spencerific93

Now that I've been on these forums for about 8 or so months, I feel I should probably stop lurking and contribute some content. And this idea I've been pondering for quite a while seems like a good starting point.
After getting my '86 IROC-Z28 a little over a year ago, I've been coming up with nonstop ideas on what to do with it. One of my persisting ideas was taking the stock louver'd hood — which looks awesome but does absolutely nothing for the car's performance — and converting the recesses in which the louvers sit into NACA-style air intakes, with the back cut out to form what almost looks like the nostrils you see on MOPAR cars. Another idea was to duct the air through a set of reversed louvers along much the same path. But with my limited real-world knowledge on cars and more specifically performance upgrades, I have no idea if this design is at all feasible.
One thing I noticed almost right away is that the two intakes would actually sit behind where the air is normally ducted into the TPI unit on my car by around a foot, requiring the air to flow along an "s" shaped path to the engine. Could this possibly negate the effect of a ram-air hood design? More importantly, would this route possibly give my car any better airflow than the stock snorkel intake?
Considering my fabrication skills (and budget) at this point are pretty much null, I was hoping I could get some insight from people who have had similar ideas or have actually worked on this type of thing before I decide to start undertaking this project.
So, what does TGO think? Could this work?

red rock

iTrader: (2)

With enough imagination and time anything is possible. I have a fully functional Ram Air hood on my Camaro. I bought the car with it already on it. I personally don't like the looks of a Ram Air hood on a Camaro and think they look better on the Firebird, with that said, I do like the Ram Air effect. You can browse the photo gallery here on TGO for idea's. The cowl inducted hood is over common, so finding or fabricating a good looking functional hood is your job here on TGO. Lol

Scorpner

iTrader: (4)

There are raised mounting points on the louvered hoods that would make fabricating rear intakes more difficult. There was a metal version around 1984 and an earlier fiberglass version that might be easier to adapt. Probably better for a carb/TBI intake though.

You also might want to consider what happens when it rains. Stock intakes usually have a relief where the water collects and then sometimes a tube to allow it to run off. They also close and redirect intake air as well. There's kind of a system to there to manage different situations.

The S shaped flow path isn't as efficient but it works on the same principle as a cowl intake where the end result is a higher pressure area. Trying to get air back up the entire length of the hood with limited space for ducting might not work too well.

If you increase the amount of intake of air you also want to make sure that the engine isn't running too lean. I don't recall if the TPI compensates for that or not.

spencerific93

red rock:
That is exactly my dilemma. Those ram air hoods look better on the Firebirds and even better on the 4th gens, but they just look out of place on our cars. Thanks for the words of encouragement! I'm actually mocking up a model on SketchUp just to see how it would look. So far, so good.

Scorpner:
If I recall, though, those early hoods have them spaced much closer. I like the general look of the 1985+ louver'd hoods better, and they also keep the stock look. I've thought about how to collect rainwater too, and I have a few ideas that together might solve the problem: a little lip at the entrance, gravity-fed water run-off tubes, things along those lines.
Since the louvers sit roughly over the intake, and since the engine is rather far back for better weight distribution, I'm hoping the ducting wont need to be that long. I was thinking of routing the air out to the sides and around to converge at a t-junction and into the engine, somewhat in the shape of a "c" looking from a bird's eye view. Not only is there's more room there, this would also keep the air cooler than ducting it right over the engine, and it would mean more gradual cornering (I'm not sure if that matters or not). I guess the real only way to tell if this would work would be to build a prototype. Worst case scenario, this project would be a good way to cool off the engine.

Scorpner

iTrader: (4)

Oh, I was thinking of taking the air from the rear in the same way the earlier hoods did. The shape preceding the intake holes would help move the air into the holes giving it some momentum. I'm not sure how you would get pressurized air into it otherwise.

Gradual cornering (without creating turbulence) is around seven degrees in free air iirc. Since it's enclosed that changes things but there would be a lot of friction involved along the walls imo.

Opening it up might be a good way to keep the engine bay cool. This is from a thread showing what looks to be an actual IROC car.
https://www.thirdgen.org/forums/post...351-post4.html

spencerific93

Exactly, using the shape of the louver recesses to create something like a NACA intake. Doing what you showed in the thread you linked to (it looks familiar, I may have read through it before) would be an alternative.
That's what I'm worried about. My cousin, who has a masters in mechanical engineering, told me that I might encounter issues with friction with ducting the pipe in an "s" shape. I'm only a highschool graduate; we never made it into fluid dynamics lol. Oh well, I might just need to do a more traditional ram air hood following the contours of the louvers, then.

Scorpner

iTrader: (4)

Yeah, there are a few things to look at like the momentum of air, and two kinds of resistance. One is pressure and the other surface friction. So the S shape is changing the direction (momentum) twice and the ducting would seem to have a lot of surface area (surface friction), the overall cross sectional area would determine the speed of the airflow and loss through restriction (pressure). Theoretically, there would be a balance of efficiency between the cross sectional area and the amount of surface area, ...then the math comes into play. lol
A lot of automotive aerodynamics ignore that kind of thing though and an example would be the air dam at the bottom for the radiator. It just blocks the air to create a higher pressure area vs. trying to flow air directly into the radiator. Also, a cowl hood takes advantage of the higher pressure area already at the windshield. To add to that is the air coming into the opening is rarely straight on so you might need to take that into account as well.

spencerific93

This would be a great time to have a physics simulator to work with.

Scorpner

iTrader: (4)

Lol, yeah, but the general ideas of the variables involved give you something to think about.

spencerific93

Very true. At any rate, probably not something I'll get to soon. The IROC's got a lot of other things that need attention first. But as soon as they get sorted out, hopefully I can actually try and mock something up.

Scorpner

iTrader: (4)

Yep, keep it fun. Maybe try it on an old hood on the side when you have time, I've done that before. Sorry if I got into too much detail.

spencerific93

No, not at all. I appreciate the feedback!

Dakota W.

One of the things I did to help my old TPI to breathe better was to take the guards out of the bottom of the filter boxes. That wasn't enough for me, so I just flat out gutted the whole bottom of the filter boxes with a grinder. There was a noticeable improvement in throttle response, maybe even horsepower according to the butt dyno. I think NACA ducts on the hood would be pretty cool though.