Thread: Radiator fan conversion.

Thanks,

I will certainly be checking the fans as well! they seem smooth and quiet, but you never know... a dodgy brush like yours had won't make them noisy!

seeya,
Shane L.

The recent hot weather had me thinking about all those people who are having issues with their cooling systems. Oswald of the Ardennes as we like to call him seems to be doing quite comfortably in this stinking 48 degree weather with the ac on full bore.

But it did get me thinking about a modification I was wanting to do a little while ago, and that was to alter the sheetmetal on the bonnet just behind the radiator, to aid in extracting hot air form the engine bay.

I've obviously thought more than twice about it, thought about reverse scoops on the raised sections, and a bunch of other things.

Which is why I just wanted to add a couple of images to this thread as well as link back into a couple of other related threads, which may assist some people in understanding what is going on with regards to airflow at the front of the vehicles.

Basically the idea is to try and leverage the low pressure areas just behind the radiator, to get the bulk of the heat out of the engine bay. This is why I've included a couple of JK wrangler hood mods as well. Defender owners may be interested in those.

Bear in mind that things like auxillary driving lights in the middle of the bullbar will impede airflow to the front of the vehicle which pushes the high pressure area forward of the radiator grille, and can increase the temperatures in the vicinity. It can also be a contributor to the viscous coupling fan running more often and longer, because the higher ambient temps and reduced airflows.

anyway - here tis.
JaguarExahighres15cropped.jpg
2pickupcfdconsulting.jpg
aev6.jpg
aev14.jpg

Project bonnet scoop

Fors and against Bonnet scoops

if that really is a low pressure area .... I can't see why it wouldn't work very well! The trick is finding out if you are putting the vent into a low pressure area. Does anyone have a way of check

Because of where I live, over the last several years I've done a huge amount of research into this, with a much more scientific approach this year, (er, with time allowing, anyway).

There's too much to get into here, but basically the airflow into the radiator isn't as good as you'd think it would be, and I think that having a bullbar has a lot to do with it. The air seems to hit the front of the car and then go off at 90-degree angles instead of straight in the middle. The other big thing is that airflow out of the engine bay seems to be particularly bad, and the result is that these cars wind up with a big "pillow" of hot air over the engine, because of the bonnet shape.

I've had various radiators and two types of viscous fan over the years. The electric fans were fine until I was doing a lot of highway driving in hot weather, with a two-speed setup, and the low speed just wouldn't turn off. Also, they dimmed the spotlights a bit when I switched the fans to high speed. Eventually I went back to the factory viscous and highway speeds were fine but hot idling was a bit high. It was after that when I found the melted plastic on the blade fuse for the since-removed electric fans!

That was before I put the aircon in. Now I've got an EA-EB Falcon viscous clutch and fan with a shroud I made from aluminium, and a Fenix ally rad. It's been great, but I think I'll go back to electric fans because it was running too cool while down south, and this big fan makes so much noise and has so much resistance it was making the fan belt squeal at high(ish) revs. But the big challenge is to get that airflow sorted out so that the electric fans aren't on all the time because there is more turbulence, with air going into the engine bay from underneath, than you'd think.

Otherwise, I've got vent holes on the sides of the bonnet and decker panel, and two forward-facing scoops on the bonnet, in line with the hinges. This took a lot of work to decide where to put them, complete with wool tufts taped to the bonnet, but the next step is to put tufts under the bonnet with a camera to see where that air is actually going. Certainly, that "pillow" of hot air over the engine isn't nearly as bad.

I've also put a seal between at front of the bonnet, the idea being to reduce the air coming through there. This was because at this stage it seems to be far more important to get the air out of the radiator than into it, (if that makes sense). Anyway, if I ever get some actual results I'll have to start a thread on it!

Originally Posted by DoubleChevron

if that really is a low pressure area .... I can't see why it wouldn't work very well! The trick is finding out if you are putting the vent into a low pressure area. Does anyone have a way of check

A manometer. There is an Autospeed article about using one.

Originally Posted by DoubleChevron

if that really is a low pressure area .... I can't see why it wouldn't work very well! The trick is finding out if you are putting the vent into a low pressure area. Does anyone have a way of check

That first image is a CFD model of the airflow (digitized) and uses an L322 which s only slightly less boxy than an RRC. Red is high pressure and dark blue/purple is low. the ribbons are the vortices shoting turbulence maps.
The likelihood of the RRC being much different will be negligible, if anything the frontal area of high pressure will be far larger, the side flow more turbulent and the windscreen will have 2 high pressure areas, one at the bas and the other on the top edge.

Davo, are you satisfied your "holes" are in the best possible spots, and if so - any pics/dimensions?

Bloody hell, my last two replies are gone.

Okay, once again, yes, I think the scoops and holes are in the right place to ventilate the messy underbonnet airflow. Like I said before, it ain't pretty, and also when the scoop was pointing backwards it didn't make any difference. I still have to get a camera and put it in the engine bay with some wool tufts to see what's actually happening under there, but certainly the air coming through the radiator makes little difference.