The subject of air dynamics can get pretty complicated, but a good example of the Bernoulli principle would be a pneumatic siphon or sandblaster. You wouldn't think pumping large amounts of air through a tube would create any vacuum, but it obviously works.

 

same idea with the bubbles in guinness http://www.stanford.edu/group/Zarela...ess/index.html

 

Imagine explaining these vicious looking things on your hood...

http://cgi.ebay.com/ebaymotors/STAIN...spagenameZWDVW

"So what kind of vents are those?"

"Um... They came off my boat."

 

Hey guys been working all day and just got the PM from Mark. The Sport Hood from the later model Runners WILL fit on a 96 without any modifications! I also will try to dig up the part numbers you'll need to get all the pieces that go inside the bulge of the scoop itself. You don't need all the parts that toyota puts in there so I narrowed it down to the parts I considered necessary for a complete and safe installation. Part Numbers to come!!!

 

Found my list of parts and numbers that I ordered for the scoop. these are the only parts I used and didn't find a need for anything else. Just use your existing hinges and don't buy the hoodliner unless you just want to have it. here goes:

hood
nuts (4) 90179-06324
cushions (4) 90540-05028
rivets (2) 90269-04054
bulge 76181-35901
guide 76182-35020
plate 76192-35010

 

Thank you Jonathan!

RIGHT ON!

 

Yikes is right. Though still a lot of postulating and not many people offering much more than speculative answers (something you'lls ee from me below). What I found interesting was the person who mentioned a surface vent would result in much less air disharge than a vent that protruded past the boundary layer.

To take this a step further, or a step back. The basic heat transfer equation has convection, conduction and radiation components. Looking at heat sinks (whether it be computer chips or air cooled engines) we find fins. Perhaps a finned hood is truly best for dropping engine temp?

Or extrapolating from cooling towers - a mist system for the surface of the engine? The surface of the hood?

Many routes to explore if cooling and not looks are in order.

But to take a step back to reverse facing vs flat vents - I think the flat vents may have one noticeable advantage (Assuming both are in the boundary layer of the faster moving air). The change in form of the back facing vent will result in drag and air turbulence - hindering the assimilation of engine compartment air into the air stream. In fact you'll have eddy currents of air that flow back towards the open (reverse facing) vent. See rain drops versus semi-trucks. Flat vent would have none of the adverse aerodynamics.

Something tells me that in practicality neither vent has substantive advantages over the other vents. We've seen posted in this thread photographic documentation of all vent styles on quite high end cars.

EDIT - point being its aestethics.

 

For what we're looking at, i.e., an off-road truck that gets REALLY hot on the trail, yeah, I'm not gonna sweat the dynamics too bad.


BTW! I visited my truck tonight and took a quick measurement for this:OMG IT'S __HUGE__!!!

It's 22x28, and the 28 is basically the whole length of the hood, the 22 is REALLY wide! So, I'm back to vents, or maybe the other scoop that I bought which is 5" wider than the one I have. It should be here soon.

 

A vented heat sink directly on top of the supercharger protruding out of the hood would be the best way to go...

 

And... Scoop #2

Opening front:



Opening rear:



I like it better than the other one, and I like it facing rear, it may be a bit too tall, but I think it'll grow on me.

What you guys/gals think?

 

Mark, I think the second hood scoop has better porportions alone, but it still doesn't quite look big enough to me (ie total area on the hood not height) and looks too much like an old musclecar scoop (takes a bit away from it being a Toyota IMHO). I like the look of the first scoop but the size is a bit small width-wise. What about using 2 of the first scoop and mount them next to each other paying careful attention to porportions.

Kinda like this one here:


I could see it looking pretty bad ass with two low scoops side by side (mounted rear or forward facing)


Just my $0.02 anyway for whatever that's worth.

 

I wonder how much of a (negative) difference that bug shield would make if a scoop was installed?

For some reason I am leaning towards vents myself...

 

great info

 

btw... I found a local body guy that comes highly recommended to do the work. VERY reasonable, and I've asked him to pull out the dent that I've had in my hatch since backing into a tree 3 years ago! Oh... And I decided to go with the larger scoop, turned backwards (opening facing the windshield).

Dan (The Dude) brought up an EXCELLENT point btw - when making a plastic scoop active, it will be subjected to some nasty temps. A buddy of his did it, and the scoop started warping from the heat. Dan has a plan to reinforce the scoop (I think he's gonna put a coat or two of a resin on it) so that it won't happen.

Looks like he'll be starting sometime next week - should be about 3-4 days. I can't wait!

 

Get another scoop so you have two and face them forward. That would look awsome

 

oops, guess i shoulda glanced at the last page.

 

actually, other folks have suggested that I use two of the big ones and graft them together, so you were covered.

I looked at doing that, and I realize that the scoop on the Toyota Sport Hood is bigger than what I'm doing, but I want to be different than that. Functionality wise, I think this size is fine, aesthetics side, maybe it "should" be larger, but Dan came up with a paint idea that I think will have the aesthetics angle covered.


Obviously... I'll be posting pics when I have them.

 

I bought a sweet scoop from a Subaru outback sport that is bolted down and can be made functional or non... do a quick search and you'll see what it looks like!

 

Hmm... do a search on YT? I searched on "subaru scoop"; "scoop" by 98LimitedCustomized; "subaru" by 98LimitedCustomized... nothing.

Thanks though!

 

Sorry Mark I meant google it... but I got it loaded. I wish I took something else in the picture for reference but I think it's around 2 feet wide. I think they charged me all of $5 for it!