precision-engineered piston that opens and closes the thermostat valve. Compared to the thermal elements in some thermostats, Robertshaw's Power Pill® has major advantages:

    1) Rapid response. The Power Pill's piston is activated by a temperature-sensitive mixture of metallic powder and wax. Some thermostats use an all-wax charge, which responds slowly to temperature changes. Other brands mix copper powder with the wax for faster response, but the copper quickly separates from the wax. Robertshaw developed a process to maintain suspension of the copper powder in the wax, so the fast response doesn't deteriorate and the thermostat will not "stick-open" to cause the engine to run cool.

    2) Reliable performance. Most manufacturers use a one-piece rubber diaphragm to seal the charge and drive the piston. If the rubber part ruptures, the thermostat fails. Robertshaw uses two separate parts: a diaphragm to seal the wax, and a stem seat or plug that drives the piston. Rubber material for each part is formulated especially to meet each part's unique requirements. Wear or damage to the stem seat still allows the thermostat to operate satisfactorily.

    3) Precise performance. Every Robertshaw Power Pill is calibrated to bring the thermostat's start-to-open temperature within strict tolerances.
     
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  4. 462 Chevelle

    462 Chevelle 462 chevelle

    I never ran a thermostat in my bbb, but I live in an area where there is no traffic so I don’t have to worry about sitting at a red light. If I did end up in the rare occasion of sitting there idling I was always nervous.

    I have no good logical reason for this though, just the way I did it. The engine was designed to have a thermostat by someone a lot smarter than me.
     
  5. rkammer

    rkammer Gold Level Contributor

    OK. Point taken. Thanks.
     
  6. Jim Weise

    Jim Weise EFI/DIS 482

    For what it is worth.. and I hate to mention it, this is probably my most controversial opinion..

    But you need to hear it. All of you...

    I have not run a thermostat in a BBB for about 30 years.. not race motors, not in street motors during the warm months. These BBB street applications were not A body toys, they were 3/4 ton pickups and Suburbans used for manly work..like towing 10 thousand pound enclosed car trailers, boats, and toting new motors to the dyno.

    With both alum and brass/copper radiators, the engine coolant flow speed dictates the operating temp. That speed is adequately balanced by water pump output vs the restrictions in the block. This is documented by my dyno work.. my dyno operator measures coolant pressure... zero pressure would be a free flow, no restriction.. as restriction to flow increased, the psi in the system would also increase. The average american V-8 runs at about 4psi on that dyno.. our Buicks took 6 psi.. more restriction..

    On a hot summer day, towing a heavy load, the trucks would run around 195-200.. Really hot, pulling going up hills, the clutch fan would lock up and keep it there..

    In the customer cars I have built, during normal driving, they run between 180 and 200, depending on how good the radiator is.

    The only time those vehicles got a thermostat installed in them, was in the wintertime, so the heater worked. I would put it in around Halloween, and take it out again around Easter. why you ask?,.,. I had one of those damn things stick shut on me in that first truck, that cost me that motor.. overheated it, and it never was the same. When I freshened it up, no way was I going to have a piece of equipment in it, that is simply not needed in the summertime.

    It is a fact, that in the summertime, the thermostat opens, and stays open.. it does not cycle. No radiator I have ever seen can remove enough heat to get the water so cold, that it goes back into the motor, thru it, and back to the thermostat, and it gets there under the thermostat set point. In the summertime, a thermostat opens and closes partially a few times during warm up an then opens fully and stay open.. it does not cycle..

    It does not happen, and never will, in ambient temps above 60* or so, once all the coolant in the system is up to temp.

    Now it is true, some engines do need a thermostat to slow down the water to keep it in the radiator long enough to expel the heat. I had a set of restrictors on hand to put in place of the thermostat, should they be needed.. but it those applications, they never were.

    I am currently building a customers car.. he lives in Juneau Alaska... and that car will not have a thermostat in it. It's a convertible that he never puts the top up on..

    Yes, it takes a couple minutes longer to warm up to operating temp, but this is not an issue at all. And it is not as long as you might guess.

    Keep in mind guys, I run engines on my test stand all the time, not one of them ever has a thermostat in them.. my test stand alum radiator and the system and BBB engine, holds just over 4 gallons of water. At cam break in speed, it takes about four and a half minutes to reach 180* when I click the electric fan on.. then it will rise to about 200, and stay there, thruout the rest of the 15 minute break in.

