Rear mounted water "helper" radiator
 

Belts and braces...
Basically, I never want to worry about cooling ever again...no matter what the situation, so I'm adding a small "helper" water radiator inside the rear bumper (in addition to a second oil cooler up front).
Its 280x189x37mm (21 Row) Plate and Fin with a 9" Spal puller fan.
An electric booster pump will feed it (which can run up to 27 litres per min), with both fan and pump triggered whenever the front radiator fans activate.
There is a heap of vacant space in the rear bumper shell, and with the reversing light unit removed, quite a decent sized vent directly into what I would assume is a low pressure zone. (A serious amount of flow exits when the fan is active)
I see it mainly as a helper with cooling down straight after a hard run.
The radiator is mounted and the pump is in place and the electrics are live, so now I'm in the process of running (5/8) hose from front to rear..and back.
There will be wire mesh protecting both sides, and even though it looks vulnerable to rocks etc from under the car, it is surprisingly well protected...sitting up fairly high, and with a large muffler in front (which I am going to wrap to all but stop any radiant heat).
I'm going to be fascinated to see if it works and how it goes (fingers crossed!).

Where are you pulling oil from?

Sent from my ONEPLUS A5010 using Tapatalk

Coolant

Oh I saw you say oil cooler and assumed this was that. But I remember you from your other thread now. Why not just get a bigger radiator? That would offer much more cooling than this thing. Not that this won't work, cuz it will. I just don't believe it will work as well

Sent from my ONEPLUS A5010 using Tapatalk

Yeah, already have a bigger and more efficient front (PWR) radiator, and I quite like the idea of taking any heat I can away from the engine bay area.

could also consider running an aluminum hard line for most of the length underneath the body. it's not going to add much cooling, but would add more cooling than a rubber line in the same scenario...

I dig it, also reminds me of the diff cooler openings on the cup cars.

https://s36.wheelsage.org/format/pic...6b0d5409ea.jpg

Hmm .. how rad is protected from rocks flying in air intake path and puncturing it? how it's protected from dust or dirt getting by in air intake path and clodging rad up (probably even more of issue with rad fan sucking extra of that when it's operating)?

I dont think it will be too much of a worry, it sits up quite high, and is shielded by the muffler.
I'm also going to put some wire mesh in front of it, to make sure. :)

Passed its first proof of concept test, with flying colours.
No leaks, electrics working properly and the pump is very effective.
Lots of heat!
The 9" fan overlaps the edge of the radiator so there are some heavy plastic shrouds top and bottom to stop the fan drawing air from around the edges.

Do you run a rear diffuser?

lol that reverse light is awesome.

Have you ducted your radiator? The front one I mean.

Where in the cooling circuit are you pulling from and returning to?

This is pretty sweet setup.

You could also replace sections of the lines to/from the rear rad with something like this
CK100-8 Single 16 Inch Pass Heat Sink Super Flow Fluid Cooler.

Also if you don’t have already a radiator mister helps a lot. A lot of rally guys use this.

No I dont (and cant, as i do a lot of dirt roads), but I think it could be a benefit... it could possibly mean you could run a larger core and also perhaps use it to direct flow into the radiator.

Diffuser technically shouldn't have any flow over the top

Sent from my ONEPLUS A5010 using Tapatalk

No I haven't , my thinking is that because
I dont want to run bonnet louvres, and I have a large alloy sump guard fitted I simply can't get the air out of the engine bay.
It's interesting when I have the car jacked up and running, how much better the flow is when the fans kick in when the sump guard is off...and how when it's bolted back on, you can hear the fans working harder, with much reduced flow past the guard.

I'm running a 16mm "T" connector immediately at the start of the heater inlet pipe at the top of the engine, which runs down to the pump, then on the return leg runs into another "T" just before the heater pipe return hits the water pump.
So effictively its a circut that bypasses the heater unit (but the heater can still operate if needed)

Yeah those heat sink coolers could be good, but its a super tight squeeze to even get 5/8" hose to the rear and back, and tucked in so it wont get hit by rocks etc.

I think you're right about the water mister, that could be my final play if I still have dramas.

Ducting is still important. As you want the air coming through the grill to actually go through the radiator instead of around it. As I'm sure you can imagine, radiators are an air RESTRICTION and it would much rather go around then through.

Depending on your usage of the vehicle, you might be about to modify your cowl(windshield wiper surround) to allow air to escape up the windshield without modifying the hood itself. I'm not sure what affect that opening might have during daily driving. Cause your climate control air to be hot? The OEMs seal it up for a reason, but I couldn't tell you what it is. It's not uncommon for people to put risers under the back of the hood to achieve that gap. They seem to do ok. Modifying the cowl would be nearly invisible from the outside

Sent from my ONEPLUS A5010 using Tapatalk

Making a gap at the back of the hood might be counter productive as there is high pressure air in front of the windshield (when the car is moving at speed) that would limit the air flow from under the hood. I fabbed up some garnish vents. That area seem to have relatively low air pressure.

But is the pressure higher than in the engine bay

Sent from my ONEPLUS A5010 using Tapatalk

Good question. It is my understanding that both areas have high pressure. That's why hood vents are placed closer to the front and/or sides of the hood where the relative pressure is lower.

If you put a gurney flap at the front of the opening it helps suck air out by creating a low pressure void. My Driveway Labs duct is designed that way and it moves quite a bit of air. I believe the gurney is also on the Verus ducts.

I can't visualize where the Gurney flaps you describe are located. I've seen them on rear spoiler and wings but not on the front of a car. Any Pictures?

This is from Verus's webpage, but you can see the little flaps at the front of the ducts. This is also how splitter endplates help, they pull the air from the wheel wells.

I am not sure how having the windshield behind would affect things. Sounds like some string testing would be in order if someone where to try this :D

https://www.verus-engineering.com/we...unique=d2632ae

How are the lines protected under the car? I'd be concerned with losing coolant for how little extra surface area you added. Interesting idea though.

For sure I agree, but my cooling issues are specific to a low speeds and high revs combination, when the fans are doing the heavy lifting (which is also why I added the second oil cooler with fans). I dont really have any cooling issues in other circumstances.

In reality it adds an extra %20 surface area, and as it is a %30 thicker core, probably a little more.
The lines run protected along side the brake lines (under the underbody cover), then skirt around the bottom of the wheel well, but behind the damper, then into the rear cover.
I will be making a small alloy shield for the small portion where they enter the under body cover along side the brake lines.

Decided to give the setup a proper check after a week of hard use, so took off the rear bumper.
Its working really well, temps appreciably lower in areas/uses that used to concern me, and cool down after a hard run is noticeably quicker.
It's venting very well, and appears to be drawing a reasonable air flow through when the car is at speed, and the fans are not operating... the negative pressure at the rear might actually be working to some degree.
So far, a success. (touch wood!)

Great design, I think you've inspired me to move my air to water intercooler to the rear