Functional 1967 GS hood scoops on a 1965 Buick?

[elagache]

Dear mid-60s Buick owners who are open to "mods" that are functional improvement,

It has been known for probably decades that you can back-fit the decorative 1967 GS hood scoops on a 1965 Buick A-body.  Here is a few examples of the modification:



On a silver car:



Finally a front view of the first car:



I assume that mid-60s Buick types either love or hate it depending on their respective bent on originality.  However, the balance of that issue could be shifted if the hood scoops would no longer be decorative but actually serve some purpose.  I have an appointment at a local body shop to have these paint chips repaired on Biquette's driver's side door:




A while back I got my hands on a set of 1967 GS hood scoops that were in tough shape.  However, I had the bezel rechromed and got the nice reproduction inserts.  Here is a picture of what I have right now:



Since I'm having some painting work done, I have to ask myself if I want the hood scoops painted at the same time.  Here is a close-up of the front of the scoop with the bezel:



At the time I bought them, I was looking mostly for the "cool" factor.  However, since then I've lost my taste for hood scoops as pure decoration.  On the other hand, my trusty wagon's engine bay is extremely hot even with the jet hot coating for the headers.  I've already decided that I need to somehow cobble a cowl cold air intake.  Even with that, the top of the engine bay is a furnace.  So the question seems worth asking - could you get any value by making the 1967 GS hood scoops functional?

To solve that problem, I tossed some numbers around.  Here is the front of the steel part of the scoop:



To pull off this stunt, the steel running across the front of the scoop would have to be removed.  Considering the thickness of the steel, that already would be quite a chore.  Fortunately, you can do mathematics without actually cutting the steel.  The opening is 3/4" x 6"  If you are careful to estimate the area (compensating for the rounded ends) the combined surface area of both scoops is 10.75 inches-square.  So how much air could such a small surface area bring into the top of the engine bay?  Well, at 60 mph if you assume naively that all the air in front of scoops actually gets into the engine bay in a minute it works out to around 300-400 CFM.  That's about 1/10 the output of a radiator fan.  Bringing 10% of the radiator fan's output right at the top of the engine seems worthwhile.  The air temperature just above the engine could be as much as 50-80? warmer than the ambient outside air.  So introducing ambient air at that location should aid in cooling the top of the engine.

Okay that sounds good, but what about that assumption of just getting all that air moving over the hood scoops into the engine bay?  Well, there is a not so small problem with that assumption.  Of course the surface area of the radiator is - a lot larger - than 10.75 inches-square!  Behind the radiator, on my wagon, are two powerful electric fans.  All this should cause the engine bay to be effectively pressurized when driving at freeway speeds.  That air pressure certainly should be sufficient to overwhelm what pressure is generated by the shape of the hoods scoops.  So is this hopeless?

Well one possibility is to fight fan pressure with fan pressure.  They are hard to come by, but you can find small fans that can take engine bay temperatures.  Here is a Spal 4" fan that might work although it is more expensive than I would prefer:

https://webstore.spalusa.com/en-us/product/0697/products/fans/4-fans/30103009/va32-a101-62s-4-p-12v-sum.aspx

I believe I have come across more reasonably priced small fans which could operate in an engine bay, but I'm not having any luck finding them at the moment.  The big idea that I'm pondering at the moment would be to create a sump at the back of where the hood scoop would sit and provide a raised center were the fan would be mounted.  Any water that gets into scoop would fall into the sump were it could be drained away.  The fan would then pull air from the scoop and push it into the engine.  It could be connected to the same circuit that turns on the main radiator fans or perhaps could be left running all the time that the engine is running.  With a fan pulling air through the scoop, it should now provide some benefit on the order of 300 CFM or 10% of the air flow coming from the main radiator fans.