    If your going to ignore my advice, that is fine, but make sure you get the thermostat that sticks open when it fails.. because they all will fail eventually. And they will cost you an engine. Might still run , but will never be the same.

    Been there, done that..

    JW
     
    Last edited: Apr 6, 2021
  7. Schurkey

    Schurkey Silver Level contributor

    MISTAKE IN LOGIC.

    These thermostats do not "FAIL" in the open position. The whole point of a "failure" is that it's undesirable operation. You can't make something that "fails" in a certain way, because a failure means it's doing something it's not supposed to.

    These thermostats LOCK OPEN (as opposed to "Failing open") when the engine overheats for some other reason than a failed thermostat. Your radiator is corroded, and you're towing a trailer up a mountain road? The fan clutch suddenly leaks out all the silicone fluid so it doesn't engage? The engine overheats, the thermostat locks open, reacting to the high temperature. It's not "failing", it's working the way it's supposed to.

    And, of course, it's a marketing scam, because any thermostat that's working properly will open fully if the temperature gets high enough. And when the temperature goes back down, it closes again. With the Safe-T-Stat, (I've also seen them branded as "Fail-safe" thermostats) you throw it away after it locks open.
    https://motorad.com/products/fail-safe-thermostats/
    MISTAKE IN LOGIC

    Maximum "cooling" means maximum heat transfer.
    The hotter the liquid coolant can get the metal radiator tubes, the more heat transfers to the air fins, which then transfers heat to the air passing by the air fins. Until the liquid coolant is flowing through the radiator tubes so fast as to cause cavitation or some other oddball thermodynamic problems, FASTER FLOW MEANS MORE HEAT TRANSFER because there's a greater difference in temperature between the air blowing through the radiator, versus the temp of the metal of the radiator heated by the liquid coolant.

    A problem with fast flow occurs with top-to-bottom-flow radiators (as opposed to crossflow radiators.) The pressure cap on a top flow radiator is on the HOT tank, AHEAD of any restriction from the rad core. It's fairly easy to have a fully-open thermostat, so the rad cap has full static pressure (let's say 16 lbs as stamped on the rad cap) PLUS the water pump pressure flowing past the fully-open thermostat. (Especially if the rad core is corroded or otherwise restricted excessively.) This over-pressures the rad cap, and coolant blows out the overflow hose. The cooling system loses coolant and pressure, loss of pressure leads to increased boiling, which blows even more coolant out the overflow.

    By comparison, a crossflow rad has the pressure cap on the COOL tank, BEHIND any restriction caused by the rad core. The pressure cap is acted on by the static pressure of the rad cap, minus the suction of the water pump. In short, the crossflow rad is a better design.

    THANK YOU!

    For practical purposes, the only way that "slowing down" or restricting the flow improves cooling is if there's something very goofy going on in the cooling system. One way this could happen is if the restriction (a thermostat or a restrictor disc, for example) helps build coolant pressure in the engine--static pressure; plus water pump pressure due to deliberate, incidental, or accidental restriction to flow. The added pressure in the engine raises the boiling point of the coolant. Or, added pressure might reduce or eliminate cavitation of the water pump impeller. Either one could, in the right circumstances, improve the cooling system performance. So folks believe that "slowing down flow" solved the problem, but the truth is that slowing the flow didn't do squat, it was the restriction causing increased pressure on the coolant in the engine that made the difference.
     
    Last edited: Apr 6, 2021
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  8. Bens99gtp

    Bens99gtp Well-Known Member

    Almost every major custom radiator company I have ever talked in depth too all say itbis possible to pass coolant too fast through the radiator not allowing enough time to cool down.

    I guess they are all wrong.

    I'm sure a proper balance between volume of flow and speed of flow is the ultimate key.

    It makes sense the the hotter s fluid is going into the radiator the greater the temp difference the greater the amount of cool down

    It makes since the longer the coolant is in the radiator the more time it has to cool down

    It makes since the longer the coolant is in the motor the more heat it can pick up

    It also makes sense that in thought that the more fluid that can be exposed in the radiator that it should cool better too...

    I can see since in all these thoughts even though some are contradictory to others.....so it makes best since to have a proper balance..

