Anyone have any info on the funcionality of the Mustang hood scoop on the rear deck...does it really provide air into the engine?
The reason I ask is that 1) I like the look and 2) I have a 4.9 and was going to be one of those old style round air cleaners on it(chorme pan on top and bottom with round air filter inbetween...you know the old style hot rod air cleaners).
Will this set up really work or is the hood scoop more for show?
"if" you cut a hole in the deck....YES they work! BUT they let hot air OUT not suck it in the side grates pull it out as well. the stang scoop just helps get all the hot out better. go for it!!
oh and the air cleaner, well the scoop will not work for what you want to do. maybe reroute the intake to the sides where the stock air intake scoop is. You may see people use bigger scoops on the sides for better cold air intakes.
[This message has been edited by revin (edited 04-05-2010).]
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12:18 PM
Blacktree Member
Posts: 20770 From: Central Florida Registered: Dec 2001
Most people just put them on for looks or for hood clearance on engine swaps..... The air on a Fiero engine compartment actually comes IN at the BOTTOM and OUT at the TOP. A scoop that pulled air in would disrupt the air movement and make for hotter underhood temps.
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06:21 PM
olejoedad Member
Posts: 19728 From: Clarendon Twp., MI Registered: May 2004
I know that, when at speed in the wet, my back window gets sprayed with water that "jumps" from the bottom lip of the spoiler. Its kind of cool, actually.
Outstanding everyone, THANK YOU...great information! Where else can you go and find a brain trust like the one on this forum. I'll be mounting mine this weekend!
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05:27 AM
Oreif Member
Posts: 16460 From: Schaumburg, IL Registered: Jan 2000
Im talking about with the opening facing the front to force air in. It yours is open at the back, then the forward moving air goes in it and right out the vents behind the window. I can see where that would take off some residual heat.
Still, the Fiero is designed to bring air in at the bottom and exit at the top vents. If you rammed a lot of air in the top, it would keep cooling air from the bottom from moving thru the engine bay.....
That air coming in the bottom is greatly over-rated. When I did my tests there was very little air flowing out of the vents and besides, the air would be coming up from the transmission casing to the driver vent, and up the front of the engine on the passenger vent. This does very little for the plenum or manifolds. The little trunk fan is a poor joke IMHO.
The air moving from back to front really does work when the vehicle is moving. I have a 14" chrome air cleaner and believe me, I have to clean the dust off it regularly. The air pumps over the top of the engine and moves the radiant heat away from the plenum. Of course I help the effect with a Hayden 10" fan in the scoop, which cycles on with the rad fan.
Remember, when the Indy was done the forward facing scoop pulled air down to the engine. If the bottom up theory worked well, then why would they do a top scoop?
Arn
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03:48 PM
Francis T Member
Posts: 6620 From: spotsylvania va. usa Registered: Oct 2003
I have scoops -not mustang- on both my GTs and they work great, but have fans in each pulling air from the engine compartment. If you want it really work good, add a fan.
Ironically, from MY tests, a great amount of air moves OUT of the engine vents. Yes air does flow towards the glass over the decklid when there is no scoop. When there IS a mustang scoop, is the air pressure under the decklid greater than the air pressure ontop of the decklid? This is what will determine the flow, NOT whether the flows forward or back.
[This message has been edited by Jncomutt (edited 04-06-2010).]
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05:03 PM
Patrick Member
Posts: 38384 From: Vancouver, British Columbia, Canada Registered: Apr 99
...is the air pressure under the decklid greater than the air pressure ontop of the decklid? This is what will determine the flow, NOT whether the flows forward or back.
Well, isn't that a given? Who would argue otherwise?
At one point I installed 7 computer fans in the scoop venting outward. When the car was sitting still they worked fine. I found though, that at speed the engine did not cool off as it should. It turned out that the forward air flow was strong enough to stall the fan blades. I then reversed the fans and the engine cooled down much faster. Plus, I started getting the dust on the air cleaner.
As it stands now, when my rad fan kicks on, so does the scoop fan. It usually runs under a minute to cool the engine down below 180*. This even in hot weather.
Remember that at 60 miles per hour, the air moving forward is travelling close to that speed. It is a powerful air movement.
This is the reason the air coming out of the vents comes out low and flat and at about 45* off center, out toward the side of the car. The air pressure piles up behind the back window and the turbulence back there is very noticable when you deploy ribbons or yarn to track it.
Patrick, the other posts made it sound like since the air was moving forward along the decklid that putting a hole there will cause the air to just go right into the hole. I was just stating that might not be the case. The air could still move forward with the scoop, but it might stay along the decklid, then go up over teh scoop and be joined with air coming out of the scoop, for example.
Arn, I deployed smoke. There is a LOT of air coming out of these vents from what I've seen. The smoke comes upward from the vents to the roof line and then the two sides form a V shape at the rear of the car towards the lock cylinder.
This is with NO spoiler.
[This message has been edited by Jncomutt (edited 04-06-2010).]
Thanks for all the great comments and thoughts. You inspired me and challenged me...so, I went out and taped 9 strips of white cloth on the deck of my 88 GT, with wing and filmed it at 25mph, 40mph and 55mph. Nothing is really happening at 25..but when you get to 40+ the strips on the center of the deck (where the scoop would be) move toward the window. The strips on the grills flow backwards as do the strips at the front edge of the spoiler.
I have put the videos on Youtube...is this a scientific experiment...NO...I didn't measure anything.
NOT to get BACK on track or anything.... But where can we still get the 1979-1983 Mustang GT/Mercury Capri. I have looked all over the internet for them and cant find the things...
Let me know if you have any info on where I can buy one Thanks
------------------ '86 2m4- Auto, Daily Driver '87 GT - 5spd, Project Car -------------------------------------------------------------------------- So now you'd better stop and rebuild all your ruins, For peace and trust can win the day despite of all your losing
Arn, I deployed smoke. There is a LOT of air coming out of these vents from what I've seen. The smoke comes upward from the vents to the roof line and then the two sides form a V shape at the rear of the car towards the lock cylinder.
This is with NO spoiler.
At what speed? At idle, it moves fine. At any kind of speed it goes down fast. Unless you have access to a wind tunnel there is no way to do smoke at 60mph. I did 1" ribbons. It was pretty self evident. At highway speed those vents get maybe 25% ventilation in stock mode.
Arn
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09:34 PM
Francis T Member
Posts: 6620 From: spotsylvania va. usa Registered: Oct 2003
So you have fans working against the natural air flow?
Yup, and it works great. On the turbo car there is 2nd fan for the intercooler. That one blows down into the engine compartment through the intercooler and then over the turbo and out the other scoop. Natrual flow ent nothing compared to fans. BTW: the fans are on thermostats.
when you get to 40+ the strips on the center of the deck (where the scoop would be) move toward the window. The strips on the grills flow backwards as do the strips at the front edge of the spoiler.
I agree the air moves forward on the decklid at this point, but that does not mean 'into' the scoop.
the side grates pull it out as well. the stang scoop just helps get all the hot out better. 
