Suggestions for Velocity Stacks?
 

Hey there, folks :tiphat:

I am working on a new project: The goal is to fit a velocity stack to the inside of the OEM airbox.


First, with some careful prying, I was able to separate the airbox into front and rear halves.

http://www.the370z.com/members/jordo...40511-0000.jpg





Next, I need to fit a velocity stack at the inside intake inlet similar to one of the pictures below...


http://www.the370z.com/members/jordo...80-vstack2.jpg

or

http://www.the370z.com/members/jordo...78-vstack1.jpg


I'm not sure which variant will be easier to fit or work "best" (although I'm leaning towards the one in first pic on the right), and I'll probably have to figure out a gasket of some sort too.

I'll either have to drill in screws to secure or take my chances with JB weld (not sure if that's a good idea after the filter...)

The problem I'm having is in finding velocity stacks I can work with. Ideally it will have a 2.25" ID and an OD that will mate up nicely to the intake inlet on the inside without any gaps (again, I may have to make a gasket of some sort...).

This means it will either need a built in flange or snap into the inlet area without reducing the ID.

I'm having a very hard time finding suitable velocity stacks... internet search points me in directions that have thus far not been exceptionally helpful.

Does anyone have any suggestions on where I could find something that might work?

I'm leaning most toward the flatter flange type fitting, but I'm open to suggestions...

Thanks! :tup:

EDITED for correct ID!

Maybe it's just Chrome, but I can't see any pics.

I'm interested to see how this works out. I've got an idea similar to what you're working on, but I haven't picked up another set of airboxes yet.

What is the goal you are heading towards?

Improving flow -- some nice bellmouths on the inlet side should smooth out flow and give me a reasonable bump in power -- say, 5+ across the board, with improved throttle response to boot.

It might be worth making a second one leading to bumper to airbox inlet, but this one is the one that should make the most difference.

A lot of OEM airboxes have one -- kind of surprised Nissan didn't bother...

I think I can make a nice gasket out of rubber, so it will flex and cover any gaps -- all I need now is a bellmouth with a flange.

I was looking at some throttle body and carburetor parts as a possible solution...

Can anyone direct me to flange mount velocity stacks like the one on the right in the first picture above?

Can't see the pics.

Uhhh... they're linked to one of my galleries... they should be viewable. :confused:

No pics are showing up for me either.

I figured out the problem -- pics will be visible in just a sec... sorry about that... :o

Okay, should now be visible... sorry, I had the album set to private by accident... D'OH!

Could you cut a velocity stack out of another manufacturers factory airbox?

Sub'd, very interested in seeing how this turns out :tup:

Sure -- if I had one handy or if someone knows of one that is the right diameter. And, I need two... :o

I've been scouring sites like this one

AIR HORN<br><font color="red">52840.010</font>

But have not been able to find one yet with an ID of 2.25" (can someone confirm the ID of the intakes?)

Another possibility is here

Velocity Stack Filters

They have a 2.28" ID, which is close -- PJM-VS-3.

Looking to see how much for two of those with a flange.

I'd really like something identical to the one in the first pic on the right, but no luck so far :(

If anyone knows of a place where I can get what I am looking for (ideally on the cheap) please let me know!

This is a fairly easy mod to to, should net easy power with the OEM set up (and of course I'll test on dyno like I always do).

I'm hoping to find that this, plus K&N panel+smooth tubes easily meets or exceeds G3's in performance (it should, as just the K&N+tubes got one in the ball park).

Interested to see how this turns out.

Ohh this looks easy enough...bet you I could cnc machine some ;)

Hey, actually let me confirm that I am an idjit: The ID of the OEM intake appears to be NOT 2.5", but rather 2.25" (it's wider after the MAF to accommodate the intake tube, but all air measurements are based on a diameter of 2 1/4") -- can someone confirm this????

If so, I can definitely find ones with that ID.

just get two megaphones, remove the horn, shave them down to whatever size you want, and badabing! velocity stacks!

I thought of looking for some speaker components -- by any wild chance do you know where I could track some down with an ID of 2.25" (57.15 - say 58 mm max)?

