Outer Limits 4x4 Board

I know i may be setting myself up for a flaming - but i have an old Bonnet scoop from a Mustang, which is sitting around the shed gathering dust. Its Boxy, like the zuk bonnet, and is the right size to fit on the bonnet.
I understand the principals behind why to fit a bonnet scoop - however if i do put it on, i will be putting two holes in the bonnet for cooling/heat removal only, and wont be hooking it up to the air cleaner.

So now, i want your vote here: Bonnet scoop or No Bonnet Scoop?


My Wife says 'Hell NO', but the little kid inside me is saying 'Hell YEAH'

p.s. this is my toy car... if that makes a difference

put a pic up with it around the other way, at least it will let heat out them.

I don't see the need for it but if you really want it then turn it around so the opening is at the back. Not only will it work better, it won't scoop up water and mud etc.
Use the high pressure zone at the base of the windscreen to your advantage.
And lose the fugly bar!!!

spin it around the other way and remove the farm gate bullbar, and i might say maybe.

Yeh i agree, it should look good around the other way

Did someone say "perhaps put the effort into something practical first?"

turn it around and make it functional then maybe yes. On my Sierra I cut 5 x 40mm holes on the back of the bonnet to help aid cooling when it had the 5K in and it made a marked difference. Mind you, you couldn't see them from the front of the car so didn't look dicky and an added benefit was it helped keep the windscreen defrosted in cold weather

sierrajim wrote:Did someone say "perhaps put the effort into something practical first?"

Layto.....

There is very little effort involved, as it wont take me long at all to fit it...

I will get a pic of it the other way round, if that helps... will putting it backwards stop the ram-flow affect and let heat escape easier?

Is there any legality issues with facing it backwards (ie - splashing/smoke being directed onto the widscreen ?)

Also - the farm gate was just put on over the weekend! Coz it was cheap (2nd hand), and i couldnt afford a full ARB bumper bar!

grimbo wrote:turn it around and make it functional then maybe yes. On my Sierra I cut 5 x 40mm holes on the back of the bonnet to help aid cooling when it had the 5K in and it made a marked difference. Mind you, you couldn't see them from the front of the car so didn't look dicky and an added benefit was it helped keep the windscreen defrosted in cold weather

If his car isn't overheating, its not practical.

If his car is overheating he's better off finding out why its overheating then fixing the problem as opposed to putting a band aid over it.

Foward = ricer + water/dirt/mud on engine
Backwards = Old school torana

Both = No good on sierra

A bonnet scoop is usually fitted to allow more air into the engine.
Wether the scoop faces forwards or backwards makes little difference to airflow.
If you face it forwards you have more wind resistance and a sharp edge to potentially get defected for.
If you face it rearwards you won't have a wind resistance issue and you still get all the benefits of airflow.
No matter how big a rear facing scoop is it WILL NOT extract heat OUT of the engine bay, as you are driving, air hitting the windscreen builds a high pressure zone. this high pressure zone pushes the air into the back of the scoop. This is called COWL INDUCTION. Just like all those big american muscle cars of the 70's.

Keep in mind that if you increase the pressure in the engine bay you will reduce the amount of air coming through your radiator thus may have cooling issues

I put one on once to fit the engine and used a nissan patrol scoop. Now I have a different engine and Im stuck with a dicky scoop that I regret doing it dosnt seem to effect cooling either way round. I was thinking of getting rid of it and doing what Grimbo suggested but talking to a hot rodder he,s seen a guys engine blow and were does the oil go? Straight out the back covered the windscreen and the guy crashed and died. Just a story I was told but made me think. Maybe swift?? style small rectangular ones either side just behind the radiator infront of the engine would help cooling.
Just my thoughts.
Nik

NIK wrote:I put one on once to fit the engine and used a nissan patrol scoop. Now I have a different engine and Im stuck with a dicky scoop that I regret doing it dosnt seem to effect cooling either way round. I was thinking of getting rid of it and doing what Grimbo suggested but talking to a hot rodder he,s seen a guys engine blow and were does the oil go? Straight out the back covered the windscreen and the guy crashed and died. Just a story I was told but made me think. Maybe swift?? style small rectangular ones either side just behind the radiator infront of the engine would help cooling.
Just my thoughts.
Nik

I'd say someone is having a lend of you there.
If the car was travelling at any more than about 30km/h then the positive air pressure on the screen would push oil/smoke/flames out the bottom of the engine bay NOT out the back of the scoop onto the screen.

want33s wrote:A bonnet scoop is usually fitted to allow more air into the engine.
Wether the scoop faces forwards or backwards makes little difference to airflow.
If you face it forwards you have more wind resistance and a sharp edge to potentially get defected for.
If you face it rearwards you won't have a wind resistance issue and you still get all the benefits of airflow.
No matter how big a rear facing scoop is it WILL NOT extract heat OUT of the engine bay, as you are driving, air hitting the windscreen builds a high pressure zone. this high pressure zone pushes the air into the back of the scoop. This is called COWL INDUCTION. Just like all those big american muscle cars of the 70's.

