[Fireman]

Does anybody know what the real purpose of the "shelf & air horns" are for in the airbox?

Thanks... :huh:

 

[bjankuski]

Noise reduction.

 

[ods dan]

and they actually draw more fuel , by the design..thats one of the reasons, why removing them seems to make more power, it leans out a bit..

 

[ZRJoe]

Do the airhorns have anything to do with synchronising the intake pulse thru the carbs?
Theoretically you should be able to tune the intake pulse with a horn just like velocity stacks.
Has anyone actually done some dyno pulls with and without them in. leaving all else the same?

Just curious.
It really doesn't make much sense that they are there only for noise reduction. There are much cheaper ways to reduce the intake noise!
(Not that I want to!)

 

[bjankuski]

Noise reduction is the main reason for the air horns. There is another article in this forum that shows dyno runs with the 900, with and without the stock air horns and shelf. With the removal of the air horns and shelf the engine picks up anywhere from 3 to 5 HP.

 

[Fireman]

Thanks for your replies. I'm going to remove it and jet a little on the fat side, see what happens and watch the plugs.

 

[aczr600]

at a little testing session at c&h dyno around '97 ,we removed air box from zr 700 picked up 2 hp ,then we removed air box from 900 t-cat and picked up 3 hp,but thats dyno hp.without air box on tail,engine would injest warm air trapped under hood,while air box draws from outside air.