To settle an argument - bonnet scoops

Backyard_Brumby · Post by **Backyard_Brumby** » Sun Jan 02, 2011 6:46 pm

So my father and I are about to start our brumby project and although I am not usually a fan of bonnet scoops I think the brumby's I have seen on here with them look great as well as far as I am aware do serve a good purpose with increasing cold airflow into the engine bay.

As far as I see it the positives are

Looks great (subtle but there is something about the brumby that I think matches the bonnet scoop well)
Increase airflow meaning more cold air going down the carby

Negatives
No good for any water crossing (but don't plan to be doing many/any)
also wondering whether it would be chopping up a perfectly good bonnet for just cosmetic purposes

Anyway my father and I have been debating over this as he thinks it is a bit of a waste of time due to most bonnet scoops being too far up the bonnet that they aren't effective

Any thoughts on the matter? guys who have done the mod, any issues etc

Cheers James

RSR 555 · Post by **RSR 555** » Sun Jan 02, 2011 7:09 pm

Bonnet scoops on the Suby isn't to cool the engine bay.. it's there because they run a Top Mount InterCooler (TMIC) but if you're looking to get cooler air in your engine bay then you really need the reverse facing scoops like..
http://www.kakumeimotorsports.co.uk/ima ... %20WRX.jpg

spike · Post by **spike** » Sun Jan 02, 2011 7:22 pm

RSR 555 wrote:Bonnet scoops on the Suby isn't to cool the engine bay.. it's there because they run a Top Mount InterCooler (TMIC) but if you're looking to get cooler air in your engine bay then you really need the reverse facing scoops like..

the reverse facing scoops are to get air out into the low pressure area not into it

if you want to get more cold air to the carby to should make an intake pipe that runs to infront of the radiator.

the biggest problem you will have is getting it past the line of sight rules =(*

RSR 555 · Post by **RSR 555** » Sun Jan 02, 2011 7:28 pm

The best way to get cooler air into the carby and be away from water is to use a snorkel

88 STUBARU · Post by **88 STUBARU** » Sun Jan 02, 2011 7:38 pm

do it !!!! i would if i had time and inclination etc

scr33ch08 · Post by **scr33ch08** » Sun Jan 02, 2011 7:57 pm

while we on bonnet scops would a 2000 model WRX bonnet bolt straight onto my RX ?

littlewhiteute · Post by **littlewhiteute** » Sun Jan 02, 2011 8:20 pm

spike wrote:the reverse facing scoops are to get air out into the low pressure area not into it

if you want to get more cold air to the carby to should make an intake pipe that runs to infront of the radiator.

the biggest problem you will have is getting it past the line of sight rules =(*

Sorry Spike, you're wrong, reverse facing scoops allow the engine to draw air from the "high pressure" that exists at the base of the windscreen.

This is how Nascar does it, A9X Torana plus a few other American Muscle cars all use reverse scoops.

It's how air flows into your cabin, all cars have some form of cowl induction for the interior ventilation system.

Reverse scoops also don't suffer from as much airborne dust and insects etc, less likely for large volume of water entry,
(unlike people that run hoses to under the front bumper bar), and the rules for vision are bit relaxed since the scoop is a tapered shape, not blunt like a forward facing scoop.

littlewhiteute · Post by **littlewhiteute** » Sun Jan 02, 2011 8:22 pm

scr33ch08 wrote:while we on bonnet scops would a 2000 model WRX bonnet bolt straight onto my RX ?

The whole bonnet should be a straight swap.

(I have a 2002 WRX Evo 5)

spike · Post by **spike** » Sun Jan 02, 2011 9:15 pm

[quote="littlewhiteute"]Sorry Spike, you're wrong, reverse facing scoops allow the engine to draw air from the "high pressure" that exists at the base of the windscreen.

This is how Nascar does it, A9X Torana plus a few other American Muscle cars all use reverse scoops.
QUOTE]

yes and no
the low pressure are is directly behind the scoop pulling air into the area when possible, for the scoops to work properly the place the air is going must be properly sealed (found this out the hard way at classic adeladie a few years back)
the base of the windscreen is traditionally high pressure though

aerodynamics is a very tricky and (for the amature) imprecise. we spent over a month working on getting the most out of the A9X and some TVR thing. all of our tests were done on the open road with cameras mounted on the cars and somone in the back of a ford territory throwing talc powder out the rear window

AlpineRaven · Post by **AlpineRaven** » Sun Jan 02, 2011 9:20 pm

LOL, to me on a older style cars with a scoop looks wrong.. that is my point of view..

Cheers
AP

spike · Post by **spike** » Sun Jan 02, 2011 9:45 pm

AlpineRaven wrote:LOL, to me on a older style cars with a scoop looks wrong.. that is my point of view..

