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hood vents: ideas...


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#41 JMortensen

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Posted 29 June 2007 - 08:52 AM

Oh, I'm sorry, I thought Owen did those himself with basically the same method you linked to, and did the rest of the fiberglass work to blend it in. He's pretty good with FG...

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#42 tube80z

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Posted 29 June 2007 - 09:15 AM

I agree that the hood-popping data strongly suggests that venting underhood air to the foreward/side is effective in reducing pressure.
If there is another wind tunnel session, I would really like to see a stock hood instrumented to give us a pressure map across its entire surface.


You don't need a wind tunnel to do this. Use a simple water manometer and do the test yourself. Then drive the car at various speeds and have a passenger record the pressure results from inside the car.

Easy and cheap. Your local Home Depot or Lowes has everything you need.

Cary
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#43 capt_furious

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Posted 29 June 2007 - 09:22 AM

Oh, I'm sorry, I thought Owen did those himself with basically the same method you linked to, and did the rest of the fiberglass work to blend it in. He's pretty good with FG...


You know, I could be wrong. I found something that looked exactly like what he's got, but he could have done that himself.
- A.J.
'74 260Z #1048, swapped L28, 5 speed, R200.

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#44 speeder

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Posted 30 June 2007 - 12:09 PM

You don't need a wind tunnel to do this. Use a simple water manometer and do the test yourself. Then drive the car at various speeds and have a passenger record the pressure results from inside the car.

Easy and cheap. Your local Home Depot or Lowes has everything you need.

Cary


Right! - I'm gonna put 20 manometers connected to 20 holes in my hood and drive around to get a pressure contour map.

I don't think so.
Rick Bowers
'77 280ZT (Not as fat as I thought) - Awaiting 260ci Twin Turbo Buick Stage II - Finally out of machine shop jail after 2+ years!
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#45 74_5.0L_Z

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Posted 30 June 2007 - 02:16 PM

Oh come on Rick! You are an instrumetation type guy. Are you so selfish that you are unwilling to put a few small holes in your hood?

Hell, look at the hole I put in my hood.

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You wimp.:rolleyesg

#46 speeder

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Posted 30 June 2007 - 06:05 PM

Very nice work, Dan - I need to come over and see.

Me = Wimp!:mrgreen:
Rick Bowers
'77 280ZT (Not as fat as I thought) - Awaiting 260ci Twin Turbo Buick Stage II - Finally out of machine shop jail after 2+ years!
'78 280Z (Soon to be for sale)
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"Speed costs - How fast do you want to spend?"

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#47 heavy85

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Posted 06 October 2007 - 09:11 PM

1. Nissan put a sealing lip on the rear edge of the hood opening ... How is the stock rear sealing lip of any benefit?


I'm guessing it has nothing to do with engine cooling or aero but rather to help keep hot engine bay air from going into the fresh air vent in the cowl box ... otherwise you may get full time heat coming out the interior vent ...

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#48 texis30O

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Posted 07 October 2007 - 08:35 AM

Owen was supposed to at one time make a mold of his vents to sell. I was involved in a thread that he said that he was goin to do that but have not heard anything from him in a LONG time.

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#49 denny411

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Posted 20 December 2007 - 08:12 PM

I have been sitting in the background for awhile, quietly observing the whole aero,cooling dilema. I`m somewhat concerned with some of the things that I`ve done but encouraged by others. here is the rundown of what i have accomplished so far.

1. shaved drip rails
2.shaved marker lights
3.shaved sail panel vents
4.3.5" cowl induction hood
5. whale tail
6.installed fiberglass MSA front and rear bumpers
7.cut out the inner fenders behind the strut towers
8.installed Z28 heat extractor vents in front fenders
9.headlight covers(yet to be installed)

I am in the process of flush mounting the windshield and hatch glass, and building a box to isolate the "cowl induction" intake to the carb/air cleaner.

Even before it was such a popular concern, I had planned to enclose the front of the car and channel all incoming air through the radiator. I never realized so little air was necessary to keep the engine cool.

Micheal and I have had several extensive conversations over the years regarding the aerodynamics "or lack there of" that these cars actually have,So it`s been in the back of my mind all through the paint and body process.
I`m really surprised that the wind tunnel results were not worse.

It seems that the whale tail turns out to be a good thing for which I am thankfull. It flows so well with the lines of the car and I`ve got alot of time in bodywork making it fit the way I wanted. It would really suck if it was "all for looks"

I guess it`s still up in the air as far as the shaved drip rails go. I would really love to see some CD numbers. Maybe in the future we could have a car tested with them shaved. Either way I LOVE the smooth look without them, and I have no intentions of welding them back on.

