Velocity stack air cleaner?

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Aug 30, 2008 | 10:56 PM

fogcity123

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Velocity stack air cleaner?

I've heard these don't work so well. I just got a former '89 Heritage Softtail that's been chopped. The engine has had some new pistons (11:1 comp) and cams and an S&S Super E Shorty, and has a 4 inch velocity stack with a wire screen across the front. I like the look but I've heard they are bad for anything other than drag. This true? I need to change it anyway because it blocks me frm being able to use the rear brake, but if they're not doing any damage then maybe I can go down to a 2'' stack? With or without some kind of filter element? Thoughts?
Thanks

Aug 30, 2008 | 11:43 PM

paulies 07

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From: National City, Calif.

Velocity stacks are for looks, you really need an good air filter, but there is a lot out there to choose from. Try the J&P catalog, a bunch there, good luck

Aug 31, 2008 | 12:50 AM

fogcity123

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Okay. But, do I really need a good air filter? What about a 2'' stack with a screen and some of the black mesh stuff?

Aug 31, 2008 | 04:08 AM

hogcruzen

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stacks are really only good for shows and drags . very hard to tune , its eather off or on , no in between .

Aug 31, 2008 | 07:34 AM

tmitchellof PG

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Joined: Sep 2006

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From: Punta Gorda,FL

Velocity stacks, with screens, do a great job of keeping small birds from being sucked into the engine.
Tom

Aug 31, 2008 | 08:06 AM

rbabos

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From: Woodstock, Ont , Can

The only real purpose for a v stack is to provide an area in front of the carb to provide an area of fuel stand off that happens with normal breathing, cam overlaps, blah blah,blah. Wind will blow this fuel cloud away without some extension in front of the carb and it would run lean. 2" may not be enough to do the job. As for no breather, the engine will last much longer with one than without one. It's a dirty world out there.

Ron

Aug 31, 2008 | 08:38 AM

glens

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Joined: Jul 2007

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From: Indy area

Quote:

Originally Posted by rbabos

Not entirely applicable, but that reminded me. It's neat to watch the fuel cloud develop just outside the carb throat on a good chainsaw with the air filter off, not that you'd want to use the saw that way, since, if nothing else, the mixture would be wrong if it were "right" using the filter.

I can't help but think that the velocity stacks would also work for much the same reasons as a proper "horn" on a loudspeaker transducer does its job, which is converting between high-impedance/low-velocity and low-impedance/high-velocity conditions; also somewhat, loosely, akin to what a transformer does with A/C voltage.

The only person I can think of who has a velocity stack on his Harley pretty much uses his throttle as an on-off switch. All the time. I don't know if it's because part-throttle response is poor or just because he likes to make a lot of noise.