Best air filters?

[Kensai]

Wanted to get some opinions on the different types of filters available for twin HS4's. I'm currently running velocity stacks myself, mostly because they were sitting neglected in Bcliff's parts supply, and because they just look so neat. Is there an accepted <span style="font-style: italic">best</span> filter setup, or is it just a matter of opinion?

 

[PaulP]

I've been trying to answer the very same question. I think it depends what you mean by "best." Does best mean high flow, high filtration effeciency, good looks, all of the above...

Seems like many looking for an upgrade choose K&N. From what I've been able to read, K&Ns give you a bit more flow w/ lower pressure drop at the expense of slight poorer filtration. I'm considering running w/ stock paper filters w/ endcaps (something like this): https://brokenheartstudio.googlepages.com/filtercaps

Here's an interesting comparison article I found:
https://www.bobistheoilguy.com/airfilter/airtest3.htm

If I were going to go with the K&N I would choose either the RU-4410 or RU-2790. I believe Hap has posted some pics of the RU4410 before.

Here's what they look like:
https://www.cibolas7.net/17963.html

Good Luck - Paul

 

[twigworker]

You are making a BIG mistake by using stacks on a street car. It doesn't take much time for an engine to pull in enough grit to trash itself with unfiltered air and besides, stacks are of nearly no improvement in performance under regular circumstances.

The reality is that the part of tuning that involves velocity stacks is extremely precise and can only be performed after everything else is brought into strict compliance with a very detailed construction process, read "specialized racing engine". From that point on the best way to spec stacks is on a dynamometer or less accurately on a test track.

The best thing that you can do for normal street use is to use the base plates from the stock air filter canisters and install DEEP style filters over them. The standard depth filters, K&N or stock style paper ones, allow for a relatively calm pool of air to be presented to the carb throats and the radius of the stock base plates is near on to being perfect for air turbulence and transition into the carbs themselves. Hap Waldrup and I and several others have worked up varying approaches to using these base plates, some being more elegant than others. I am not sure if Hap has posted his work on this board. If he has though you should be able to find it with a Search. Otherwise let me know and I'll shoot you some information.

K&N supplies naked filters and ones with chrome cover plates. They both allow more flow than stock paper ones and in doing so sometimes require changes in mix or even changes in needle profiles. Stock paper filters allow plenty of flow for all but the most demanding performance AND they are cheap. If you want to ditch the canister cans you can use the allow base plates and either make a set of covers or buy a pair from Rusty Koester at brokenheartstudio@gmail.com or brokenheartstudio.googlepages.com/hom. I use Rusty's caps as I found that making a good looking set out of aluminum is WAY more time consuming than it looks. LOL

Jack

 

[PAUL161]

Wanted to get some opinions on the different types of filters available for twin HS4's. I'm currently running velocity stacks myself, mostly because they were sitting neglected in Bcliff's parts supply, and because they just look so neat. Is there an accepted <span style="font-style: italic">best</span> filter setup, or is it just a matter of opinion?

I agree with Jack in saying NEVER-NEVER run a street engine without filtering the intake air. Velocity stacks are for race car engines and some times even that is debatable, depending where the car is running. There is no comparison to the cost of an engine and the cost of a pair of air filters. Put a little sand between your hands and rub them together, imagine one hand being a piston and the other the cylinder wall, mixed with a little bit of oil of course, you know, to help keep the sand in there.

 

[Hap Waldrop]

Even on the rae cars where we use the bell shped velocity stack we still use filter, I used uni-filters I sourced from motorcycle shops in the past, even racers filter thier air into the carb, well atleast smart ones do

 

[PAUL161]

Wow, those engine bays look like sterile operating rooms!

 

[billspohn]

Even on the rae cars where we use the bell shped velocity stack we still use filter, I used uni-filters I source form motorcylce shop in the past, even racers filter thier air into the carb, well atleast smart ones do

Geez, Hap - it looks like you only have half enough filters there.....is that the economy version..... :thumbsup:

 

[bcliff]

I guess we better get the air filters on this car ASAP.
Bruce