It is possible to have a filter prior to the velocity stack.  The stock air filter on the Porsche 911/914-6 engine has a canister that fits around the top of the carb/velocity stacks.....and then a large air filter housing fits on top of the carbs.  This provides both the performance advantages of a velocity stack - and the benefits of a filter....and it makes the intake weatherproof!





And for those who want something a bit lighter.....they do have aftermarket paper, gauze of foam filters that can fit over the velocity stacks.





And you can get them with rainshields that keep water from dropping into the filter.




Is this as efficient as an open velocity stack?  Probably not - but it deals better with the dirty air and water that a street driven car or bike has to endure.  Grit in the air can drastically shorten the life of the piston/rings/cylinder.

Kris01 wrote on 06/08/16 at 19:31:26:


Absolutely.  The length must be matched to cam timing and harmonic(s).  The total length (atmosphere to valve) is what must be taken into consideration.  Very generally speaking longer promotes low-speed TQ and shorter promotes high-speed TQ.

For a great test on stack lengths see here:  http://www.phaedrus.me/id158.html

As you can see the impact can be dramatic and substantial.  In my case it was both and the change to midrange TQ was just crazy.

My doctor told me to reduce my intake.

I said

Phhhhhhht!

Here's a pic of the velocity stack inside my Enfield's airbox. It replaces a paper filter that used to fit inside the airbox (lousy design) and the filter is relocated to the outside of the box in a custom made lid. It makes a worthwhile improvement over the stock  setup.

Is that a purchased bit of hop up stuff or did you do that all by yourself? If you did it, take more than one bow to the well deserved
Standing O

Because it looks Mahvelous, simply Mahvelous.

mastercarstech wrote on 06/22/16 at 21:04:09:


A bell mouth opening flows much better than a straight pipe. You'd do well to curve the entrance to the intake.

From the carb to the tee is heavy reinforced rubber.
The tee is steel.
And I'm a little busy at WFO to notice.