    The great debate continues
     
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  9. 87GN_70GS

    87GN_70GS Well-Known Member

    Agree with all of your points except this one. Once the water warms, it pick up less heat than cool water. Heat transfer works on the temperature difference (delta T). If the water is the same temp as the cylinder metal, there will be no heat transfer, as an extreme example. Ice cold water will transfer the most heat, as the opposite extreme example. The longer it's in the block, the hotter it gets. So we want it quickly moving thru the block, like blowing on a spoonful of soup to cool it.

    If we could hook up a fire hydrant and have it blast thru the block, it would keep the metal very cool (ignoring, turbulence, nucleate boiling, non laminar flow etc)
     
    chrisg likes this.
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Scott, if you have a mechanical temperature gauge. Get the engine up to temperature, then shut the motor down and watch the gauge. It won't take long for the gauge to rise 5-10* as the coolant heat soaks.:)
     
  11. Bens99gtp

    Bens99gtp Well-Known Member

    It still takes time for heat to transfer from 1 object to another.......its not an instant process......and the coolant and the metals are rarely in a homeostasis temperature balance.

    I guess thinking of your blasting water example I guess there could be 2 trains of thought that could give a net endvsame result.......tons of water blasting quickly through pulling few degrees out but making a big difference by volume passed through. Or slower passing pull more heat.

    Guess it like selling cars. Sell 10 at 500 profit each or sell 1 at 5000. The end result is the same just different path to fet there.

    I'm glad this hadn't turned into ppl getting upset at other thought process.....its nice to have ppl challenge ones way of thinking and having several ideas to ponder
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Here's the bottom line, you can tell how good your cooling system is working by how close the engine runs to the thermostat rating. I have a 180* stat, and I never see more than 185*.

    Interestingly enough, I always glance at my gauges as soon as I get out of it after the traps. The temperature is always about 195*, and by the time I make the turn off onto the return road, it is back to 180* or a bit less. Gotta figure the coolant is circulating at maximum speed at 5500 RPM plus, so there is evidence that coolant traveling too fast might not have time to transfer as much heat.
     
  13. FLGS400

    FLGS400 Gold Level Contributor

    Not to hijack Ray's thread, but while we're on the subject of thermostats, what's the secret to getting that bugger to stay in the manifold, while you place the gasket, sealer, and housing over it? I've tried the self adhesive gasket method and the-try-to-get-it-all-together-before-it-falls method and still have a slight leak there. The second method mentioned failed miserably.

    For reference, car has a 400 with Eldelbrock Performer manifold, Stant thermostat, and stock thermostat housing.
     
  14. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I just use some Indian head gasket shellac in the manifold recess, then stick the thermostat in, more gasket shellac, gasket, and carefully assemble. Examine the gasket surface of the stat housing. They have a tendency to pit. Use a large sharpening stone with some oil. Move the stat housing back and forth until the gasket surface is smooth and flat.
     
  15. FLGS400

    FLGS400 Gold Level Contributor

    Thank you Larry!

    I have some Permatex hi-tack, is that the same thing?
     
  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    That will do.
     
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  17. DaWildcat

    DaWildcat Platinum Level Contributor

    And I've done the Permatex Hi-Tack trick too, just use sparingly!

    And I submit that it's been many years since my college Thermodynamics, Material Properties, Macro/micro Physics, Fluid Power classes...but, there's a ton of stuff happening in a heat exchange system, especially in automotive, where air and liquid coolant flow and temperatures are constant variables.

    This linked discussion I found was helpful, maybe for the layman too...even if just to get a glimpse of the crazy amount of what's involved:

    https://www.eng-tips.com/viewthread.cfm?qid=432703

    Devon
     
    Last edited: Apr 8, 2021
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  18. rkammer

    rkammer Gold Level Contributor

    I didn't expect this much discussion on my OP and so many differences of opinion. But, it's good discussion and I've learned a few things.
     
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  19. Bens99gtp

    Bens99gtp Well-Known Member

    Its amazing how unsimple a basic cooling system is. The base theory is a very simple idea, that get drastically complicated very fast
     
    Last edited: Apr 8, 2021
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  20. TrunkMonkey

    TrunkMonkey Well-Known Member

    Good thing the OP didn't axe about the hot and cold of wimminz.

    You want complicated? That's how you get complicated!
     
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