Rear Mount Radiator Questions

[JungleMatic]

...But Mine is a big heavy copper rad, might do it in aluminum someday to shave weight...

Maybe save 1-2 lbs?? lol. I can't see a different rad weighing much more.
People will add an alum rad to save weight, but it then tripples the water capacity and you end up actually adding like 10lbs (right to the very front of the car as well ). Only run as big as you need.

[dhall0519]

Why not use Evans "waterless" coolant & whatever rad fits nicely?
Waterless coolant is so much better to work with. Protect from -40 to +375' , no pressure caps required. System runs at atmospheric pressure with expansion tank.
Currently run this set up in my car on a 2 row core & never does the gauge creep.
Hers's a link: http://www.evanscooling.com/products/coolants/

[JungleMatic]

Did you overheat before using it though?...

[VickersGTS]

Why not use Evans "waterless" coolant & whatever rad fits nicely?
Waterless coolant is so much better to work with. Protect from -40 to +375' , no pressure caps required. System runs at atmospheric pressure with expansion tank.
Currently run this set up in my car on a 2 row core & never does the gauge creep.
Hers's a link: http://www.evanscooling.com/products/coolants/

I read about that stuff a while back and it looks awesome. I hadn't heard about anybody doing it in a Toyota though. Worth a shot before doing any other ridiculous stuff

[Chewy]

Get a VW header tank, have it pull from the top with drop vents or NACA ducts and vent out the rear or bottom of the car. Ducting would probably be easiest with just sheetmetal to begin with, unless you're real good with composites.

My .02 might be to add an aux elec water pump with a bleedback into the header tank to ease any cavitation in the engine water pump. I'm not much of a fluid dynamics guy, but I imagine this happening with drifting since you have such rapid changes in rpm and therefore speeds at which all that fluid is surging and then drawing back. All my feels tell me an aux pump with a bleedback would give more of a smooth flow.

[clay72]

Here is a pic of a dead simple setup. Uses a header tank to get the coolant fill nice and high.

[Dirt-McGirt]

I am assuming this car will stop from time to time, be in line, etc, and he will also want to warm it up to operating temp before thrashing it.



I'm not following here. I guess you figure having the ability to purge it and to have a header tank are 2 different things? Is a header tank not a means of purging?

All in all it sounds like a pain in the ass but i would like to see someone do it and work out all the bugs. Someone who is not me. I have a 3 row fox body mustang aluminum rad and will have a big pusher on it because its a street car.

The rad fan scenario is an example. Fans, by design, are ment for street cars. A well setup system, on a race car, doesnt need them. Its an example i use to try to explain things to people. Thats also why i said a happy meduim is needed for a rear mount system that will see idling. Now for the purging, dont confuse created steam with intial purge. Purge means a loss. In a proper header setup, the steam created in an air lock system is used to pressurize the header tank to create a proper coolant flow, its not a purge, its used to create pressure and induce flow paths. Alot of systems dont use normal rad caps, there working pressures are high as a giraffs ass and the typical rad caps can come loose due to vibrations in endurance racing.

That Evans ****, heres my take. when people remove there T-stat, they run cooler water temps, no doubt. Theres a reason though and its actually terrible for your engine and a rookie mistake. The size of your T-state ID is fine tuned to create system flow pressure. (dont confuse this with absolute pressure) Flow pressure is what scrubs air pockets and steaming away from heads. This is why T-stats are always on the outlet, not the inlet. If they were on the inlet, it would create a lower pressure prior to entering the WP and engine. With out it, your **** isnt collecting and moving heat, its allowing air to stay there and create an isulation barrier. Now think about that. Your insulating your combustion chambers from energy transfer. (heat) Now in most systems, both flow and absoulute pressures work together. In an evans, you have no absoulute (the hold down pressure) to scrub steam. Thats why cars with no T-stat will show lower coolant temps, but reach there Knock limit way before normal. There is no transfer happing.

