Stock-ish spiral air intake duct

John Larkin

Sublime Master of Turbology
What do you think about this Chuck? I know you are an Aircraft Spruce fan. This looks substantial enough to use for a turbo inlet, yes? Heat tolerance is good, it''s 3" also.

wrote a lot about this some years ago....posts 17 - 20 in thread below...

The "engineering types" say the convoluted tube will have a higher-pressure loss than the same hose with a smooth wall.
I have 2 experiences to share.
1.When doing a dyno test on a TBSS with a convoluted CAI system, the engine appeared slow to get up on the rollers. As a test, we put a short length of smooth tubing in place of the convoluted.
Much better results as in 15 RWHP.
2. I replaced the convoluted drain pipe under my drive.
The search info math revealed a significant increase in flow with a smooth pipe, when using the same parameters.
A call to the local supplier confirmed this.
IMO, I don't use either the convoluted bends or tubing.
On another note, there's considerable discussion as to how much the edges of a pipe will affect airflow, such as intake pipes that don't butt up in the coupling, etc.
Someone with a flow bench would probably help more.....
AnthonyP, thanks. I never read that thread. The CEET is a little more but it is smoother inside though convoluted. Being it is a low pressure draw through for the turbo inlet, I can't imagine it restricting the turbo.
I hear what Chuck is saying...

for my bone stock, untouched, unopened garage queen I was considering using a NOS MAF tube from the shelf vs looking more into what Pete Tomka used for his 4 inch cold air kits. Pete used Aeroduct brand which led me to the aircraft industry, finding sources for both Aeroduct brand and CEET hose.

After finding the aircraft industry hose, I decided to preserve the Flexfab MAF hose I installed in 1992 as NEW for use if I attended a show, use a 3" CEET hose for regular driving around, and keep the NOS hose on the shelf.

CEET hose, and its equivalent, Vena-MTD is double lined meaning the wire reinforcement is sandwiched between the layers just like the factory GM hose made by Flexfab. it works fine.
I'll add...

the reproduction MAF hose sold by some of the Buick vendors and internet retailers is the convoluted hose Chuck referenced. some might remember Tyler's 10 year resto project, his comments re: searching for a stock appearing MAF hose, and that the reproduction seeming for sale everywhere using convoluted hose is not the answer. I believe he eventually found someone willing to give up a NOS spare FlexFab hose for his project.

vacuum cleaner hose, shop exhaust hose, etc, if the term convoluted is not recognized, is not a good choice when a smooth wall, wire reinforced, flexible hose like the OE FlexFab hose is available via the aircraft industry suppliers.

As shown by the Penflex chart provided by Chuck, there are too many frictional losses to airflow when using vacuum cleaner convoluted hose as a stock MAF hose replacement.
I finally got the hose from Aircraft Spruce, it was out of stock for months. Here is the new intake arrangement, before and after. Not dramatic but more stockish. I don't really like the white spiral but that is how it comes. FYI, if it say 3" hose, it's 3", no give. My turbo inlet is 3.125" and it would not stretch, it has a spiral wire that has no give. I had to make some adapters out of 3" exhaust tubing I happened to have a chunk of. Worked out but even those were a struggle to finesse inside the hose for connections. I will likely change out the blue hoses for some black at some point. I only needed one foot of hose so it was a cheap $10 experiment.


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Just make sure it doesn't start to collapse inward , but maybe not with that turbo lol
We used a similar product on a pickup truck/LS app.
On the dyno, the numbers appeared lower than expected.
We pulled the air cleaner off and picked up 5. Unhooked convoluted tubing and picked up an additional 10WHP.
It appeared that the "ribs" in the tube were causing very turbulent air flow.
Maybe we had a "Tornado" device? Some may remember them....
John, R U going to do a dyno session?
No sir. It's a one foot long connector, smooth enough inside that I see no issue. The pro cars always do better with no restrictions of any kind, turbos hanging out the hood or through the grille with an inlet bell. With a MAF and an aircleaner, there is going to be a restriction of some kind no matter what method you use to link it all together. I use the Z06 MAF for better or worse and a 14" K&N that seems fine to me, never noticed being held back. I am not interested in throwing any more pieces at this car, it has gone as far as I plan to take it and it is plenty exciting to drive.