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Re: yenko style engine hood flaps, anyone do a template
Posted by: coleslaw31 ()
Date: October 09, 2017 09:48AM

gkellogg Wrote:
-------------------------------------------------------
> I first saw this thread a few years ago and had to
> revive it as I finally found a solution for Yenko
> flap hardware. My local go-to shop devised this
> solution and I'm pretty happy with it. Thought I'd
> put it out there for posterity since there aren't
> a ton of examples out there. Quick disconnect
> fittings attach to one post to hold open and the
> other to hold closed.


Thasts some Purdy mod work! I would even consider doing that just because it is neat.

South Carolina Upstate



68 Monza convertible 140 4spd A/C (coming soon)
66 Corsa coupe 140 4spd

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Re: yenko style engine hood flaps, anyone do a template
Posted by: MattNall ()
Date: October 09, 2017 10:29AM

Has anyone thought of using NACA ducts?





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
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..............................110-PG.................................................Webered-Turbo

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Re: yenko style engine hood flaps, anyone do a template
Posted by: BobV66Vair ()
Date: October 10, 2017 10:03AM

Thanks Marty. This is very helpful. Nice to have science weigh in!

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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Re: yenko style engine hood flaps, anyone do a template
Posted by: American Mel ()
Date: October 10, 2017 12:34PM

MattNall Wrote:
-------------------------------------------------------
> Has anyone thought of using NACA ducts?


Yes.
I have thought about it many times.
I have thought that if I ever get around to doing an all out custom, I would like to do N.A.C.A. ducts high and forward on the sides of the rear fenders.
A position similar to the fake brake cooling scoops on the mustangs.
But, I would feed them directly to the carbs.

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Re: yenko style engine hood flaps, anyone do a template
Posted by: triumphcorvair ()
Date: October 10, 2017 02:42PM

American Mel Wrote:
-------------------------------------------------------
> MattNall Wrote:
> --------------------------------------------------
> -----
> > Has anyone thought of using NACA ducts?
>
>
> Yes.
> I have thought about it many times.
> I have thought that if I ever get around to doing
> an all out custom, I would like to do N.A.C.A.
> ducts high and forward on the sides of the rear
> fenders.
> A position similar to the fake brake cooling
> scoops on the mustangs.
> But, I would feed them directly to the carbs.

Several (?) years ago someone posted here a pic of a customized early model painted lime green with flames. They had fabricated something similar to what Mel had suggested by putting scoops on the top of the outside rear fender to duct air into the carbs. I admit it looked good. Wish I could find the picture.

Darrell McCracken
Huntsville, Texas

65 140 Monza
71 Triumph Bonneville

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Re: yenko style engine hood flaps, anyone do a template
Posted by: BobV66Vair ()
Date: October 10, 2017 03:46PM

Interesting idea to use NACA ducts. Would you use them as brake cooling ducts or engine air ducts?

I can see trying to capture some of that HP air on the rear fenders to supply cold air to the intakes. I wonder what that would do to the cars class for AutoX and road racing?

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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Re: yenko style engine hood flaps, anyone do a template
Posted by: MattNall ()
Date: October 10, 2017 04:12PM

Weare talking engine lids in this topic...

I'm curious as to how they would work without the Tail spoiler / Air dam..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: yenko style engine hood flaps, anyone do a template
Posted by: American Mel ()
Date: October 10, 2017 07:38PM

BobV66Vair Wrote:
-------------------------------------------------------
> Interesting idea to use NACA ducts. Would you use
> them as brake cooling ducts or engine air ducts?
>
> I can see trying to capture some of that HP air on
> the rear fenders to supply cold air to the
> intakes. I wonder what that would do to the cars
> class for AutoX and road racing?


Bob, if you read my entire post you will see that it states, . . . .
"A position similar to the fake brake cooling scoops on the mustangs.
But, I would feed them directly to the carbs."
I am referring to the higher ones like those on the '69 Mach 1, not the lower ones as on the '65's.
As far as how it would be regarded in racing circles, I have no idea, or concern, It would be strictly for my own enjoyment.
.
And now back to our regularly scheduled (un-hijacked) thread, I think N.A.C.A. ducts on the hood itself would also look really good. But you had better design into it a water drain ! ! ! eye popping smiley

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Re: yenko style engine hood flaps, anyone do a template
Posted by: ensys ()
Date: October 10, 2017 09:31PM

This thread is close to being an interesting discussion of real-world aerodynamics. Despite the snide crack, all that is needed is to resist the easy lure of myth and cosmetic issues and to embrace the "science" of aero itself.

The yarn exercise is a simple first step that does well enough to show laminar "flows" at the surface, but one must remember that the true picture is much larger, most notably with regard to pressures at and above the surfaces and the flows that are at least 12" thick around the car.

Of course, the definitve picture can be found in a modern wind tunnel, a data set that is, sadly, difficult to come by. But if one is even a casual observer of such tests done on other vehicles, one can make some educated guesses about flow/pressure behaviors around a vehicle like the Corvair.

Finally, one must be able to distinguish the difference between what works at low to medium speeds (like autocrossing/short-track/street use) from those that provide benefit without greater penalty at long-track/sustained road speeds.

Call it heresy, but the only elements of Fitch's aero mods that produced any beneficial effects in the real world, were the front air dam and the rear spoiler. Those deck flaps, cum air intakes, are an aero nightmare, besides largely failing their primary function, at medium-to-high speeds.

And between the raised inlet and the blocking turbulance-inducing lid, the aptly-named "mobile home" vents are an even worse solution, even if one overlooks their butt-ugly configuration.

Chevy's first approach to feeding the engine was the then tried-and-true deck louvers that employed "suck-back" to separate wet from dry air, but the volume wasn't sufficient and maintenance (when none was needed for a conventional car at the time) was an issue in inclemant weather regions.

Hence the large trough with built-in wet separation that they spudded into the only area big enough for the task. Unfortunately, that point at the base of the back window is a low-pressure area that dilutes the effectiveness as an air intake.

Chevy was right in the first place, as the deck sees a useful level of pressure, but they were too timid to provide the intake area and configuration of moisture mitigation needed for the engine environment. Thus, the primary function of a rain tray is only realized when slow or at rest.

For a good example of this principle in action, one has only to examine the various solutions devised by others, most notably Porsche.

It should be noted that the "drop-thru" method (a simple opening in the deck surface) has one interesting advatage: when in motion, heavy moisture (rain) has, from its mass, a greater momentum, and tends to mostly pass over an opening in the surface, while air is readily drawn in.

So, if I was looking to get more air into the engine room, say in a LM, I would do some cut-outs that avoid the lid's bracing, located from the middle, back toward the tail where the high pressure is most consistant.

And since I would believe that the Factory plenum sufficient to provide cooling, I would, by clever ducting, direct this air toward the hungry combustion intakes.

Just one fellow's $.02 worth...

Keep 'em flying...

S.J.Szabo

From America's
Automobile Heartland

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