Sizing an intercooler scoop

So, with my intercooler top mounted in the civic, I need to force air into it. Any kind of guidelines to scoop shape and size, or just make it look right? I think I'm going to form the scoop out of aluminum and have it poke through the hood, rather than form a scoop in the hood. Shaker style, except that it won't shake.

As for functionality.... i think Subaru and Toyota had it down pretty good.... Plus, they look decent.

I'm more partial to the more rounded Toyota style (celica alltrac), but that's just me.

early '70s pro stock FTW:

The book I read by cory bell said it needed to be 1/4 the surface area of the cooler. so if your intercooler is 12"X12" the scoop needs to be at least 3"X3" . That is what I remember.

snipes wrote: The book I read by cory bell said it needed to be 1/4 the surface area of the cooler. so if your intercooler is 12"X12" the scoop needs to be at least 3"X3" . That is what I remember.

that's only one-sixteenth the area, ie it takes 16 3x3s to cover a 12x12. but dave's pretty sharp, so with your rule of thumb, i'm sure he can do the math.

If Corky says 1/4, then that sounds pretty good to me. And yeah - it'd be 12 x 3.

Sorry about the math. I am a home builder you would think I could calculate square feet / inches.

snipes wrote: Sorry about the math. I am a home builder you would think I could calculate square feet / inches.

And now I have a mental image of a mock-Stonehenge that's in serious danger of being trampled on by dwarfs.

It also helps if the scoop is above the boundry layer on the hood, so it will get airflow that isn't affected by the flow around the body work. On '70s era cars, the airflow would often separate from the car body as it went around the hood, so a scoop an inch above the hood and towards the front could be in a negative pressure spot. Not sure if separation's as big an issue with the nose on a Honda, but if the opening is within the first couple inches of the leading edge of the hood, it could be.

It almost seems like your best bet for an intercooler scoop if you were having it attached to the engine would be to use something like a cowl induction hood, although I'm having a hard time imagining how you could set up an intercooler to work with that in a typical Honda engine compartment. You'd practically need to fab an upside down manifold to pull that off.

"the area of the intercooler air inlet, when properly positioned in airflow, should be at least 25% of the intercooler's surface area which is normal to the airflow direction."

^^^That's so creepy I can't not look at it!

I just peed a little

DILYSI Dave wrote: Shaker style, except that it won't shake.

Solid engine and trans mounts? If not, it will shake ;)

John Brown wrote:

DILYSI Dave wrote: Shaker style, except that it won't shake.

Solid engine and trans mounts? If not, it will shake ;)

Intercooler is mounted to the body. If you know the underhood of an EF Civic, it's where the battery used to reside, roughly 1" down and parallel to the angle of the hood. The plumbing is connected with silicon couplers, so they should isolate any engine movement, of which there is very little anyway due to poly filled mounts.

I was digging through my scrap pile and the only aluminum I can find that is big enough to make a scoop is some polished treadplate. I haven't decided if a treadplate scoop would be cool or stupid.

Have you thought about feeding the thing via a NACA duct? They have a rather small drag penalty but must be mounted where the boundary layer is thin. Of note a flush mounted / submerged NACA is less efficient than a raised scoop design, but that should be common sense.

Even a Civic's nose will experience separation - the ideal point for a raised scoop will be behind this point, however it should be in front of the localized bubble that forms around the cowl / windshield base as well. Kind of a tricky thing to figure out, but one that's somewhat easily observed by taping wool tufts to the hood and having somebody with a video recorder or camera photograph the thing - preferably from the front & side - as to disrupt the direct airflow as little as possible.

These are two of the setups I've done in the past few months. I do plan on re-checking both of 'em with wool tufts before the finish work takes place. The first one was mainly for additional cooling, as further induction on that motor is...well. It's not needed.

http://images39.fotki.com/v1282/photos/3/316525/6632563/DSC_7250-vi.jpg

This is the one that has an airbox that will be sealing to the underside of the hood and feeding the LS2.

Minimal rise, but it does rise high enough (hopefully...) to stretch slightly above the boundary layer as I actually filled the body line and dropped the area leading up to the scoop by ~1.25", so the opening not only sits above normal height, but the 'floor' was dropped out from under it as well... hopefully it will prove worth the extra effort and verify the thought behind it once checked with wool tufting.

http://images42.fotki.com/v1378/photos/3/316525/6347068/DSC_9338-vi.jpg

http://images45.fotki.com/v1259/photos/3/316525/6347068/DSC_9329-vi.jpg

NACA ducts scream "Science!". It's actually shocking how well they work.

Unless they're turned around backwards to be vents, then they scream "doofus!"

AngryCorvair wrote: early '70s pro stock FTW:

Hmm that actually looks good.

Another dignified style of scoop is like the ones on an AE92 levin, although the opening is small:

http://ae92.00page.com/andrew.html

(also I want that chin spoiler)

If you want to go high-tech, auto-opening scoops can give big openings and good looks at the same time...

Here's an article from Sport Compact Car on how they installed a NACA duct into a carbon fiber hood for their Turbo RSX project and here's one from a human-powered vehicle builder on how he made a NACA duct. The second link includes templates. The original NACA (NASA) papers are here (warning: PDF with LOTS of math)

I built some on the first big FM race car, the Track Dog.

Based on the NACA dimensions, but I had to shorten them to make them fit the headlight covers. It was simply a matter of figuring the shape, cutting the headlight and then building the side panels. Not too hard really.

not to hijack, but the Track Dog was the car that opened my eyes to the possibility that a miata might be the answer.

I could have sworn Corky's book said 40% of the core surface area, but I could be wrong. It's been a while.

The scoop will be in roughly the same place as this one, but larger, with the extra dimensions going toward the center line of the vehicle and the windshield.

Make sure the air has some place to go once it is "scooped" into the hood. Otherwise you won't get the flow through the intercooler you were hoping for.

Dave said: I haven't decided if a treadplate scoop would be cool or stupid.

Yes.

Corrugated tin would be moar awesome. I could make you one 6" wide X 6" deep X 36" tall if you'd like.

OR:

X 6.

OR:

OR:

You could nail a Titmouse to the front to discourage wayward avian critters.

Beer cans! I vote for this!

Speaking of cool cheap ideas like this.... i was at Import Day at Edgewater Park this past summer... and there was a guy with a turbo CRX who's intercooler piping was made out of brake cleaner cans. It was awesome.