GXP Airbox - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Performance, Brainstorming & Tuning Talk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

Reply
 
 
 
Thread Tools Search this Thread
Old 08-15-2007, 09:38 PM   #1
Senior Member
Posts like a 4 Banger
Thread Starter
 
Join Date: Jul 2006
Posts: 127
Thanks: 0
Thanked 0 Times in 0 Posts
2.3 Turbocoupe is on a distinguished road
Default GXP Airbox

After reading this thread discussing the GXP airbox, , I decided to examine the airbox on my GXP and determine specifically what might be done to improve it. After examining the airbox, I felt there were 3 areas that could possibly be improved:

1) The tube that connects the 2 halves of the airbox is on the small side. The ID of the tube is 2 5/16s (about 59mm) at the smallest point. (This was not measured with dial calipers, but with careful checking and rechecking using a cardboard template). Iíd be interested in an expert opinion on whether this size is less than optimal for a 275 horse N/A engine. After removing the air filter lid and the top half of the airbox, the tube can be popped out by simply lifting on it. The tube will come out along with part of the dividing wall. (see the 6th pic posted by ReallyAGXP in the thread referenced above, and youíll see what I mean). At that point you are left with a flat opening that is a little wider at 2.5 inches, and definitely taller. The dividing wall could be further opened up quite a bit more, but if you do that, you wonít be able to return the airbox to stock.

2) The tube that carries air from behind the grill into the airbox is of reasonable size. So normally that would not concern me. However, Iím not thrilled about the fact that ití* up there pretty close to the headlight, and the headlamp harness is hanging down right in front of it. I pushed the harness aside, but Iím sure ití* back.

3) As mentioned in the previous thread, the accordion tube that connects the MAF to the TB has huge ribs that are not great for flow. It does need to be very flexible to accommodate engine movement. I may try to see if I can find a flexible inlet hose that might flow a little better.

So anyway, because ití* so easy, I popped out the tube the other day, and have been driving without it. I really canít say for sure if the car is any faster. It feels a bit stronger, but I have to wonder if thatí* because I want to believe ití* quicker. There certiainly does not seem to be any loss in low-end torque since the car lights the tires the same as before. Drives perfectly fine too. But hey, it only takes 15 minutes to pop it out, so someone else try and let me know. Iíd rather not hack up my airbox, but I have a feeling that I am going to give into temptation and cut away the rest of the wall at some point. But I want to do either a dyno or track test stock first so I can find out for certain if there is anything to be gained here.
2.3 Turbocoupe is offline   Reply With Quote
Old 08-15-2007, 11:55 PM   #2
Senior Member
True Car Nut
 
Join Date: Jun 2003
Location: Climax Springs, Missouri
Posts: 2,493
Thanks: 0
Thanked 0 Times in 0 Posts
LittleHoov is on a distinguished road
Default

Why not just fab up some sort of CAI or FWI using some tubing?

It would take a lot of convicing for me to believe that a tube can be outflowed by a box, its just not logical.

Thats why you have a garden hose, not a garden box-like structure.
LittleHoov is offline   Reply With Quote
Old 08-16-2007, 09:00 AM   #3
Senior Member
Posts like a 4 Banger
Thread Starter
 
Join Date: Jul 2006
Posts: 127
Thanks: 0
Thanked 0 Times in 0 Posts
2.3 Turbocoupe is on a distinguished road
Default

I may fab up a CAI at some point, and I did do that on my older vehicle. But this is a newer car still under warrantee. My main concern is relocating the PCM since it resides inside the airbox and is cooled by the inlet air. I want 100% rock solid reliability for this vehicle for now. But I would like to know what others have done with the computer when they went to a CAI.
2.3 Turbocoupe is offline   Reply With Quote
Old 08-16-2007, 09:42 AM   #4
Junior Member
Posts like a Ricer Type-R
 
Join Date: Aug 2002
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
willwren is on a distinguished road
Default

The pcm doesn't need to be cooled, and will have no adverse effects from being left exposed.

There are dozens and dozens of them just like that on this Forum alone, and many more on others. The PCM is weather-proof.
willwren is offline   Reply With Quote
Old 08-16-2007, 11:56 AM   #5
Senior Member
True Car Nut
 
Join Date: Jun 2003
Location: Climax Springs, Missouri
Posts: 2,493
Thanks: 0
Thanked 0 Times in 0 Posts
LittleHoov is on a distinguished road
Default

As for me, I left a slightly modified portion of the bottom piece of my airbox in place, the part that in my application holds the PCM. I did have to do some hacking away on it though, which I would understand if you dont want to do. But you may have enough clearance to run some tubing and keep that portion in place, especially if you go with a CAI over a FWI.