I know most **** on forums is taking with a grain of salt, but this is what I have learned from my expierence in Dedicated racing that is considered world class.

Trust me. In indurance racing, Cooling systems and heat exchangers of any sort are a primary focus.

[Dirt-McGirt]

Also in that pic, i dont see a dedicated header?

Never mind, i see what there trying to do. I would like to see it run hard like that.

[JungleMatic]

The rad fan scenario is an example. Fans, by design, are ment for street cars. A well setup system, on a race car, doesnt need them. Its an example i use to try to explain things to people. Thats also why i said a happy meduim is needed for a rear mount system that will see idling. Now for the purging, dont confuse created steam with intial purge. Purge means a loss. In a proper header setup, the steam created in an air lock system is used to pressurize the header tank to create a proper coolant flow, its not a purge, its used to create pressure and induce flow paths. Alot of systems dont use normal rad caps, there working pressures are high as a giraffs ass and the typical rad caps can come loose due to vibrations in endurance racing.

That Evans ****, heres my take. when people remove there T-stat, they run cooler water temps, no doubt. Theres a reason though and its actually terrible for your engine and a rookie mistake. The size of your T-state ID is fine tuned to create system flow pressure. (dont confuse this with absolute pressure) Flow pressure is what scrubs air pockets and steaming away from heads. This is why T-stats are always on the outlet, not the inlet. If they were on the inlet, it would create a lower pressure prior to entering the WP and engine. With out it, your **** isnt collecting and moving heat, its allowing air to stay there and create an isulation barrier. Now think about that. Your insulating your combustion chambers from energy transfer. (heat) Now in most systems, both flow and absoulute pressures work together. In an evans, you have no absoulute (the hold down pressure) to scrub steam. Thats why cars with no T-stat will show lower coolant temps, but reach there Knock limit way before normal. There is no transfer happing.

I know most **** on forums is taking with a grain of salt, but this is what I have learned from my expierence in Dedicated racing that is considered world class.

Trust me. In indurance racing, Cooling systems and heat exchangers of any sort are a primary focus.

Awesome post.

What additives/products did you guys use?

[widebodystarlet]

I'm interested to know more about creating low pressure zones. I understand where they exist naturally on the car, but could you create a low pressure zone, say on the front hood (so air flow through the rad exits a scoop on the hood) simply by making a lip around where the air would exit? How would you determine the appropriate size of the lip needed and is it based on the flow area through the rad?

[Warren]

Streamers and wind.

[matt t]

I'm interested to know more about creating low pressure zones. I understand where they exist naturally on the car, but could you create a low pressure zone, say on the front hood (so air flow through the rad exits a scoop on the hood) simply by making a lip around where the air would exit? How would you determine the appropriate size of the lip needed and is it based on the flow area through the rad?

Are you referring to a positive pressure behind the rad to exit hot air?
An easy rule to remember to create a positive pressure is you would make your air outlet 1/3 the size of your inlet. Creating a positive pressure, most effective with ducting and sealing off other unnecessary ports into the engine bay.
Not to get too off track, this is a good topic with some good info.

[clay72]

Awesome post.

x2.

Thanks.

The only thing i am having trouble with is whether the header tank is there because it has to be to create that positive pressure system, or because the cooling system requires it because of other difficulties in getting air out. When fluid is flowing through a confined area (the block) it doesn't know that it is under pressure, does it? I'm just wondering how coolant paths are affected by pressure. Maybe you mean it forces out airlocks that will naturally form in the system every time it cools.

its used to create pressure and induce flow paths

Just thinking in a standard (non-header tank) system the rad plays the role of the header tank. There is less volume for air expansion as with a header tank system, so vapour pressure should be higher than a header system? Just thinking about air that is dissolved in the coolant system (not purgable air pockets) that is evolved at higher temps.

You don't have to explain any of this stuff to me if you don't want to waste your time, I'm just curious and would like to know it better.

[clay72]

Pre-pressurized systems now

http://www.crracing.com/tech/cooling...colling-system