extraction hood
#101
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all you need is a vent that pulls air out, not pushes air in.
im wondering about that scoop too, it would work just like the 600 track dog racing hood, but cheaper. the only problem i see is that it would weaken the already thin, light, weak miata hood. but who needs a strong hood?
but, there are also a lot of aftermarket scoops/vents that dont work, there just for looks.
im wondering about that scoop too, it would work just like the 600 track dog racing hood, but cheaper. the only problem i see is that it would weaken the already thin, light, weak miata hood. but who needs a strong hood?
but, there are also a lot of aftermarket scoops/vents that dont work, there just for looks.
#107
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agree to disagree.
im sorry, didn't mean to affend anyone who wants to do the "hole in the hood" thing, im just willing to pay for quality. you and everyone else on this forum are diy's, im not. the holes would work fine i guess, but the extraction vents would be best.
probably not worth the money for a street car though. i see your point.
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probably not worth the money for a street car though. i see your point.
#109
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Sure you could have a scooper on the bottom of the extractor, and a little raised lip at the leading edge on top to create a larger pressure delta. They may be slightly beneficial to extraction. But the point is, the air moves through the hole because it is equalizing pressure. IE moving from high pressure to low pressure. The top section of the hood is a low pressure zone. No vent, duct, or scoop can work to counter this. That is why hood mounted Ram Air induction vents are not effective.
Yes, on my hood I bent the leading edge up and trailing edge down. Honestly, if I got a second crack at it, I would just cut out the rectangular vent without bending the edges. I am not comfortable with the body work necessary to make them look right. And by not having the trailing ege come down, the actual vent area would be larger.
My hood was a low cost (almost no cost) experiment. If I had a bunch of extra money, I'd go with a aftermarket extraction hood like FM's or the one that RotorNut posted.
Oh, and I still have not cut a vent over the turbo. But it is my feeling that having a vent behind the radiator to encourage flow through the mouth coolers, coupled with TSI and/or NACA intakes flowing fresh air across the motor surfaces and through a second set of vents closer to the windshield is the ultimate solution. Think of it as a combination of FM's hood and Rotor's hood, but using stragegically located smaller vents.
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Last edited by Ben; 07-27-2007 at 11:40 AM.
#110
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yeah the scoop thing was what i was trying to say, before spending money on anything, i would look up why and how the bumps,slants, etc. work to get more air out. then id look for the cheapest way to try to copy that.
also wouldn't the engine bay be a low pressure zone? dont know but thats what iv heard, probably wrong.
finally, what u were saying about the holes, i was thinking along the lines of the hood raising and holes back by the windshield, which i know is a high pressure zone.
i personnally dont like the looks of the holes. but thats not what we were going for here.
sorry for the mixup, my bad (...im new here)
also wouldn't the engine bay be a low pressure zone? dont know but thats what iv heard, probably wrong.
finally, what u were saying about the holes, i was thinking along the lines of the hood raising and holes back by the windshield, which i know is a high pressure zone.
i personnally dont like the looks of the holes. but thats not what we were going for here.
sorry for the mixup, my bad (...im new here)
#111
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ahh, and another experiment I want to try is removing the undertray, or at least the "rear" part of the undertray. Rob's experience w/o undertray was that his hood balloned out at speed. I think he mentioned at around 100mph on the track. Which tells me that there is a wonderful source of fresh air available under the car, but it has to be allowed to escape from the engine compartment if let it. Otherwise it defeats the entire purpose of the effort. But if sucessful, it could be a constant supply of air moving from the bottom of the motor to the top, and out of the hood.
Complete removal of the rear half of the tray may be a bit extreme. A possible solution may be to cut a couple of vents in the tray with a hole saw. If it works, I might be able to leave my turnsignals in the nose. Which I would prefer to do as I like my twilights a lot. Corky Bell says he recommends ditching the undertray completely. I'm not sold on that concept, but find it interesting that he is. Perhaps his cool air scooper and hand made intercoolers are just that damn good.
brad, here are some pics from a car with this same type of mod completed. I know it looks like *** unfinished, but check out this hotness
![](http://i84.photobucket.com/albums/k6/3genX/NewImage.jpg)
More pics:
http://www.rx7club.com/showpost.php?...78&postcount=9
That's with some cleaning of the edges, screen I dunno epoxied maybe, and paint.
Complete removal of the rear half of the tray may be a bit extreme. A possible solution may be to cut a couple of vents in the tray with a hole saw. If it works, I might be able to leave my turnsignals in the nose. Which I would prefer to do as I like my twilights a lot. Corky Bell says he recommends ditching the undertray completely. I'm not sold on that concept, but find it interesting that he is. Perhaps his cool air scooper and hand made intercoolers are just that damn good.
brad, here are some pics from a car with this same type of mod completed. I know it looks like *** unfinished, but check out this hotness
![](http://i84.photobucket.com/albums/k6/3genX/NewImage.jpg)
More pics:
http://www.rx7club.com/showpost.php?...78&postcount=9
That's with some cleaning of the edges, screen I dunno epoxied maybe, and paint.
#118
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the stage 21 hood is a really nice extraction hood
http://clubroadster.net/forum/viewto...highlight=hood
He, cut all but one of the rear vents to allow more air flow.
http://clubroadster.net/forum/viewto...highlight=hood
He, cut all but one of the rear vents to allow more air flow.
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Next course of action:
http://cgi.ebay.com/ebaymotors/1981-...QQcmdZViewItem
PS, any of you ******* bid on that, and I'll ban you.
http://cgi.ebay.com/ebaymotors/1981-...QQcmdZViewItem
PS, any of you ******* bid on that, and I'll ban you.
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