Hood Venting, NACA Ducts

[Lunatic]

I just ordered two Naca ducts or vents in my case to put in my hood. I want to suck the hot air out.
Question, where should they go? Front of the hood, middle, or back.
I am thinking right over the alternator and power steering pump. I'm trying to copy the efect of the hood on my Minibusa (pictured).

[Lonewolf]

There has been some discussion about hood vents in this thread (mostly for FI applications, but some applicable to NA)

http://www.ft86club.com/forums/showthread.php?t=53580

[Lunatic]

Originally Posted by Lonewolf

There has been some discussion about hood vents in this thread (mostly for FI applications, but some applicable to NA)

http://www.ft86club.com/forums/showthread.php?t=53580

Thank you, I read that entire thread last night, but didn't see anything about vent placement.

[86-tundra]

Wow, interested to see what you are going to do here. definitely keep us updated..

[FlamingRectumSyndrome]

The only way to really know is by doing actual wind tunnel testing to find out whether there's a low pressure area. That's where you'd want to place an induction type duct. Without actual data, you'll be wasting your time and money.

[extrashaky]

Originally Posted by Lunatic

I want to suck the hot air out... I'm trying to copy the efect of the hood on my Minibusa (pictured).

The hole in that picture doesn't look like it's intended to suck hot air out. It looks like it's designed to suck more air through the radiator to make the liquid cooling more efficient. Hot air off the engine looks like it would still well up under the hump behind the fan with nowhere to go.

As for NACA vents, I believe those are designed to suck air in, not out. They're replacements for scoops to get cool air into the intake or to route cool air to the brakes. Usually if you're venting to suck air out, you use louvered vents facing away from the direction of travel, like so:



These give you lower pressure above the hood and higher pressure below, so that the hot air sucks right up through the louvers. You usually want them high up on the hood, since hot air rises.

NACA vents have the higher pressure on the outside, ramming the air in the wrong way for what you say you want to do. And I don't think turning them around the wrong way will help.

[Lunatic]

Originally Posted by extrashaky

The hole in that picture doesn't look like it's intended to suck hot air out. It looks like it's designed to suck more air through the radiator to make the liquid cooling more efficient. Hot air off the engine looks like it would still well up under the hump behind the fan with nowhere to go.

As for NACA vents, I believe those are designed to suck air in, not out. They're replacements for scoops to get cool air into the intake or to route cool air to the brakes. Usually if you're venting to suck air out, you use louvered vents facing away from the direction of travel, like so:



These give you lower pressure above the hood and higher pressure below, so that the hot air sucks right up through the louvers. You usually want them high up on the hood, since hot air rises.

NACA vents have the higher pressure on the outside, ramming the air in the wrong way for what you say you want to do. And I don't think turning them around the wrong way will help.

Actually no hot air under my Mini hood as the engine in mounted in back, mid engine.
Maybe I'm wrong about NACA scoops. I thought they would work either way.

[Lunatic]

Yesterday I removed the plastic inserts from my fenders. Using my hand held cut off wheel I cut an opening in the inner fender. Took the car for a drive, got it hot, and with the engine and fans running you could really feel a lot of hot sir blowing out. The air flow was enough to blow a Bic Lighter out at 8 inches away.

I have a friend who is a carbon fiber guy and he took my inserts and is going to make me screened, vented, carbon fiber inserts. I think this should help allot for removing hot air from under the hood.

[retoocs]

NACA ducts are for moving air in.

[wheelhaus]

Yes, NACA ducts are designed to suck air in from a flat surface that sees laminar airflow.

The slatted vents pictured above are called louvers, and are usually to let hot air escape.

The location of the inlet and outlet vents is somewhat important, can't just slap them anywhere. Need to consider high and low pressure, so an inlet vent is in an area of higher pressure, or the outlet vent is in an area of lower pressure, or both. You could have vents all over the place and surprisingly, they may not do much at all if they're not in the right areas.

[Lonewolf]

Originally Posted by Lunatic

Yesterday I removed the plastic inserts from my fenders. Using my hand held cut off wheel I cut an opening in the inner fender. Took the car for a drive, got it hot, and with the engine and fans running you could really feel a lot of hot sir blowing out. The air flow was enough to blow a Bic Lighter out at 8 inches away.

I have a friend who is a carbon fiber guy and he took my inserts and is going to make me screened, vented, carbon fiber inserts. I think this should help allot for removing hot air from under the hood.

A couple of members have done something similar to the fenders and they all commented that they could really feel the hot air pour out after a drive. Looking forward to how yours turns out...

[radroach]

Originally Posted by Lunatic

The air flow was enough to blow a Bic Lighter out at 8 inches away.

Show us a vid, I want proof!

[bama_brz]

Originally Posted by Lunatic

Yesterday I removed the plastic inserts from my fenders. Using my hand held cut off wheel I cut an opening in the inner fender. Took the car for a drive, got it hot, and with the engine and fans running you could really feel a lot of hot sir blowing out. The air flow was enough to blow a Bic Lighter out at 8 inches away.

I have a friend who is a carbon fiber guy and he took my inserts and is going to make me screened, vented, carbon fiber inserts. I think this should help allot for removing hot air from under the hood.

Really looking forward to see how this turns out.

[Frozen_skidmark]

Is heat a problem? I've had the car out in 36℃ 96.8℉ with the A/C on In traffic and never seen the needle go past the second line. Does it start climbing if you're in Texas per se?