Concern Making Custom Hood Vents, Routing the Rain Water? Options

[mgnt232]

Ok so doing some research and need some help with this.
Im looking to make one of two supra hood for my orange celica. I will add the pics at the bottom of both. Keep in mind im pretty set on one of these hoods, there is no reason to bash on the style or have negative comments.

1) The first hood doesnt look like it has any sort of draining system, maybe because the vents are fairly far forward on the hood, and most of the water would fall in front of the engine itself. But I still feel like if i made this, I would want to add in some sort of duct system for re-routing the water.

2) The second hood is much different and looks like it will need some sort of drainage system built underneath. Im curious if anyone here has done anything close to this?

3) Also I know the GT-4 hood has a vent, how do they address the water issue?


Thanks everyone, just looking for some ideas. I want to move forward with this idea. Also the supra hood I assume is much wider than the celica so thats not an option (the front bumper from the supra I cut like 6" out of the middle to make it fit)

First Hood







Second hood





I think this picture the vents are much larger than the other pictures, I dont plan to make them quite that open

[Box]

Keep your ricer Need For Speed, Fast & the Furious **** to Hondas.

See, since you said not to say anything I had to.

Now that the formalities are out of the way I can help. What you would want to do is like what the GT-Four does. There's a pan beneath the vents that diverts water away from the engine. Preferably you'll want to route the water away from any hot bits. I want to say the GT-Four hood routes the water on top of your hot plastic radiator tank, so that's not good. The main issue is when the car is sitting still, as when it's moving rain getting in won't be too much of an issue. That or place your vents to the sides where water wouldn't hit anything hot. Since you're already making vents you should make a ram air scoop right over the air filter.

[playr158]

don't drive in the rain -__-

[czwalga]

My quick vents during service. Underhood temps were crazy. 90 degree weather, at 7000 rpms for about 100 miles. Angle grinder to the hood! I'm going to do something better here soon.




Vents I made in my Rx7. No worries about rain. That **** evaporates as soon as it gets in there.

[presure2]

No worries about rain. That **** evaporates as soon as it gets in there

ding ding..ladies and gents..we have a winner.

[Sunny]

Hi,

the engine does not become in danger in front of some water, forget this point

the reason to use vents is to lower the engine bay pressure to get more air through the radiator package, picture 1-3 is not good designed, the airflow break-away edge in front of the vent
has to be higher then the highest vent point
design 4-5 is pretty nice
air is a hard to appraise medium, but i'am sure every designt except of 4-5 has no advantage or a negativ one

the next point is the cars angle of slope, thats affected the vent too
further you should use a area on top of the hood where the air pressure is low, not the front and windshield area

hope it helps

greetz

[czwalga]

Sunny, You can get into a long engineering debate on how to design the vents.


My thing is though, vents no matter how they are designed are better than no vents at low speeds. Most of the overheating that my rx7 would see is sitting in traffic with almost no flow over the radiator because you're not moving. The headers are sitting in there and it's just creating a heat box in the engine bay.

When i'm sitting in traffic I can just see the heat pouring out of my hood. I realize that mine do not have a ridge creating the low pressure, but it does the job in a traffic environment.

[Sunny]

Hi,

absolutly, when it becomes that hot on traffic, the issue is the amount of air that enters through the bonnet is the same amount that not flows over the radiator package where it should cool the engine, escpecially
when you drive hard

when i bought my ST205 i had nearly every time running fans in the city, with pure hot air out of the engine bay
now they nearly never run even in the city, sometimes i check them standing still with the engine on idle a few minuetes

there any some good tips & trick out there to raise the cooling power so cutting the bonnet would be not the first, two of the bests and cheapest are

- raise the water ammount, i drive 1/3 anti freeze and 2/3 water, alcohol has damatically less specific heat capacity and heat transfer against water, no one ever had developed a better fluid to cool agaisnt water
- the hose from the radiator to the water pump is often a problem which pulls together, a hard pipe instead solves that (worst case = 70% less water flow)
(even in the best bleeded engine there will be 200-300cc of air on the pressure side of the pump -> engine, thats the amount the hose pulls together)

possible this can help you get things more under controll

greetz

This post has been edited by Sunny: Jun 17, 2013 - 11:42 AM

[Box]

No worries about rain. That **** evaporates as soon as it gets in there

ding ding..ladies and gents..we have a winner.

