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Discussion Starter #1
I'd been thinking of making my own custom intake for the R/T based on things I've learned here and some other sites (well... and 30+yrs working with cars).

Something I wanted to incorporate in the design are features to induce / promote laminar flow. I've seen all the "turbinator" swirly flow type junk but I don't think the air would have much swirl left as it snakes through our manifolds (I'm talkin' about the 3.5HO) and finally to the port where the mixture takes place. However, increased charge density through velocity management is a real enough gain.

I had thought of using a venturi set up using two concentric tubes and some honeycomb guides at the ends. The inner, carrying a lightly charged (semi-ram air) and the outer drawing from ambient pressure. Theory being that the inner charge at higher pressure & velocity will create a vacuum (in the larger tube) as it passes through the mixing point and into the TB. I may or may not need a 'tuning bell' to optimize flow on the first prototype (final position / shape would be then rolled into design).

Then I saw this: http://cgi.ebay.com/ebaymotors/Weapon-R-Cold-Air-Intake-Chrysler-300M_W0QQcmdZViewItemQQcategoryZ38634QQitemZ8003067105QQtcZphoto

This uses the concentric tube concept for developing the venturi effect, but they stick to the "swirly is good" tenet, where I'm tempted to stay laminar and allow the venturi to manage velocity / pressure.

Any comments, ideas...
 

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Um, in English please. Just joking. Peva is the one you'd want to alk to on this stuff. He's an engineer and might be able to lend some knowledge. Interesting stuff, though. I haven't heard the word "venturi" since the carburator days!
 

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Somebody else posted about that ebay intake. From looking at their "tests" I'd say if their filter shows increased air flow then it ain't filtering. I'm not suprised to see the K&N show a slight bit less air flow than with no filter at all, indicates to me that its doing what its supposed to do, filter the air.
 

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Discussion Starter #4
Yeah, not too sure how adding a filter (=restriction) adds to the overall flow ?

I see something a little fishy in the 'baseline' test w/3" std tube. The upper and lower plastic tubes on the test rig are equalized via the small tubing and doesn't seem to go to the vacuum gauge like the other tests.

I'm sure the venturi idea would help overall flow / charge density. Another benefit is drawing from two air sources. One being a true cold-air ram (say, in the front fascia) and one from the wheel-well. The cold air would help cool the warmer air charge and if I got water in the ram, the secondary source would breathe free.

Seeing something so close to my idea on ebay tells me either it works or it's f'n snake-oil... or a little of both.

I sorta planted this post looking for the peva and JoeKD types to chirp in.
 

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The only thing i would ? Is that it is made of metal. Which means will get hot and stay hot. And it looks shorter than Joekd's or KN's. And it would be sucking hot air from the motor and the cat right under it. No block off's like KN's have.
 

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SPOOK R/T said:
The only thing i would ? Is that it is made of metal. Which means will get hot and stay hot. And it looks shorter than Joekd's or KN's. And it would be sucking hot air from the motor and the cat right under it. No block off's like KN's have.
Yeah good point. If its metal tubing then there is the high probability of the intake soaking the heat from the exhaust right below it. I guess that's why the intake instructions I've read in the how-to's has a pvc sleeve over the metal tubing, to insulate the tubing from the heat.
 

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Discussion Starter #7 (Edited)
Well, I would hope that the volume and speed of cooler air travelling inside the steel intake tube would more than make up for the hot air soak. Agreed, the location of their filter isn't very good (they show the same pic for every car model but prices are quite different so I'll assume the intakes are somewhat custom fitted by vehicle).

I don't intend to copy this design, I just noticed that it uses some of the features / concepts I'd like to include. I had this notion long before I saw their intake design. I would have the primary intake as a ram-air in the front fascia with the secondary pulling from the wheel-well (with a cover to block engine compartment air). In effect, both sources would be cold air. Let's say the primary is potentially a 'wet' source and the secondary, 'dry'. Hydro-lock is prevented by allowing full flow from the secondary if the primary encounters resistance (as in ponds).

An added thought would be a reed-type check valve on the secondary to prevent the ram-air pressure from backing up through the secondary filter.
 

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The e-bay ad copy gave me the best laugh I've had in a week. Just two examples for your reading pleasure: "...they used psychology to 'convenience' you they are the best..." and "...intake is designed more 'preciously' for the air to move smoothly..." I hope the product is engineered better than the spelling and grammar.
 

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Discussion Starter #9 (Edited)
I talked with some well known OEM engine & fuel engineers that say the 'bells & whistles' on this ebay intake are full-on snake oil.

"If you look at intake systems that are designed for efficiency at one speed, what do you see?
no filter, no funny shapes, one tuned length, reasonably shaped trumpet."
- basically, a velocity stack. Not practical for our cars.

I was told that my conceptual use of a ram-air primary and (check-valved) secondary makes good sense but trying to tune for a venturi effect is pointless.
 
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