Hello,
I've searched and read most of the posts regarding z-tubes, popchargers, and K&N filters...
I know there is someone out there who has modified their intake box (removed the "powerduct" thus increasing the airbox opening, and added rubber/insulation around just the airbox opening.

I just installed the z-tube and K&N high-flow filter.

My question: WITHOUT taking sound into consideration,
which is better (which is faster): leave the powerduct on the airbox as it comes stock, or remove the powerduct?
I've heard powerduct produces maybe a ram-air effect?
I've heard removing it produces bigger hole thus bigger airflow?

Once and for all, what does the powerduct do for you, and what does removing it do for you?

Again, I don't care about sound/noise/growl, I just care about performance. And without any other mods.

Thanx in advance for your responses.

2004 G35 Coupe 6MT Atlanta

2004 G35coupe 6MT Silver
Roswell, GA.

 

I am taking the same intake route as you.....K&N Drop-In with the z-tube and I am asking the same types of questions.

Right now, I have not seen any dyno-proof of which set-up is better: Power Duct in vs Power Duct removed. I was looking at my stock intake this weekend with an 'Engineering Eye" and was thinking through why it was designed the way it was. It appears that the long, narrow intake above the grill is "assisted" by the Power Duct. What I see as the design is the Power Duct draws air into the airbox and creates a venturi effect to allow more air to be pulled from the the long, narrow intake above the grill. The two working together allow more cold/outside air to be drawn to the surface of the filter than just an open airbox. Venturi's work by forcing the same amount of fluid through a reduced sized opening thus increasing the velocity of the flow. This increased velocity not only allows the air to move faster to the filter surface but also can develop suction to allow more air to be rushed to the filter surface. This additional or make up air is introduced from the long, narrow intake above the grill. The K&N filter is porous enough to allow the increased air flow (both velocity and quantity) through the MAF and into the z-tube. Changing the size of the opening of the power duct could potentially slow the air velocity down and ruin the venturi effect reducing the effectiveness of the system. (Yeah, I am an Engineer by degree....I should have mis-spelled a few words just to prove it.....and this is the way I see that the stock intake was designed). Getting dyno results on any changes from stock would prove whether one set up is better than another. But right now it is hard enough to get Dyno results on any mod except for the two I consider Bibles of this subject which are great Dyno Day results from neffster (with his FLA Dyno Day thread) and DrSifu1 (with his CA Dyno Day thread)....those two compilations of results provide a wealth of information but it will take more of us doing the same thing testing and publishing the results to move the 'sceince' forward as to which set-up is better.

This is the way I see it. I could be wrong.....I gave up being an Engineer for a living because I was too cool and I could make more $$ doing something else.

I thought I'd throw this out there to share my views and see what others thought. Feel free to disagree and dispute.



Memphis
04 G Coupe 6MT | IP | Clear Bra | 15% Tint | Clear Corners |

 

Check out the RAM AIR setup we did, and let us know what you think of it, thanks.

 

Hi,
I live in Roswell ....and have tried many different intake setups and done the dynos to test them. So far, stock airbox with minor alterations is the best (for me)
PM me and I'll tell you what I think.

"I like you.....You remind me of myself when I was young and foolish"