maf and throttle body diameter

[ccstud17]

HB; Looks great and trully is a REAL cold air intake!!!!!!

question, Why not give more room between the filter and the engine? Meaning the side of the airbox closest to the engine does not allow a lot of room between filter and airbox wall. wouldnt increasing that gap give the filter potentially more "gulping?" cause as of now you might as well have half a cone since the half in question is trying to suck the airbox wall?

I really hope you understand wtf im trying to say hahah

[KRAM36]

Some pics of my modded 987 intake box using the 986 MAF housing.



I molded the 986 MAF house into the 987 MAF so I can clip it on and off.



Used Honeycomb Airflow Straightener so the MAF sensor gets a better reading.

[Reebuck1]

Nice work KRAM !!!! Much better than my mod. I am trying to feed a 996 3.4
and I still think I need more air flow.

[KRAM36]

Originally Posted by Reebuck1

Nice work KRAM !!!! Much better than my mod. I am trying to feed a 996 3.4
and I still think I need more air flow.

I don't think you have anymore room for larger piping lol. That's tight!

[Reebuck1]

Still have about 1/4 inch left !!!!! MAYBE A 3.6 !!!!!

[KRAM36]

The area I have circled in red in the pic is just a muffler, right?

I'm planning on removing this. Any downside to doing that other then more intake noise?

[Smallblock454]

Hi KRAM36,

this is not a muffler, this is a resonator. And to be exact a Helmholtz resonator. It enhances the acoustic of the engine by reducing oscillations in intake sounds at high rpm. Makes the engine sound more deep and throaty without aggressive peaks at these rpms. Also it optimizes the resonance / air flow. So i would not recommend to remove this part.

Regards from germany
Markus

[KRAM36]

It just seems to me it would be disruptive to the air flow. If it's just there for sound, I don't think removing it would be harmful, actually I think it would be benefit the air flow.

I'm going to get enough deep and throaty sound by adding the 987 air box.

[Smallblock454]

Hi,

no it's not only for sound. It optimizes the air flow at higher rmps. As far as i understand this cooperates with vario cam system, because it works at 5.000 rpms plus. And it influences the air stream velocity. So this is not only a sound designing tool. And please note that the intake system is optimized with this part, and not without this part.

Please take a look at: http://en.wikipedia.org/wiki/Helmholtz_resonance

If you want to remove it, i would recommend to first complete your intake conversion and than do an A/B test with and without. Best would be with an A/B test on a dyno.

[The Radium King]

meh. if it was important enough they would have put it on more cars. they didn't put one on my 2000 S for example. the theory is that (a) better sound, and (b) air racing down the intake slams into closed valves and creates pressure waves that travel back up the intake, potentially interfering with airflow - the muffler attenuates these waves.

EVERYONE removes it. porsche racing removes it. all aftermarket intakes remove it. i suggest you will see negligible, if any power loss, more than offset by the the other gains you will see.

[KRAM36]

Thanks TRK. I was hoping you would post on this.

[Smallblock454]

Continuous VarioCam came with US MY2003 and the 260 HP Boxster S engine. These engines do have the resonator. But just do what you like.

Good luck.

[jaykay]

Originally Posted by KRAM36

Some pics of my modded 987 intake box using the 986 MAF housing.



I molded the 986 MAF house into the 987 MAF so I can clip it on and off.



Used Honeycomb Airflow Straightener so the MAF sensor gets a better reading.

I like your MAF housing....how did you make it fit up to the 987 air box out let flange? Your air box looks like a work of art....What did you do to it. Its the best looking moded 987 one I have seen so far

[jaykay]

My stock 2000 S intake pipe does have a small Helmholtz chamber built into it which I lost upon installing a 74mm TB.

These acoustic devices certainly do have performance enhancing merit. I have seen them in Titanium FI exhaust systems. I would hope that in the case of the Boxster intake pipe that the design intent was a more favourable performance result rather than just a noise reduction effort.

I actually found that I attained better throttle response below 4500 rpm by re-introducing a chamber into the intake tract. I also went from a 3,25" to a 3,0" tract diameter at the same time so perhaps this was the more dominant factor. Anyway this set up seems to work well with the 74mm TB and stock airbox. I measured these effects via 100% throttle position and engine rpm vs. time. Peak HP is a whole other matter!

With the above modifications, I also found that my custom snorkel gave better response above 4K while the stock snorkel slightly improved 3-4K throttle response. Looking at what is termed the "drip tray" on the stock snorkel and the direction of airflow into the side vent, I would guess that the drip tray was actually intended as an airflow director...so I left it on. Sooo if ever I track my Boxster again think I would fit my jaykay snorkel so that I might just pull by that pesky 964 in my run group.....

...yes my air box snorkel tang holes are just about shot!

[The Radium King]

Originally Posted by Smallblock454

Continuous VarioCam came with US MY2003 and the 260 HP Boxster S engine. These engines do have the resonator. But just do what you like.