Just do some looking around, take things apart, take measurements, brainstorm, all that good stuff.
LittleHoov is offline   Reply With Quote
Old 08-29-2007, 06:48 PM   #6
Senior Member
Posts like a 4 Banger
Thread Starter
 
Join Date: Jul 2006
Posts: 127
Thanks: 0
Thanked 0 Times in 0 Posts
2.3 Turbocoupe is on a distinguished road
Default

Sure enough, I gave into temptation and cut the right side of the wall out. The car feels a little stronger, but that can be deceiving, and I cannot make any statements about performance gains until such time as I can verify them. I will be able to reinstall the right wall and tube with the help of some silicone to allow for reverse testing.

It is nice to know that I can do a CAI and not worry about the PCM. Gutting for now since it is free and easy.
2.3 Turbocoupe is offline   Reply With Quote
Old 08-29-2007, 07:37 PM   #7
Senior Member
Certified GM nut
 
Join Date: Mar 2007
Location: Yuma, AZ.
Posts: 1,936
Thanks: 0
Thanked 0 Times in 0 Posts
GXP_Vince is on a distinguished road
Default

What did you do exactly can you post some pics?
GXP_Vince is offline   Reply With Quote
Old 08-30-2007, 04:04 PM   #8
Senior Member
Posts like a 4 Banger
Thread Starter
 
Join Date: Jul 2006
Posts: 127
Thanks: 0
Thanked 0 Times in 0 Posts
2.3 Turbocoupe is on a distinguished road
Default

I apologize for not taking pics, the battery in my digital camera was dead. I will try to find time to open it up and take pics at some point. But it is really simple to do this, and there are detailed pics of the airbox in the previous thread. Once you remove the top half of the airbox, ití* all pretty obvious. But here is a step by step guide:

1) loosen the hose clamp where the airbox connects to the MAF.
2) There is a small hose (approximately 2Ē in diameter) that connects to the airbox. It just slides off.
3) Remove the air filter cover by loosening the 2 wing screws, tilting it up, and then pull it toward the fender to release the 2 tabs at the back.
4) This exposes the air filter, but the top half of the airbox is still in place. Loosen the 3 (or 4?) Phillips screws holding it in place, then gently lift the top half of the airbox off. Like the air filter cover, it has tabs that hold it in place on one side, so pull it toward the fender as you remove it to release the tabs.
5) At this point you are staring at the tube that connects the 2 halves of the airbox. Just lift up on both ends and it should easily slip right out, along with part of the wall that separates the 2 halves of the airbox.
6) Optional: With the tube removed, there is a ľĒ hole in the bottom of the airbox where the tab holding the tube snapped out. OCD compelled me to seal it with a dab of RTV. Can you imagine all the hot engine air that ľĒ hole could let in?
7) Now the tube is gone, but youíll see that on either side of where the tube was the remainder of the wall is still in place. I removed the side of the wall closest to the fender. Ití* pretty tight in there. I alternated between a 3Ē cutting wheel on a drill and a dremel cutting wheel on my die grinder. But hey, ití* plastic, so ití* still a piece of cake!

I did not yet bother with the other side of the wall because a) the PCM is still mostly blocking that side even if that part of the wall was gone, and b) air coming from that side of the box is going to have to make a hard turn when it gets to the airbox outlet. And finally c) the size of the original opening through the tube has been increased by a factor of something like 3 or 4, so ití* no longer a bottleneck.
2.3 Turbocoupe is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Went Through The Entire GXP Airbox Assembly Yesterday... 1999Daytona500PaceCar Performance, Brainstorming & Tuning 11 06-16-2006 07:16 PM
GXP/Aurora airbox gut? Custom88 2000-2005 5 05-26-2005 03:29 PM
Little black box next to the airbox Mayhem_3 1992-1999 5 04-02-2003 06:54 PM
Factory Airbox on SC engine iRocco 2000-2005 58 02-10-2003 02:12 AM
Airbox question. Dillon 1992-1999 7 02-06-2003 05:36 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 05:52 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.