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Old 11 July 2011, 05:03 PM
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Karl B
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Default reverse bonnet vent

hey just a quick question, is it better to keep the original scoop on the car forcing air into cool the engine down or is it better to have a reverse scoop letting the hot air out as ive got a FMIC
Old 11 July 2011, 05:51 PM
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Harvey did some testing and found the original scoop had better cooling properties than the reverse vent.
Old 11 July 2011, 06:18 PM
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DCI Gene Hunt
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A reverse scoop... ffs
Old 11 July 2011, 06:19 PM
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It was also designed to let air down the transmission tunnel, or so i read on one of harveys posts.
Old 11 July 2011, 06:38 PM
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I would of kept the original scoop as I only changed mine due to the bonnet lifting pretty badly on accelleration.
Old 25 July 2011, 03:43 PM
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Can anyone point me in the right direction to find Harveys tests results on reverse scoops??
Old 25 July 2011, 04:45 PM
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Originally Posted by Hammer man
Can anyone point me in the right direction to find Harveys tests results on reverse scoops??
I've tried finding it myself after reading it a while back, the one thing that I would say is that having given the car 'the beans' over the weeked up at the Colin McRae weekend that the vent does seem to perform a valuable function.

It was quite alarming to see the heat rising out of the engine bay through the reverse vent, it was similar to heat haze as you could literally see the hot air escaping from the vent.
Old 25 July 2011, 06:33 PM
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Originally Posted by Hammer man
Can anyone point me in the right direction to find Harveys tests results on reverse scoops??
Here it is, scroll to post number 25.
https://www.scoobynet.com/general-te...the-point.html
Old 25 July 2011, 06:56 PM
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Originally Posted by Cannon Fodder
I've tried finding it myself after reading it a while back, the one thing that I would say is that having given the car 'the beans' over the weeked up at the Colin McRae weekend that the vent does seem to perform a valuable function.

It was quite alarming to see the heat rising out of the engine bay through the reverse vent, it was similar to heat haze as you could literally see the hot air escaping from the vent.
Thanks for the info Ty. Have you considered "bonnet raisers", just from a point of view to allow more of the heat to escape?
Originally Posted by mike h
Here it is, scroll to post number 25.
https://www.scoobynet.com/general-te...the-point.html
Cheers, I hadnt looked back that far. Interesting to read that the top of the bonnet area is a low pressure point. I assume the pressure will be different too, depending on which version car it is, ie classic, bug, blob, hawk, as the front of the car and indeed the bonnets are different.
Old 25 July 2011, 06:59 PM
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Originally Posted by MattyB1983
Harvey did some testing and found the original scoop had better cooling properties than the reverse vent.
Why did rcm ignore that on the gobstopper?

TX.
Old 25 July 2011, 07:01 PM
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Originally Posted by Terminator X
Why did rcm ignore that on the gobstopper?

TX.
At a guess, drag.
Old 25 July 2011, 07:04 PM
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Not to throw a spanner in the works, but doesnt Duncan @ RaceDynamix run a reverse vent?

And didnt people from the F1 Red Bull race team help him with aerodynamics on his car?
Old 25 July 2011, 07:37 PM
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I think the thing to remember is that Harvey tested a reversed scoop and not a reverse vent which will if properly designed will draw the hot air from out of the engine bay, something to do with the vortices (possibly vorticees) which are created by the air flow over the vent.
Old 25 July 2011, 07:38 PM
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And of course the difference in air pressure when at speed between the air either side of the reverse vent.
Old 25 July 2011, 07:43 PM
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Originally Posted by Hammer man
Thanks for the info Ty. Have you considered "bonnet raisers", just from a point of view to allow more of the heat to escape?
Not a big fan of the bonnet ajar/not closed look tbh I can see the logic and the reason but from an asthetic point of view definitely a for me.

But if I could make the below and have the best of both scoop and vents.


Name:  P1010138.jpg
Views: 0
Size:  97.4 KB

Also has anyone noticed how much their bonnet scoops (particularly the Blobeye) flex/move when at speed when on 'private roads'.
Old 25 July 2011, 10:39 PM
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I've got a FMIC at 400BHP but still run a Bug STi scoop.................because that's how they should look

For Track / Drag / Rally / time attack applications there may be good reasons to run without a scoop but for looking like an impreza and making people look twice in the rear view mirror there is no substitute

Shaun
Old 25 July 2011, 10:47 PM
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ive actually stopped and checked my bonnets closed before on my hawkeye from the amount the bonnet was moving about :S
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