Hood Scoop? Need suggestions

[dslocal]

Hey I am looking into doing a hood scoop as much as I hate them. I have a set of blitz turbos and the way I had to mount the intake makes it suck in a ton of hot air from the turbos.
I am going to make some kind of a scoop in the hood right behind the passenger side headlight and I am not sure what would look good, I am thinking of doing a reccessed style one that didn't stick out, I looked and I couldn't find any pictures, Does anyone Have any?

[Canuckrz]

Could do something like this but on the hood rather than the headlight: http://www.revlimiter.net/mods/duct_install.html

I'd make an airbox as well/instead personally, rather than just a scoop.

[sous]

like the stock but 2 inch higher

[ERA]

Stout hood?

http://i16.photobucket.com/albums/b47/mightymijo/ToyotaFest%202009/IMG_2004.jpg

[dslocal]

That one^ would be perfect! But I am feeling kind of cheep right now and I have a spare hood just laying around and I have all the materials so I was thinking about trying to make my own and that naca duct looks pretty easy to replicate, I might sharpen the edges a little bit because there aren't many curved lines on the mk3, What do you think
If you want I will post some pics and maybe get some suggestions along the way.
Figured I would throw these up to show what I'm Trying to feed, (I already have a piece of 3" tubing feeding it from where the fog lamp was, I just want more,http://i236.photobucket.com/albums/ff232/honda450rider255/P1030598.jpg

Pic of whole car, still got my 4x4 going:nono:
http://i236.photobucket.com/albums/ff232/honda450rider255/P1030600.jpg

[fazzt73]

im musing this in my ae92 project its about 9x16 in
http://i152.photobucket.com/albums/s189/aeroworks/universal%20parts/giantnacaJPG.jpg

[hvyman]

if u do cut the hood you should round the edges. the body has sharper lines than the mk4 but there still rounded edges. round it out just like the stock hood scoop so it matches.

[dslocal]

Well I figured It was time to post some updates, now it has only been welded, I still have to bondo it and primer it, I also need to ad some new supports underneath because I had to cut some of them out.

Tell me what you think.
http://i236.photobucket.com/albums/ff232/honda450rider255/P1030605.jpg

http://i236.photobucket.com/albums/ff232/honda450rider255/P1030601.jpg

http://i236.photobucket.com/albums/ff232/honda450rider255/P1030603.jpg

http://i236.photobucket.com/albums/ff232/honda450rider255/P1030604.jpg

[Canuckrz]

Haven't seen an naca duct mounted backwards to be used as an exit before, I wounder how it will flow.

[gaboonviper85]

Honestly...that looks horrid in my opinion.

Maybe when it's done it will look better...but right now I hate that you went all crooked and have two vents! Sorry bro:-(

[hvyman]

^i would have to agree. i think the corners are to sharp also. the bumper corners are about the sharpest lines on the car and there still not that sharp.

[Supracentral]

Haven't seen an naca duct mounted backwards to be used as an exit before, I wounder how it will flow.

Neither have I.


Maybe when it's done it will look better...

I suspect it will. It certainly looks like it will be functional, provided that NACA duct flows properly in reverse.

[Canuckrz]

I've looked up some information on reverse mounted NACA ducts, and there's a lot of conflicting opinions on whether they will flow efficiently or not, but here is the one that seemed to make the most sense to me:

http://www.aviationbanter.com/showthread.php?t=1013

Reverse NACA duct ... Bad Idea!
Several years ago I read about someone installing a NACA scoop, pointed end
aft, to remove air from the cabin. I thought I would do the same for my
plane but first decided to test the idea. I built a NACA scoop and ran
high speed water through it in both forward and reverse directions. In
forward the water flowed as expected. In reverse the water exited at
nearly 90 degrees to the slip stream.
I believe a NACA scoop will just add drag, especially to fast
planes....Better to just use a ramped exit.

Russell Sherwood
Houston, TX

It is hearsay though, but it makes a lot of sense regardless and appears to have testing to back it up. There are people who think it would flow fine in reverse who seem knowledgeable but the majority of them are against it.

EDIT: Found another comment in the thread to do with it.


I had heard that too, so I contacted NASA about it. Spoke via E-mail
with one of the aerodynamicists. I told them I thought I understood
the principle of the NACA duct and that I'd like to use it to
facilitate removal of cabin air.

He replied that "obviously" I did NOT understand how NACA ducts
worked, or I would not be suggesting that I use one to draw the air
out of the cabin because that's not how they work.

So I meekly asked what might work, instead of a NACA duct and he
replied almost any opening would work, as long as it was placed in a
low pressure area.

So if he isn't lying which I highly doubt he is; the NACA duct is a bad idea in reverse, strait from the horses mouth.

[dslocal]

ok well I am stoked that I got all these opinions!
So now judging by the opinions based from ^ I was thinking about taking the naca duct and just making it into a straight duct, Leaving the larger opening the same and just widening the back part? Opinions?
As for the front one, I am definatly going to straighten it out, I was looking more closly at the pictures and I Hate it now... Its got rice stains all over it. So anyways I am going to even it up along the top of the vent and I was planning on rounding the edges out more once I went to bondo it and smooth it out a little, Any other ideas?
Maybe someone with photoshop?
Thanks

(one more quick thing, does anyone know where the paint thingy is on a mac, or even what its called? I am pissed off at this pos. User friendly my ass)

[Supracentral]

(one more quick thing, does anyone know where the paint thingy is on a mac, or even what its called? I am pissed off at this pos. User friendly my ass)

There used to be something called MacPaint, but I think it went away with the introduction of OS X.

