<center><img src="http://pictureposter.audiworld.com/711/hiflob4vs3.jpg"></center><p>
candidates should have a stock airbox with a paper element that has fewer than 20k on the odometer. Also only candidates with OEM style O2 sensors and no generic/universals of ANY kind, PERIOD! Prefer fresh/recent sub 50k miles O2 sensors. Sub 40k would be even better!

I've got one tester in town running flawlessly with new OEM sensors and one with generics sensors that throws codes daily but he can't afford to upgrade and I need to find out why these hate generics as well as tired old OEM sensors. The codes in the generic-sensor equipped car go away when key is turned off and back on but I'm not convinced that car is performing as well as it could because every time th CEL comes on it starts to idle a wee bit rougher than it does without the CEL. You can definately "feel" the CEL come on even without benefit of the light that confirms it. This VS puts a LOT more air at a MUCH higher velocity across the MAF sensor wires and will eliminate the need for sensor tip o-rings in EVERY MAF housing I've ever made/offered! But that "may" require a bit more from 02 sensors than they deliver with stock induction system.

And to avoid complications I need this to be a "real deal" B4 and not a C-chassis car with a B4 airbox. It just cannot be a valid test at this point in time if it's done any other way. We'll get to those other cars later but for now I'm trying to eliminate any/all variables that could influence the new VS's efficiency.

One thing I will tell the prospective testers is that you WILL feel this VS compared to it's predecessors and it's a dramatic improvement over all airbox VS's that have gone before. After ECU adaption engine will idle smoother and pull much more aggressively to redline... especially at &amp; above manifold switchover RPM.

I'm getting slightly better performance with these being fitted permanently to the airboxes by "swaging" them into place in the airbox outlet bore but due to cost and logistics am struggling with making that a mandatory option as it ould reuire "exchange units" be offered/sold with accompanying deposits and the quality of airboxes I'm seeing on the used market vary GREATLY as far as physical condition... they are warped, scratched, hairline fractured etc etc. I have to look thru 15-20 airboxes in the salvage yard to find 5 I'm willing to pay for. And that doesn't bode well for any attempt at "what-you-send-is-what-you-get" airbox lid exchange program.

Selected testers are free to use, test and evaluate these and keep them at test-end with my thanks. If a new design is required due to test findings those testers will also receive that free of charge including shipping. And we'll keep doing that til I get it right. But these are pretty damn good even today!

Pic shows old style on left with hi-flow units on right top/bottom.

I will move on to other applications once I have a widely endorsed B4 that is working flawlessy and to eeryone's satisfaction. Does me no good to approach this with any kind of wide-dispersal fitments until the basic platform works

Looks pretty good, willing to divulge trade secrets?
Shucks I've got two B5s in the garage.

<center><img src="http://pictureposter.audiworld.com/711/hiflob4vs2.jpg"></center><p>
comes from this design which stems from reverse-flaring the outlet end to a very specific taper angle degree and length. This is accomplished by swaging the VS into the airbox lid over a mating die that has the exact outlet angle required for smoothest airflow after the VS is installed in the airbox outlet bore. This serves the multi benefit of increasing volume, velocity and simultaneously smoothing the air column flowing thru it as well as locking the VS into the airbox outlet by swaging the aluminum VS outward at a very specific angle and against the airbox oulet bore ID.

Every time I make one of these even in the slightest different configuration to flow-test I have to destroy the VS to remove it from the airbox outlet bore. To-date there are well over 60/70 in my recycle bin!

non modified airbox. Mann paper filter. RS3 MAF. 77K on the ODO or do you mean on the filter?

S3 Maf and hose kit, less than 10k on oem sensors. less than 5k on paper filter.

far less than 20k, however i have just bought a stock air box that i need to install and alleviate my steering/alignment problems

I have an early 95 B4 90 quattro sport. It has an AAH 12V. I have intalled an "s" TB from an A6 Avant. I have also done the DIY 471A MAF conversion and am running an o-ring in there. No CEL's since install 7000 mile ago. Replaced oxygen sensors with bosch 3 wires that I soldered and heat shrinked 10,000 miles ago. New Audi air filter 3,000 miles ago. DIY intake hoses. Running NGK BKUR6ET-10 plugs. Car has 97,000 miles on it. Timing belt service is done. It runs real stong and I would love to be a tester for this VS. I am new to the forum, but have been following it for 5+ years. This is my second AAH 90 Quattro.

and require no soldering/crimping or heat shrink to install. Far far too many issues associated with universal/generic O2 sensors on these cars to be a reliable test platform. The local tester throwing codes is identical to your setup, ie; soldered-in Bosch Universal 3-wire sensors.