The flush mounted windshield will interest many of you. I`ll get some pics in my album soon so everyone can see how i did it. It`s way to complicated to go into now but it has been and will be very time consuming to finish. I will say it does look sweet.

I am planning to do a full belly pan for the car to channel the remaining air in the engine bay through the transmission tunnel to help cool the viscous posi diff. it will be modified behind the rear axle to let air escape smoothly under the rear of the car without catching inside the rear valance and bumper like a parachute.

The entire theme of my car is "smooth,sleek,and MEAN" It`s not fully assembled and still looks like it`s doing 150mph sitting still.It won`t be a sleeper in any way shape or form. especially when they see and hear the fenderwell headers and 3.5" sidepipes.
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#50 JIM73240Z

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Posted 22 January 2008 - 09:12 PM

dragging this thread from it slumber. i have taped on my hood and fenders several areas to make vents. the hood is a fg hood from 280zone. nice by the way. i plan on cutting 1/2" wide vents to get air out of the engine. also the hood has the snorkel that i think is more geared for the v8 guys but i am thinking that a hole in the front that goes straight out the back might draw out more air. kind of a flow through. the vents in the fenders aould look similar to these only i will cut out each one instead of the panel

http://www.raceace.com/products.html

or these

http://www.racerpart...ting_And_Sheets

here is a pic of my hood

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any comments?

let the bashing begin. ready, set, go

jimbo
it makes perfect sense, ok. run with me on this. if you eat food, you crap out you butt, right? ok, keep with me here, it get a little complicated. if you eat food and crap out your butt, then maybe if you stuff food up your butt, you'll crap out your mouth. thats not dumb, thats genius.

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#51 Mauisnow13

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Posted 22 January 2008 - 09:37 PM

Just my opinion but I think you should tilt your spoiler a bit flatter. I know it has nothing to do with the hood issue but It was the first thing I noticed. hahaha



As for the hoods, I think 74_5.0L_Z's idea is a great one. Especially if it could be a longer scoop. hell, Ferrari and the Ford GT use this kind of design, it must work to some extent, right?

#52 MJLamberson

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Posted 22 January 2008 - 10:22 PM

yeah I think that spoiler would look better if it were almost parellel
to the ground, just MHO
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#53 JIM73240Z

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Posted 23 January 2008 - 08:10 AM

Just my opinion but I think you should tilt your spoiler a bit flatter. I know it has nothing to do with the hood issue but It was the first thing I noticed. hahaha



As for the hoods, I think 74_5.0L_Z's idea is a great one. Especially if it could be a longer scoop. hell, Ferrari and the Ford GT use this kind of design, it must work to some extent, right?




i would do a hood scoop like that if i was running a v8, no question about it. with the l6, there is no room for a feature like that. that is why we are looking at other vent areas. as far as the wing goes, the safest spot in my garage right now is on my car. it is just sitting there not bolted on so. i have not even bolted it to the fg hatch yet to even start to adjust the wing to close to level. it is on my long list of things to do.:mrgreen: there's a ton of things on that list.

jimbo
it makes perfect sense, ok. run with me on this. if you eat food, you crap out you butt, right? ok, keep with me here, it get a little complicated. if you eat food and crap out your butt, then maybe if you stuff food up your butt, you'll crap out your mouth. thats not dumb, thats genius.

- eric cartman


auto-x is like watching porn. racing is like being in one

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#54 Gollum

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Posted 23 January 2008 - 09:04 AM

I like what you have taped off so far, but I thing the inner vents on the hood could extend down a few lines farther, just to balance out the look of the other vents. Plus I think there's plenty of air to vent to need it when you're going 60mph+ on a track.

I really like 74 5.0l Z's hood vent, and is along the lines of what I'll be doing if/when I get a S30. Kinda in the vien of the GT40 hood vent, let the air come in, and the push it right back out upwards. Depending on motor choice I'd mount the radiator at an angle as well to help, if there's room for it.

'75 280Z, L28ET, Street going rat rod

http://forums.hybrid...ms-dd-l28et-75/


#55 JIM73240Z

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Posted 23 January 2008 - 09:28 AM

I like what you have taped off so far, but I thing the inner vents on the hood could extend down a few lines farther, just to balance out the look of the other vents. Plus I think there's plenty of air to vent to need it when you're going 60mph+ on a track.

