Patrol bonnet scoop?
Submitted: Friday, Oct 07, 2005 at 22:33
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ACDC
I have heard from several people that the scoop on the GU patrol bonnet does not work, the air pressure under the bonnet is greater than above, so air actually comes out of the scoop instead of in, hence hot air through intercooler instead of cold air.Any thoughts? (bigger scoop?)
Reply By: Member - Roachie (SA) - Friday, Oct 07, 2005 at 23:36
Friday, Oct 07, 2005 at 23:36
G'day,
I'm a bloke whose fitted a 3L scoop to my 2000 model 4.2 TD (non-intercooled). I fitted it on the opposite side to normal in the belief that it might direct air over the turbo and help keep motor cooler. I did that on New Years Day 2004. I initialled tried it fitted reverse as I'd read that it would help "extract" hot air from the engine bay, up onto the windscreen. That didn't help the coolant temp, so I've since turned it around to face forwards. At one stage I attached some cotton to the fin in the hole of the scoop and (from memory), it did blow outwards as much as it "sucked" inwards....this was with the forward facing aspect.
It's still on there, but if I knew then what I know now, I wouldn't have bothered fitting it.
The Patrols do have a plastic "air dam" under/behind the radiator, angled back/down at about 45 degrees. The sole purpose of this is to cause a vacuum effect within the engine bay to draw hot air out through the bottom of the engine. I would imagine that that the intercooler, being sealed by a rubber fitting on the 3L, would have a positive air flow through the scoop and air would be drawn through and downwards.
Just my observations.
Cheers
Roachie
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Reply By: muzzgit (WA) - Saturday, Oct 08, 2005 at 00:30
Saturday, Oct 08, 2005 at 00:30
I have two things to say.
1. When driving at 100 kilometres per hour, stick your head out the window and tell me if you recon air wouldn't be rushing in throught the scoop on the bonnet. When travelling a low speeds the scoop does may not work, but I recon it would at highway speeds.
2. If infact what you say is true, why is the patrol engine puting out more pony's compared to the navara, which has the same motor but doesn't have the intercooler?
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Follow Up By: TroopyTracker - Saturday, Oct 08, 2005 at 08:36
Saturday, Oct 08, 2005 at 08:36
Muzzgit,
Ever noticed how a leaf or similar will sit ont the bonnet of the car at speed if you take off with it on there? Doesn't seem to be to much flow on top of bonnet if a leaf has trouble blowing off-at least on my bonnet anyway.
Cheers
Matt
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Follow Up By: Brett_B - Saturday, Oct 08, 2005 at 09:46
Saturday, Oct 08, 2005 at 09:46
I agree with Matt, I'm no expert but I would have thought there would have been a pocket of disrupted air on the top of the bonnet, caused by the initial "push" of the car through the air.
I have noticed a similar leaf effect as Matt explains but with bugs/flys etc :-)
Wonder how much a bull bar disrupts the air flow across the bonnet ??
All the rev head WRX rocket owners move their intercoolers behind the front grill, for what reason I wonder !!
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Follow Up By: Member - ROTORD - Saturday, Oct 08, 2005 at 10:57
Saturday, Oct 08, 2005 at 10:57
A common way to observe air flow in wind tunnel testing is to glue strands of wool to the area of interest . A dozen 50mm strands 100mm apart around the scoop may give the answer .
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Follow Up By: ACDC - Saturday, Oct 08, 2005 at 17:52
Saturday, Oct 08, 2005 at 17:52
Well here's another, remember XY GT Falcon with shaker on the bonnet the scoop did nothing because it was to low to bonnet line.
If you look at drag cars they use raised scoops at least 100mm above bonnet (letter box) to collect air!
I believe you can buy a bigger scoop for wrx's why?
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Follow Up By: Member - Davoe (Widgiemooltha) - Saturday, Oct 08, 2005 at 20:45
Saturday, Oct 08, 2005 at 20:45
How do you figure the shaker on the xy did nothing? It is a different situation from the patrol as the patrol relys on air being passivly forced through the intercooler where as the gt was activly sucking cool air from outside the bonnet through the carby.
And as for bigger scoops for WRX it is for the same reason as the bigger rear wings 14 inch dump pipe and really big stereo - It looks good parked at the Maccas
carpark at midnight ----- thoooomp thoooomp thoooomp
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Follow Up By: ACDC - Saturday, Oct 08, 2005 at 21:01
Saturday, Oct 08, 2005 at 21:01
I read it in a magazine years ago, it was common knowledge in racing .
Obviously the carby suck the air in but none was forced in.
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Follow Up By: ACDC - Saturday, Oct 08, 2005 at 21:02
Saturday, Oct 08, 2005 at 21:02
I read it in a magazine years ago, it was common knowledge in racing .
Obviously the carby suck the air in but none was forced in.
There was the advantage of cold air from the outside at full throttle.
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