Thanks for your offer but at this point in time and to eliminate variables I need one more person using the identical setup that came on the car when new from the factory sensor-wise.

<center><img src="http://ecx.images-amazon.com/images/I/41FSFN8R0ZL._SS500_.jpg"></center><p>...may change. See more detail of Bosch's fix here:

http://www.boschautoparts.com/NR/rdonlyres/31354756-68E6-41BC-B3D4-11E7422EE8DD/0/ConnectSystem.pdf

The above photo &amp; drawing shows Bosch's recent attempt to address what it obviously also recognizes as part of the "Universal" problem. This is their "fix". You can read all about it here; see "BACKGROUND OF THE INVENTION" under " Description:" (it's long):

http://www.freepatentsonline.com/6672900.html

However as...

"...Currently Bosch offers (-only-) 12 different 4 wire sensors and (-only-) 2 different 3 wire sensors to provide the <u>closest</u> (emphasis added) match to OEM sensor performance." (from Bosch's own description of their aftermarket universal heated oxygen sensor program)

...perhaps "closest" still only counts for horse-shoes &amp; hand-grenades?

Mance, If you still need a volunteer, my filter-box is probably still stock enough, my sensors &amp; filter recent enough &amp; I'd like to try it cause my modded V-stack of yours is so similar to your new one! If you read it through (link below), you'll see that no "flat edge cut off its' perimeter" is just what I asked for!

Oh, &amp; I promise not to take a hammer to it till after the trial! You may still have my "ship to" but I am in Canada.<ul><li><a href="http://forums.audiworld.com/showpost.php?p=24019726&postcount=14">my filter-box &amp; modded V-stack...</a></li></ul>

and not the narrow-band our ECUs require. Early-on I tried numerous curved tapered wall configuration VS's and couldn't get within 12% of the flow that a straight tapered wall VS netted me at that location. They were also more turbulent/disruptive across the sensor wires. I did get better flow with a slightly curved tapered recovery sleeve but the airbox outlet positively hated a true radiused "trumpet-curve" VS inlet. I have no idea how/why that is other than perhaps something about the pleated paper filter media contributing to or aggrivating some unknown situation. Certainly wouldn't have cost more to make curved dies than straight walled ones but I just couldn't get them to behave as well or flow as much air at the airbox outlet.

...I'd like to.

tonight at an outdoor venue and probably won't hear from the guy till he gets off work and I'll be long gone by then til midnight or so.

if it makes it that far I would donate my a4 for any testing such as this . newer oem filter less than 2k 15k on o2 sensors S3 maf installed but i have hoses and an sxtb+ to install ... I would remove any of this if needed for testing purposes i know its probly along way away if it even happens but i just thought i would mention this :)

<center><img src="http://www.eurometrix.ws/hbf1.JPG"></center><p>
...largely "straight wall" concept for the Filter-box Exit Velocity Stack vs. the Recovery Sleeve. The former appears to work by:

-increasing the <i>effective</i> entry diameter;
-straightening the air flow; &amp;
-increasing the air speed, which in turn

induces more mass flow.

While the latter may only need Bernoulli's Principal to function, and a simple constant curved wall venturi there, may provide the least restriction.

I think any significant cone wall curve in a V-stack design, may in fact choke off the air speed gain that a shallow angled, straight-walled cone, V-stack provides.

The above photo is Eurometrix's reproduction of the classic Porsche high-butterfly V-stack. Porsche's numerous &amp; apparently successful designs all seem to follow this model.

What I achieved (see photo below) was, in part, really only to eliminate from your original, the two transitions: from rim to cone (the entry); &amp; from cone to tube (the exit). The cone wall proper, now only has a slight curve:

<img src="http://pictureposter.audiworld.com/124134/b4_bucket_.jpg">

I particularly like your new design as you appear to have been able to get the entry-bell turned/rolled back further than I could with your older one (see above).

from TWM Induction:
"The full radius (entry) design is accepted by the performance industry as the best for maximum air flow." This even though they also sell non full-radius types.

They are in effect saying that the full radius type function better than the "shorty" type.


<img src="http://www.twminduction.com/AirHorn/AirHorn.imgs/williams_2.jpg">

An example of their full radius horns above; &amp; below.

<img src="http://www.twminduction.com/AirHorn/AirHorn.imgs/AirHornDimension2.gif">

Below is their <i>non</i> Full Radius "shorty" type:

<img src="http://www.twminduction.com/AirHorn/AirHorn.imgs/AirHornDimension3.gif">


I believe that the best V-stacks may require this -<i>straight</i>- cone wall feature in order to function as the classic designs all seem to share this common characteristic. Perhaps this is the missing feature that caused your curved-wall filter-box exit V-stacks to flow less favourably?

I'd be glad to participate.