@live free & drive - Yep, but first I need to build vents that I can test. At this point, I'm operating on the assumption that it's more a question of sheer air flow volume. As I mentioned, my car currently over-cools so I'm less concerned about the absolute performance of the vents. They just have to work "well enough" to allow for adequate cooling.

If the vent design inhibits or otherwise negatively impacts getting sufficient airflow, then I'll have to look at something else.

For those of you who may get tired of my never ending, iterative approach, apologies. I really am making it up as I go along.

Today, it's all the way back to Square 1. @RetroRacer Tony's design has a far more finished look than the "bend-a-vents". I'd really like to see if I can get closer so I'm going to try and fab a "frame-then-vents" model. I feel like I need to try this, just to see how it turns out.

Here's the initial design. The cut lines are in black, the bend lines are in red. It'll have a .8" frame and I'll bend down the walls. The .5" slits in the walls will be where and how I locate the separately made vents. I THINK I got the calculations right so that once the walls are bent, the locating slits will line up at all the correct angles. We shall see.

And yes, there are a few spots where I'll have to make a piece to connect the wall corners once they are folded into place.

And @AZBanks - Great minds. You can see I'd already accounted for an attempt to open up the inner wall as much as I can. The issue with simply bending the mesh to close everything off is that, without a wall, I end up with a visible seam in the mesh that has zero chance of looking very good.

I suggest you reduce the width of the "blades" to about 1" or less to improve the visual, which I believe would not significantly adversely affect the air flow.

Trackspec has some interesting looking louver designs:

https://trackspecmotorsports.com/shop-by-part/hood-louvers

I treated myself to a GoPro! Based on the recommendation of @Matty900 Matt, I went with the Hero8 Black. Thanks Matt!
Anyway, I figured I should figure out how to make it work and what better motivator than sticking it on my car and taking them both out for a short test drive. I'm still tweaking the throttle linkage and wanted to give the latest adjustments a try.

A couple things:
- I needed to re-clock one of the fuel line connections and left off the fire wall access panel so when you see me glancing back, I'm just triple checking there are no fuel leaks.
- The back window isn't in the car and the camera is suction cup mounted to the engine lid.
- You'll see the car get a little squirrelly just before I turn back into my lane. There was a damp spot, the clutch is still quite abrupt and I didn't rev match, there's a ton of engine braking and the tires are surely cold. Still, I wasn't expecting that!
- I can't believe how much hair I've lost!

Boy, oh boy, I LOVE that intake roar. All this said, the tune has not yet been updated since the throttle body and bell crank updates so I'm expecting even more improvements once it has another session with the tuner.

And with the GoPro, now when I'm in the shop, I can make those fast-motion videos of everything I do to my car! I know you can't wait for those.


https://www.youtube.com/watch?v=v3JK6xlMMlg

Nice video, car sounds great and one can tell it is going to haul @$$ when you put your foot into it.

What do you think of the gearing with that transmission?

I am smiling ear to ear! Dang, that's got to feel good! Sounds awesome!

That sounded so good. You need to add a passenger seat in that bay for the next time I come over.

It sounds awesome and it's working so well. No wind noise from the camera, only beautiful music!

Sounds and runs great!!!! Congrats! Can't wait to see more video!

The gopro 8 is a great choice!!! Dad and I use a 7B and I have a spare 5B but as I found out at WCR it has horrible wind buffering. I want to try the new 9 if there is a BF deal. One can never have to many gopros

@Mueller Mike - So far, the gearing seems fine. First may be a tad low but until I get a new tune and replace the clutch master cylinder with the smaller bore model, I'm not going to have a much better idea. But I haven't heard any complaints from anyone else with the LS/G86-20 combo.

Oh that tone change when the RPMs climb
ps
Your steering wheel makes me think of Andorians...

Had a few really nice pulls with some sweet, heavy breathing from your exhaust...she sounds like rocket!

