Bonnet Scoops

[landrovermick]

I was talking to a mate last week who told me something interesteing.

The tale goes like this :

When a Range Rover (and for that fact i guess a Discovery) drives along, the engine bay area pressurises. This is caused by the amount of air flowing under and over the vehicle.

My mate tells me that by placing a scoop on the bonnet area of the vehicle we have got the problem half solved..... but - remeber when i think it was ferno posted , have to go get my A9X scoop for my bonnet????? that is the thing to do - The A9X scoop runs backwards, that is with the opening towards the windscreen, now im not saying go out and buy one of those big buggers , but it might make sense bearing this theory in mind to place the scoop on a rangie - disco backwards.....

Also another cheap effective way to scoop the bonnet is by using the side vents on the "C" pillar of a rangie and grafting them into the side rear of the bonnet.

This scoop running backwards lets the built up air pressure escape with the air that is flowing over the roof.

just food for thought ....

Oh also, and check me if im wrong, dont some of the vehicles that have scoops on the bonnet facing front have the scoop directed to the intercooler so as to increase cooling?

Regards
Mick

[Rovernaut]

Another thought on the subject.
When wading the engine bay as a big air pocket and keeps water out. If a scoop was added then the trapped air pocket would not exist.
:roll:

[landrovermick]

true - I guess its battle of soft versus hard roaders

[one_iota]

I think that the Patrol 3.0 Tdi has the bonnet scoop for a top mounted Intercooler as opposed to the LR Tdi front mounted IC.

I was`wondering though why having a pressurised engine compartment was a problem requiring some relief. :?

[landrovermick]

Basically its not a problem, though some of us do complain about heat levels.

[one_iota]

Forgive my being thick.

Diesel Engines I guess don't suffer from vapour lock and all that. Only a raft of other things.

It has triggered a memory of a forum discussion elsewhere which I will try to retrieve for what it may be worth.

[Mick-Kelly]

Watching with interest

[one_iota]

Nothing of substance found whilst searching apart from Jeepers suggesting that bonnet scoops look cool.

Some thoughts though:

Engine compartment heat can't be good for the battery(ies).

I'm not sure where the air in a v8 is drawn from but if it comes from a hot engine compartment then the air is less dense and therefore carries less oxygen for volume. But it is "pressurised". If the compartment was depressurised then maybe the addition of a snorkel would assist? Cooler pressurised air.

[duff]

I think you will find the A9-X scoop faced rear wards to actually draw clean cool air in down into the engine bay, away from the high pressure area that forms in front of most vehicles windscreens( same theory why most heaters draw from that area). This not only sourced cool air but it reduced the drag from the high in front of the sceen This scoop fed the carbies and from what I understand the excess air was drawn down over the hot extractors and away and rearwards(this also helped prevent the high engine bay temps) via the vaccuum formed under and behind the vehicle by its dams at the front lower parts of the vehicle.
To feed the carbies from a forward facing scoop you pressurise the engine bay and start to loose airflow capabilities for radiators etc.(unless you have sealed delivery to the carbies only)
If you place the vents rearward facing but on the outer edges and slightly forward of the screen you will start to draw up and out but the opposite will occur in the centre and close to the screen.(on most cars and especially bricks like landrovers)

Get some light ribbon and tape it every two inches acrss your bonnett and youll see how the air is flowing
Have a close look at a SD1 Rover they have used the theory very well if you look close at and under the bonnet.

[fernockulated]

:roll: hmmmmmm.........very interesting, and much food for thought!!! oh, and by the way , it was a FORD gs bonnet scoop ,not an A9X, so i dunno where that came from????anyway i have aquired an old fridge vent cover from an old derelict caravan and was considering grafting some of it onto the bonnet of my series , now i dont know whether to face them forwards or backwards?????? :? :? :? :?