maf and throttle body diameter

[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

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.

[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.