Good looking parts.

 

I have a Hesco pump on one of our XJs and modified my thermostat housing with die grinder and it works great. Next time would save some money and get the CNC Flowcooler pump.

 

I just put a flowkooler on my 4.0 stroker yj, I figured I'd switch it up for the xj build and see how the two perform over time.

 

Could you get me a reliable reference on that..I'm not doubting you I would just like to read up on that especially since I deal a lot with offroad trucks and motorcycles that run everything from the mint 400 to baja..there must be a calculation that we could use to determine the perfect capacity and flow rates for maximum performance and with this calculation we can determine our needs for different engines. We could design water pumps that could run adjustable vanes or speeds which would allow us to we dial the flow rate in for maximum cooling, performance and engine life. This would also help with the seasons and ambient temperatures.

So when I added a larger radiator and kept everything else stock it didn't improve cooling at all since this would also change the flow rate to slower and may be keeping the water in the respective areas too long this producing overheating?

I have lived in the NV desert for 22 years and trust me a hi quality aluminum radiator with a larger capacity does produce a better cooling system correct?

So hi flow thermostats, larger radiators, extra cooling fans, water additives, hi flow water pumps and hi flow housings, hood vents are all a waste $ on a stock 4.0 engine?

Like I said I'm not doubting you I would like to understand more about this subject for my own knowledge. If you can just PM the info to me so we don't step on this thread.

 

Firestrorm500 is correct in my race motors I use restrictor washers in the thermostat housing to control flow rate by the size of the hole.

 

But how do we figure out the correct pressure and flow for optimum cooling in a stock 4.0? That could save some $ over time. Thats my question....like i said im not doubting, just wanting to learn more on the heat transfer coefficient of a car radiator.

I live in the Mojave Desert and I can tell you cooling can be an issue out here especially when you are offroad or rock crawling. I have a ceramic coated intake, ceramic coated header, vented hood, hi flow water pump, thermostat housing, three core aluminum radiator, dual electric fans...It took all that to keep my 4.0 at a safe operating temperature.

If you took a stock 4.0 with no upgrades out with me in August you would run in to some serious overheating issues. So if the stock design is best why the overheating?

http://www.flowkoolerwaterpumps.com/cooling_faq.html

 

So on your race motor what was the science behind the washer? To slow down the flow and create more dynamic pressure?

http://www.flowkoolerwaterpumps.com/cooling_faq.html

Debunking Grandpa's Flathead Theory
"But wait a minute, I know Grandpa used to put washers in his flathead to slow the flow and cool his engine." We know people did this too. They still do it but the cooling benefit is not from the slower flow but the increase in dynamic pressure in the block that builds from the restriction. Consider that Grandpa had two flathead water pumps sending twice the volume through the same size radiator core. At some point Grandpa maxed out the throughput and began building pressure. Building pressure in his block helped reduce the onset of hot spots on his cylinder walls and formation of steam pockets in his block. This is a real benefit and does help cooling but is only realized when throughput nears capacity or is at capacity. While these restrictions may make sense when your rpm is excessive or your flow rate exceeds your heat exchanger throughput, they do not make sense for most applications. If you doubt this thinking then try this simple Ask Dr. Science experiment; clamp off the lower hose while you watch your temp gauge. Hopefully, you will debunk Grandpa's theory yourself before you experience vapor lock and melt your engine.
Restriction is not all bad if it serves to prevent cavitation. Cavitation occurs when a pump turns so fast that you generate lower pressure and air bubbles or vapor forms. These bubbles eventually implode and damage the engine block wall and impeller. Rapidly spinning the impeller can literally rip the air from water but may not actually move the fluid, it's tantamount to turning an eggbeater in a paint bucket. Restricting the fluid flow to raise system pressure in the block may help prevent cavitation at higher RPM but is it necessary for most vehicles?
No. Most vehicles do not need to restrict flow because they do not reach or sustain high RPM. Additionally, thin aluminum radiators already restrict by design e.g. fewer rows of tubes. Restrict it further and you may as well hose clamp the lower radiator hose and we know how that works out. When you face Grandpa on the track you may want your washers, otherwise, keep them in the toolkit.
Simply put, you have a far better chance of keeping your cool with greater flow rate through your heat exchanger and exiting the system than holding it in your heat exchanger while generating heat in your engine block.