My $.02 worth. If your goal is evacuating hot air from the frunk but you're not expecting to need extreme measures, then why not try picking up on the narrow openings in the cowl vent? The ribs closer together could give a more finished look and you may not need the canted vanes to move enough air for the purpose. There are a lot of variations available, including a few canted vanes into the mix.

BTW, do you ever feel like the peanut gallery is just jerking around a cat toy on a stick..........and you're the cat?

I prefer the angled option.

the "straight" version looks a lot like something I see on an appliance . Or venting for a garage.

I am now in the paralysis by analysis phase. I like the angled vents more but think the venting needs to be finer or smaller gaps. Regardless of our thoughts, I know Chris has a great eye for this stuff and it will not only be functional but it will look bitchin' too.

I like the straight vents better but I think they should start straight and then each vent should curve a little more until the last vent matches the curve on the back edge.

Chris, you nailed it earlier: You have to spend some time with these, and let them sit. You'll know what you like.

It's a tricky one, and the first time I've seen hood vents done to a high level besides the usual open rectangle in the middle of the hood (which I do like…for race cars).

As always, very into your craft…

incredible build !!!
Learned things that I apply to my future Builds!
Thanks!!!

Chris,

Perhaps you could extend the panel back a few inches, and angle the inside edge so as to avoid such wide and abrupt trailing edge? It might give the rear edge a more finished look. I think you've still got some room before running into the bulkhead to do so. I think a similar concept was posted somewhere here on 914WORLD before.
Just a thought, FWIW.
BTW, good on you for your willingness to model several iterations to have a look-see and get a feel for how each one looks! Invaluable!
Andys

After seeing the straight across version, my immediate reaction was, like @Cairo94507 Michael's, that the angled version needs more vents. As bold as those larger vents look, they seem a bit out of scale on the car.
And as @buddyv Robert mentioned, the straights have a bit too much of a "home floor heater vent" look. Well, at least this current version does, IMO.

So, how to proceed? Well, I'm going all in on ANGLES! Frankly, it's important to me that I do all I can to honor @Retroracer Tony's original design. Plus, I think they fit the vibe of the build.

So, I spent a bit of time and worked up a new design. The key changes this time are:
- vents went from 45 to 60 degrees
- scaled the vents down to make room for a 7th vent (nature abhors even #s!)
- incorporated the "bend area" design from the straight version

IMO, this last point lends a more finished look to the final product. Compare the bend areas and you'll see that the current angle design is simply twisting a small area that I worry will crack at some point. The new approach leverages what I've seen on the commercially available vent products.

Not only does this seem a safer way to do the bend, it also means the upper edge of the vent moves outward, causing the top corner radii to finish proud of the inner edge of the frame. It just looks more "finished" to me.

Pics of the real one on the car in the next day or so. And if you're asking yourselves "when will this silliness end?", know that I'm wondering the same thing.

Hi @tygaboy , Chris - I like the scale of that much better as well as the changes in angle and shape. I am looking forward to seeing the actual vent on the hood.

Oh! The carnage! But I am happy with the detail I can get with the plasma. There is a bit of minor clean up to do on the underside of some cuts but overall, it's pretty nice.

And the latest, starting with the cut but not yet bent panel.

The plan is that the headlight eyebrows, covers and the vents will be painted black so it'll look different from this, for sure.

Time to sit and look at it.

60 degree angle = approved. Just the slightly redundant triangular hole top left needs attention?

- Tony

@Retroracer Tony the design is nice. Chris I would play with the vane angles a bit, and it will allow you to fill the gaps a bit while still pulling the air out. That will keep it from looking like a grate for my grill. Or a trash receptacle at a cars and coffee.

More angle is not better, need design ideas these are proven in SCCA and NASA. Reduce your angle of attack.

Track Spec Motorsports

Liking the evolution of this—looks more "complete" and "factory" with the recent tweaks. Rand was spot on, looks like. And I remain blown away by your ingenuity, Chris!

Agree that the little triangle needs to be addressed somehow. Not sure how, though...

I agree with Pete & Tony on the little triangle. Other than that, I think you have a design you can now move to the next step on. To get the whole feel we really need to see the hood with two vents installed as well as headlights and eye brows.

Yeah, I wasn't sure about that corner triangle either. But it was on the last design and I was more focused on the new angles, more vents and new bendy approach. So...

The issue for me is that seems like too big an area to just leave plain. Here it is with nothing and on the right, with a little bit of a treatment to lessen the visual weight of the plain corner.

I spoke with Tony @Retroracer and we agreed that this right hand version would be a good next attempt.

Tony reminded me that my yarn test showed the majority of the airflow is at the rear of the vent so opening up that area makes sense. And from a design perspective, if anyone were to notice, the solid area is now a dimensional match to the other corners.

I think before I build another version, I'll paint the headlight eyebrow, cover and current vent black and see how that changes the overall look.

Onward.

The mesh under the triangle may make the triangle less noticeable.
I still think 8 is great;)

I can't help but think those steep angles will create unnecessary turbulence. My gut says less angle will not only look better, but also work better. I also vote for losing the triangle. I think it looks better without.

