Rear facing bonnet scoops.

[chester]

G'day all,as you may know im putting a V8 in my GQ,i was thinking about putting 2 bonnet scoops on it and face them backwards.
I was thinking this may help get rid of underbonnet heat and there for help keep running temp's down.
Don't really want to face them forward and drop into a deep river or bog hole and have water rush into them and dump over the engine.
Was wondering what your thought's on this are?????
Also if you have done this could you please post some pic's.
cheer's
chester

[Silver]

This is a fascinating question Chester.

A neigbour of ours - Bob of Bob and Doreen fame, had a G60 before he bought his GU ute.

The G60 had a 250 Ford cross flow on dual fuel.

It used to run hot - so he attacked the bonnet and installed louvres. No good. Attacked the inner guards, cutting heaps away. No good.

Long story short on professional advice he ended up closing up most of the holes he made - and I think upgraded the radiator.

So, too much airflow is not always a good thing. I think he said in in some strange way his mods had decreased airflow through the radiator.

All of that said, two bonnet scoops, whether they are working or not, has to look pretty tidy :-)

[chester]

I have heard that silver,but my theory is because they will be backwards no air will getting forced into them,allowing the heat to vent out,as you know the bonnet is always hot to touch.
It should work the same as spacing the back of the bonnet up,i did say SHOULD.

[Silver]

Sounds convincing chester.

Qld Transport have rules about bonnet scoops and their locations - intended to maintain visibility and pedestrian safety.

Vic probably has some too?

[AB]

I had a 351 short block in an Xf ute with an XD front end.

The heat was too much, at the lights the temp would climb up, etc.

I actually put one rear facing scoop to get the heat out exactly as you are thinking but this did absolutely nothing...lol

The only thing that worked was big twin thermo fans on a manual switch so I could manually put them on knowing what was coming up in the traffic. This did not reduce the temp but it 100% maintained the temp at whatever degree it was at the time of putting it on.

It saved the engine for sure.

Having saying that it may have been a combination of both large twin thermos along with the rear scoop to exhaust the heat not to mention putting the heater on full blast on 40 degree days in a ute cab...lol.....Those were the days of V8 love....LMAO

[chester]

Yer silver will have to check that.
Not sure which scoops to use was thinking GU one's.
I will be putting a new radiator and Genuine nissan fan on it.
I know what you mean AB Used to have to turn the heater on in my old MQ to keep temp down in the drive through.

[janderson]

Nascar had their air cleaner cut out at the back. The bonnet was also cut out to receive the air directly of the windscreen to the air filter. MORE AIR BETTER BURN OF FUEL.

[purplebus]

rear facing scoops and spacing bonnets up are a pain in the butt. i have tried both with my bb chev in the gq. all they do is push hot air up the screen and you will feel it coming through the cowl panel into the cab unless you run recycle air in the dash setting 100% of the time. when you hit water it will steam up and fog the windscreen as it flows out the rear of the bonnet. i ended up fitting all the factory inner rubber fillers under the guards and 2 gu bonnet scoops to run the air down the side of the eng and under the truck how nissan intended.before i fitted them the bonnet would be dry in a light shower and you couldnt put your hand on the bonnet if you had driven it. even the floor near the clutch was hot inside before fitting the scoops. after fitting the scoops it was awesome, even dropped the eng temp. the eng bays are designed to flow around a straight 6, bang a v8in there and you restrict flow massively. i guessed the position towards the rear of the bonnet to push the air down and hopefully help to draw the air through from the front.

[MQ MAD]

rear facing scoops and spacing bonnets up are a pain in the butt.

Not only that , but they help spread all that oil on the screen when the engine spits the dummy
Hence why they were banned in racing ....
A rear facing bonnet scoop will create turbulence between the scoop and windscreen, so depending on its height off the bonnet, it could help with engine bay cooling
There are laws in most states regarding scoop height of bonnets,(yay for pedestrian freindly laws)so check that out

Im in ore how many can have massive engine bay heat at or near idle or stationary for minmal time

Maybe graft an XB/XC twin vent bonnet skin onto your bonnet ????
Seen it done to MQ/MK/GQs looks good