I beg to differ, I think cowl induction scoops take benifit of low pressure zones created by there design and by having the air filter in this low pressure zone the engine sucks are more effectively. I doub't there would be a build up of pressure from a cowl scoop even on a almost verticle style windscreen like the sierras. I think the desired affect with cowl scoops and no drop in plate for a air filter is to have air flow through the radiator grill and out the top for freely instead of hitting the firewall and being forced to go down under the car. Just my opinion.

On the other hand I would love a high mount intercooler with a drop in plate and a combo scoop that forces air down into a drop in plate and out the top of the bonnet through cowl scoop.

GRPABT1 wrote:
I beg to differ, I think cowl induction scoops take benifit[sic] of low pressure zones {???}created by there[sic] design and by having the air filter in this low pressure zone the engine sucks are[sic] more effectively. I doub't[sic] there would be a build up of pressure from a cowl scoop even on a[sic] almost verticle[sic] style windscreen like the sierras. I think the desired affect with cowl scoops and no drop in plate for a[sic] air filter is to have air flow through the radiator grill[sic] and out the top for freely instead of hitting the firewall and being forced to go down under the car. Just my opinion.

On the other hand I would love a high mount intercooler with a drop in plate and a combo scoop that forces air down into a drop in plate and out the top of the bonnet through cowl scoop.

I suggest you try searching "Cowl induction" [Google perhaps] so you have some idea of what you are talking about before you embarrass yourself further.

Heres how it would look - mounted backwards. Probably the best option, and i believe it looks better as it follows the lines of the bonnet better:




By the look of it, legally you can fit a backwards scoop, without an eng cert, as long as it aint too high, doesnt obscure my vision out to 11metres, doesnt have rough edges that would cause injury in an accident, and is made of fibreglass (or of material lighter than the bonnet itself).

Refer DOTAR regs: Section 4 (page 11) of this link http://www.infrastructure.gov.au/roa...s_3Feb2006.pdf

But there is also your local govt road rules for anything extra.
UPDATED: WA regs Found! : http://www.dpi.wa.gov.au/licensing/1913.asp
- if scoop is rear facing, need to obstruct the opening to make sure no 'splashback onto the windscreen'

P.s. I have even printed out a copy of each to keep in the glovebox if the boys in blue kick up a stink... And when i do a trip to clark rubber to get the rubber for the bonnet holes, i might get some foam to stuff in the end of the scoop so 'if' i blow a hose, sh*t doesnt go all over the windscreen (as per WA regs)

Its funny, as there is some discrepancy about cars that came out of the factory = there seems to be no regs against massive scoops on factory models??

Anywho - enough politics... my head hurts...

I dont have any cooling problems - but i do have an old scoop in the shed, and have a bunky toy car... if it doesnt work out all i have buggered is the bonnet (which is easy enough to replace).

want33s wrote:

GRPABT1 wrote:
I beg to differ, I think cowl induction scoops take benifit[sic] of low pressure zones {???}created by there[sic] design and by having the air filter in this low pressure zone the engine sucks are[sic] more effectively. I doub't[sic] there would be a build up of pressure from a cowl scoop even on a[sic] almost verticle[sic] style windscreen like the sierras. I think the desired affect with cowl scoops and no drop in plate for a[sic] air filter is to have air flow through the radiator grill[sic] and out the top for freely instead of hitting the firewall and being forced to go down under the car. Just my opinion.

On the other hand I would love a high mount intercooler with a drop in plate and a combo scoop that forces air down into a drop in plate and out the top of the bonnet through cowl scoop.

I suggest you try searching "Cowl induction" [Google perhaps] so you have some idea of what you are talking about before you embarrass yourself further.

ahem...

well I also beg to differ.
ever seen on tv the cars in the wind tunnels doing aero dynamic tests? The air flows over the bonnet, UP the windshield and over the roof. I think that its this movement of air from front to back that creates a VACUUM at the back of the cowl, thus speeding up the rate the hot air is moved OUT from the engine bay.

If im wrong, i won't mind. Definetly nothing to be embarassed about. If I knew everything there is to know about cars I wouldnt be a member of this forum.

my opinion on scoops is that its just a way to funnel mud and dust into the engine bay - most zuk driving is done at 10-60km/hr and a scoop probably wouldnt do a thing...