And I'm still jealous of your plasma table.

We established the top angle. Can the vents match the angle? Don't go crazy with curves on each, just match the curve of the average. Some of the previous angles seemed polar opposite of the direction I was thinking. Vent angles matched to top angle (almost mirror reversed if you can visualize what my words mean... flow flow, same directions flow, vent angles MATCH the curve instead of oppose)...
Oof, bro, you are getting input overload.

Click to view attachment

This is not the design idea, but trying to show the opposite angle that compliments the curves of the hood and front of car.

Click to view attachment

Ugh, altitude sickness. Let's see if this horrible hack makes some sense... angles left to right... See the difference in angle flow??? Opposing vs. complimenting. Don't judge the edit, it's a quick and dirty to show angle differences. Chris would perfect it.

Click to view attachment

Sorry man, lol... You'll sort it.

When I heard the saying "Everyone's a critic", I thought it was a euphemism.

Turns out, it's closer to literal.

I think Rand is on the same general idea I had.
The front vane should be parallel to the front edge. The last/back vane should be effectively parallel to the back edge. Each vane moving front to back should angle a little more to go front the front parallel to the back parallel.

Yes, everyone is a critic and we are all jealous of your skills. We live vicariously through you, don't let us down.

This man does have a point. Or 29~ points, actually.

And yet I take a certain (perverse) pleasure in seeing that pile of vents on the floor of @tygaboy's shop in one of the photos above—as someone is trying something new, and something few of us outside of an actual styling studio can. I'd have bailed out a long time ago and just vented to the wheel wells, but as much as I'm a hot-rodder, I'm a bit of a purist when it comes to factory bodywork.

But it's just a hood.

Kinda like that was "just" a firewall. Rock on, Chris!

2 cents for Free... Lines Lines , everywhere there's Lines

Since I have nothing better to do (!) and am always interested in trying new stuff, I figured "OK, lets' see what the @azbanks and @Rand idea might look like. Rand's big red letter "WRONG" aside..."

The original straight version on the right, the new one on the left.

So, this new one takes the difference in length of the vertical sides and divides that by seven. Starting with the bottom vane, the distance between its "long side" bend point and the same side bend point of the next vane grows by 1/7 the difference. That 1/7 is again added to the previous distance until all vanes are located.

That 2nd pic is a composite of the top edge from each vane (91.4" radius), showing the unique angle of each.

If you think the vanes' top edges should follow the frame's curve, they can't. If they did, once the vanes are bent into position, the upper edge corners would sit higher than the middle, as was pointed out to me by @dr.tim , back on post #2403.

Anyway, there you go. I'm out of material so it'll be a couple days before I cut anything else.

And I'm with @Cairo94507 Michael, I need to get the vents set on both sides and start looking at a more complete front end view.

Here's the composite of the vane top edges.

True, just trying to help you out with design well mine is more proper function.

Your attach angle is too great, I attempted to make a joke about it in hopes it would catch, but fell flat.

This will give you the basics, Aero 101

Add a disrupter in the front, a 90 degree flap I recommend a vortex generator, this creates a negative pressure zone over the vents. Then the Vents will work if they are not also to steep of an angle. This also works best if it is ducted correctly.

In my book sometimes in aero things get ugly before they get better

M1 tank fan I know works

Sorry buddy, no filters.
Every damned time you are on it.
You can feel free to disregard every one of my words. You got this. (I mean, it's what everyone does... just roll)
OH wait.... you'd roll the edges of the vents...

@914forme Stephen - No worries, I got the joke. My comment was simply commenting on all the comments! Of all the stuff I've done to this poor car, I was just surprised at how much input/commentary these vents generated.

In terms of the aero stuff, my "testing" to date indicates there's more than enough airflow to prevent overheating, which is the only actual requirement I have for the vents. I figure if I meet that one, I know they are functionally OK, maybe not ideal, proper or optimized (the use case for this car doesn't require that) and I can focus on aesthetics.

Remember, the title of this chapter of the build is "It's Only a Hood"

And I can't believe it took me this long to recognize where the saying "I'm just venting" comes from!

Carry on...

So been thinking about this, and keep experimenting, but:

Porsche started directing air from the center radiator upward with the 996.2 GT3 RS, something it followed with the 997.1 and 997.2 GT3 and GT2, and then every 991-based GT car since—not to mention the 918 Spyder, Cayman GT4, and new 718 Spyder.

And, in thinking about that, I wonder a) if isn't worth thinking about some advantages when it comes to anti-lift up front, and b) how big does the vent area need to be (I wonder if too big may be a downside both for cooling and for canceling lift). Granted, the center radiator they were venting was pretty small and one of three, but the next question is: how much do you need? Might be worth painting up a hood that can accept your various prototypes and running the car to test coolant temps with the various setups. Maybe you're ten steps ahead on that front.

Then hit the visuals.

Which brought me to another idea: If you don't need huge holes, I wonder if you could create ducts that vent just behind each headlight but don't look much bigger than an oversize headlight gap—maybe with a single vane in there to make their intention clear, and to make them finished looking?

