Your brother is talking about an old wive's tale (read: myth) which has no basis in fact. On that, clearly he is wrong, and you are correct. I've run vehicles without a thermostat at all (equal to stuck "WFO" <g> in most vehicles), and found them extremely difficult to get up to proper operating temperatures.

HOWEVER, it is also true that the overheating problem he is having with his
LT1 may not be caused by the thermostat at all. The LT1 reverse flow cooling system is quite trouble prone, for example there can be problems with clogging, trapped air, and the water pump has proven to be unreliable.
I've had so many questions and complaints from people about LT1 cooling problems that I've written an article on the subject, which I will send in a following message. The article details the sources of cooling problem (and solutions) that I've found with the LT1. Let me know what the source of his cooling problem turns out to be in the end. Scott.

My main comment is that it is obvious he has never studied physics or engineering, and from the impression you are giving me, at this late stage he may be untrainable. <g>

But I like a challenge, so I'll give it one LAST try:

Cooling really is a fairly simple principle, it involves the transfer of heat from one material to another. The more of each material you can get into contact with the other, the more heat will be transferred. This means that if you move MORE air through the radiator in a given amount of time, more heat will be transferred from the coolant to the air. It also means that if you move MORE coolant through the engine in a given amount of time, more heat will be transferred from the engine to the coolant as well.

The one thing I've found that most people *don't* understand about engine cooling systems is that the thermostat only controls the MINIMUM temperature an engine will run. Once the T-stat is WFO, the actual engine temperature depends on the capacity of the cooling system to transfer and remove heat balanced against the thermal output of the engine.

Real world example: I had a '78 Riv (2-door B-car) with an Olds 403 (6.6L) in which I had installed a 180 degree thermostat along with an accurate VDO temperature gauge. With the gauge, I could accurately track the engine temp and even see exactly when the T-stat opened. After starting the car, the engine temp would rapidly rise to 180-185, whereupon the needle would visibly stall, maybe even drop 5 to 10 degrees, then slowly rise to between 190 and 200, where it would generally stay under MOST conditions. However, in 90+ degree ambient temperatures, with the AC on and running at highway speeds, the temperatures would begin to creep upwards to as high as 225. That is still an acceptable temperature (most factory stock engines are designed to run that hot before the fans kick on in fact), but I wanted to see if I could get it to come down.

So I installed a 160 degree T-stat in place of the 180. The only difference I noted was in the initial warm-up. The engine would rapidly rise to 160-165, I could see the gauge needle stall as the T-stat opened, then it would slowly rise and stabilize at between 170-180 under most normal conditions. However, just like before, in 90+ degree ambient temps, with the AC on and running highway speed, the temperature would again creep up to 225.

Finally I decided to remove the thermostat altogether. What this did was make the engine incredibly slow to warm up, and the temperature it would run at was largely influenced by the ambient temps. In the morning for example, I could barely get the engine to rise over 130 to 140. On a normal 70 degree day with the AC off, it would rise to 170-180. But just as before, with 90+ degree ambient temps, the AC on and cruising at highway speeds, the temperature STILL rose significantly higher, but I did note that it would generally max out at 220 instead of 225.

I attributed that minor 5 degree reduction at the top end to be the elimination of any coolant flow resistance by the thermostat, since even when a T-stat is wide open it does provide some resistance to flow.

BTW, I later *repeated* this experiment almost exactly with an '88 Caprice
9C1 with an LM1 350, noting all of the temps I experienced were virtually identical. In fact my friend still drives this car TODAY (250K miles) and has been *removing* the T-stat EVERY SUMMER since he bought it from me many years ago. He also completely ripped out the AC and installed a larger Modine aluminum radiator. Once the AC was ripped out (esp. the condenser in front of the radiator) the max. temps immediately dropped 10 to 20 degrees (increased airflow through the radiator), and subsequently adding the larger aluminum radiator dropped the max. temps another 5 to 10 degrees. Now even under the worst ambient conditions, he barely hits 195 on the gauge.

What all this should tell you is what I have KNOWN all along, which is that the thermostat only controls the MINIMUM temperature that the engine will run. Once the T-stat is open, the capacity and performance of the cooling system balanced against the thermal output of the engine is what decides what the coolant temperature will be. Meaning that even though the T-stat is fully open (or even removed entirely) the temperatures will equalize at whatever point where the engine thermal output balances against the capability of the cooling system to remove that heat. As the engine warms up or the load changes, the system will reach a stable temperature (depending mainly on ambient temperatures and engine load), which if the system is designed properly, will always be below the point where any damage can occur.

If one wanted to improve the performance of a liquid cooling system in order to reduce any rise in temperature that would occur AFTER the thermostat was open (or removed), then there are two main things that cold be done: transfer MORE heat from the engine to the coolant, and/or MORE heat from the coolant to the air.

To transfer more heat from the engine to the coolant, you would increase the flow speed and therefore volume over time of coolant circulating through the engine. This could be accomplished by changing pulley diameters to spin the water pump faster (of course also keeping it below the point where cavitation would occur), or by designing a pump that used larger impellers to flow more coolant at a given speed, or a combination of both. As any cooling system engineer could tell you: if you flow MORE coolant through the engine in a given amount of time, you will absorb and therefore remove more heat as well.

Of course the performance of the entire system depends not only on transferring heat from the engine to the coolant, but then also transferring that same heat from the coolant to the air. Improving one side of the system won't have any benefit unless the other side is up to the same or higher capacity as well.

Increasing the size, capacity, and surface area of the radiator will allow more of the heat to be moved from the coolant to the air. Likewise, increasing the speed of the airflow over the radiator (or removing restrictions like the AC condenser) will also enable the transfer of more heat, which is why at lower speeds a larger or higher CFM fan could be used.

If your B-I-L were correct (I'm imagining some sort of alternate universe where the laws of physics are upside down <g>), then flowing MORE coolant through the engine would somehow transfer *less* heat, and I guess by corollary he would say that flowing MORE air over the radiator would transfer
*less* heat as well. Yeah right. <g>

All I can say about *that* is this is obviously *not* the way it works in the *reality based* universe you and I live in. <g>

OK, time to end this. At this point all I can say is that if he recognizes the truth, then my mission was a success! (yay!) If however he remains unconvinced, then I have failed (boo!), and unfortunately would have to believe that any further attempts at education in this matter would also be in vain. Let me know how it turns out, but in either case I consider the subject officially "closed." (yay!) Scott. <g>

PS: Tell your B-I-L not to take any of this personal, I tend to be a bit of a smart-*** in messages like this, all in fun of course. <g>