Under valance oil cooler scoop

[KobaltBlau]

Ok, for reference, this is the "right" way to get more air to a cooler on an impact bumper car:

Oil Cooling Upgrade - Yes Again

or you can cut out the headlight bucket.

But I don't really want to cut my stock SC valance. I do not have a front spoiler.

my A/C condenser and protecton bar protrude roughly 1" below the valance. it seems that instead of simply blocking off the bottom with sheet metal, you could fashion some sheetmetal into a scoop right under the valance about 1"x5-6", and attach the back to the lower oil cooler mounts. It would be more vulnerable, but perhaps not that vulnerable since the condenser and bar are down there too.

Anyone tried this and/or think it is a good or dumb idea?

Thanks in advance!

[masraum]

That would probably work pretty well. If you have a lip spoiler then the scoop would be too low, but since you don't you should be OK. Another option would be to get a Carrera valance.

[KobaltBlau]

Thanks, Steve. I think the fogs are pretty useless (where I live anyway), so I'm not sure what I would do with the other hole on a carrera valance; I could also buy another 74-83 valance and cut it, but my car is a rare color so it's a bit of a PITA + $.

[emcon5]

[makaio]

MAn that red car in the link sure looks good

[emcon5]

Originally posted by makaio
MAn that red car in the link sure looks good

I don't know, I alway thought the red cabs looked kind of pimp-ish.

Tom

[KobaltBlau]

Thanks, Tom. So how'z it work?

I.E. temp before, temp after? Are you still running this?

TIA

[emcon5]

I really don't know. It was only on there a few months, when I:

a) put a fan on the cooler
b) installed a chin spoiler that blocked the airflow to the scoop.

I still have it on there, I extended it a bit so it clears the chin spoiler. It drags fairly often, but it is made from cheap sheet aluminum, so it is easy to fix if need be.

I also did this a couple weeks ago:



Tom

[Lukesportsman]

GM once showed at a engineering seminar that a NET was more drag than the actual tailgate on a pickup truck. The individual holes would create venturis and make like a hundred little areas of drag versus just the top 4" wall after air stacks up on the tailgate.

Reason for this statement: Does anyone know what the ideal size/pattern/shape of holes to use to maximize airflow. I know that Jack Olsen quoted a size (>.25") on the other thread and the ss mesh comes in several sizes from racing supply houses. I guess we could reference what the professional race teams use, but do any of you engineers actually know?

Why not install a NACA duct? Just the difficulty or other?

[911pcars]

I don't think NACA ducts work well on a vertical surface. Better to have a leading edge for air to spill into the duct. Even a hole with sharpe edges has issues with air flow. Like the contoured shape of a car body, air must move smoothly lest it be disturbed.

Sherwood

[KobaltBlau]

Thanks, Tom. I was thinking something that boxed right up against the bottom of the valance and sealed on the sides. only useful without a front spoiler, though. I'll probably end up cutting a valance or using a 3.2 valance, but it's good to see alternatives.

Luke:

In this application maximizing airflow is not really a problem. A friend of mine has a rectangular hole cut in his SC valance that is barely over 1/2 the area of the foglight hole on a carrera 3.2, and that is plenty of cooling for the track, with the bottom blocked off. The bumper isn't cut out either.

One big hole would be better than many small holes here, for airflow. However, the holes that Tom has preserve the strength of the valance better.

[klaucke]

Engineers, can someone explain the science behind the NACA duct shape?

[Lukesportsman]

Understanding the smooth thing and realizing the most theories that apply to good port flow would apply to other "holes", where do we take it from here? Is a bigger grid always better than a finer mesh? Should you always use the largest spacing in the grill for the application that you dare do for debri protection? This kind of goes back to an earlier reply of house screen vs. "chicken coupe" size mesh. I always figured that those "new" truck grills with flat ss patterns and holes punched into them would flow terribly. (kind of like pinched tailpipes into a chevy bowtie.....why????)

So this question wasn't so application specific as it was a general ducting/venting question.

[JMPRO]

I also tried the sheet metal scoop under the valance but because my car is lowered and has the spoiler lip i could'nt get the scoop low enough to do any good without scraping the ground every tome i went up a driveway. Thats when i designed this scoop.

[IROC]

Originally posted by klaucke
Engineers, can someone explain the science behind the NACA duct shape?

I don't know the "real" answer to this, but am willing to apply some engineering logic...

I would assume that the NACA duct was created as a way to duct air from the surface of a body to the interior without causing as much drag as having a "scoop" out in the air path. Having said that, if you examine the various cross-sections of the duct (which I have never done, unfortunately), I would bet you'll find that either they are of constant area or slightly decreasing area as you move from the leading edge to the "outlet". The constant area cross section would neither accelerate nor decelerate the air flow (since flow rate = area times velocity) and the decreasing area would slightly increase the velocity which would create a slight negative pressure which might act to draw more air into the inlet of the duct.

Or maybe not. :>)

Mike

[911pcars]

"...Is a bigger grid always better than a finer mesh? Should you always use the largest spacing in the grill for the application that you dare do for debri protection? This kind of goes back to an earlier reply of house screen vs. "chicken coupe" size mesh."

An instructor once pointed out to me (upon sizing up my window screen "air filters" on my hot rod Corvair engine of a number decades ago), that the net air intake area with screening is determined in part by computing the area of the wire mesh and the number of wire strands, then subtracting that from the intake area (I think he was trying to tell me to lose the screens, in a nice way). However, airflow into an engine is a little different than airflow over a skinned surface, but the restriction aspect still applies.

As to what provides better airflow, flat panels with holes versus round wire mesh screens, I'd think there's better airflow characteristics with wire mesh, but probably because the use of wire mesh usually involves larger air intake openings.

Sherwood