Vent testing. Let me start by saying that this isn't yarn. And it's too stiff. But, in typical fashion, it's all I had on hand.
Next, please excuse the horrid belt squeal when the fans come on. @markhoward has been after me to tighten it since the day he and @buddyv Robert helped with the first start.

All that said, it sure seems like there's sufficient airflow as the fans will cycle off after just a bit. And re: the too stiff, you can see the string does bob around nicely, once it's been freed from whatever it was hung up on. Those little vents closest to the corners sure don't seem to do much! But something is likely better than nothing.

Next up: the road test!

https://www.youtube.com/watch?v=Gzp4LucAZTc

Also, the testing is happening with this latest version of the vent.
Changes include adding a notch in the lower, outside corner. This greatly simplifies clearing the area of the support structure where that rubber-nubber height adjuster screws in.
An added bonus is that I can slide the vent that much closer to the headlight opening.
But best update of all? It's al-u-MINI-um!
I used .063 material and it gives the vent just a bit more visual heft, which I prefer. Plus it weighs nothing.

Let's get some wind tunnel time. Someone else scoffed at my comment about the angle of the louvers affecting potential airflow lift or low pressure. It does matter.

Very nice Chris...

Over the top..please slow down, I don't want this thread to end.

For a second I thought you were giving Mark & Robert a test ride.

Click to view attachment


Oscar

Suction the GoPro to the hood, aim it at the vent and off we go. This is after the car has warmed up a bit.

And this is the first time I've "floored it". Wheelspin, baby... Hence that slow shift to 2nd. I am on a public road, after all. Back to the vent test:

Before you comment, please note that I actually did this video before the earlier fan test so the string didn't blow back into the positions you see in this video. This is where they started. Again, I'll redo these tests with yarn or some more suitable material.

I'm no aerodynamicist but, does it look like maybe I could use a Gurney flap right at the front of the vent? Non-yarn aside, it seems those lower vents could use some help.

And remember, the car still doesn't have an overheating problem. In fact, that earlier fan test was after this drive, then sitting in the shop, running for another few minutes to even get the fans to come on.

OK, enough from me - let the critiques begin!

https://www.youtube.com/watch?v=U3KUuusPffs

I have to say, this is a pretty momentous occasion for me. Tony @RetroRacer drew up what I think is the best looking H2O cooled 914 vent set up I've ever seen and today, I drove my car with real live versions of his design in place and functioning.
I say "his design" and by that I mean, the closest I could get with my current skill set. I hope I did you proud, my friend.

Tony,
THANK YOU so much for taking time to do that drawing as well as all that time you spent talking with me about all the details. You have added what I think is the key design element in my build.
I owe you BIG TIME.
Thanks again!

Man, I LOVE this forum.

Clearly I am out of my depth. I look at the strings and see the car is moving and they are just blowing with the wind hitting them. How does that show air being drawn from the radiator out of the vents? If you tied string to the same location on the driver's side, would the string not blow around too?

How about a fogger machine you sit in front of the car and turn on to see if the smoke comes out the vents?

OK, never mind, my mom always told me, "Better to remain silent and be thought a fool than to open your mouth and remove all doubt". I never learn.

@Cairo94507 Michael - At some point, I don't really care WHAT'S happening, so long as the cooling system functions well. The litmus test for me is that the car doesn't overheat - and so far, it doesn't. And, any air that's coming through the openings in the nose has nowhere else to go but out these vents.
If there were insufficient airflow while driving, the fans would come on. They don't - until the car sits for a bit. Even then, as demo'd in the earlier video, they cycle off pretty quickly.

These vents were always a styling "form over function" effort and an attempt to avoid cutting the inner fenders. Worst case, if they didn't "work", I could always open up the inner fenders a little at a time until, in combo, things did work. At this point, these sure look like a success.

Yes you are seeing the flow, the one real way to know is with smoke generator in front of the RAD and drive, and see where it leaks out. My guess is it will come out the vents, it almost has too, some might seep out around your seals, and if your separation seal is bad or not in, might come into your cowl area and seep out into the interior.

Other way would be with infrared video look at the temp difference in the airflow, or temp sensors placed all over the car.

