Drivetrain Hood Vents-part 3
Joined: Mar 2005
Posts: 3,989
Likes: 1
From: Westerly, RI
Well, i think im gonna go for it with a cowl scoop.
I sound a 27 inch long x14 widex4 inch tall cowl scoop, mold on style from summit for about 60 bucks with my discount.
i think i'm gonna pick it up and just cut a big slot in my hood to get as much air out as possible.
i'll throw some pics up to give you an idea soon.
I sound a 27 inch long x14 widex4 inch tall cowl scoop, mold on style from summit for about 60 bucks with my discount.
i think i'm gonna pick it up and just cut a big slot in my hood to get as much air out as possible.
i'll throw some pics up to give you an idea soon.
Oh, and don't forget these...
6th Gear
Joined: Sep 2002
Posts: 2,196
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From: Hampton, VA
Having driven for 3 days now with the DF/CAI scoop and diverter, I am pretty sure the blast of fresh air from the front of the car going directly into the airbox is working! Will's analysis would reinforce the idea that I am pushing sufficient fresh air into the airbox to the following effect:
1. much more fresh air than is getting in through the stock duct that comes via a serpentine route from above the radiator, and
2. much more fresh air than comes in via the cowl inlet under normal (40-60mph) speeds
Anyway, I think it's a keeper. It certainly seems to have made a bigger single impact on the performance of my car than any other single mod, including the DFIC.
cheers,
1. much more fresh air than is getting in through the stock duct that comes via a serpentine route from above the radiator, and
2. much more fresh air than comes in via the cowl inlet under normal (40-60mph) speeds
Anyway, I think it's a keeper. It certainly seems to have made a bigger single impact on the performance of my car than any other single mod, including the DFIC.
cheers,
Ir you're looking to make this a flow through design then your next step is to reduce or remove any influence creating the above mentioned positive pressure.
How you ask? Haven't a clue
6th Gear
Joined: Sep 2002
Posts: 2,196
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From: Hampton, VA
Alright, I'll chime in. Carefully.
Is there negative pressure at the windshield? Yes. There's also positive pressure. Just depends on where you are measuring. We've done pressure measurements and confirm that there is higher than 1 ATM (~14.7 psi) pressure in the vicinity of the cowl vents (as long as the wipers are present/down). Does this make it an intake?
Well...no. Because pressure measurments at the cowl and in the box are really only half the story. Pressure differences are what cause flow. So, if you find that the pressure is higher inside the air box, which I think is the case most of the time, than it is at the surface of the cowl vent, then air is going to flow out of the cowl vent, no matter if there's positive or negative pressure (with repsect to "ambient" at 1 ATM) measured at the cowl vent. The difference is all that matters.
So can you open the rear of the hood and get venting? Very possibly, yes! As long as you are at a speed that produces a higher pressure inside the engine bay than is seen at the vent opening. Of course, there are two possible outcomes of opening up the rear of the bonnet. First, you could vent hot air at speeds. Second, you may end up drawing cool air in, and it will travel down over the header and out the bottom of the engine bay. I suspect, though, that both of these conditions will occur depending on the speed which you are traveling and how it changes the flow underneath the car.
Is there negative pressure at the windshield? Yes. There's also positive pressure. Just depends on where you are measuring. We've done pressure measurements and confirm that there is higher than 1 ATM (~14.7 psi) pressure in the vicinity of the cowl vents (as long as the wipers are present/down). Does this make it an intake?
Well...no. Because pressure measurments at the cowl and in the box are really only half the story. Pressure differences are what cause flow. So, if you find that the pressure is higher inside the air box, which I think is the case most of the time, than it is at the surface of the cowl vent, then air is going to flow out of the cowl vent, no matter if there's positive or negative pressure (with repsect to "ambient" at 1 ATM) measured at the cowl vent. The difference is all that matters.