Good luck.

boxster didn't get variocam+ (continuous variocam) until 2007 (996 got variocam+ in 2002). according to pet, a helmholz chamber was only used on base 986 boxsters; the higher performance 's' models didn't get them *** i stand corrected - my 2000 S did have a small one also!! *** the 987 does have one however it is now located before the maf on the airbox - it is the thing you have to cut off to fit the airbox in the 986. my understanding is that it only has benefits at lower rpm as it contributes to intake pulse tuning; if you can keep it fine, otherwise it is one of the sacrifices you make when building a higher airflow intake.

[KRAM36]

Originally Posted by jaykay

I like your MAF housing....how did you make it fit up to the 987 air box out let flange? Your air box looks like a work of art....What did you do to it. Its the best looking moded 987 one I have seen so far

Thanks. I'm pretty happy with how it came out. I just cut the 987 MAF house, leaving around an inch or more, pulled the wire filter out of it, then used some high strength glue to mount onto the plastic on the 987 MAF house. Filled in the extra area around it with windshield glue. Then I used the plastic iron to melt the 987 MAF house to the 986 MAF house. On the other end I cut the plastic at an angel and use gasket maker to fill that in and coned it to push the air into the 986 MAF house.

[KRAM36]

Originally Posted by jaykay

My stock 2000 S intake pipe does have a small Helmholtz chamber built into it which I lost upon installing a 74mm TB.

These acoustic devices certainly do have performance enhancing merit. I have seen them in Titanium FI exhaust systems. I would hope that in the case of the Boxster intake pipe that the design intent was a more favourable performance result rather than just a noise reduction effort.

I actually found that I attained better throttle response below 4500 rpm by re-introducing a chamber into the intake tract. I also went from a 3,25" to a 3,0" tract diameter at the same time so perhaps this was the more dominant factor. Anyway this set up seems to work well with the 74mm TB and stock airbox. I measured these effects via 100% throttle position and engine rpm vs. time. Peak HP is a whole other matter!

With the above modifications, I also found that my custom snorkel gave better response above 4K while the stock snorkel slightly improved 3-4K throttle response. Looking at what is termed the "drip tray" on the stock snorkel and the direction of airflow into the side vent, I would guess that the drip tray was actually intended as an airflow director...so I left it on. Sooo if ever I track my Boxster again think I would fit my jaykay snorkel so that I might just pull by that pesky 964 in my run group.....

...yes my air box snorkel tang holes are just about shot!

This is making me rethink the removal of the Helmholtz chamber. I'm not sure if I'll have the room to leave it on though. You know how tight it is in there when adding the 997 Distribution T. Tomorrow I start the tear down process. Once I get the 987 air box in, knock sensors, starter replaced, 997 Distribution T and 996 76mm TB installed I'll see what I can figure out.

[jaykay]

Originally Posted by KRAM36

This is making me rethink the removal of the Helmholtz chamber. I'm not sure if I'll have the room to leave it on though. You know how tight it is in there when adding the 997 Distribution T. Tomorrow I start the tear down process. Once I get the 987 air box in, knock sensors, starter replaced, 997 Distribution T and 996 76mm TB installed I'll see what I can figure out.

Keep in mind my experiences are with the stock 986 air box. There are quite a few who have lopped the helmholtz chamber on their 987 box ( you have no choice in order to get it in) and seem to getting great results.....even big bores.

The 987 is a lot of work to end up getting bad throttle response....so didn't do it. There are many that now have reported good stuff....I would like some data but hey..

[KRAM36]

Originally Posted by jaykay

Keep in mind my experiences are with the stock 986 air box. There are quite a few who have lopped the helmholtz chamber on their 987 box ( you have no choice in order to get it in) and seem to getting great results.....even big bores.

The 987 is a lot of work to end up getting bad throttle response....so didn't do it. There are many that now have reported good stuff....I would like some data but hey..

Sorry for the late reply, but that's odd. Got my 987 Air Box, 996 76mm TB, 997 Distribution T and K&N Air Filter installed around 2 or 3 weeks ago. The car has no bad throttle response at all. It's running like a beats right now. Still have my winter tires on which are taller then my summer tires and before on the highway at say 64 mph with the cruise set, the car constantly hunted between 61 to 64 mph. Now she stays right at the speed I set her at. From a stop or rolling, punch to the throttle and she goes like a monster, no hesitation at all.

I couldn't be happier with the air intake mods. I think it put at least 20 hp into the car.

[CraigM]

Finally all in with 150 miles on it! Holy crap what a difference. Feels improved throughout entire range. Traction issues in 1st now, occasionally in 2nd even; 3rd and 4th pull HARD on the freeway compared to how they used to.
No real data on anything, sorry. Best I got for you other than butt dyno is this: there is a strip I always floor it along, doing 50 on the dot by the end of it very consistently before this rework. The 2 times I've done it since, I have been at 60 and 63, and that is feathering the traction issue through 1st, which was not an issue before.

***Thanks so much to everyone in this thread that figured all this out!***

Car is a 2000 2.7 5-speed.

Used a K&N filter (no codes), gold wrapped the airbox (no one will see it, and may keep the incoming air a little cooler, so I went for it), kept MAF where it was but added honeycomb, 996TB, 997 plenum.

Other performance mods are Circuit Werks secondary cat deletes, Baluga Racing exhaust, and TechnoPulley.