maf and throttle body diameter

[Wret]

Originally Posted by Overdrive

BYProvider, since no one seems to want to answer you, I think I may try. That airbox seems to be the one that comes with something like the few CAIs made for the Boxster. It may very well not be, but that's the first thing that comes to mind for me. Hopefully whoever posted the picture will divulge their source if it isn't a custom part.

I believe the air filter box is sold by these guys:
Gemballa USA

I used to make similar air boxes back in my mitsu eclipse tuning days. I invented the original kabob skewer contour guide.

[Homeboy981]

I got it my Cold Airbox to work! I am using ONLY Cold Air and the FULL WIDTH of the side air duct!

The problem the 'other designs' seem to suffer from, IMHO is that they are taking hot air from the top of the engine bay…where it's the hotter than anywhere (due to heat rising). My Stage 2 design suffered horribly from this dilemma. HOT air = BAD, COLD air = GOOD.

This new design (Stage3) employs a simple 'inverted' cone that is inverse of the Cone Air FIlter. Thereby creating an 'air space' the engine can gulp air from. The Stage3 is held in place by the 'friction seal' against the firewall (I will revise this and make tabs to mount). The ONLY SOURCE for air is the 3"X 5" duct - and it uses the WHOLE thing!

Here is a shot of the engine cavity mold, with the Cold Air Intake mold in place.


Here the airbox is sealing out all the hot air (except this post). Yes, that is duct tape, Needed for this prototype but not used in production.


Here airbox is connected to the 4" silicone tubing.


How the airbox seals up against the firewall.


Here is it in place with NO GAP at the firewall.


TDK, you were right! It makes a HUGE difference between taking "engine warmed air" and the cold air our cars were destined to run on.

This is the third revision of the original design. There will be another that will have "rabbit ears" on it to mount in the engine bay. This is by far the largest air filter that will fit under the hood. It can take a HUGE GULP of air, with fewer restrictions than the factory. Inspired by watching Eric523!

If anyone is interested…I have a mold to make more!

[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 !!!!!

[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!

[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

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.

[rhinoman]

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.

This looks like a super neat job and is the step I cant get my head round for my conversion, any chance of a little more explanation on how you did this please.

[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.