So can you open the rear of the hood and get venting? Very possibly, yes! As long as you are at a speed that produces a higher pressure inside the engine bay than is seen at the vent opening. Of course, there are two possible outcomes of opening up the rear of the bonnet. First, you could vent hot air at speeds. Second, you may end up drawing cool air in, and it will travel down over the header and out the bottom of the engine bay. I suspect, though, that both of these conditions will occur depending on the speed which you are traveling and how it changes the flow underneath the car.
Former Vendor
Joined: Dec 2005
Posts: 306
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From: Richmond, VA
Further out. Once the flow becomes sustained (watch the water drops during a rainstorm) then you can make a pretty fair guess that the air is not stagnating, which is the primary cause of positive pressure. The stagnation, or vortex, zones are destroyed by the vacuum of the air rushing around the a-pillar surrounds.
6th Gear
Joined: Sep 2002
Posts: 2,196
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From: Hampton, VA
I had already experimented with this a little while ago.
I had an HAI for a couple days and got a piece of clear tubing from Home Depot, it was near the end of the roll so the tubing was somewhat oval shaped and curved already. I stuffed one end of it into the intake duct and let the other end hang down right behind the grille slats. I also "sectioned" the tubing behind the grille to act as a scoop.
The HAI filter was very cool to the touch after a good run.
I had an HAI for a couple days and got a piece of clear tubing from Home Depot, it was near the end of the roll so the tubing was somewhat oval shaped and curved already. I stuffed one end of it into the intake duct and let the other end hang down right behind the grille slats. I also "sectioned" the tubing behind the grille to act as a scoop.
The HAI filter was very cool to the touch after a good run.
Made mine out of duct tape and cereal boxes
It was basically a funnel that stepped down to about where the second slat is in the grill. Right at 6" wide. Didn't have a significant impact on IC temps which is what I was working towards. Then of course I forgot about it and drove in the rain and made a big mess.
Joined: Mar 2005
Posts: 3,989
Likes: 1
From: Westerly, RI
I don't know if I would enlarge it, then we lose the stock intake duct fitting. That means making more parts.
6th Gear
Joined: Sep 2002
Posts: 2,196
Likes: 0
From: Hampton, VA
Further out. Once the flow becomes sustained (watch the water drops during a rainstorm) then you can make a pretty fair guess that the air is not stagnating, which is the primary cause of positive pressure. The stagnation, or vortex, zones are destroyed by the vacuum of the air rushing around the a-pillar surrounds.
Thanks. I've intended to buy a Magnehelic for ages and keep putting it off.
Mr Procrastinator
Joined: Mar 2005
Posts: 3,989
Likes: 1
From: Westerly, RI
I did something like this while the insulate the CAI thread was a hot topic.
Made mine out of duct tape and ceral boxes
It was basically a funnel that stepped down to about where the second slat is in the grill. Right at 6" wide. Didn't have a significant impact on IC temps which is what I was working towards. Then of course I forgot about it and drove in the rain and made a big mess.
Made mine out of duct tape and ceral boxes
It was basically a funnel that stepped down to about where the second slat is in the grill. Right at 6" wide. Didn't have a significant impact on IC temps which is what I was working towards. Then of course I forgot about it and drove in the rain and made a big mess.
Do you think any of these ideas being tossed could make a decent impact on IC temps?
Joined: Mar 2005
Posts: 3,989
Likes: 1
From: Westerly, RI
Can you photochop that?
Joined: Mar 2005
Posts: 3,989
Likes: 1
From: Westerly, RI
Getting it to the airbox would be a challenge.
6th Gear
Joined: Sep 2002
Posts: 2,196
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From: Hampton, VA
These are the one percenter solutions I like to see and do.
None of them alone do much but as a collection they have positive impacts on performance.
Insulating the CAI
Better induction path
Waxing the car
Better IC diverter(s)
etc.
Hard to measure but fun stuff.
I like the duct in line with the inlet tube idea. Way too chicken sh** to do it.
Also the hood scoop right into the CAI box.
Joined: Mar 2005
Posts: 3,989
Likes: 1
From: Westerly, RI
Originally Posted by obehave
Also the hood scoop right into the CAI box.