Now in case there was any doubt, I'm feeling way over my head at the moment!     Among other things, I think I would need to replace the present EFI throttle body because it sits too high on the engine.  So I couldn't take on the project of functional 1967 GS hood scoops right now.  Still the idea seems intriguing enough that I think I should simply hold off on painting my hood scoops and see if I could create this more ambitious functional scoop arrangement. 

What do you guys think?  Have I overlooked some sort of obvious problem that is going to derail this sort of a scheme?

A curious mind would like to know!

Cheers, Edouard 

[GS66]

You could get some value out of them letting cooler air in or out from under the hood. You see a lot of Sportwagons out there with added scoops and they look good.

[TrunkMonkey]

I like the look.

Without a wind tunnel, the only input you would have would be after the fact and measuring the temps under same conditions, blocked off and open.

Not knowing the airflow over the front of the hood and if there is boundary layer the keeps airflow from entering the scoops, it is a WAG. But the airflow out the bottom rear of the engine compartment might provide a low pressure conditions and pull air through the scoops.

And you might find that opening from the rear (putting the scoops on backwards) might actually draw air via lower air pressure as it passes over the intermediate of the hood. (in theory, not expecting you to put them on backwards  )

Working on fighter jets, there were many instances of using such devices to work to eliminate heat, gasses and such from engine bays/nacelles.

All that said, the 64-67 hoods are very close in profile and area as well as the shape of the grill area, so it should work about the same as the on the 67.  If folks have made them functional, then you might be happy with them working.

On the '68, I am going to be trying to bring fresh air in the to horizontal slots and duct to the air cleaner, or use air diverters along the bottom of the bumper and see if I can catch enough to make a difference. But that is a ways off.

[Rollaround]

I like the scoops on the 65 hood, helps break up that large flat hood.  TrunkMonky (wish I knew his name) is correct, those scoops would work better if mounted backwards and closer to the high pressure area below the windshield.
You have a lot of mass under that hood and it all makes heat. You might be better off if you could duct outside air directly to the carb inlet.
Boat style bilge blowers will move 300 cfm for about $40   

[TrunkMonkey]

I added my name to the signature, Kevin.

Did not realize I had left it off. :)

[WkillGS]

I think the bigger problem is getting hot air OUT of the engine compartment. Guys used to raise the back of the hood just for that purpose. Even functional fender louvers (or portholes) would let underhood air out. Punching louvers in your hood work work well, but I'm sure you don't want to go that route!

There is a lot of air coming in the front thru the radiator. I have no idea if the engine compartment becomes a bit pressurized at speed, but I would think so. You could test the pressure with a manometer. If there is positive pressure, it's going to be difficult to get cooling air in there, even with some tiny fans.

I wonder if a ducted front spoiler could add cool air to the compartment at speed.  Or those under-bumper ram-air scoops.

I can't see the 67 scoops being able to be much benefit considering their size..... 3/4" x 6" is under 9 sq inches for the pair. (how do you get 10.75 sq in?)

If you seriously want to test your theory.... get a leaf blower, add a shop vac hose to it and duct it under the hood to add cooling air.... kinda like the 'Roadkill' episode where they tried to supercharge their Monza with a pair of leaf blowers!

[GranSportSedan]

with all the air being introduced by the radiator and frontal grill area at even low speed i feel those hood scoops will never serve any noticeable or measurable function.

[Rollaround]

with all the air being introduced by the radiator and frontal grill area at even low speed i feel those hood scoops will never serve any noticeable or measurable function.

But they look cool!

[Mister T]

A few decades ago, I remember reading an article discussing airflow over cars from that era and how effective Ram Air setups really were. Although my memory is not what it once was, the one item that stood out was there's about one inch or so immediately above the sheet metal where air does not move very well. I think it had to do with aerodynamic lift.

I cannot recall the technical name for this effect, but the article's write seemed to believe that most Ram Air setups weren't that effective, especially at lower vehicle speeds. My 71 Mach 1 had Ram Air, called NACA scoops. Their openings were about 5-6 inches wide, and maybe 1 inch high. It created a cool sound when mashing the go pedal, although it was more likely due to the big Holley carb opening wide.

