Thinner and wider would get rid of more heat if your like Andy escoz you would won't the others as his is going in both quarters

 

the rear of the car is at low pressure relative to the duct on top of the boot so the air would flow the reverse way to the arrow in that duct, bypassing the radiator when the car was at speed

 

I wouldnt have a duct from the tailgate window.

That area looks like it would be high pressure and would act against the air being scooped up from below.

The area that is deffinately low pressure it the back panel especially with the spoiler breaking up the airflow.

Its all about having a higher pressure one side of the rad more than the other

The greater the pressure difference, the more airflow and greater cooling

These are interesting

AutoSpeed - Undertrays, Spoiler & Bonnet Vents, Part 2
AutoSpeed - Blowing the Vortex, Part 1

 

Often the radiator was put in the back for weight distribution purposes -
eg - better traction/ weight distribution on a RWD mk1 / 2 Escort rally car or to help balance the front-heavy Audi quattro

As sierra1off has said - if the inlet is in a realatively high pressure area, and the outlet in a low pressure area - flow will occur - the highest pressure area is the front of the car (grill etc) everything else is medium/ in-between - the back panel is the lowest pressure area, as long as the exit is at the extreme back of the car, (eg, back panel) this low pressure area will "suck" the air through ducts of any shape or size on the top, bottom or sides of the car, with or without nrca ducts, big scoops etc

Because when the car moves through the air a low pressure area is formed at the rear of the car (realative to the top, bottom, or sides)

If the inlets are lower than the outlet/s, the the heat rises (a "chimny" effect) out of the outlet/s aiding cooling without fans even when the car is stationary, if this is the "wroing way round", it can cause problems or a reverse flow situation or this effect may work against the flow of the fan/s or the normal flow of the air when the car is moving


An electronically controlled electric waterpump does not need a thermostat, the temprature is controlled by switching the pump off/ on or turning it up/down automatically to reach a pre - determined (adjustable) temprature, the electric waterpump only works on demand/ proportional to need, and does not "rob" any power from the engine, the pump can be set to run after the engine is turned off and often the radiator fan/s can be dispensed with (saving weight- they only work under about 40mph in an efficiently vented system, anyway) it is more expensive than a mechanical pump but is more effective and is easier/ quicker to change - a lot of hot rods/ dragsters use them and some rally cars/ track cars - if i was building a rear mounted radiator - i would use an electric pump - i used one on my (front mounted radiator) project.

 

It also gets a lot of heat out of the engine bay which is a good thing

 

Lol all this said by me and few others back in the post

But can be bad if you loos to much heat graham

 

You can just change the thermostat tho heat soak is a bad thing mine seems to run ok never had it on motor way tho

 

Old thread I know
I have done some more work on my rear rad conversion,
Im taking air from both sides of the car
I have made these air scoops out of carbon
They feed 2 inner air channels again in carbon to
Quite large air pipes into a air pressure box again carbon lol








Air will flow out the back HOPE fully lol
Still a lot of work to do but getting there
Good place to store the workmate fits perfect lol

 

Is the air exiting the rear panel or underneath ?
as the air under the car isnt normally very low pressure unless you have a deep spoiler at the front of the car keeping air from traveling underneath

That ducting looks good

 

It's not finnished yet but the air is leaving from just under the
Number plate ,
I have to make the duct for that yet
I have worked out the size it needs to be to
Have low pressure area as the air leaves the rad,
I'm going to be using a gopro camera and some wool tassels
To see what's going on,
I have tried to gas flow (Lol)the system to aid the air flow
The ducting was bstard to make !!! 3 piece mold ..

 

The air is leaving through this .
I hope LOL

 

That looks awesome!

 

quick question on the rallycross rear rad setups, have been looking at the newer mk7 fiestas, they all seem to have such a small air intake hole, outlet is only the number plate cut out, how are they achieving such good airflow,

 

Cos they spend most of their time sideways!!!!! A lot of cars have ducts in that area for cooling.