Cone fileters on a 3.2 or 3.6

[NoLift911]

Originally posted by thrown_hammer
Jeff, Got any pics?

Yeah I knew that was coming...not yet. I actually was going to produce a do it yourself on the whole dealio of cutting the face off of the box but you know how that goes. I reached for my digital camera and the card was missing

I apologize - I gain so much info from this site and everyone takes time to post pics and stuff, makes me look like a slacker. I will try to get some pics posted soon.

The short answer is I bought a new mondo teeth blade for the table saw and it cut the box like butter. Really fine teet for cutting laminates and paneling. I just used the fence as a guide and off it came..took about 3 minutes. I used 1000 grit paper on my jitterbug sander to smooth out any rough edges and it looks pretty good IMO. Tons of room in the bay now and yes, I can finally get that lower back latch hooked without being a contortionist.

-Jeff
nolift911@hotmail.com

[jthwan22]

I don't have big fingers and I can never snap all 4 clips down on the airbox. Cone filter cure that problem.

[CrossT]

jthwan22

Quite frankly, that is why I got my cone filter. The non-existent performance gain wasn't.

todd
86 cpe

[Steve W]

It seems some guys have noticed a sucking noise when cutting open their airbox cover which I never noticed - and it suddenly dawned on my why. The induction noise comes from air entering the intake mouth at the relatively small bell shaped entry. I didn't think the intake bell was large enough, enough to disturb the laminar airflow and create noises and some restriction. When I modified my airbox, not only did I cut open the airbox cover, but I extended the mouth of the bell shaped intake with Bondo and some wire reinforcement. It looked like a pink doughnut around the intake flare, much like the intake venturi stack on a F1 racing motor. This allows the mouth to draw air smoothly from all the way around the mouth, as much as 180 degrees from the opposite direction of the intake flow. The intake sound was clean to me - no wierd sucking noises, just a nice roar (whaaaa.....) at full throttle past 4000.

[NoLift911]

Interesting observation Steve. I noticed a the huge sucking noise much like a friend's 72T with MFI. I mean litterally with the windows down and sunroof opens it sounds/feels like someone is sucking the air out of your ear drums...borderline painful.

So you cut off the face of your box and then modded the internal piece that guids the air behind the filter? Have any pics of this?

Not sure if the induced intake roar from the box being cut open is better then the quieter flow that I used to have...seems like it is better but who knows for sure? My take was the swiss cheese method disrupts airflow more but then I read another article that said a few well placed 2 inch holes are better than no cover at all? Who knows? I took the gamble, air box lids are cheap.

-Jeff
nolift911@hotmail.com

[Steve W]

I wish I had a pic of my airbox to show you guys, but that piece is at my parents' home. I did what I did to improve flow by minimizing the restriction at the mouth. The reduction in turbulence is probably why I did not hear any strange sucking noises. My airbox was cut with three large trapezoidal holes. I think a bunch of small holes is more restrictive and bound to make some strange noises which could resonate within. Later I switched to a Broadfoot Racing cone intake which sounded also the same, no strange noises. But then I also put on a MAF with a big bell mouth intake and still no strange noises to me. But then, what is noise to others is music to me, so who knows. Or perhaps my hearing is shot from all the loud music I have been exposed to over the years.

[Jarrett88]

Just make your own adapter plate for a cone filter. I saw that they were charging like 200 bucks for a adapter with filter for my 88 3.2L, just took some spare plate metal trasfered the openings for the gasket onto the metal then drilled a couple holes, including a 3" hole w/a bimetal hole saw for the filter then welded a small section of 3" exhaust pipe that i got for free from a exhaust shop, went out and put on a cone filter i picked up from a local parts store, $25 bucks for the filter and an hour later i had a new filter and adapter. I did this because my original filter housing had cracks in it after the K&N that was mounted in it. Resulted in odd ball power surges under full throttle acceleration. The new system definately adds a quicker snap to the throttle.

[greglepore]

Almost all the autoparts chains now have a flat plate with the appropriate (3in?) flange-if you need to modify the bolt pattern, have at it. Or pay some high dollars to MSDS or Powerhaus or whoever.


They all whistle at certain throttle openings.

[Steve W]

When Bernd Andritzky of BMW was dyno testing some of the chip mappings we were working on, two dyno runs were performed on an U.S. spec 89 Carrera with and without the airbox cover. It was fitted with a Euro premuffler, and the chip was the same on both runs. Here are the results of the two runs. These particular runs were runs #10 and #11 and were 10 minutes apart from each other. The first run, #10 is with the stock airbox cover. The second run is with the cover removed. Comparing the runs shows a 0.7 rwhp loss with the cover removed. But that could be dyno tolerances, or my theory is that the warmer air cycling inside the motor compartment on a static vehicle on a dyno is reducing the hp with the less dense air. On a moving 911, this could be different with the turbulence behind the vehicle drawing cooler air into the engine compartment. With a tail Bernd theorizes that even cooler air denser air may be drawn in. Obviously these were done on a German dyno, and the rwhp #s don't correspond to U.S. dynos, so don't try to compare this to a different dyno. Anyways, here are the two runs:

Run #10 with airbox cover


Run #11 without airbox cover

[Paul Franssen]

Interesting to see these German test-results. Note that, on result no. 11 (with lower bhp figures), the air temperature is 19 (iso 20 on no. 10) and ... the oil temp. is only 16, respectively 17 degrees centigrade. Those are very low oil temperatures! Does that mean they do those full-power tests with a cold engine?? In fact, how can it be that the oil temp. is LOWER on the 2nd test. Just some curious things...

[Steve W]

No Paul, the engine was actually pretty hot, with each run after another in 10 minute increments. The oil temp sensor was just not hooked up and is just measuring ambient air temperture.