Weber Air Filter

Tim Kay · 05-24-04, 12:45 AM

Any opinions on Weber Volocity Stack Filters (tea strainers) vs. K&N Filters in regards to air flow. Does one give better performance over the other?

Mainly for appearance, IMHO it would be nice to see eight volocity stacks rather than an air filter covering each of the four webers. But if the individual filters on each stack is restrictive then what's the point [img]/ubbthreads/images/graemlins/crazy.gif[/img]

Tim

Once you've tried to change the world you
find it's a whole bunch easier to change your
mind.

Kalun D · 05-24-04, 02:38 AM

There is a thread recently that discussed this at length HERE

I'm going with some filters on the inside of the intake air ducts, and a cold air box that seals to the body, so filtered cold air and still have the 8 air horns visible.

Tim Kay · 05-24-04, 03:26 AM

Kalun, thx. I knew I had seen a thread on this somewhere. Being that my search was spelled 'volocity', nothing came up. What a moron, huh?

Kalun D · 05-24-04, 04:08 AM

hey hey hey, don't be so hard on yourself. I read your post and never noticed your mispelling. An honest mistake doesn't mean your a moron, besides you CAN'T be a moron, you own a GT40, AND, your a member of this forum [img]/ubbthreads/images/graemlins/grin.gif[/img]

Fred/Belgium · 05-24-04, 05:04 AM

Kalun,

Can you send a pic of these airfilters inside the airhorn or any adress where we can find them?
Tx
Fred

JP · 05-24-04, 05:10 AM

One thing that was not discussed was the viability to run no air filters.

I think we forget that most Ford blocks in a high state of tune have limited life anyway. My engine is to be rebuilt on an annual basis. I am also aware that after about 3-4 seasons use I will require a new block so I won't be running air filters as durability is not an issue.

So air filtration? Probably a necessity in a dusty environment, especially where sand is prominent.

Also, if you are going to add air filters. I have been told to forget using individual stack filters unless you want to lose power. It needs to be done properly using a custom made air box. Have a look at ITG who make filters for the old Ford Cosworth F1 engine.

Unfortunately the best systems look pretty unsightly. There is a guy with CAV with a nice filtration box using lexan. I am sure you will come across it!

Regards,

J.P

Tim Kay · 05-24-04, 12:49 PM

Thx JP,
As suspected, I felt individual filters may restrict some air flow. As for the lexan box, it sure looked nice on the stand but under operating conditions there would be gas splatter and spray all over it which would be quite unsightly. I once ran down the street with no air filters and when I got back the whole back window was dripping with gasoline. (Don't ask why, but when I remove the K&N tops they are relativley dry, minor gas residue.)

Kalun, according to my kids I'm still and will always be a moron, GT or no GT.

Tim

I spilled Spot Remover on my dog... Now he's
gone. -- Stephen Wright

Ron Earp · 05-24-04, 10:59 PM

Someone dynoed a GT40 with and without the small air filters. I think it was Gordon Levy, the former RF dealer. If memory serves me the filters cost around 38-40 REAR wheel hp - a bunch!!!! The ones they had looked like a large disc with a lot of big holes in it. Under the metal disc was the filter material and the whole thing plugged into the trumpet.

But, that is just one engine, one filter, one example. Take it for what it is worth.

Adam C. · 05-25-04, 10:27 AM

The primary runner is the single worst place you can put any restriction, such as a filter, throttle, ventruri, etc.

The pressure drop across any element can be approximated by:

deltap=K*(1/2)*density*velocity^2

where:

deltap = pressure drop across the element
K = loss coefficient for the component (usually found experimentally)
density = density of the fluid
velocity = average velocity of the fluid flowing through the element

The biggest thing to notice is that the pressure drop increases with the square of velocity. Because the primary runner has the smallest cross-section (besides the valve) in just about any induction system, the velocity there is also the highest. Combine this with the fact that most stack fiters have high K values, and it is easy to believe the 40 hp loss. I'm actually supprised it wasn't more.

Neal · 05-25-04, 10:34 AM

We dynoed with and without the "tea strainer" type filters and saw a reduction of about 6 HP.

Tim Kay · 05-25-04, 12:13 PM

More or less settles that idea for me. Thanks for the info guys.

Next question: is there any performance loss running IDF's without velocity stacks under a K&N filter?

My delima is that on the two rear IDF's my K&N filters, being 2 1/2" tall, are only 1/2" from the rear clip window. Velocity stacks when installed are to close, IMO, to the lid of the filters. So I'm forced to run IDF's without velocity stacks. I've heard there are short, 1 1/2", velocity stacks available but I still wonder if the filter would inhibit the performance of the velocity stack vs no velocity stack.

(Kalun, I think I've master the spelling now [img]/ubbthreads/images/graemlins/tongue.gif[/img])

Tim

You can't have everything...where would you
put it? -- Steven Wright

Bill Bayard · 05-25-04, 01:47 PM

Tim,

I posted a short stack vs. tall stack, horsepower chart a

couple of weeks ago. Search "Trumpet Height", and it may

help you. At least in the case shown, short stacks made more

horsepower than the tall ones did. The data is from TWM

Induction, using their air horns on a 4 cylinder Alfa.

Bill

Tim Kay · 05-25-04, 08:10 PM

Bill,

Great thread, just the info I asked about. Although, what about the necessary clearance from top of velocity stack and the air filter lid [img]/ubbthreads/images/graemlins/confused.gif[/img]

Kudos to Adam Christian for the great thread regarding "Primary pipe length formula". Some read, will take me some time to digest [img]/ubbthreads/images/graemlins/tongue.gif[/img]

Bill Bayard · 05-25-04, 10:53 PM

Tim,

I don't know what you could do about clearance from the

rear two stacks/filters to the window, other than lower the

engine and gearbox. Would that be an option for you?

Bill

Tim Kay · 05-26-04, 11:50 AM

Bill,

The thought crossed my mind, but I'm having too much fun driving the damn car to put it on stands [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/cool.gif[/img]
When, not if, the trans screams in submission it will become necessary to do some major work I will take up that task and see if lowering things is an option.

Tim

I invented the cordless extension cord --
Stephen Wright

40 Bud · 05-26-04, 08:29 PM

Tim, I don't know what the Tornado uses for a fear tranny mount but if it is similar to the GTD, you can dump the approximately 2 inch thick doughnuts for a much thinner one. Using one from an early 60's Pontiac Catalina (1964) automatic lowers the tranny over 1".Here are some part numbers from after market suppliers in the US. Seal Power # 270-2206; Perfect Circle # 220-1084; Republic # 31-2206 or Napa/Balkamp # 602-1061.

Kalun D · 06-14-04, 07:10 PM

""Can you send a pic of these airfilters inside the airhorn or any adress where we can find them?""

It's air filters after the body air intake ducts where they go into the area underneath the rear window. It's just a concept right now. It will probably be like an air filter box made from sheet aluminum or fiberglass, one on each side, with rectangular or square filters. Then the area will be sealed completely so air can only get to the induction intakes through the filters.

Tim Kay · 06-14-04, 07:55 PM

Kalun,

Search for this thread: Velocity Stack Filters

Maybe this is what your looking for.

Tim

Neal · 06-15-04, 10:46 AM

An alternative might be a foam element like this...

Pierce sells these for IDAs...

Peruch · 06-15-04, 12:18 PM

one inch minimum clearance