Factory Airbox Mod
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Former Vendor
Joined: 06-03-08
Posts: 4,169
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From: Grand Rapids, MI
Factory Airbox Mod
We have been doing dozens of dyno pulls on our new SS/T trying out new parts and tuning in multiple combinations. After trying a few intake mods, I decided to modify the factory airbox. Here is a step by step inexpensive modification if anyone is interested:
The airbox inlet and fenderwell tube are shown here. The ID of the fenderwell tube necks down to about 2.5", and therefore becomes restrictive on high HP setups.
After removing the airbox, notch the plastic as shown:
Next, cut the fenderwell tube just before it starts to bend. Remove the plastic brackets from the tube. I cut all of the bracket off and it left a hole in the tube. You can leave some of the bracket on and avoid the hole. It will still fit fine in the new configuration.
With the airbox back in place, connect the fenderwell tube to the airbox using a 3.25" silicone coupler and 2 clamps.
Completed:
Method #2 without silicone coupler to connect snorkel:
Remove the headlight and then remove the headlight mounting bracket shown here-
Unplug the MAF sensor and remove the airbox lid:
Unbolt and remove the airbox:
Remove the snorkel bracket bolt shown to the right:
With the tire removed, you can more easily access the retainer clip behind the snorkel:
Cut off the long snorkel bracket as shown:
Cut the snorkel just before the first bend and smooth the edges:
Pic showing how the snorkel will slide into the lower airbox tube once the box is reinstalled:
With the airbox reinstalled, slide the snorkel up through the fenderwell. Use a screw to hold the pieces together:
K&N air filter installed:
Installing the AEM silicone intake:
Position the clamp on the turbo inlet for easy tightening as shown:
Connect the coupler to the airbox lid before fastening the lid to the airbox. This makes it easier to keep the coupler straight on the MAF housing:
Connect the airbox lid and fasten the clamps. Plug in the MAF sensor. Install the vent tube into the silicone coupler with the opening facing towards the MAF. Connect the vent tube assembly:
The airbox inlet and fenderwell tube are shown here. The ID of the fenderwell tube necks down to about 2.5", and therefore becomes restrictive on high HP setups.
After removing the airbox, notch the plastic as shown:
Next, cut the fenderwell tube just before it starts to bend. Remove the plastic brackets from the tube. I cut all of the bracket off and it left a hole in the tube. You can leave some of the bracket on and avoid the hole. It will still fit fine in the new configuration.
With the airbox back in place, connect the fenderwell tube to the airbox using a 3.25" silicone coupler and 2 clamps.
Completed:
Method #2 without silicone coupler to connect snorkel:
Remove the headlight and then remove the headlight mounting bracket shown here-
Unplug the MAF sensor and remove the airbox lid:
Unbolt and remove the airbox:
Remove the snorkel bracket bolt shown to the right:
With the tire removed, you can more easily access the retainer clip behind the snorkel:
Cut off the long snorkel bracket as shown:
Cut the snorkel just before the first bend and smooth the edges:
Pic showing how the snorkel will slide into the lower airbox tube once the box is reinstalled:
With the airbox reinstalled, slide the snorkel up through the fenderwell. Use a screw to hold the pieces together:
K&N air filter installed:
Installing the AEM silicone intake:
Position the clamp on the turbo inlet for easy tightening as shown:
Connect the coupler to the airbox lid before fastening the lid to the airbox. This makes it easier to keep the coupler straight on the MAF housing:
Connect the airbox lid and fasten the clamps. Plug in the MAF sensor. Install the vent tube into the silicone coupler with the opening facing towards the MAF. Connect the vent tube assembly:
Last edited by Matt M; Oct 2, 2009 at 11:20 PM.
Thread Starter
Former Vendor
Joined: 06-03-08
Posts: 4,169
Likes: 8
From: Grand Rapids, MI
We did a few mods to the stock intake and picked up over 10HP. I don't have numbers for this mod alone, but I'd guess it's worth a few HP.
Thread Starter
Former Vendor
Joined: 06-03-08
Posts: 4,169
Likes: 8
From: Grand Rapids, MI
Senior Member
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From: pa/jersey
the joys of not being chained to a desk
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Joined: 08-05-08
Posts: 1,460
Likes: 1
From: Iowa
THANK YOU MATT!!!
I just did the factory airbox mod. It was pretty easy and straightforward. It didn't take very long to do and only cost me a few dollars.
I'm tuned with K&N drop in and BPV spring upgrade. I'm not going to lie and say it was like night and day or something like that. But a difference was noticed.
I used to have a dead spot right around 6K rpm to 7K rpm where the rpm rise was noticeably slower. After the mod that dead spot is pretty much gone.
HUGE thanks to Matt who posted it!
It's weird that GM did that. It starts out 3"... necks down and then returns to 3"...
I just did the factory airbox mod. It was pretty easy and straightforward. It didn't take very long to do and only cost me a few dollars.
I'm tuned with K&N drop in and BPV spring upgrade. I'm not going to lie and say it was like night and day or something like that. But a difference was noticed.
I used to have a dead spot right around 6K rpm to 7K rpm where the rpm rise was noticeably slower. After the mod that dead spot is pretty much gone.
HUGE thanks to Matt who posted it!
It's weird that GM did that. It starts out 3"... necks down and then returns to 3"...
Senior Member
Joined: 08-05-08
Posts: 1,460
Likes: 1
From: Iowa
You could, and I gave that thought. But it would just be like a short ram pulling in air from the engine bay. It wasn't difficult at all to just do this and get cold air. It's really not hard at all. Didn't take very long either.
Thread Starter
Former Vendor
Joined: 06-03-08
Posts: 4,169
Likes: 8
From: Grand Rapids, MI
Aside from drawing air from inside the fenderwell, the snorkel is also nice because it has a radiused inlet just like a velocity stack. This can improve airflow over a tube that just begins without a radius.
I'm glad you like this mod. It really is easy and we are still using it on our upgraded turbo. We also have the KN drop in.
THANK YOU MATT!!!
I just did the factory airbox mod. It was pretty easy and straightforward. It didn't take very long to do and only cost me a few dollars.
I'm tuned with K&N drop in and BPV spring upgrade. I'm not going to lie and say it was like night and day or something like that. But a difference was noticed.
I used to have a dead spot right around 6K rpm to 7K rpm where the rpm rise was noticeably slower. After the mod that dead spot is pretty much gone.
HUGE thanks to Matt who posted it!
It's weird that GM did that. It starts out 3"... necks down and then returns to 3"...
I just did the factory airbox mod. It was pretty easy and straightforward. It didn't take very long to do and only cost me a few dollars.
I'm tuned with K&N drop in and BPV spring upgrade. I'm not going to lie and say it was like night and day or something like that. But a difference was noticed.
I used to have a dead spot right around 6K rpm to 7K rpm where the rpm rise was noticeably slower. After the mod that dead spot is pretty much gone.
HUGE thanks to Matt who posted it!
It's weird that GM did that. It starts out 3"... necks down and then returns to 3"...
Last edited by Matt M; Apr 4, 2009 at 08:41 PM. Reason: Automerged Doublepost
