928ntslow

In continuance of Andrews thread on DR's new intake system got me to thinking. The debate over a "better" intake (naturally aspirated) system has been the topic of conversation for years now. In looking at DR's system, a light popped on in my head.

DR's "coffee filters" are located further up stream of the throttle body. His results show an improvement in HP, which can only be attributed to better airflow or available air on demand. So, it seems he has created a larger area of available transient air to be used and sucked into the throttle body based on the lengthened distance from the filter. So we know that spacers on the intakes help with having more air available for induction, wouldn't it stand to reason that the further forward one locates the air filtration system, the larger the reserve of unobstructed air is available? It's like having a reservoir of air right there ready to use, rather than working hard to pull air through a a thick filter in such a short distance. Get my my point? Thoughts???

mark kibort

doesnt work that way. a "reservoir" of air would only be useful for first fraction of a secont anyway. however, the greatest pressure drop, is due to the restriction of the entire intake system. the reason the large plennums work so well, is that they offer better air flow to the runners to each cylinder. I have tested the lowest pressure drop with our filter boxes with a KN. Ive also used spacers, bell mouthed inlets to our MAFs and large cone filters with bell mouthed internal inlets.

the only gain ive seen with our air boxes, is when the filter is entirely removed. then, only a 5hp gain was seen. not only me, but anderson saw this too.

MK

JEC_31

Data Points:

A) Nearly every attempt to deviate from the OEM intake upstream of the throttle results in slight losses or miniscule gains (which in themselves are not REALLY verifiable due to being smaller than the known variances in chassis dyno measurements) or at best no improvement. This is true for complex new airboxs, cone filters, running filterless, etc.

B) DR's Blackbird design is a breakthough in that it results in measureable power gains.

C) Investigation and experimentation in this "upstream" area is much less expensive than fabbing new intake manifolds for downsteam power gains (although I would like to someday!).


So we are compelled to study the Blackbird.

Twin cone filters another foot or so up from the OEM rectangle filter, which is eliminated but rectangle-to-tube venturi shape is retained. Note that instead of the flat-roofed "plenum" above the rectangle-filter location DR has blended in the twin tubular pipes to large-radii turn-downs into the venturi.

Filters - the necessary restriction if you prefer to not have bugs, sand, gravel, kittens, etc attacking the MAF, throttle plates, valves, and combustion chambers.

The best I can come up with is that the twin cone filters offer less restriction than the rectangle, and the Porsche rectangle-to-venturi still flows so well without a filter right at it's mouth that it amplifies the better flow from the twin turn-downs: and we have the results of (small but measureable) power gains and (claimed) throttle responsiveness.

I think that venturi is the key. It rocks.

John Speake

""Twin cone filters another foot or so up from the OEM rectangle filter, which is eliminated but rectangle-to-tube venturi shape is retained.""

Where is the rectangle shape in this set up ?

JEC_31

I thought the Blackbird ends at the OEM filter mounting spot, which is a black plastic rectangle that funnel/venturi's down to the tube that runs through the V.

Am I mistaken, does DR's kit replace this item?

glork98

Don't overlook the systematic ascpects of performance improvements.

The 928 intake and exhaust systems appear to be well balanced between the capabilities of each portion of the system. Making an improvement in one area, as many have tried, usually results in a disappointing result. This is because the other components are operating at their maximums and a single improvement doesn't change the overall capability. It's the complement of the "weakest link" theory; making one link stronger doesn't improve the chain.

So... It's a neat design but is the rest of the car stock? No exhaust mods or valve timing? Re-mapped ECU?

John Speake

I assumed you had seen a Blackbird system..... I would think the most likely place for DR's system to finish is at the intake flange of the MAF.

JEC_31

OK - Just looked at the pic on 928 Spec's site again - enlarged this time.

Doh! I stand corrected. DR's new plumbing DOES completely replace the lower portion of the rectangular airbox with a new two-into-one venturi/funnel.

So, is it:
A) twin cones
B) new two-into-one venturi/funnel
C) combination thereof
that yields the good results?