There are tons of downloadble freeware paint apps for the Mac however.

Paintbrush is one of them:

http://lmgtfy.com/?q=MS-Paint+equivalent+mac+freeware+paintbrush

Ugh.. Macs...

[Neodeuccio]

I'm not a fan of the original angled design, but I think it will look awesome once it's straightened out! Be sure to post more pics as it progresses!

[Canuckrz]

I'd take the NACA duct and put it where the forward duct is now and make a simple reverse vent where it was. The NACA duct is VERY effective given it is in the proper orientation.

[Supracentral]

Something like this? (very quick and dirty photoshop...)

http://www.supracentral.com/private/QDP1030605.jpg

[Canuckrz]

Yeah like that ^ but with the naca duct as forward as underhood space will allow.

[Neodeuccio]

That would be sweet... If it works.

[dslocal]

i wish i had figured this out before i went and cut into stuff.
Anyways It would probably just be easier to get another hood, There is actually a white supra at the junkyard now so I might go get that one...
Anything else I should do to the hood while I'm welding on it?

And thanks for the photoshop by the way^

[dslocal]

Yeah like that ^ but with the naca duct as forward as underhood space will allow.

the only thing I really have to watch out for is the intercooler pipe coming off the rear turbo. I will see what I can do.
Have any idea of approximate demensions I should use for naca duct?
Thanks again. SM kicks ass!

[Neodeuccio]

the only thing I really have to watch out for is the intercooler pipe coming off the rear turbo. I will see what I can do.
Have any idea of approximate demensions I should use for naca duct?
Thanks again. SM kicks ass!

Check this out: NACA_Profile_Calculator.xls (http://dsr.racer.net/tech_info/aero/naca_profile_calculator.xls)

This should allow you to measure how much space you have available, then calculate the the maximum size duct that will fit in that area while still maintaining the correct proportions.

And yes, SM is fucking awesome! I just hope that in some small way I help. Good luck!

[supraman7mgte]

okay,Q;do you still have the plastic underliner? just curious if adding an air inlet on the hood will affect the abilty of the other duct to remove engine heat.i just figure that just the air coming in through the radiator area across the the engine and then OUT the hood would be best.by no means am i stating that my idea is the best,i just left it to best guessing.plus it looks kinda cool.

[Neodeuccio]

That's a good question. Far beyond my ability to calculate. I never was any good at fluid dynamics...

[Canuckrz]

Hm, good point, but as long as the exit vent is large enough the pressure change shouldn't be significant enough to disrupt the flow to the rad/ic. I can't really say for sure though.

Personally I'm only putting in an exit vent because I'm going to be running a cai so increasing the flow to my IC/rad is what I'm going for rather than getting air to the turbo/in-bay intake. But that being said my plan is much different than yours, though you could run some kind of cai/air box easily as you already have a ffim so no ic pipes to get into the way; and then you could just blanket/ceramic coat the turbo's/downpipe/exhaust manifold to decrease engine-bay heat and the turbo would likely spool faster because it would keep the egt's high and because gases expand as they're heated yadda yadda yadda you get where I'm going with this.

Its a bit more complicated but likely more efficient. But to each his own; 1 size doesn't fit all; etc etc.

[Neodeuccio]

yadda yadda yadda ...etc etc.

That was a really good post. I approve, both on the technical parts and the babbling.

[dslocal]

ok well thanks for that link, Neo. Big help. Anyways to supraman I do not have the plastic underliner thingy anymore, Mine was all torn to hell from the previous owner so I am making a new one out of some 20 ga aluminum I got from a street sign. Hahaha.
And as far as a could air intake goes or the air box, I already have a piece of 3" tubing feeding in cold air from the right fog lamp, I just need to mount it, But I am still trying to lower intake temps because lower temps equal a cooler charge and more power.
Btw the manifolds, hot sides on the turbos and the downpipes are already cermac coated...

One question though, How does the air normally flow on a stock mk3? Through the front grill, intercooler, radiator, Then where? Out the bottom?

[Canuckrz]

Not completely sure, which is why I'm doing my hood like this to give it a better path http://www.supramania.com/forums/showpost.php?p=711272&postcount=33

It will give the air coming off the fan shroud a better exit so it promotes more flow through the IC and rad; and it should suck some of the engine bay air out while its at it. Besides that its simple, clean, and looks like sex.


Here's something else you might be interested in, its a silicone gasket which helps block the heat that the intake manifold would absorb from the block normally: http://store.driftmotion.com/static/i-heatshieldinggasket1jz.php

Also I'd get the ffim and any IC piping inside the engine bay ceramic coated as well to help prevent heat soak.

I'd make an air box for the filters regardless personally, because once you come to a stop that 3" pipe and hood vents will be near useless to the air intake and it would go back to sucking in engine bay air. Personally I'd rather have a setup that got outside air all the time, more predictable intake temperatures, etc etc...

The modifications you're looking into are much the same as I'm planning to do myself, which is basically make the engine/air intake as cool and efficient as possible rather than just stuffing more fuel and air in. So I've been looking into a lot of these various things for a little while now. Good luck with your build I'll be interested in watching it as it progresses.

@Neodeuccio

Thanks man, nothing can be technical without some babbling involved eh? :biglaugh: