Topic: Air Restrictor Removal Mod

[Guardian7]

Air Restrictor Removal Mod - Removal of the Air Restrictor used on certain year Jeep intake systems may help your engine breath! Models: 91-95 YJ Motors: 2.5 or 4.0L may have these restrictors. Some people claim to gain 10 hp when removing it so I thought I would post the mod which takes 10-15 minutes, costs nothing, and can easily undone. The computer needs to be reset and allowed time to re-learn the new intake configuration much like a TB spacer install which requires a week or so of driving. When Jeepers install after market intake systems their doing away with as much restriction as possible to help the engine breath better but the exhuast needs to breath more too for the full benifit. The great pics are from Jeepin Jays page. http://members.fortunecity.com/jeepinjay/id10.htm

[SMC4WD]

Nice little write-up and pictures!  

Did you know that you could pop out the front restricter tube too?

I also took the side of the air-box, where the rivets are, and took that off too.  It opens up the air-box alot, and still does a good job of keeping water from getting up into that area.

[Jeffy]

The venturi aka:'restrictor' is there to create a vacum to pull Crank case vaports from the CCV.  Which is why there is a slot in the muddle of the venturi and why the CCV line attaches to the same area.  The venturi as many know speeds up the air which causes a vacuum.  Since the air speed in increased the CFM probably isn't decreased much if any.  (It could also be reduced.  Someone would have to check it with a metter.)

Is it worth it to remove the venturi?  Well, I put mine back in.  I still have the turn down at the front of the airbox, too.  That's there to keep water from entering the airbox.  What I'd like to maybe try is to attached a 2" ABS tube to the front of the airbox and route it around the radiator and up against the grill opening. Although you could plastic weld a 3" flange and that would be interesting...

[larryp]

I removed mine a while back and it actually decreased performance and milage went down the tube. I put it back in and things went back to normal. I'm now a firm believer in the venturi's effectiveness.

[SMC4WD]

This kinda sucks to hear...   Sometimes you hear of doing an upgrade that ends up being a downgrade  :?

Um...  anyone got a venturi or two laying around that they wanna send up to Washington?

[Jeffy]

This kinda sucks to hear...   Sometimes you hear of doing an upgrade that ends up being a downgrade  :?

Um...  anyone got a venturi or two laying around that they wanna send up to Washington?

Guardian7's got one!  

Actually anyone who went with a CAI should have one.

[Guardian7]

Very Cool, sounds like SMC4WD figured out how to open up the intake even more! Now I'll have to go re-examine my own intake to see if I can try some additional mods to my own Air-box.
On a serious note, my 89 YJ does not have the restrictor, Jeep started using them in 91. Some people claim to gain 10 hp when removing it so I thought I would post the mod which takes 10-15 minutes, costs nothing, and can be easily undone. The computer needs to be reset and allowed time to re-learn the new intake flow parameters much like a TB spacer install which requires a week or so of driving. When Jeepers install after market intake systems their doing away with as much restriction as possible to help the engine breath better but the exhuast needs to breath more too for the full benifit.