I like grimbos idea of modifying the actual bonnet to let air out though - if a mesh was used on the inside to stop big chunks dropping in it'd probably be great - however in a water crossing youll lose the air bubble under the bonnet faster too... which isnt a good thing for the air intake =)

Get a WRX scoop and mount it backward that looks even worse

and you might need to get a rear wing!

side skirts!

want33s wrote:

GRPABT1 wrote:
I beg to differ, I think cowl induction scoops take benifit[sic] of low pressure zones {???}created by there[sic] design and by having the air filter in this low pressure zone the engine sucks are[sic] more effectively. I doub't[sic] there would be a build up of pressure from a cowl scoop even on a[sic] almost verticle[sic] style windscreen like the sierras. I think the desired affect with cowl scoops and no drop in plate for a[sic] air filter is to have air flow through the radiator grill[sic] and out the top for freely instead of hitting the firewall and being forced to go down under the car. Just my opinion.

On the other hand I would love a high mount intercooler with a drop in plate and a combo scoop that forces air down into a drop in plate and out the top of the bonnet through cowl scoop.

I suggest you try searching "Cowl induction" [Google perhaps] so you have some idea of what you are talking about before you embarrass yourself further.

I'm not embarassed mate, I said it was my opinion not solid gold facts. I will do that google search though and also ask some drag racers opinions. I'll post what I find out.

cjdeane10 wrote:Heres how it would look - mounted backwards. Probably the best option, and i believe it looks better as it follows the lines of the bonnet better:

By the looks of where it might go all this "Cowl" induction talk wont mean a thing. It would be to far forward to be effected by the windscreen. It would just create a vacuum behind it and suck out hot air. (bit like this thread at the moment )

It wont need to be going at pace to work in cooling the engine bay as hot air rises and this will be the highest place in the engine bay and it will just let the air out.

BTW, cjdeane10 if you do mount it, backwards looks best. That is what you are asking about afterall. Not about high and low presure zones.

I woiuldn't bother wasting your money and time...spend both on improving your cars driveability off road...

Yeh dont do it, either way round it looks naff

A quick google came up with these answers:

"The Cowl works better for getting more air, but it too is not a pressure builder like a couple of snorkels in the grill.

There is one thing that you need to be careful of with these cowl hoods. If the carb is not sealed to the hood right, then you can get turbulence in the engine compartment that will actually pull gas out of the carb. You really want an air cleaner made for the cowl hood to seal the hood and the air cleaner to force air in, and not all around the outside. I have heard cars pop really badly because of this turbulence pulling gas out."

"The cowl induction hood is not a new idea and it actually works. That's why NASCAR uses them in their Winston Cup Cars. As the air passes over the opening, it creates a vacuum of cold air over the windshield. This allows the hot air from inside the engine compartment to escape letting the engine breathe cooler air and therefore running stronger and longer."

And yes it does appear the general opinion is it's most affective as close as possible to the windscreen.

GRPABT1 wrote:A quick google came up with these answers:

"The Cowl works better for getting more air, but it too is not a pressure builder like a couple of snorkels in the grill.

There is one thing that you need to be careful of with these cowl hoods. If the carb is not sealed to the hood right, then you can get turbulence in the engine compartment that will actually pull gas out of the carb. You really want an air cleaner made for the cowl hood to seal the hood and the air cleaner to force air in, and not all around the outside. I have heard cars pop really badly because of this turbulence pulling gas out."

"The cowl induction hood is not a new idea and it actually works. That's why NASCAR uses them in their Winston Cup Cars. As the air passes over the opening, it creates a vacuum of cold air over the windshield. This allows the hot air from inside the engine compartment to escape letting the engine breathe cooler air and therefore running stronger and longer."

And yes it does appear the general opinion is it's most affective as close as possible to the windscreen.

How did you manage to find totally contradictory statements?
Why don't you quote your sources?

to scoopes on zooks.... Australian's say NO

want33s wrote:

GRPABT1 wrote:A quick google came up with these answers:

"The Cowl works better for getting more air, but it too is not a pressure builder like a couple of snorkels in the grill.

There is one thing that you need to be careful of with these cowl hoods. If the carb is not sealed to the hood right, then you can get turbulence in the engine compartment that will actually pull gas out of the carb. You really want an air cleaner made for the cowl hood to seal the hood and the air cleaner to force air in, and not all around the outside. I have heard cars pop really badly because of this turbulence pulling gas out."

"The cowl induction hood is not a new idea and it actually works. That's why NASCAR uses them in their Winston Cup Cars. As the air passes over the opening, it creates a vacuum of cold air over the windshield. This allows the hot air from inside the engine compartment to escape letting the engine breathe cooler air and therefore running stronger and longer."

And yes it does appear the general opinion is it's most affective as close as possible to the windscreen.

How did you manage to find totally contradictory statements?
Why don't you quote your sources?

Geez you're a hard one to please aren't you? Do your own google search and you'll find them too, there isn't alot on there actually.

Type 'cowl induction' into google and you'll get 153,000 results.... not that many huh?
You must be some sort of freaky speed reader.