Hood Aero
 

I've been having pretty high underhood temps forever, and expect this to continue. In an effort to reduce those temps and increase front downforce, I decided to vent the hood. I understand the basic concepts, but I'm wondering which of the following I can do to really improve this:

Initial scenario, vent present and nothing else, like this:
http://i44.tinypic.com/214cmjk.jpg
Note how in front of the hole there is no raised lip or anything. I remember this being problematic, in that it created turbulence at the hole rather than directing airflow over it. If I'm remembering that right, I'm surprised Lotus did it, but whatever.

Potential scenario 1: small "lip" in front of hole:
http://i41.tinypic.com/k0fqj6.jpg
I've seen it with the sidepieces and without. Assuming with is better at preventing turbulence.

Potential scenario 2: STi/WRX hood scoop at front/on top of hole:
http://i44.tinypic.com/2n6ey3k.jpg
For the life of me I could not find a picture of this already done. The scoop outlined in green would be what I'm dealing with, but turned backwards with the outlet facing the windshield. It is kind of tall. I also have a smaller WRX scoop available, but it would mean a significantly smaller hood hole as well, and would not completely cover the hole like the STi would. My idea is that the scoop would be best for airflow direction. But, seeing as how no one does this, I question my logic (which is loose to begin with).

I recognize that this might turn out ugly as sin :P Looking for functionality though.

Advice from aero people?

Re: Hood Aero
 

Stink, that lip will create an area of high pressure which I believe acts as a vacuum. It being a vacuum will let it cool more efficiently. However, I remember Andrie saying the design on the Lotus, that is to create more downforce as opposed to cooling (get both effects but the downforce is what the vehicle gets out of it).

Or you can always be a stunna and put washers in the back of your hood hinge. LOL

Re: Hood Aero
 

Hmm. Cooling is the primary function, but I'd really like to get additional downforce as well. The hood propping will not be sufficient :P

Re: Hood Aero
 

Im pissed. I looked up posts by KIWI and Andrie. I cant find it! There was a question about radiator cooling points must be stock. KIWI drew a diagram where the radiator was mounted at a 45 degree angle and used the factory radiator mount points. KIWI was making this argument while Jeremy was saying "at your own risk". Then Andrie said something along the lines of GT cars use this method which create a large amount of front downforce.

I looked back mid last year and could not find it.

Re: Hood Aero
 

I remember that discussion too, actually. It was about HC legality, right?

Re: Hood Aero
 

remove headlight(s) and put 1" holes in the back side of the wiper cowl. gets air in and out. cowl mods arent HC legal, but it tt/pt its good.

i've tried the hood proped up in the back. doesnt do much

Re: Hood Aero
 

Hey Stinky have you read the lasted edition of Grassroots magazine it has a great and informative article on aero that is pratical with good tip it even mentions about venting the under hood high pressure to a lower pressure area.

Where Johnny Mac our resident Aero engineer?

Good Luck and let us know your results.

Re: Hood Aero
 

Spenc I think that would hurt cooling. You want the air to go through the radiator, not around it.

Re: Hood Aero
 

I'm not trying to run this off track, but do you mind sharing your cooling set-up? Full width or half width radiator, duct work for the rad, oil cooler?

Thanks,

Re: Hood Aero
 

Renan, benny, Ryan, Greg all run a scoop like that, helps with aero and temps IIRC.

Afterhours performance sells the vent too. (Renan's sponsor/shop)

Re: Hood Aero
 

Like which one, Jimmy?

Spence, I'm not concerned with legality on this one, just looking for the thing to do its job. Thanks though.

civichb, I did read that article and it got me thinking more about it. Unfortunately, it doesn't go into too many details about specific applications (the details I'm examining in this case).

Patrick, who are you asking for the setup?

Re: Hood Aero
 

https://honda-tech.com/attachment.ph...1&d=1259686587
http://www.urbanracer.com/articles/a...sp?a=3985&z=2#

Re: Hood Aero
 

Ahhhh, hmmm.....

Thanks Spence :thumbup:

Re: Hood Aero
 

Found the old discussion: https://honda-tech.com/forums/showth...diator&page=13

And this from SPMS website:
http://www.specialprojectsms.com/image/TECHNICAL.gif

Unfortunately, no direct mention of the front of the hood hole design :(

Re: Hood Aero
 

i see a raised section at the opening of the hood vent.... doesnt really increase the frontal area of that section much and still allows air to flow over the vent... pulling air from below up through the cutout. I should asks some of the aeor majors in this room hehe

Re: Hood Aero
 

hmmm... might try that... i'd probably use bigger holes though, 1" seems kinda small 2" would make sense I think...

Re: Hood Aero
 

the largest you can fit. i'll put it that way.

stinky- since u have no rules at all to abide by, build a shroud around the radiator that connects to a duct in the hood. so all the hot radiator air goes out of the engine bay. unless your still going turbo. then you won't realy have space. but a vent to get the turbo heat and radiator heat out will work well. theres realy nothing special to the design.

Re: Hood Aero
 

good searching skills Stinky ... Kiwi is the man give him a call ?

Now we need Johnny Mac and Kiwi to post?

Re: Hood Aero
 

I spoke with Brad earlier about the little Gurney flap idea. Seeing both the Lotus and Renan's car without that makes me wonder though. I think I'm going to make the hood such that I can attach a few different designs, and then test them out. I'll report back with findings :)

In the meanwhile, I wouldn't mind any additional info.

Thanks guys!

Re: Hood Aero
 

pm john baker (h2 crx #32)
he made this set-up on his car to help cool it and it came out sick.

Re: Hood Aero
 

Renan's hood is bad ass.. also has the headlight ported too.
Check Team Gear X's hood in the April 2010 Honda Tuning page 52.
It has something like you illustrated Adam.
Since Kiwi drove this car in the 25 hour he would be the best person to ask how it worked for him.

Re: Hood Aero
 

In regards to the hood vent... will that work and clear a K24 in the bay?? I may be interested in trying something like that out for cooling as well...

Re: Hood Aero
 

I'm not sure personally. If you don't find out you can check mine out in June.

Re: Hood Aero
 

the one that Spenc posted (of renan car EG civic) will. It does need to be trimmed (for any application) though.

Re: Hood Aero
 

I can't find any where to buy either the complete hood (which I don't really want to spend $$$ on) or the vent alone (which I would be willing to pick up potentially). The Afterhours site does not have anything in the "Products" category, and I'm unable to make phone calls currently. Anyone know if the scoop can be purchased separate from the hood? Brad found it at one point, but lost the website.