As Walt stated, the bigger issue to me is effectively removing (hot) air from under the hood.

[elagache]

Dear Michael, Kevin, Walt, Bob, Tom, and mid-60s Buick owners who are fans of cool in as many senses of the term as you can get! 

Okay, sorry it was a long post, but many of you are focused on the question of whether or not the scoops would actually work as designed.  I've already given up on that idea.  After all, they are only decorative and as such, they don't provide a lot of surface area.

The big breakthrough was to change from trying to use the scoops directly to using them as an inlet for some powered fans.  Each scoop has an inlet surface area of about 5-3/8 square inches.  I still haven't found the fans I'm really looking for, but these 3" PC case fans might be robust enough to do the job:

https://www.amazon.com/Sunon-High-Performance-Magnetic-Wires/dp/B009BHRZTM

The surface area of a 3" case fan is around 7 square-inches.  That makes the scoop intakes about 25% smaller than the surface area of the fans.  I hope that wouldn't be too much of an additional load on the fans.  These fans are rated 113 CFM.  So compromise and call it 100 CFM but double it since 2 would be needed.  That would bring 200 cubic feet of air into the top of the engine bay every minute.  I just checked the dimensions of the engine bay and they are roughly 4-1/2 by 3 feet.  So the area is probably only about 10 cubic feet of actual air.  Even two small PC case fans would exchanging the air in the top of the engine bay in a fraction of a minute.  Since air is a poor conductor of heat, pushing ambient air into the top of the engine bay should help all the electronics.  I won't do much for the engine, but it won't hurt either.

To make this scheme work I would need to do something like this fellow must have done on this hood that was for sale on eBay some years ago:



To make them functional he - very crudely - cut openings like this:



Obviously, I would insist on a much higher standard of workmanship!  The big idea though is to not simply leave the holes in the hood but instead create a sump that would allow the water the drain, and mount the PC case fan somehow in the sump.  As I am visualizing this I'm imagining a sump with something of the shape of an angel food cake pan - something like this:



Obviously not as deep and rectangular on the outside.  Still there would be a raised center where the fan would be mounted.  That way the fan would be kept away from the water that would drain down into hoses to be eventually dropped harmlessly away from anything I don't want to get dirty.

Making that sump is where I'm stumped right now.  I can visualize exactly what it would have to look like, but I would have a real hard time coming up with a CAD drawing of it.  Even if I had that, how could I turn a computer rendering into a piece of cast or stamped steel?

I'll have to go back to scratching my head! 

Cheers, Edouard 

P.S. So I'm greedy!   I want hood scoops that look "kewl"   and really are cool as well!

[TrunkMonkey]

...

I cannot recall the technical name for this effect,...

Boundary layer.

And speaking of that, several aircraft utilize boundary layer control (BLC)

on the F-4 C/D and Recce, as well as the Navy/Marine F-4B, BLC was "enhanced" by bleed air from the engine's 17th stage turbine, bypassed and vented across the leading top edge of the inboard wing behind the flaps and leading edge of the rear flaps when the flaps were fully extended, and only on the leading edge of the wing at 1/2 flaps.  The hot air flow "moved aft" the boundary layer in effect, increasing the laminar flow above it, since laminar tends to not interact with the boundary layer, but "glides" over.

Sort of like walking, vs walking on a moving sidewalk that is sliding over the same ground.
If you (laminar) walk 5mph, on the moving sidewalk that is going 10mph, (bleed air boundary layer), the net effect is you walking at 15MPH.

That BLC helped keep the boundary layer and the laminar layer from separating and "spoiling" the lift in low speed/high angle of attack (Alpha/AOA) attitude and created more lift and drag at lower speeds allowing for better takeoff and landing on carriers for Navy/Marine pilots, as well as greater load-outs in all services.

