Do I have enough clearance with these stacks to install a K&N?

[twobone]

I'm looking to add a K&N filter, but i think my stacks are too long on my weber DCOE 40 carbs.

 

What would you guys suggest. I have very little clearance so maybe I need to replace the stacks as well. I just don't like the foam sock covers that I've got

[pi7ot]

The K&Ns should fit over the stacks with the nets removed, but I reckon you'll need shorter stacks anyway in order to have decent clearance for the incoming air to turn into the stack mouths.

(Basing my answer on the idea that air has mass and needs space and time to turn in a cooperative manner.) :cooldude:

 

m

[KiwiBirkin]

Your stacks are longer than the ones that were on my Weber 40s with K&N filters on so i think your going to need to shorten the stacks, the best bet would be to buy your filters and then have a talk with a local weber agent and ask what size he would recommend

[11Budlite]

From what I remember you want to have 1.5 times the length (or is it dia?) of the velocity stack for clearance to the air filter cover plate. So if you are running a 4" height filter you can run a 40mm stack with no issues. I think you can run up to a 50mm stack resulting in 50mm clearance to the cover plate but it's not optimum. Check out TWM's website for their different applications: http://www.twminduction.com/AirHorn/AirHorn-FR.html

 

They even have carbon fiber!

[twobone]

So do I need stacks inside a K&N filter? Can I just ditch the stacks all together?

 

Without the stacks will I get reduced airflow and therefore poorer performance?

 

The cost of smaller stacks and a set of K&Ns if pretty steep

[DeanG]

I used to run short stacks with K&N filters in my Elan. I pulled the filters out as far as I could toward the bell of the horn. When I put a stock set up back I was concerned with how close the horn was to the air box wall. I never could feel any difference but I didn't do any testing. Apparently the modern thinking is to dispense with the horn and just have a radius. I use that on my Se7en which has SU carburetors and pancake air filters.

 

I got mine from http://www.aptfast.com/ you might want to talk with them.

[MoBoost]

I use the 1.75" deep K&N on my car that has 40DCOE's. The 3.25" deep filter, which also would allow the normal air horns interferes with the clamshell fender. You might think about that as it looks like it might be tight on your car also.

I purchased shorter air horns (from APT), but the filter back plate needs to be opened up for the velocity stack to fit through and I haven't done that. K&N doesn't make a 1.75" deep filter that allows fitment of air horns, or at least they didn't last time I called them. So, I'm running with no air horns currently. Maybe another call to them to see if they'll make what I want.