DIY CAI.... spitballing

sipman · 05-15-2012, 08:38 PM

Hi all,

I've been contemplating a DIY CAI and want to spitball some idea with the forum.

First off, as an owner of CAIs for my others cars, I'm not going to say I'm a disbeliever. But the term Cold Air is a little suspicious to me. I mean, the heat shield will block some radiant heat, but at a dead stop, the intake still sucks in heated air. So the metal barrier that comes with all these aftermarket CAIs may work at slower speeds, but at track speeds, I'd hope there is lots of fresh and cool air rushing around the engine compartment.

I'm trying to put my $$ towards track days, so buying one of the prefabbed CAIs for hundreds of dollars seems like money better spent on tires or pads. But being able to hear the engine from the front as well as the muffler will really help when I'm trying to heel/toe in traffic.

So I thought a great solution would be to buy a K&N cone filter and mount it to the tube leading into the 'Intake Muffler' as BMW lists it. The problem is, the tube is part of the Intake Muffler box, and houses the Mass Air Flow Meter. And cutting the box portion off the Intake Muffler makes little sense, as the replacement cost for an Intake Muffler is about the same price as an aftermarket CAI!

What I'm wondering is if the tube that houses the Mass Airflow sensor is a common size for BMW and it I would be able to substitute anything for this? In my mind's eye, I see two tubes. One large for the cone filter to attach to, and one small, mounted perpendicularly to the larger housing the MAF. Sounds simple? But where to start? Try and make one from PVC or ABS pipes from the Depot? Go to a piping supply house and see if they'll sell me an offcut?

Anyone think harder on this than I have and come up with the reasons why to vs why not to?

sipman · 05-15-2012, 09:14 PM

I might have a solution. K&N doesn't make a kit for this car, but they make a kit for the '01-'05 M3. K&N 69-2001TWK is the model I'm thinking of.

Do you think this would work, minus the heat shield?

seank · 05-15-2012, 10:14 PM

I think its a great platform to work from, as long as you are able to place the sensor in it. You can build whatever box that you want and I know you can make one that increases horse power. Make sure you have high pressure and insulate it from the engine tips.

Let us know how it goes.

BTW. You posting in the FS threads.

OG_M3 · 05-16-2012, 12:06 AM

just gonna leave this here for you:

http://www.zpost.com/forums/showthread.php?t=413915

gferil · 05-16-2012, 11:17 AM

Good luck, can't wait to see what you come up with.

I feel you on the whole "CAI" thing. To this day, oddly enough, I still think the best CAI I ever bought was the IceMan intake for my Acura Integra back in the day. It was overpriced to all hell, but boy did that thing work great. It piped the filter all the way to the lower front bumper for true cold air, and you could even set it up like a normal intake for the rainy seasons if you don't want to risk sucking up water. Maybe my butt dyno was still in development due to young age but I swear it made the car perform better in the high end and sounded awesome as well!

Oh the days of simple "tuning"...hahah...

05-15-2012, 08:38 PM	#1
sipman Private First Class 19 Rep 196 Posts Drives: 2007 Z4MC Join Date: Jan 2010 Location: Philly iTrader: (1)	DIY CAI.... spitballing Hi all, I've been contemplating a DIY CAI and want to spitball some idea with the forum. First off, as an owner of CAIs for my others cars, I'm not going to say I'm a disbeliever. But the term Cold Air is a little suspicious to me. I mean, the heat shield will block some radiant heat, but at a dead stop, the intake still sucks in heated air. So the metal barrier that comes with all these aftermarket CAIs may work at slower speeds, but at track speeds, I'd hope there is lots of fresh and cool air rushing around the engine compartment. I'm trying to put my $$ towards track days, so buying one of the prefabbed CAIs for hundreds of dollars seems like money better spent on tires or pads. But being able to hear the engine from the front as well as the muffler will really help when I'm trying to heel/toe in traffic. So I thought a great solution would be to buy a K&N cone filter and mount it to the tube leading into the 'Intake Muffler' as BMW lists it. The problem is, the tube is part of the Intake Muffler box, and houses the Mass Air Flow Meter. And cutting the box portion off the Intake Muffler makes little sense, as the replacement cost for an Intake Muffler is about the same price as an aftermarket CAI! What I'm wondering is if the tube that houses the Mass Airflow sensor is a common size for BMW and it I would be able to substitute anything for this? In my mind's eye, I see two tubes. One large for the cone filter to attach to, and one small, mounted perpendicularly to the larger housing the MAF. Sounds simple? But where to start? Try and make one from PVC or ABS pipes from the Depot? Go to a piping supply house and see if they'll sell me an offcut? Anyone think harder on this than I have and come up with the reasons why to vs why not to? __________________
	Appreciate 0 Tweet Quote

05-15-2012, 09:14 PM	#2
sipman Private First Class 19 Rep 196 Posts Drives: 2007 Z4MC Join Date: Jan 2010 Location: Philly iTrader: (1)	I might have a solution. K&N doesn't make a kit for this car, but they make a kit for the '01-'05 M3. K&N 69-2001TWK is the model I'm thinking of. Do you think this would work, minus the heat shield? __________________
	Appreciate 0 Quote

05-15-2012, 10:14 PM	#3
seank enthusiast 48 Rep 1,695 Posts Drives: e30 m3,e90 wagon,sprinter,z4m Join Date: Dec 2011 Location: sacramento, ca iTrader: (4)	I think its a great platform to work from, as long as you are able to place the sensor in it. You can build whatever box that you want and I know you can make one that increases horse power. Make sure you have high pressure and insulate it from the engine tips. Let us know how it goes. BTW. You posting in the FS threads.
	Appreciate 0 Quote

05-16-2012, 12:06 AM	#4
OG_M3 First Lieutenant 22 Rep 335 Posts Drives: ae86; z4mc Join Date: Mar 2008 Location: So Cal iTrader: (3) Garage List 2011 BMW M3 [0.00] 2007 BMW Z4MC [0.00] 1985 AE86 [0.00]	just gonna leave this here for you: http://www.zpost.com/forums/showthread.php?t=413915
	Appreciate 0 Quote

05-16-2012, 11:17 AM	#5
gferil Captain 30 Rep 740 Posts Drives: 06 Z4MC Join Date: Dec 2010 Location: San Francisco, CA iTrader: (6)	Good luck, can't wait to see what you come up with. I feel you on the whole "CAI" thing. To this day, oddly enough, I still think the best CAI I ever bought was the IceMan intake for my Acura Integra back in the day. It was overpriced to all hell, but boy did that thing work great. It piped the filter all the way to the lower front bumper for true cold air, and you could even set it up like a normal intake for the rainy seasons if you don't want to risk sucking up water. Maybe my butt dyno was still in development due to young age but I swear it made the car perform better in the high end and sounded awesome as well! Oh the days of simple "tuning"...hahah...
	Appreciate 0 Quote