Thanks! Brace back on and here are the impressions:

I have to say, the difference with the new hose was dramatic. Moreso than the change after adding just the filters. Response, tip in power, torque, and sound all changed noticeably. Honestly it surprised me and I have a pretty well calibrated Butt. This leads me back to my feeling that the stock boxes are not the weakest link. What is, is the accordion hose and 2.5"ID path. Opening this to 2.75 is a 21% increase in surface area, Volume is increased, flow is smoothed.. There is still a restriction at the stock MAF holders which leads me to believe the additional plenum area the 2.75 provides is significant. Interesting that Nismo has chosen 2.75" tubes for their system. Fuel trims are still in line. I have a feeling there's even more power on the table with the enhanced MAf TUBES. More when I get these done!

Keep the test coming Steve...

I like the idea of using a set up like this rather than the gen 3, not saying theres anything wrong with the gen 3, because that was originally on my mods list. I have since changed my mind simply for the installation of it. I just do not want to remove the front facia at all!

I also like that it looks as if we may be able to get colored 2.75" tubing and filter housings too...

Keep in mind this is a DIY with no intent of offering for commercial sale. I do build CAI's for another brand but those are well established and much simpler. This is just my personal project. Honestly, given the man hours invested, component costs, and fabrication needed to install as you see it, it could not be offered for a reasonable "bolt in" price...You have to "Macgyver" quite a few things which is generally not commercially acceptable. I fabricate on the fly so even duplicating this would be a chore.

Final fit with MAF tubes installed:
http://images49.fotki.com/v1500/phot...MG_1849-vi.jpg

Guess you can put the gen 3 back on the list...lol

Looks great, however I have my reservations about using silicone hoses in intakes. I'm sure it works great, but I remember a while back people were having big issues with silicone tubes collapsing. They have great strength holding pressure, but when you create negative pressure, they dont have the structural rigidity to hold their shape. If you have changing diameters in the piping, that will throw off the MAF readings as the air volume changes...I know its not FI, but still. What are your thoughts about that?

RCZ....There is really not much suction generated. Restriction through a free flow or even a stock box is pretty minimal.. I've measured it on other cars with a Magnehelic gauge. We were always upgrading the rubber intake pipe on the turbo'd Audi's to silicone and never had an issue and they suck a LOT of air.. This silicone has pretty good rigidity. Stick a sock in your filter and you may have an problem....;)

On the MAF: The diameter of the tubing at the MAF determines the velocity of the Air flow over the MAF. The MAF controls the fuel signal with the 02 sensor sending corrective info to the ECU. Since The stock Z runs rich, I am constantly seeing a -9 to 10% correction on the long term (Partial throttle) fuel trims. You can open up that tube "slightly", drop the velocity therefore reducing the MAF signal while upping the volume, and therefore bring the fuel trims closer to 0% where the car will make more power. It's a balancing act to do it right. Trust me, I've done a LOT of experimenting on this with the Audi's and have Hundreds of thousands of test miles on the Tubes I build for them. . Very careful tuning of the pipe diameter can result in real gains as long as you don't go to the extreme of needing to alter the fueling. If you go too big you will need to. Lean cars make more power than fat cars from the fueling perspective. Ideal A/F ratios are around 12.5:1. Z's with a full compliment of exhaust and intake mods still run richer than that per Semtex's dynos (11.8:1 or so). This is why tuning gets more power...It brings the car up to a better A/F ratio for power. Corrections will happen automatically with regular ECU adaptation. The stock MAF tubes are 2.34" in ID. As best as I can determine the Stillens are around 2.37" which is a 2.5% difference in surface area! More air + less fuel = more power. If you want to study up on some of the reasoning, check out my page here:
Modshack | Stage 2 MOFO (BAMM)
My initial Guestimate of a 2.5" ID seems pretty close. Just went out and ran the car for 40 miles and the long term fuel trims seem to average out to 0, + or - a few % points of correction. (BTW, The long term fuel trims or Partial throttle adjustment sets at the 20 mile mark after an ECU reset, then continues to adjust based on input from there on). 0% correction means the ECU is happy with the fuel mix and doesn't have to alter it to bring it into spec. A + number is a lean correction, a Minus is a rich correction. I need to put a few more miles on to see if this LTF % holds in that range. If it goes lean, I'll just cut some tubes a tad smaller.. It's all an experiment at this point...:tup:

Cool, good to know sir thanks.

You have shattered me!

ok..ok.. i'll start off with the group buy list...

1. kdo2milger
2.
3.
4.
5.
6.
7.
etc....

Ya, I'd be in it just for the MAF tube and the rest of hte tubing from the airbox to the intake manifold...too bad you don't plan on producing anymore :(

word is someone is making those air flowing tubes jsut like you did!

:tup: good post, love this project

I know this is a one-off, but do you have any intent on measuring gains on a dyno?

Modshack, Do you think there can be merrit to Takeda's claim of 20 hp because of the size of their inlet tube and mas air sensor tube? It seems larger than Stillen and others.
thanks

I'll do it eventually. I'm designing more for Under the curve driveability than I am for a few HP at RPM's I rarely spend time at.

Hard to say. It looks like they squeeze the pipes at the MAf mount area, but to what internal diameter I don't know. Necking down the pipe and then expanding it again does improve velocity (like a venturi) and could provide some leaning and more power depending on the ID. The placement of the MAF inside the tube will have an effect also as air flow through a tube is faster in the center than it is toward the outside. I'd tend to doubt that 20hp number though..

http://images50.fotki.com/v1528/phot...MG_1844-vi.jpg

That's precisely what I'd be interested in seeing in graphical form; not too concerned with absolute numbers, just the baseline/revised graphs overlayed.