[Squidward]

Originally Posted by cmoc-bob

Fast Monty's Garage on YouTube did a good presentation on connecting both cylinders head outlets into the heater/cooling system.

He also showed his test results, and the "more flow" isn't always better. Note the part(s) where we regulated the cal head flow into the cooling system. And the effect hose sizes had......

You can pump too much fluid too - and the heat exchangers don't have time to work.

Look at some modern cars and note the smaller radiator hoses, outlets, etc. Effort to slow things down.

Fast Monty also did some good tests on electric fans.

DeWitt's makes some quality radiators too - they note the BTU capacity of what you are buying.

Good luck !

I love Fast Monty's content. I think he does a great job with his testing to take things beyond the beat of the tribal knowledge drum.

I don't agree with the slower flow theories tho. The laws of heat transfer and physics don't support it. Q=mC(deltaT) is chiseled in stone.

Take examples from the Pontiac: stepping up in cooling needs got you either bigger radiator with more surface area/rows, a higher capacity fan, smaller water pump pulley, or a combo of the three. The bigger surface area increases the "C" in the equation, while the last two increase the "m", or mass flow rate, of the equation.

Keep in mind that there are multiple heat systems at play. There is the heat source (engine) and the heat sink (radiator). If you slow down flow to get more cooling across the radiator, then you also limiting the heat that can be removed from the engine. I haven't seen the Fast Monty episode you mentioned, but I will look for it so I can reconcile my understanding with his results.

I am in the school of more flow is more better.

[Squidward]

Ok, just watched those vids. What Mike was doing spoke more to equalizing the heat distribution on the heads, front to back. On his first test, what he showed was that providing little to no flow restriction out the back of the head actually made the overall cooling worse.

There are 3 flowpaths in parallel on a Pontiac. One is the internal recirc from the crossover to the timing cover so that there is a small amount of flow with tstat closed. Path number two is out of the tstat to the radiator. Path three is the heater hose. The water pump is capable of "x" amount of flow. Any flow going through the heater hose or the internal recirc is flow that does not go through the radiator. Increasing flow in one parallel path steals from flow in another.

What Mike demonstrated was that porting significant flow out the back of the heads to the timing cover suction port made overall cooling worse because it bypassed the radiator. When flow was restricted, it equalized temps front to back (yay!), but didn't significantly take away from the flow to the radiator. Plumbing the back nipples to the timing cover suction was less desirable, but plumbing the back to the crossover allowed equalization without diverting flow away from the radiator.

IMO, what seems to be the ideal setup would be plumb the back of the heads to the crossover, and if a heater line is desired, tap off the rear crossover, plumb to a heater shut off valve, to the heater core, and then to the timing cover suction.

Also, plumbing directly from the rear head nipple directly to the timing cover suction would be a bad idea, because it diverts flow away from the radiator.

Good stuff, thanks for the discussion.

[73ta]

Faster water flow is better according to factory engineers. That's why they changed pulley sizes to speedup water pump on AC cars!