rstarch345 said:
After looking at the opening size on a standard versus high flow thermostat, one actually wonders how enough coolant ever flowed through the thing to do any cooling.
Then you look at the t-stat housing for the 4.0L engine and see all the restrictions there, especially after you’ve seen a high flow housing.
I'd agree with that, there is a significant bottleneck in any thermostat and the wax-type balanced thermostats (which only fit the high-flow housing) will allow more flow. The issue is "do we need more flow", and since 90% of engines on the market use the same type of thermostat, I'd say designers ar OK with that bottleneck and design the rest of the system with that in mind. It can be improved and maybe needs to be on the stroker, but the stock setup *should* work with the stock t-stat. IMO....
rstarch345 said:
Well I installed both, no change in temps or anything else, but I had the self confidence that coolant was flowing better.
OK, so you don't know but you spent money on it and like it. Nothing wrong with it, but it's not data that can be used for anything conclusive.
rstarch345 said:
Now comes the point where I need to replace the water pump. I’d already seen the OEM pump impeller and had wondered how the durn thing ever pumped water with it’s inefficient impeller design. While hydraulic pumps are designed differently, they are designed to eliminate cavitation and only move oil, not air. It seemed to me the OEM water pump would cavitate as much as it pumped coolant. For those not familiar, cavitation is where large amounts of air is created around moving impeller/propeller. The more the air, the less efficient the impeller/propeller becomes and more energy is required to create the movement of water or object.
Ahhhh.....no. They are designed to move water, which has a higher density than oil. Actually most impellers designed for oil are based on water impellers. Air pumps are very similar but because it's a compressible fluid (air is just a very low-density fluid) the pumping designed for it specifically.
Cavitation is basically when the pressure at the impeller, typically right in the center of the impeller, becomes so small that it allows the water to dissociate, IOW the water is in a vacuum and is allowed to boil at low temperatures. Most pumps (not submersibles, but all others) will provide a static head (pressure measured in feet of water) that is required to eliminate cavitation. In essence, you need some amount of pressure pushing against the impeller in the direction of flow to make sure you don't lower the pressure to the point where you cavitate. Caviation will wreck the impeller very quickly, and can show up as pitting usually near the center of the impeller. An engine is a closed system, so the pressure against the impeller is the same as the pressure leaving the impeller, minus the friction losses in the system (which would be significant in this system, pulling numbers out of my butt I'd say a good 50-75%). Caviation is NOT a problem in this case, the more the pump pulls water through, the more pressure it has against the back side of the pump. Is it possible to cavitate? I'd say yeah, but it's also possible for it to be struck by lightning while your driving.
rstarch345 said:
After checking out a number of companies that manufactured aftermarket replacements, I came to the conclusion that these pump became high flow pumps simply through better impeller design. They really didn’t move more coolant, they merely moved it more efficiently.
I'll agree that the hesco pump is more efficient. In fact they claim a 6hp increase simply by switching. I'd belive that too, the stock pump is shaped much like a sewage pump which is NOT designed to be efficient, but rather to be robust even when pumping solids (most sewage pumps can handle 3-6" solids). The hesco pump is similar to a water supply pump that will never see solids, used in municipal water systems after the treatment plant typically. These give a good 15-30% more efficiency for the same amount of flow.
IMO, it comes down to this. Theory and BS aside, will it give better cooling. Tough question. The Hesco pump will give you a performance increase similar to dumping your mechanical fan, I noticed the difference when I did that, so on a stroker I'd do it just because I built the thing for power, why pinch on another 6hp when you need a pump anyway?
Will it give better cooling? Hmm. When you rev the engine using the stock pump you get more flow (gallons per minute) as the revs get higher because the pump is driven by the belt off the crankshaft. Using a high-flow pump simply moves your pump curve up, you get the same flow at 1000rpm with the Hesco as you'd get at 1500 (I'm guessing) with the stock pump. The reality is you velocity increases quite a bit in the closed system, and because losses are exponential to velocity, your not actually getting a direct increase in flow all the way through to the back side of the pump again. But, what you get is so much more efficient, that I'd think it's worth it if your simply looking for HP.
All that said, I recently replaced mine with one that has a stock impeller. $150 is too much for 6hp right now for me, but if/when I do a stroker, I'll use the better impeller.
Wow. That was way too much, sorry for anyone that tried to read all that crap-