Noet the test car (EdMD's) has a few bolt-ons such as X-pipe etc.

IcemanG17

Louies ITB system uses a stock filter foward above under the large carbon fiber intake......heres a pic

Ed MD

Keith, please PM me with your e-mail address. I've taken pictures of the BlackBird but can download them here because the files too big. So I'll send them to you and then you can submit them for everyones perusal.
The first dyno session was in Feb.(60-70 degrees F) adjusting the AFR. At that time I had the X-pipe, with hi-flo cats, RMB. The second was after SITM in June (90+ degrees F) with only change was the installation of the BlackBird. Everything else was left alone. I plan on doing a run measuring A/F ratio, to see how this addition affected it, and then adjust the AFR... and then take it to DR for optimizing with the SharkTuner. Thanks Ed M

mark kibort

intake filter position does nothing.

Take the word "venturi" out of your descriptions, as a venturi will only provide a pressure drop. with the stock design, it was an attempt to lower intake air flow noise. (think restrictor plate, or restrictive intake design

its not proven. we have seen many things increase hp on some cars and losses on others. I did spacers on my car along with a half a dozen other mods, all that lost hp while some of them showed gains on other cars. intake spacers, air box spacers, different filters, sealed filters, etc etc
all have spotty gains and some losses.

mk

Mk

Ed MD

Here's the pictures. In regard to the dyno data, there were 6 runs in Feb. (with the last two done without any adjustments on the AFR, to confirm the numbers), and 5 runs in June, there was less than 5% variation in outcomes reported in SAE. If I have time... I'll try to do runs on the stock S4 with and without the BlackBird, unfortunately I'm quite pressed for free time. Ed

JEC_31

That really is a work of art - and one that works.

Thanks for the pics.

I'm no closer to understanding the airflow dynamics tho.






Perhaps the intersection where the large diameter turn-downs collide promotes some sort of beneficial turbulence? A "swirl", if you will?

928ntslow

Sorry Ed, I was out of town for the weekend. Glad you posted without my help.

Brian, Louie's intake is radically different and he has a heavy breathing motor.

mark kibort

You can have a lot of variation between dyno runs, if you dont control the set up. One of the only ways to really tell if you have any gains with this set up vs the stock air box , is to do 2 -3 runs with this set up, and quickly change to the stock air box and do 3 runs. Often, my strongest runs are 5-6 hp more, with the same set up by run 3. in fact, the last 4 times ive been at the dyno , the 3rd run is always the strongest, and this is starting with a warmed up engine. (ie 320, 325, 328rwhp). now, i could have spit on the hood and said this caused 8hp gain between the first and the last run.

When i was at the dyno for testing of the different air box configurations, i did what was thought to be an optimal set up. a 4" cone filter, with a bell mouthed inlet sticking out of the MAF. IN fact, it was so large that the hood couldnt be shut. net gain , LOSS 5hp. put the stock air box back on, and 5 hp returned. Then, we ran the eRAM on the rear of the stock air box (that is vented to the base of the windshield) this gave us a slight hp gain, but most noticebly, it increased HP to a higher RPM.

NO doubt, this is a very cool looking set up, by I see no aerodynamic reason why it would be any better than a stock airbox. its all about flow efficiency and pressure drops. curves and bends create pressure drops. the bell mouthed inlet creates the most gains in efficiency, which the stock air box has a pretty good one. venting to the rear would probably yeild the greatest gains, even if you didnt want to remove all the base of the windshield equip. just cut a long section out, or even a couple of holes like i have done.

Bottomline, from some fairly extensive testing, the stock air box is pretty hard to beat. In fact, i would buy this set up in a heart beat, if it would be guaranteed to create any gains.
you also have to think about the increased pressure effect of the rear of the air filter sourse that almost equals the front engine air pressure rise, without having to traverse any tubing.

again, it looks great, but i would be willing to bet that it is equal or less than a stock air box with KN.

Next time you go to the dyno, try and make sure you keep as many factors controlled or the same as possble.

mk