I'm not entirely sure on that one. During a heavy downpour standing still it may be too much for the ambient temperature in the engine bay to evaporate. Also I'm sure czwalga's beast of a RX7 radiates much more heat than a stock 7A.

This post has been edited by Box: Jun 17, 2013 - 1:09 PM

[richee3]

Mine and njccmd's BEAMS still get rained on with our GT4 hoods.

[Box]

My main concern would be water hitting an exposed exhaust manifold/header. Aside from that you should be ok. Also richee, don't you mean your girlfriend's BEAMS?

[richee3]

My main concern would be water hitting an exposed exhaust manifold/header. Aside from that you should be ok. Also richee, don't you mean your girlfriend's BEAMS?

No, it's mine. The car was mine, sold it to her (that's how we met,) I put a bunch of money and work into it, then I bought her a 350Z and reclaimed the Celica. My sig only reflects whose names are on the titles. She owns the chassis, I own literally everything attached to the shell. I've replaced virtually everything inside and outside the car since selling it. But anyway, my point still stands, an NA engine bay doesn't get hot enough to evaporate the rain water immediately. Both mine and Noberto's beat shields are developing rust from rain water. I've been meaning to fabricate a new drain pan to cover my main vent but I haven't touched the car in too long.

[Box]

If that helps you sleep at night. Hmm, sand down the shield and paint in high temp paint.

[mgnt232]

Ok I moved so havent been able to get online.
I have a 3s in the car im going to do the hood on. I was really only worried about water ending up on the hot turbo (i can only assume that is bad lol)
As far as the "performance" based tip you were giving, I wasnt real concerned about that, just ascetically pleasing to me lol.
Most likely going for the first one.
I will try to figure out a draining system too.
And as its going to be my daily and I dont have access to a garage Im just worried about down pours when its parked and the speed limit on base is 20mph. As well as it will be parked for 9 months while I'm in the sandbox so I dont want it just getting rusted all out.
How much water isnt caught by the gt4 hood system?

[richee3]

Picture courtesy of BonzaiCelica:



This tray catches the rain through the main vent and diverts it down, dropping it on top of the radiator. Here is a custom vent made by delusionz:



You could very easily emulate/modify delusionz' design for your hood vents.

[Box]

Ok I moved so havent been able to get online.
I have a 3s in the car im going to do the hood on. I was really only worried about water ending up on the hot turbo (i can only assume that is bad lol)
As far as the "performance" based tip you were giving, I wasnt real concerned about that, just ascetically pleasing to me lol.
Most likely going for the first one.
I will try to figure out a draining system too.
And as its going to be my daily and I dont have access to a garage Im just worried about down pours when its parked and the speed limit on base is 20mph. As well as it will be parked for 9 months while I'm in the sandbox so I dont want it just getting rusted all out.
How much water isnt caught by the gt4 hood system?

I'd just model something similar to the GT-Four, maybe add some vents off to the side out of the way of anything that could be hurt by water. Yeah, cold water on a hot turbo housing couldn't be a good match.

[Sunny]

Hi,

there is no porblem for the turbo by the rain even for the exhaust manifold, further more there is a heat sheald above the turbo, i drive years with open hood and know people they kicked that oem cover
out in 1995 when they bought the car without problems, just a excessive amount of water on the hot turbo can make it cracking/damaging, note that your car is built for the environment it gets driven

the air vent of the ST205 is a aerodynamical disaster, the break awai edge in front of the opening is just high enough to cover the 1/3, in the second and 3rd air enters the engine bay
-> bad -> the preassure raises and lowers the air flow through the radiators

i built a custom vent which copys the lancer EVO style








the empirical formula for such break away edges is 1cm high covers 10cm in lengh, and just for the peaople who are interested in such things, this is also possible on the undertray of the car


this was just the first version , currently the edges are angled 45°







greetz

[mgnt232]

ok thanks for the pics, thats what I needed.
I will design something similar to delusionz, but I want the look of being able to see in the bay on nice days.
I think I am going to put my drain pans on hinges. So I can fold them back underneath the hood on nice days, and if its going to rain or sit there a while, fold the pans back under the vents.
I think its a pretty good idea, going to take some time to figure it all out but i thought it was brilliant lol
Keep suggestions coming always open to changes

Yes i realize this is like a little kid with a crayon but you get the idea lol



This post has been edited by mgnt232: Jun 19, 2013 - 5:11 PM

[mgnt232]

;

[Spider77]

Why does this remind me of this?