3rd Gear
Joined: Oct 2004
Posts: 241
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From: Connecticut
Better late than never I guess...
Joaquin the hood vents look really nice but, what ever happened to the idea of putting a couple of stock intercoolers under those new vents and feeding the airbox straight from the stock scoop?
Joaquin the hood vents look really nice but, what ever happened to the idea of putting a couple of stock intercoolers under those new vents and feeding the airbox straight from the stock scoop?
6th Gear
Joined: Mar 2006
Posts: 1,710
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From: Northampton MA
That should work & work well.
6th Gear
Joined: Sep 2004
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I like the looks of that..... very nice
Joined: Mar 2005
Posts: 3,989
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From: Westerly, RI
I am making one IC out of two stock units.
Would be cool to have dual ICs, but that would be some work.
I thought you were just messin' around in the PM.
Joined: Mar 2005
Posts: 3,989
Likes: 1
From: Westerly, RI
That would evacuate some serious hot air.
Funniest statement you have made 
.I was thinking - taking a second entry scoop (the very front part of the stock CAI intake, invert it and graph it together with the original one - doubling the scoop and then increasing the tubing to the CAI. Since it grabs more air it would feed the CAI sooner and at speed create more ram air to the box.
6th Gear
Joined: Sep 2002
Posts: 2,196
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From: Hampton, VA
I meant going the route of cutting the hood like in DrPhil's photoshop pic above.
My little dose of LITHIUM
iTrader: (1)
Joined: Jul 2005
Posts: 2,435
Likes: 2
From: Albuquerque New Mexico
I had an idea this morning, while checking that everything under my bonnet was still there and working (engine, check, strut brace, check, OK!)
You can't make the opening for the stock airbox tube much bigger: to the left, toward the center of the car you have the bonnet scoop, that's why the gasket above the radiator has that funny humpy shape. To the right you start running out of fresh air, and the bonnet forms down toward the latch area. But...I'm thinking about the sepentine tube--it's a funky shape to get around the intake tube to the throttle body, and then heads down to the inlet below the filter at the base of the airbox. My idea: remove the stock tube, close off the inlet at the bottom of the airbox, then run a simple almost-straight tube to the airbox to the right of the filter. The flange for the tube won't be round, but it could be pear shaped - ish and still allow a lot more direct fresh air in.
My reasoning being, that once pressurized the current shape of the tube isn't a problem, but a straighter more direct tube would allow an easier flow to the airbox.
...or not.
You can't make the opening for the stock airbox tube much bigger: to the left, toward the center of the car you have the bonnet scoop, that's why the gasket above the radiator has that funny humpy shape. To the right you start running out of fresh air, and the bonnet forms down toward the latch area. But...I'm thinking about the sepentine tube--it's a funky shape to get around the intake tube to the throttle body, and then heads down to the inlet below the filter at the base of the airbox. My idea: remove the stock tube, close off the inlet at the bottom of the airbox, then run a simple almost-straight tube to the airbox to the right of the filter. The flange for the tube won't be round, but it could be pear shaped - ish and still allow a lot more direct fresh air in.
My reasoning being, that once pressurized the current shape of the tube isn't a problem, but a straighter more direct tube would allow an easier flow to the airbox.
...or not.
Joined: Mar 2005
Posts: 3,989
Likes: 1
From: Westerly, RI
My idea: remove the stock tube, close off the inlet at the bottom of the airbox, then run a simple almost-straight tube to the airbox to the right of the filter. The flange for the tube won't be round, but it could be pear shaped - ish and still allow a lot more direct fresh air in.
My reasoning being, that once pressurized the current shape of the tube isn't a problem, but a straighter more direct tube would allow an easier flow to the airbox.
...or not.
My reasoning being, that once pressurized the current shape of the tube isn't a problem, but a straighter more direct tube would allow an easier flow to the airbox.
...or not.
Will it be attached(somehow) to the hood? or to the airbox?
A 2" Fernco cap fits the lower airbox opening perfect.