DanaT

Well,

I have been working (slowly) on a hood vent design.

This is only a portion of what I want to do to the hood. The white paper on the hood would basically be the "hole" with a little bit of additional shaping inside. Of coarse there would be a lip in the front too....

What does everyone think??






-Dana

Chris Prack

Any reason for the odd shape? I assume this is intended to duct the air out of the IC?

I have thought about this but the bracing on the inside of the hood has stopped any real attempt at doing anything more than thinking. Now if you go with CF or FG....

special tool

Dana - Look at this one. Even has the lip in front to make a low-pressure area, so that air can actually escape from under the hood.

ehall

Is you hood not latched in that pic Jim?

DanaT

Yes, I intend to have the lip.

Teh odd shape is because I like the shape and it is basically the same shape (I don't know if the same exact size) as a vent used on a certain type of turbo charged front engined Porsche race car. Thanks to Jason at Paragon, he gave me good enough pictures to model the vent in CAD. It is VERY close to the 968RS shape. There may be some minor radius differences (i used all english radiuses because they are eaier toget tool to cut those radiuses) but other than that it is very close.

However, I cannot exactly dupilcate the internal ducting due to the damn headlights and slightly smaller IC on the 951. There are some internal differences, but I should end up very close.

I could just buy the generic vent, but I just don't want that. This one will be blended and look factory when I am done.


-Dana

special tool

Ehall - yes I closed it just to act like I am hiding something under there.

Dana - The Supra aftermarket has some very nice looking vents you might like.

DanaT

Oh no. I couldn't go with a supra. That would make my car too powerful. I bet if I had a supra vent, I could put down over 1600rwhp....

-Dana

MR951

How 'bout something like this:


It's a reverse scoop on my WRX when I had a front mounted IC on. These things are fiberglass and go for $100.

Rich Sandor

the reason that the 968 turbo S and RS cars had the oval shaped hood vent, was to fit around the bent passenger side intercooler pipe.

for the most effective setup, you need to make a lower half of the vent that basically fits around the cavity directly behind the intercooler (where the airbox would go.. but is now open if you have a MAF/MAP relocated to the HL area) and seal that duct between the intercooler and hood vent.

if you want I can look thru some of my aerodynamics text books and see if they have any equations to find the correct angle and length of the low pressure lip needed in front of the actual vent.

DanaT

Yes the shape has to do with the internal ducting on the 968. This is how the internals were done. However, it won;t work as well with the 951 because of the radiator location and the headlight connector bar. Again, thanks to Jason for this pic.



Yes, you have have a book that has equations nd such for the lip/size angle that would be great. If you could scan and emal the pages it wpould even be better.

Thanks
-Dana

DanaT

PS.

That is one awesome stormtrooper.....

-Dana

z3bra

What about modifying support crossmember that the hood latch is on (i.e. remove it) You might have to keep the headlight bar there and just run it through the duct. It's not the most ideal way admittedly but without seriously reworking things it might be necessary. Other than interfering with the airflow a little it's probably not the worst design compromise in existance. It might require some black paint/powder coat on the bar to keep things looking better from a cosmetic perspective but that's probably a minor concern if you're willing to cut a hole in your hood since keeping things original is out the window at that point.

I was thinking about something along these lines myself so I'm interested to see how this turns out. I wouldn't want to run hood pins, but supposing that the hood latch was changed to two on the outside edges or something to that effect, you'd free up the major obstruction in the area by losing the crossmember it attaches to. Any thoughts as to the structural necessity of this piece? I would think that a flat bar with a piece of webbing on the top and some diagonal braces on the ends would probably be an adequate replacement that would keep enough space available for the ducting. By looking at it it seems that the crossmember is needed to some extent because of the pivot point of the headlight buckets. If you totally removed it the pivot point wouldn't be mounted securely on the inside point and would probably be prone to binding/bending when it moves. Another option would be to have the ducting itself incorporate the structural components. That's probably the most elegant solution but probably also the most expensive/complex to make.

As for airflow, keep in mind you've already got the high pressure pushing air through the IC so it's not going to need that much of a low pressure zone to let the air back out onto the top of the hood. Unless you totally botched the design, it's still going to flow better than the stock design which just pushes it into the engine compartment without much further concern to where the airflow goes other than out toward the bottom of the car with the other air coming in through the radiator and other front openings?

special tool

You don't need a duct under the hood. You have created a low pressure area above - the heat comes BARRELING out. Plus, you will also evacuate excess heat from the radiator without the duct.

testarossa_td

I am sure I am off in some areas...but a basic idea.

Campeck

I think you should flip it around so the (leading edges) would now be trailing edges. like that evo one.