Cheers
AP

must agree
the WRX scoops that people put on brumbies and slab sided types just seem to go against my style, the GQ(??) pajaro bonnet scoop looks alright though square and angled

Green_eyed_liberty · Post by **Green_eyed_liberty** » Sun Jan 02, 2011 9:48 pm

i personally love the scoops on subies. i have an 01 GT Forester scoop on mine, and its perfect as it blocks the reflection from the top of my bullbar

and i reakon the nicest one is the pajero OR the gen III or gen IV scoop

Backyard_Brumby · Post by **Backyard_Brumby** » Mon Jan 03, 2011 12:00 am

I must admit as I said originally (and I am going to be unpopular for saying this) but I am not a big fan of bonnet scoops in general, they really are against my normal style but seeing some of the more square smaller scoops that I have seen on brumbies I have become a fan. At this point I guess I have to concede defeat as I think my "P plate" mentality got the better of me wanting a scoop for purely cosmetic purposes.

quote

The whole bonnet should be a straight swap.

(I have a 2002 WRX Evo 5)

I think I have picked your brumby as the one I always see driving past, now I have to look for the wrx- you sure do have a nice Suby fleet going

discopotato03 · Post by **discopotato03** » Mon Jan 03, 2011 8:54 am

What many bonnet vents seek to do is vent hot air from the engine bay but they are carefully made and positioned so that they actually do work .
If you look back to the days of the Sierra RS500s they had something that was more like a pair louvre panels to get post radiator air back out of the engine bay .

I wouldn't think you people would be interested in Evolution Mitsubishi's but most of them got some form of bonnet venting and since many were homologation specials for Grp A Rallying if the road cars didn't get it the racers couldn't either .

My 6 falls into that category and if you get the chance take a close look at the bonnet . You will find a raised sort of apron and ridge in front of these vents and its designed to separate the airflow from the bonnet surface - avoids slow boundary layer air flow . You need to have reasonably fast separated airflow here to get an area of low pressure or they don't work unless standing still . In other words lower pressure above the bonnet vent draws the hot air out and gives it an alternate escape route . It also has what I think is called a NASA vent on the nearside which linked up to a cold air intake in the competition cars . And a large open mouthed air dam feeding the intercooler/radiator and another duct to its oil cooler .

This is actually a very involved topic and what the manufacturers have to do is make a fully populated engine bay flow as easily as possible or all the radiators in the world won't work because airflow through them is poor . So if the air pressure in the engine bay is too high air air wants to flow under or over the car rather than through its grill/rad/bay .

Been a long time since I saw a competition Torana engine bay but didn't they have a tray leading up to the air filter and venting out through the letterbox ?
Should be having sherbets with long time Aussie V8 fanatics this afternoon so will ask about that .

In a Brumby with an EA81 I don't think they get real hot if everything's working properly because they normally (if std) don't develop huge power so don't have a large heat rejection requirement .

Lastly most of the worlds population knows Brumby's don't have any form of bonnet venting standard so fitting one will make it stand out in the crowd . Is that really what you want to do ?

A .

steptoe · Post by **steptoe** » Mon Jan 03, 2011 11:31 am

get a bonnet each ? and try it out both ways !

Backyard_Brumby · Post by **Backyard_Brumby** » Mon Jan 03, 2011 11:46 am

haha that is the attitude I like to hear Steptoe, Why make a choice when you can do both?

Gannon · Post by **Gannon** » Mon Jan 03, 2011 12:14 pm

If i were to have bonnet scoop on a Brumby, i reckon a D22 Navara scoop would look the best

Post by **TOONGA** » Mon Jan 03, 2011 12:33 pm

Suparoo wrote:If i were to have bonnet scoop on a Brumby, i reckon a D22 Navara scoop would look the best

yep they do look quite nice, are they as expensive as they look?

TOONGA

Morcs · Post by **Morcs** » Mon Jan 03, 2011 2:31 pm

I was contemplating using the one off my half cut (BG5) and using the air to air ic instead of WAIC i had collected for another project.

Much more subtle then wrx/forester style.

Ended up thinking its a sleeper not a show car plus the amount of work with that style of scoop would have been a lot for not that much gain.

Mind you i am looking at a larger barrel style from PWR and larger radiator as the rs turbo one doesn't cool the charge good enough.

subybrumby · Post by **subybrumby** » Mon Jan 03, 2011 3:26 pm

You can see the scoop on my brumby in my signature photo below. I don't know what its off but its cooling the top mounted intercooler on top of the ea82T under the bonnet. Its practical and I don't think it looks too bad, certainly a giveaway when people look as the turbo spools.

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To settle an argument - bonnet scoops

To settle an argument - bonnet scoops

P Plates - a disease that can hopefully be cured with time