True about water pump pulley sizes in my experience, at least speeding the pump up for lower temps on a street/strip 512 engine.
But I arguably corrupted that experiment by simultaneously adding a fan shroud.
My best guess is those combined lowered low-speed and highway-speed temps, and I was happy with the result.
I inherited the restrictor on the racecar, and appreciated the overall simplicity and "bullet-proof-ness".
I do understand thermostats - and also how alcohol as a fuel affects engine temps, from my time with Sprint Cars.
This monkey has seen several different methods of accomplishing most of the desired parameters in drag racing, but indeed there's plenty of see/do...

You can eliminate the thermostat with an electric pump provided you pay attention to the temp gauge. Just don't turn the pump until the block water starts to get hot. Once the needle is up to 150 or so you can flip the pump on and start to circulate water. You have to be very careful about this since if you forget to turn the pump on you'll overheat the engine. Use warning lights to remind you.

You never need a restrictor plate with a Meziere water pump. None of the Meziere pumps will flow enough water to justify a restrictor plate. The more water you can force thru the engine the better. With a Meziere pump, cooling increases as flow increases.

Thanks for the input.

The pump will be activated by the Terminator ECU - as will the fan - when the engine come ups to temp The beauty of the ECU is that these can be triggered seperately at different temps.

I agree, and I suspect a lot of testing takes place to determine if a cavitation problem exists and how to reduce it. But restating my point, does that same effort get applied internally of a head for example, even if it's a less likely source?

I've used a Meziere pump WP 105 (it bolts into a stock housing) since 2007. I use a restrictor plate (basically the same size as a punched out thermostat) It's cooled the 528, 572 and 655 engine versions of my Challenger street and strip with no issues. I've had various fans and controllers on it (the breakages being due to heavy wheelstand landings). Using firmly mounted Davis twin fan digital controller (fitted recently) and Spal fans at the moment, they seem to be working well

With a restriction on the coolent exiting the engine (either thermostat, washer with a hole in it, or the fact that the upper hose diameter is usually smaller than the lower) I would expect the water jackets to be pressurized above what the whole sealed cooling system pressure is. Pressure helps prevent cavitation.

Pressure also helps suppress boiling, so that's my theory on why a restrictor plate "might" be helpful But a restrictor plate might just be making your water pump work harder for no reason. I would think the freest flowing cooling system is the best system

I agree with your logic, but, there is always but, if one determines they need more flow, enlarging the restrictor is an easy task, cranking up an electric WP, not so much.

I agree 100%. Restrict outlet flow without changing anything else raises jacket pressure. I'm just not 100% sold that pressurizing the cooling system above what the radiator cap's PSI is necessary. Like you said, testing would be needed to see if higher pressure in the cooling jacket would be more beneficial vs the flow rate. For the record, I don't believe it's possible to have too much flow through these engines

My additional take, there cannot be too much operating pressure, other than concerns for safety. Pressure solves a lot of protentional issues.

50psi is approx 281F boiling for water, meaning if you cooled the heads with relatively cool water to maintain power (reverse cooling), and had it moving slow, it could leave the block at 281F without ever boiling, and the temp delta at the radiator would be higher and therefor more efficient in taking out BTU's with ambient air, and all without ever boiling.

I don't know exactly how much block temp vs head temp for power is related. I thought general gist is cool heads hot block?

Why are you considering changes? Is it running too hot or too cold?

Regarding the "slow down the flow so the water has more time to cool in the radiator" nonsense, if that were true, then we should also put shutters on the radiator and close them down when the thing starts running hot "so the air has more time to absorb heat from the radiator".

Cab, you are not the only one who has had that experience or running hotter with no thermostat. But it is not because of too much flow. It is because the thermostat provides a restriction for the water pump to build pressure against. The extra pressure in the heads prevents steam pockets from forming. Steam does not absorb heat like liquid does, and heat builds up. This has all been scientifically proven.

"Regarding the "slow down the flow so the water has more time to cool in the radiator" nonsense, if that were true, then we should also put shutters on the radiator and close them down when the thing starts running hot "so the air has more time to absorb heat from the radiator".

Boy, if that doesn't make it perfectly clear nothing will. But then, you never really win an argument, regardless of the facts.

I run a Jegs brand electric water pump in my bigblock. I do not run a thermostat. Works fine. I control it with a toggle switch / relay combo. My electric fan assembly has a fan controller that kicks on and off at specific temps - it can also be over ridden by a switch if I want it to kick on full blast before the controller wants to.

Yes, there are a lot of bulletproof thinking in a race car and some of that does not apply to a street car. Like vacuum advance.

I guess I am the type of guy that likes to know why something is done and not the type to monkey see monkey do.

All that said, if something works for you well you can't argue against that all you can do is sort out why, if that is your kind of thing

how does one pressurize the coolant system above the radiator cap's rating ?

And why would you ?!?!?

When you have a thermostat or a washer, there are 2 zones of pressure. The higher pressure zone is between the water pump outlet and the thermostat. The pump builds pressure against the restriction. This is in addition to the overall pressure caused by rising temperature.
This high pressure zone also happens to be where the block and heads are, where the heat is generated. The higher pressure in the block and heads helps prevent steam pockets. Water boils at a higher temperature when it is under higher pressure.

The low pressure zone is between the thermostat and the water pump inlet. That is where the radiator and the radiator cap is. This area is subject only to the pressure caused by the temperature increase. It is protected from the pressure of the pump by the restrictive thermostat or washer.

If you remove the thermostat, the next area of restriction is the radiator core tubes. If you have a top tank radiator, or a side tank radiator where the radiator cap is on the same side as the upper radiator hose, now your radiator cap will be subjected to the pump pressure. The pump pressure can push past the radiator cap spring , and you lose coolant. But there's a whole lot of variables. Most radiators have a large enough tube cross section and enough tubes that it's not going to build a lot of pump pressure in the radiator tank. It's not going to build a lot of pump pressure at all, possibly resulting in steam pockets in the heads. Too much restriction at the thermostat reduces flow. Reduced flow reduces the ability of the system to cool. Ideally there should be some kind of a balance between flow and pressure in the high pressure zone.
Think of a garden hose flowing at a low rate. It's just kind of droobling out because there's no pressure. Now put your thumb over The end of the hose and try and shut off the water flow. Pressure will build in the hose until you can't hold it back. A pump can't build pressure without a restriction to build against.

It would be easy to apply static air pressure to a cooling system by simple use of shop air with a safety cap of the needed rating.
The problem is, can the plumbing system handle it, and is it worth the added risk/complexity, even if is a benefit.
In a racing environment, the safety crews would be working in a explosive super-heated coolant situation, much like a boiler.
I suspect this solution would be beneficial first at the top race levels like, if allowed, in F1 or WEC.

Sounds like a good plan. Using the Holly ECU to turn the water pump and the fan on as engine temp comes up is a good solution. If you have a Holley digital dash you can program indicator lights on the dash to show you red dots when the fan and pump are off and green dots to show you when they are on. That gives you a feed back loop so you know that things are working. You can also program warning lights to come on if the temp gets above a certain number and/or you can program the engine to shut down at extreme temps.

More useless drivel !!

Because of your superior intellect you feel the need to point this out with no other contribution to those lesser, or are you just a tad envious in some regard?