Jims5543

THIS IS A DISCUSSION THAT OCCURED IN ANOTHER THREAD, I HAVE MOVED IT HERE SO THAT OTHERS CAN SEE THE INFO AND TO KEEP THE BUILD UP THREAD FROM GOING ALL OVER THE PLACE. The discussion picks up on topic of cooling.- Rob.





FYI - I have no thermostat, no thermo pill in the e-shat and no thermostat in the oil cooler.



I am not seeing much over 165° driving around town right now with no a/c and cooler (75-82°) weather.



Its almost concerning me that I am not getting any heat into this new motor.



I am considering unplugging one of the 2 fans to see if I can get closer to 180°.



Its a great feeling to have too much cooling.

ColinRX7

Not running thermostats causes localized hot spotting, and the worse part is - no matter what car, it always looks like it's running cooler on the gauge.

Jims5543

Really? News to me, a lot of mods were made to the water jackets in the engine as well, I cannot go into to detail, but we changed both the volume of the water jackets and the surface area.



I have had my engine out of the car for almost 2 years, a lot of thought and research went into what I have now. (and a ton of porting )





I take engine water temps from 2 places on the engine one temp sensor feeds the Motec and its at the rear of the engine tapped into a water jacket, the other is taken from the standard location above where the thermostat is located.





Do these hotspots occur in engines that have the thermostat pulled but the bypass was not blocked off? You cannot just yank the thermostat, you have to block off the bypass so the water flows correctly through the engine.



I will bounce this concern off my friend / mechanic and see what he has to say, he has many years of road racing and endurance racing FB's behind him.



Right now he is modifying RX8 internals to work inside a RE engine. He is utilizing a RX8 Oil Pump, and stat gears on a customers car per their request. I find it hard to believe he would steer me wrong.

ColinRX7

The thermostat itself controls the flow of coolant between the motor and radiator, based on temperature. As the temperature increases, the thermostat opens it's valve. Of course the valve doesn't snap open, it gradually opens. The thermostat slowly allows more flow. That being said, with the coolant cold, the thermostat is totally closed. This is a flow restriction. The water pump assists efficiency by giving the coolant a direction that it always wants to flow in, working in conjunction with the thermostat. You notice how your (thermostat installed, block mounted thermistor) car will be warming up, and then the temperature gauge will rise, then actually dip, and rise again? The moment it dips is the moment your thermostat opens a crack, not open entirely. It's a testament to how well the hot coolant is being purged from the block and being replaced effectively with cooler coolant.



No restriction to flow means that the coolant isn't exactly hanging around in the block for long, so it's not going to absorb that much heat. Also it's not hanging around in the radiator very long, so the radiator doesn't effectively dump as much heat as it could potentially. Of course the thermistor is going to say everything is great - but the coolant isn't getting hot because it's not effectively gathering heat. It's just kind of circulating, just passing by crevices of the block that dynamically don't flow coolant as effectively as the more open areas, creating hot spots and dead zones. Dynamically speaking, there is no way that the coolant flow through the block can gather an equal amount of heat from all areas with a water pump alone, unless your block is a perfect tube shape through the whole circuit. You've seen the crevices in the irons and rotor housings. That's what the flow restriction is for. More time to gather heat, as the cooler water (being forced to hang around) remains in closer contact with the hotter areas and absorbs the heat, before shifting to the radiator when the thermostat allows.



But of course I'm talking about an OEM water pump. It's not exactly the most effective pump, it just assists circulation as is designed to work with a thermostat. There are guys out there with high flow water pumps and they don't use thermostats, but hey I don't know too much about aftermarket high flow pump systems. But for OEM...

Jims5543

I do not agree, more time gathering heat?



Your flowing coolant around over and over, hot spots get hotter and hotter because the fluid running over them at 180°+. I would prefer 160° fluid running over my "hot spots" than 180°+ fluid.



I have blocked off the bypass, therefore my car minus the thermostat is flowing the exact same flow rate as your car with a thermostat when its open, actually since I am not trying to pump all my fluid through a 1/8" hole I am probably flowing better. I cannot see how keeping hot fluid in the engine benefits the hot spots.



That is like saying slowing the airflow over the radiator will cool it better. Moving air really fast over it and not allowing the air to heat soak will only cause the radiator to get hot spots too.



After being burned by a OEM Thermostat that got stuck closed, I am done with them for my car, if I have to I will put an even bigger radiator in my car if coolant temps rise on the track, from what I have seen so far I seem to have a fantastic setup going and will be really surprised if they are a concern.

ColinRX7

Easy, didn't mean to wind you up.



From what I understood you had a pretty stock setup with no thermostat. I didn't understand what you meant by "bypass", so I see now you're using an oriface with the same flow rate as an open thermostat. I've never seen that before, but that's interesting.



Fair enough. I took it for "I removed my thermostat and got extra cooling capacity". If you still have a flow restriction, then you're laughing. But alot of people think yanking the thermostat means they get better cooling because they see it on the gauge. Sorry, man.



Slower airflow over the rad won't make it cool better. The outside design of a rad is actually completely different from the inside of a cooling system under pressure, when your "airflow" is recirculatory and provided by a pump, and the speed at which the "air" travels is determined by the type of pump, and it's component design.



But were kinda thread shitting on Rob now. Sorry Rob! I like your car!

Jims5543

I did not mean to come off grumpy. I have a lot of bullshit going on in my personal life right now that has me on edge. I guess I was having a bad night when I posted on here.



Yes, I failed to mention I have a restrictor in place of the actual thermostat. I am watching the temps closely and have other restrictors with bigger and smaller holes so I can adjust accordingly. Right now its looking like I got it on the first try but we will see. If I unplug one fan I see consistent 180° with both fans running I see 160° solid, no matter the speed. Even when I was doing 100+ for 10 minutes straight a few days ago, 160° solid.



The bypass I speak of is a 1/2" or so hole that you need to plug if you do pull your thermostat. This is the bypass that flows the coolant when the thermostat is closed. If you pull the thermostat and do not plug the bypass your coolant will not flow properly.

Rob x-7

figured I would clean up my thread and put this here for those wanting the info.

Jims5543

Yeah, I felt bad about the hijack sorry dude!

ColinRX7

Nice!



What I was trying to get at with more time to gather heat is the fact that there is a flow restriction implemented in the cooling system for a reason. Cool job on fabbing a restrictor, I hadn't thought of that before. Seems to work nice, eh?



Where is that bypass on your motor? Water pump housing? What model is your pump housing from?



I don't recall seeing a bypass on any of my junk laying around, but it was a while ago the last time I looked and I wouldn't have been paying attention to that sort of thing..