Thread: Will a bonnet scoop reduce heat in the engine bay?

Originally Posted by Fausto79

I’d love to get a thermal imaging camera under the bonnet and drive around with different bonnets, each with a different design scoop/louvre and see the difference it makes to under bonnet temperatures

Get a digital thermometer with a few sensors from jaycar or something, plus you can get temp hand gun

So side vents would increase venting at all speeds?
Removing driving lights from the front would increase airflow into the radiator.
Our Defender and our previous D1 both ran the thermo fans whenever the air con is on, I guess to push more air through.
Defender bonnets aren't that well sealed anyway, so I think it's easy for hot air to get out. Discos might be better sealed.

The lowest pressure areas around a vehicle are immediately behind a surface that deflects air upwards or sideways away from the bodywork behind. An example being the front side windows opening a crack and noticing the suction generated by the windscreen edge and door pillar. So in a RRC for example, my choice of vent position would be in the sides of the bonnet directly beside the battery boxes, perhaps a little further back but not much. Driving up a steep track this point becomes the highest point anyway.

Originally Posted by Ace

Hi all,

I've got the disco running pretty sweet these days, engine was done back in 08 and a new head was fitted late in 2016. I've had the radiator rodded and had a new aluminium cowel made up that bolts onto the top of the fan shroud to replace the brittle plastic one. The viscous fan coupling is new and overall it runs pretty cool, there are a few decent hills around here that see the temp increase on the digital gauge, nothing to alarming.

I've ordered a new hard top camper which wont be here for a while so i want to look at ways to keep it cooler.

So, my question is, would fitting a bonnet scoop help drive cooler air in and force the hotter are out or does it do buggar all?

Matt

At speeds under 70-80kph I imagine a scoop would pretty much do bugger all, At high speed you would get more airflow, Towing a van at high speed will also increase the engine temp so it may be of some use.
Fitting a "Camel" type grill and moving the spotties will most likely do the same job without making the truck look like a "Tacky" Boy Racer

Originally Posted by trout1105

At speeds under 70-80kph I imagine a scoop would pretty much do bugger all, At high speed you would get more airflow, Towing a van at high speed will also increase the engine temp so it may be of some use.
Fitting a "Camel" type grill and moving the spotties will most likely do the same job without making the truck look like a "Tacky" Boy Racer

I’d say either rear facing scoop or louvre. Front facing is usually for getting air rammed into an IC. There isn’t one there on D1 so pointless. If anything it may increase pressure under bonnet and slow down air from the front. Making it worse. But that is just a wild assumption with no science behind it.

I think you would het air down it even at lower speeds though. You’d be surprised at how much force a 30km/h breeze would have on a big scoop if you were holding it.

Originally Posted by trout1105

At speeds under 70-80kph I imagine a scoop would pretty much do bugger all, At high speed you would get more airflow, Towing a van at high speed will also increase the engine temp so it may be of some use.
Fitting a "Camel" type grill and moving the spotties will most likely do the same job without making the truck look like a "Tacky" Boy Racer

There are many non boy racer scoop options

Originally Posted by Fausto79

I’d say either rear facing scoop or louvre. Front facing is usually for getting air rammed into an IC. There isn’t one there on D1 so pointless. If anything it may increase pressure under bonnet and slow down air from the front. Making it worse. But that is just a wild assumption with no science behind it.

I think you would het air down it even at lower speeds though. You’d be surprised at how much force a 30km/h breeze would have on a big scoop if you were holding it.

Rear facing will let hot air out at slow speeds straight into fresh air vents

Originally Posted by blackrangie

Rear facing will let hot air out at slow speeds straight into fresh air vents

Who has them open on hot days? Air cond on or the real men's solution, wind down the windows.