A set of vortex generators would work also. Pull the airflow down over the vents.

You are fine if it is working. And if you run into issues, well you can always add ducting to help the airflow go where you need it.

If it becomes and issue you add ducting.

If it really becomes and issue, add a small snowmobile engine and a cooling fan off an M1 Abrams tank, its magnesium so it weights nothing. You will be cleaning the street as you drive. And you will see the trash fly up in front of you so you know it is working as it should.

Chris,
What are the specs on your radiator fans (Dia. CFM, amps)? Apologies in advance if you posted them before.
Thanks,
Andys

Yeah, reverend troublewho is absent?

@andys - I don't know off the top of my head. I have the Renegade set up that I got from them like three/four years back. I think they're like 14". Here's a pic - it's from before everything was done but this it the set up. And no, that's not the shroud top I have on the car now. I made one with no cut outs for "get it running/driving".

Chris - you're very welcome and am just a bit amazed that you followed that scribbled idea all the way down the rabbit hole! As others have stated, this is kind of a confilicted thread: I want to see it continuing with regular and more exciting installments, with photos and monster TIG work, metal shaped, etc; but at the same time I want you to finish the build so I can grab a ride in it!

- Tony

PS. Rear trunk / engine lid design next.....

I liked your idea a few months ago of altering the water pump speed based upon the coolant temperature...scaling as needed in either direction. That had some real teeth but of course, you could not see that - it likely would have just worked.

Not feeling this design but if you are happy with it then that is all that matters. From a functional viewpoint, I don't see anyway that is an improvement for several reasons, over many tried and true venting designs. If you just want to vent your hood differently, so be it. Would it be better on a racetrack at the limit? I think not but also could certainly be wrong...

BTW: Your car sounds great during the front mounted test - great job!

I love the yarn test! It is such a very helpful tool for us home builders. Idk if it was just the stiffness of the "yarn" or that there was not a lot of them in the front of the vent, but the airflow didn't seem to be as robust in front. This may be totally irrelevant if your car stays cool. Yesterday's ambient temperature was 60°

Love the Youtube "build update" snippets Chris
Once warmed up, your engine sounds like a MONSTER
Cheers

Yarn or no Yarn.... Chris's car can eat your car.

Great test!!!!

Here is what I see. The fans come on and show that at 100% airflow through the radiator X amount of movement is shown in the strings. This is at sufficient air speed relative to the radiator to cool it in traffic according to Renegade.

Then, at speeds of what appear to be ~50mph that flow is drastically improved.



Chris here is what I suggest for the next test.

1. Buy an airflow meter.
https://www.amazon.com/Qotone-Anemometer-Wi...0NsaWNrPXRydWU=

2. Test the system with the radiator fans on.

3. Test the system at 50mph in free air flow

4. Test the system at 50mph against the vent. (Gopro and duct tape )


Compare data and draw analysis

I say air going through one vent at 25% free air flow would be significant enough to not require any additional venting.


I would be curious how speed reflects the vent efficiency/ your total airflow efficiency.

Also curious how the vent being open vs having louvers affects airflow.

One could reposition the meter and adjust all the vanes of the louver for optimum efficiency at a specific speed

First attempt at screens only with no walls, just to see what it might look. It's a no-go IMO because, as expected, the corners where the mesh has to meet up at the different angles will never look right. And I'm not a fan of how it looks where the screen meets the hood skin.

So it's back to fabbing some AL walls. In playing around with how to attach the walls, I realized I have to make a couple revisions to the design. It's always something.

If you squint really hard, and imagine it with the lights installed, painted, with the vents finished and everything else in place, all tuned and running well...

Hey, it's what keeps me going.

I think you are just about there. Happy Thanksgiving Chris.

Chris,

Well said. Bottom line; Does it work, and do you like it?