Pete @horizontally-opposed please remember that most of these cars where built with a sanctioning body and its rule books in mind.. And how sanctioning bodies tend to limit your engineering fun is to do things like limit size of opening or even ban certain items that could radically change the overall dynamics of a car.

Fun part of this is trying to figure out a way to make the rules work for you and your build. Maybe that is just me.

@Tygaboy You are correct it will work, it will be fine, it is just not optimal.

Pretty sure homologation cars enable race cars—and/or how much further the race cars can be evolved from that starting point. So the road cars end up "over built" in many ways, such as uprights in the first GT3 RS that could be machined into what the race team wanted, or a firewall that did away with some brackets for the glovebox in the regular 996.2 GT3. As for those bumper-top vents, I suspect the street car's aero was thoroughly optimized for the street else given the stability issues customers are likely to encounter on the autobahn at 190~ mph. Ditto for cooling, as many 996/997/991/981/982 GT cars end up running at Thermal, Bahrain, etc.

In any event, my point in sharing wasn't to steal any fun, but Chris's project and the peanut gallery (including myself among the nuts) got me to thinking about what Porsche Motorsport—with its resources and know-how—has been up to when it comes to venting a central radiator. Iirc, the 996.2 GT3 RS was Porsche's first road car to leverage central radiator cooling to cancel front-end lift. The bumper-top vents weren't big, but the concept proved very effective and they've been enlarging/refining the top vent with each new GT2/GT3/GT4 variant over the last 15 years. The 914 could use a bit of help in this area, so I am wondering if any of the lessons be applied? Not sure what they would/could look like on a 914, but it's fun to think about. Chris's current setup may be the best short of the solution employed on so many 914 race cars.

And perhaps someone here knows aero, and can theorize what Chris's current vents might do when ducted.

Color change makes a huge difference. Note that the headlight cover is just a piece of paper. It's all I had - so sue me... But this is the current thinking on the paint scheme:
black bumpers and that same black on the eyebrows, headlight covers and vents. I think I'll completely fill in the bumper grill openings, too.

I'm going to again state that "these look different in real life." I don't mean that pics don't do them justice. I mean when you can walk around and see them from all the different angles, you get a bit different vibe. At least I do.

@mikey63 Mike stopped by today in his 914 - a BEAUTIFUL slant nose, wonderfully and tastefully modified '73, and he seemed to agree. Mike, feel free to chime in with your perspective?

Next, I'll paint up the existing straight version and see how those look. I really like both styles so do think I'll just go ahead and make two hoods.

The "color" isn't fixing the angle issue...

Just put servos on those babies and all this peanut gallery chatter goes away.

I like the grills and covers black! It blends and softens the look.

Straight and black (insert one-liner here ). This is the "old" straight version that you've seen before, not the new design with the fancy @Rand @azbanks changing vane angles.

So @Cracker Tony, here you go, no angles so shut up. @bbrock , you surely know what's coming: "You're a dick". All in love, my brothers, all in love.

In all seriousness, straight seems a better fit to the look of the car. What came to mind when I was swapping these designs back and forth on the hood then sitting back to see what I thought was that the straight is much "calmer". It draws my eye to that nice top curve where the angled doesn't seem to.

And if you disagree? Screw you, I say! Well, at least until/unless you see it in person, that is. At that point you'll have at least stepped out of the peanut gallery and onto the main floor!

I feel compelled to clarify: That last paragraph is me kidding you. Scheesh, such a serious group...

Anyway, the needed material arrived this afternoon so tomorrow I'll cut a RandAzBanks version and see how that looks. Then it's decision time on making a complete first set and attaching them to get an overall look.

(Have always wanted to use that emoji… )

@Krieger Andy - Totally, right? It made such a difference. You need to find a reason to get to Petaluma. I'd love to hear your opinion once you've seen them live.

That is finally getting there!

All black not helping these old eyes seeing the details. I like where this is heading now. Reduce the angles a bit more and you will have it.

Do I see a small flap in front to generate the low pressure zone over the vents?

Time to move on and let use peanuts critique your next project.

Not to be a dick but I do like the straight version. The angled ones just fight for attention with other design elements. The black also tames them. If you end up going with a dark body color like anthracite, I think they would look great painted to match and would provide more of a subtle badass look. Makes me think of the 935.

I was feeling left out of the peanut gallery, so I'm chiming in as well!

I think the last set of straight ones you posted look the best. I envy your ability to make things in real life -- I just design stuff virtually, but real craftsmanship is so much harder.

Would it be possible to lessen the bend angle of each vane as you move from front to back?

Straight looks even better! How about tomorrow am ? I have two other possible mods for ya!

Oooh booyy brother. The angles are almost there LOL!LOL.

So good.

We can agree that not everyone will agree upon what we should all decide upon, even when it's such a crystal clear decision!!!!

Hey 'yall, or is that Y'all? TonY?

Point is, Chris owns this and is an obvious master of his craft having to deal with all of us...

What I respect is that Chris listens. Through the nonsense, a few good ideas surface. And he can take a sniff here and there... And he always knows how to decipher it to come out with the best answer.

Tony, you should hook him up with a tunnnel.