I really like 74 5.0l Z's hood vent, and is along the lines of what I'll be doing if/when I get a S30. Kinda in the vien of the GT40 hood vent, let the air come in, and the push it right back out upwards. Depending on motor choice I'd mount the radiator at an angle as well to help, if there's room for it.



even if you could mount the radiator at an angle (plus there is a fmic to deal with) i do not think there is enough room to have a vent like 74 5.0l. if some has made that happen i would love to see it. i think the only pic i have seen with a slanted rad is redbirds and if i remember right, there wasn't enough room.

heres the post

http://forums.hybrid...ghlight=redbird

i can add more vent towards the front though. thats easy.

jimbo
it makes perfect sense, ok. run with me on this. if you eat food, you crap out you butt, right? ok, keep with me here, it get a little complicated. if you eat food and crap out your butt, then maybe if you stuff food up your butt, you'll crap out your mouth. thats not dumb, thats genius.

- eric cartman


auto-x is like watching porn. racing is like being in one

- clifton

#56 Gollum

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Posted 23 January 2008 - 10:42 AM

The redbird car still had an L28ET in it too. I think there's plenty of room for it in most engine bays.

Consider the SR20 engine bays (pic from vildini, hopefully alex doesn't mind)

http://www.vildinimo.... - 240z/11.JPG

In any case it'd be interesting to see how much room you've got with the engine in. Sorry, but I can't remember what engine swap you've got happening in your Z.

I don't think a vent like 74 50 Z's is really "needed" per say, but I think it's the right direction for getting drag free downforce/lift reduction.

I'm curious though, those inner hood vents, are you planning on just removing that material, or cutting the leading endge and angling it in towards the engine? Your fender vents are pretty obviously drawn, I don't find the other one's quite so clear.

'75 280Z, L28ET, Street going rat rod

http://forums.hybrid...ms-dd-l28et-75/


#57 JIM73240Z

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Posted 23 January 2008 - 10:52 AM

the enging is going to be the l6 with a bw s400 turbo. lots of plumbing in there. the vents in the hood i was just going to remove the material and cover the bottom with a screen mesh to keep the crap out. i had thought about angling them up as well. not sure which is better.

jimbo
it makes perfect sense, ok. run with me on this. if you eat food, you crap out you butt, right? ok, keep with me here, it get a little complicated. if you eat food and crap out your butt, then maybe if you stuff food up your butt, you'll crap out your mouth. thats not dumb, thats genius.

- eric cartman


auto-x is like watching porn. racing is like being in one

- clifton

#58 rturbo 930

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Posted 23 January 2008 - 06:57 PM

I am in the process of flush mounting the windshield and hatch glass, and building a box to isolate the "cowl induction" intake to the carb/air cleaner.

The flush mounted windshield will interest many of you. I`ll get some pics in my album soon so everyone can see how i did it. It`s way to complicated to go into now but it has been and will be very time consuming to finish. I will say it does look sweet.

Do you have pictures of this? I'm interested in seeing how you flush-mounted the windshield.

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#59 Daeron

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Posted 23 January 2008 - 11:59 PM

i can add more vent towards the front though. thats easy.

jimbo


Suggestion: extend the "rectangle" zone you already have most of the way forwards until its almost even with the hind side of the fender "zone" and then begin a horizontal taper towards the center of the hood, leaving you with a "zone" shaped like half of home plate, and the diagonal cuts from the center of the car then outwards.

I also don't like the holes/mesh idea.. but I DO like the thinking that a different shape to the vents themselves there would complement the "gill" vents in the fender, so maybe it will work better than I think. Any chance of finding a way to make gills that are somehow rounder (as opposed to the squarish look of the fender gills) so that the ovalish visual effect is retained, but its not just a straight hole?



Here is a question that has been burning my mind.....

Why not vent the intake/exhaust/turbo side of the hood (on L28ET cars) and leave the spark plug/battery side solid? Why waste that airflow when we can push it ALL past out intake AND exhaust tracts? Even on crossflow engined I6 vehicles, I would imagine it better to bias the flow on the exhaust side.

Obviously there is a potential for off-center drag/thrust in this concept; would such an assymetrical ventilation setup be detrimental in any way?
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#60 L.S.Racer

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Posted 12 February 2008 - 03:26 PM

My opinion on your cowl hood dilema is the understanding of it. I view a cowl to give a greater amount of volume in the engine compartment lowering the pressure. This is similar to limiting the air flow in while creating more downforce. With the rear of the cowl opening moderately close to the windshield, you will allow the air to exhaust over the car creating downforce. It would be impossible for the cowl to allow any backflow into the engine compartment or under the car. It is the same theory that creates lift for a airplane wing. When air flows around a object that has a larger surface area on the top than the bottom, the air on top has to speed up to meet back up with the air going under it. The faster moving air creates a low pressure area creating lift. This faster moving air pulls out the air in the engine compartment. This can be easily demonstrated by blowing compressed air across a full water bottle at about a 45 degree angle. Anything in the bottle will be sucked out.
Hope this helps you.




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