Hood venting

[sd_pace]

Looking to find a way to vent the hood on the v6, came across this hood on the tiger site. was wondering about how it was done, any ideas out there? I like the look myself

 

[Barry]

Either a carbon or fiberglass hood with the vents molded in or a metal hood with some nice metal work.

Either way, the base of the windshield is typically an aerodynamic high pressure zone and I doubt that openings in that area would result in any effective outward "venting" with the car moving at any appreciable speed.

 

[sd_pace]

I was thinking it was similar to the lat hood vents ... lookin to push or pull air out of the engine bay. i have a slow build up now of heat that wont pass thru, perhaps it will assist the side vent in thru-put.

 

[DanR]

I can't understand why you are having heat build up? What do you and I have that is different? Mine runs cool....

 

[PROCRAFT]

Punch some holes in the inner fender near the fire wall bleed the air into the wheel well ! worked for us many times in the past also saw it done on Leno's Elan must be on to something there?

 

[Billm]

Honda Civic or Accord hood vents from the early 80's? Hard to find. I had seen these too.

 

[sd_pace]

I am going to put in a flex tube to help pull air to the side vent I put in (image). but hadn't got around yet, not sure what the honda vents look like.... but I do like the clean look of these... whether is positive or negative pressure it can only help right?

 

[Barry]

I am going to put in a flex tube to help pull air to the side vent I put in (image). but hadn't got around yet, not sure what the honda vents look like.... but I do like the clean look of these... whether is positive or negative pressure it can only help right?

Your vents look nice!

Air flow mostly occurs because of pressure difference and the direction of flow is from higher pressure to lower pressure. The more pressure difference, the more flow. No pressure difference = no flow. Reverse pressure difference = reverse flow.

For air to flow out of the engine bay, the air pressure in the engine bay must be higher than the air pressure on the "outside". Fender flanks are typically an area of lower air pressure when the car is moving forward at speed.

As Joel noted, cutting a hole through the inner fender will vent air from the engine bay into the wheel well. Air in the wheel well is almost certainly turbulent and higher pressure than outside the fender flanks, so I doubt that it would be as effective as fender flank vents, but it would certainly be a lot simpler.

 

[DanR]

Still working on my Side Vents.... They will connect from the engine compartment up high just from under the hood and run out through the fender well to the out side of the fenders just behind the Alpine Script.

These PIC's are more of the work in progress.

1st PIC is rather rough but you can get the idea that it will have a flange to cover the edge surrounding the inner fender.

2nd PIC shows the vent tube in between the inner fender and the outer fender to carry the hot engine air to the exit.

3rd PIC shows the Vent tube continuing to exit on the outside of the fender. I have the flange taped in this picture inorder to get a contour between the fender and the vent tube.

More works in the making

 

[sd_pace]

so Barry with the hood vents positive, and the side vents negative, I should be able to create some flow out of the engine bay,

Dan, vents lookin good, are the tubes plastic? They are higher up the fender wall than mine, those will work well.

 

[MikeH]

Still working on my Side Vents.... They will connect from the engine compartment up high just from under the hood and run out through the fender well to the out side of the fenders just behind the Alpine Script.

These PIC's are more of the work in progress.

1st PIC is rather rough but you can get the idea that it will have a flange to cover the edge surrounding the inner fender.

2nd PIC shows the vent tube in between the inner fender and the outer fender to carry the hot engine air to the exit.

3rd PIC shows the Vent tube continuing to exit on the outside of the fender. I have the flange taped in this picture inorder to get a contour between the fender and the vent tube.

More works in the making

Dan, are those repro LAT vents? I bought a set of those a while back. I also have a set of hood louvers from an ‘85 to ‘92 Firebird Trans Am and a set from a Chevy Lumina Z34. One set of louvers I plan to use on my MGB and a combination of the hood and fender vents on the Alpine.

 

[DanR]

Dan, vents lookin good, are the tubes plastic? They are higher up the fender wall than mine, those will work well.

Yes Steve, they are "Printed".

 

[DanR]

Dan, are those repro LAT vents?

They are not the LAT's....I borrowed a set several years ago and went through quite a time trying to fabricate them be be the same. Did not like the results!

Decided to go a different route and size them down in proportion to the fender placement. I wanted them to be higher up than what I had seen on the Tigers.

Thinking (IMO) they were a bit too large for a nice look in a higher placement on the Alpine fender, I started sizing them down to what I have now.

My Draftsman/Engineer seems to think they will draw air from the higher location which is almost straight out of the engine compartment thru the inner panel and on out to the outer fender flank.

As Barry and others have stated there seems to be less resistance along this area (if I understand his remarks correctly)

 

[Barry]

so Barry with the hood vents positive, and the side vents negative, I should be able to create some flow out of the engine bay,

Maybe. Not sure how much heat would be extracted by air going downward from a rear hood intake to a fender flank vent, but there should be some relative air movement. The wild cards are the air pressure and turbulence in the engine bay which have a lot of variables (true for any engine bay intake or exhaust vent).

 

[Thor 1211]

Seems to me that if the hottest spot under the hood is the exhaust manifold/header wouldn't it make sense to try and flow the air out from a point close to and at the same level as the manifold?

 

[DanR]

Thor, It doesn't seem to me there would be enough pull down under the car to provide enough a cooling effect.

That is an interesting idea though....?

 

[260Alpine]

I'll probably do similar to this to match the side vents:

 

[Barry]

I'll probably do similar to this to match the side vents:View attachment 15310

Don't see how vents in the high pressure area near the base of the windshield are going to exhaust air at road speed, but they look cool.

 

[260Alpine]

Barry, mostly for looks, but at speed should let cool air into the engine compartment and at a stoplight vent warm air a little.

 

[sd_pace]

I have pondered the hood scoop also, that would probably solve some of the air movement problem, but with the side vents in , the hood louvers would not be needed. I liked the looks of the louvers more without the scoop... (all about the clean lines right?)