This nerdy interlude brought to you by someone who misses the "old times"... 

[TrunkMonkey]

Edouard,

I was typing while you posted.

I think if you create a chamber which sits under the scoop opening and has an incline at the back and then a "step up" of an inch or so as a sump, then a small drain using 1/2 inch hose, and a bit of hardware cloth on the bottom inside of the "sump" to catch leaves, small bugs and the occasional deer entering in the scoops, then transition that to the "tube/fan/tube". (if you can visualize, and if I am understanding your thoughts)

If you want to sketch your ideas, I'll generate a CAD to help in the design/concept for you.

It will take a few back and forth of ideas, as well as input from others.

Let me know. :)

[elagache]

Dear Michael and mid-60 Buick owners who like to think outside of da' box!

If you want to sketch your ideas, I'll generate a CAD to help in the design/concept for you.

Thanks you for your generous offer!     However before I can make any sketches, I need to make up my mind on a few key components and how they would be arranged.  After I wrote my posting, it occurred to me that perhaps I really need to have an automotive grade fan to be sure it would be reliable.  That got me thinking about routing the air from both hood scoops to the back of the engine bay were there would be space to mount a single one of these Spal fans that I mentioned in my original post:

https://webstore.spalusa.com/en-us/product/0697/products/fans/4-fans/30103009/va32-a101-62s-4-p-12v-sum.aspx

The surface area of a 4" fan is only about 5% larger than the combined surface area of the scoops so that would reduce the velocities at the scoops to about the same as the air flowing through the fan itself.

If I go this route then I'm creating something of an HVAC styled ducting from the hood scoops to some point at the back of the hood where the fan would be located.  That provides more space to locate a sump somewhere in the ducting.  However, there is an aesthetic problem that would have to be overcome.  This ducting would be visible, so it would have to be done in a way that was clean and wouldn't detract from the appearance of the engine.

However, there is a prerequisite problem I would need to solve before I could pursue any of this.  The FAST Sportsman throttle body is considerably taller than a carburetor.  As a result, the air cleaner is right up against the top of the hood.  You can see the problem in this picture:



If you look carefully, the air cleaner element is only 2-1/2" instead of the standard 3".  I had to do that to keep the wing nut that secures the air cleaner from doing any more damage to the hood insulation.  If you look at the hood insulation just above the air cleaner, you can see the hole the wing nut cut into it!

This air cleaner already has 1" of drop.  I've never seen any air cleaner with additional drop.  I can't imagine being able to put in any ducting without at least an additional inch of clearance between the hood and the air cleaner.  Any bright ideas on how I could get some additional clearance?

Otherwise this project would have to wait for an EFI upgrade that I'm sure will eventually happen, but doesn't need to happen any time soon.

Thoughts anybody? 

Cheers, Edouard

[TrunkMonkey]

Perhaps run the ducting attached to the hood, at least to the rear of the hood/firewall, and have the duct "nest" above and parallel to the valve covers with enough clearance so they do not contact the covers.

The ducts could be fiberglass formed to allow a different shape (like conformal fuel tanks on the F-15E).

Contoured to the underside of the hood, and like a "belly" that is as wide or narrow as need be, to keeping the cross section as consistent. The air flow really won't care in this application, and the "interface" at the back of the hood to a box, similar to a heater box on the firewall, that exhausts/vents where you choose.

If you did the "box", you could use a blower motor and get 200-250CFM, with a motor designed to run continuously in a hot environment.

Then, paint the ducting to match/blend in, it would be on the underside of the hood, and not detracting to the engine details which you have done so well.

[35chevcoupe]

edouard , does the base of that air cleaner drop down or is it flat across the bottom . from the photo it looks like theres plenty of room for the air cleaner base to drop down further around the edge so you could get a taller air filter element . The aftermarket racing industry has some really nice air cleaners .
Thats one disadvantage about the old factory air cleaners they were very restrictive , especially the bigger CI. engines  .