It's times like these that I miss my former stylist/designer neighbor, Mike Williams, who could rattle-off the appropriate aerodynamics and make it look great as well. He designed bodywork for the Can Am Championship winning Shakee Can Am racer, various Indy and exotic car projects, worked at Pontiac and Jeep, and his own design studio. He truly had a gift. I was fortunate enough to work on a few projects with him.

Andys

Earlier I'd mentioned I wanted to try a "straight across" version. Here's the first attempt at the design. I need to update a couple minor things but my first impression is that I kinda like it.

What's nice about this design is that, compared to the previous version, it doesn't require dissection of near as much of the support structure - so much simpler mods to the hood.

And I think I can get away with adding a single strake to better stabilize the vents.

couple more

I almost commented earlier but didn't figure my input mattered. However, since you brought it up....

Notice the curve of the front. And the curve at the top. (of the hood)
I think the curve in the middle should be a variance on that curve. The hood has curves at top and bottom, so I think you should average in between. The design is already there for you to work with!

Visualize the curves and match.
Doesn't have to be a curve as short as they are, but match the angle.


Click to view attachment

@Rand - sorta like on the left?
It was one of the minor design changes I mentioned I wanted to make... Great minds?

You are on it already! But as narrow as they are, it doesn't even need to be as complicated as a curve on that part, just match the angle with a straight cut like the right.

Always admiring your work!!

Really liking this, and it hits what was bugging me before: the arbitrary angles.

This setup looks like it references the lines of the backs of the headlights, which makes it look like it belongs there. See Rand's point, too, but not sure what's more important to pick up—the back of the headlight (closer) or the curve at the back of the hood (farther).

The average inbetween! (that's what I meant by average/variance with the front if it wasn't clear) We are all right / er, correct

@Rand @horizontally-opposed Maybe it's just me but "it looks different in real life".
The current version's upper and lower edges match the headlight cut outs. It looks pretty good (in real life) but depending on where you stand when you look at it, that top edge can feel too straight, regardless of its angle.
You're more than welcome to come by and give it a look-see.

Anyway, I'm sure there will be a few more test versions made before I make a final decision.

Plus, I got some actual yarn! So I'll do a "flow test" on this newest version in the next couple of days.

Some of the earlier photos showed a strong angle, that we commented on. We know you'll do it right.

I kinda like it too. The angled vents looked good in isolation but somehow didn't quite work with the rest of the bonnet/headlight.

Can I suggest another variation to the 'straight across' - how about if the vanes got progressively shallower from front to back i.e. keep the front one the same as now and then gradually reduce them in height until the rear most one is say only half an inch high. Or do it the other way round - small at the front, taller at the back ?
I'd do a sketch but you'd cut the metal and be on the road faster than I can sharpen my pencil.

I have a strong feeling this design will flow significantly more.

The latest updates:
First is the "straight across with a curved top". If you compare this to that last CAD screen grab, you'll notice I ended up lengthening the outer vertical edge. I wanted to make the curve at the top more noticeable. BTW, the radius of that curve is? You guessed it: 91.4"!

I think if I allowed the top edge frame to grow wider as it curves (vs that straight edge) as it moves outward, it might look a little better. Something to play with, at least.

Then came the newest "Shortened 45 degree with curved top".

I made both versions then headed off to start celebrating my lovely wife's "BirthWeek"!

For sure that's far more important than any car stuff, but it means I didn't really look at either of them on the car, beyond taking these pics. I'll need some time with them before any next move but my initial reaction is that the straight one gives the car a more "refined" feel vs the 45s "tough guy" look.

I like them both and may just build two hoods and swap them onto the car to suit my mood.

This vent work continues to be a really fun effort. Forget "process of elimination". With me it seems to be "process of evolution", as evidenced by that pile of, oh, let's call them "trial vents" in the background of the last pic. Oh, plus the two randomly sitting on the hood, and some that aren't in the pic...

Whatever it is, I'm enjoying it and feel like I'm getting close. I will say that having tried to turn @Retroracer Tony's sketch into a real part? I now fully understand when there's some really cool design element on a show car and it's pointed out "well, that'll NEVER make it into production...", there's a REALLY good reason why!