They my even have mounting tabs...

I have had some luck carb stacks that might fit... but they are pricey. I want to do this on the cheap since the odds are moderately high that it won't fit and I'll just be stuck with them.

Would an autozone or pep boys carry carb stacks? I guess I could look around for an old school speed shop...

As to having ones machined -- anybody on here up for the project? If so, PM me!

If it works out, we could have a little cottage industry on our hands :tup:

Hmmmm.... Speaker ports?

Speaker Port Tubes in the Speaker Components Department at Parts Express | 320

Very promising -- and cheap, which is always good for a project like this.

Looking them over now -- thanks! :tiphat:

Open to any and all other suggestions by other folks as well! :tup:

i don't know if this is of much help but Specialty Z and I have been using these Velocity stacks on 300ZX and Evo X for a while with huge success

MAF Delete Venturi - 300ZX

Thanks -- but I think those are probably the same size as these one's made by Blox that I picked up -- too big to fit inside the airbox :(

I really need something flanged that would mount to a TB or carburetor with an ID between 57.15 and 58 mm, similar to the one's in the Rev-up airboxes for the 350 motors in the first post...

Any idea where they might have been sourced?

I found two but I think they are too big for what you are doing.
Your Search Results - JCWhitney

Stacks were pretty popular back in The Good Old Days and you might find what you need on sites that cater to that crowd. I've seen stacks on motorcycles - might try some of the custom parts stores.

Give me a length, the outside diameter of the largest part and outside diameter of the smaller part and ill draw something in cad and make a "prototype"

Awesome -- thanks!

Well, I'm not 100% sure on how to make the flange perfect, but something with at least three mounting locations would probably be good.

The inside diameter should be 2.25" and there appears to be enough room for a 3" bellmouth, ideally elliptical, with a rolled edge.

Length... I think we want to keep it close to the inlet -- too long might interfere with savaging from behind the stack, so, maybe 1.5" or 2" at the most in length?

Hell, if you are really serious and we can work something out to compensate your for your time, I'll just mail you the halved airboxes to work on.

what about sourcing a couple from a 2006 350z intake box?

http://i122.photobucket.com/albums/o...2006airbox.jpg

that is a straight on shot but it is a venturi ring, they changed that from the earlier versions to improve air flow. should be the size you are looking for also

Give me a few hours to get things rolling in the shop and ill draw it up in cad.

I'll talk to our machine shop who manufactures the other ones for SZ, he does all kinds of aero space and might be able to draft something up for yah.

-Juan

Nice work. :tup:

Shirley there is a page out there with the formula(s) you need to design/select this thing right. I found several pages with formulas for the length of a stack connected directly to the carb (primarily motorcycle use) but didn't dig very deep. See if you can find a page by someone who has already done the research and see what the optimum dimensions for the "bell flare" radius and the overall width are. The best "bell width"-to-throat ratio would be a big help.

From what little I've read while doing the above searches, best case is a 1-2% gain and that's starting with a "square" opening (radius of the flare is 0). If the boxes you are using already have some "contouring" your gains will be even less. But that's just what I read on the internet - all my experience with flow dynamics is related to flow measurement.

Looking inside, there's definitely room for improvement -- it might also be worth modifying the entrance to the airbox itself, but the intake inlet seemed like a good starting point. Check out the link below with projections on gains to airflow based on various lengths of stack vs bellmouth design.


Excellent! Let's work something out to make these things happen -- PM me?


Here's some info on ideal dimensions -- I think anything from the 7 - 11 range should be ideal (and maybe #11 would be best/easiest?).

http://www.classiczcars.com/forums/a...pipeshapes.jpg

Curious, but if we can work this out, and decent power is netted, would people be interested in sending us airboxes to modify to defray costs?

If nothing else, AzSpeng, let's you and I work something out so we can develop a prototype and test the design -- I think this could be really promising, and a nice relatively inexpensive alternative to other aftermarket intakes, but even as a 1 or 2 off project, it certainly shouldn't hurt power!



I'd be down for sourcing those venturi's but haven't be able to find them. I can't even find the airboxes on the cheap -- they still go for over a hundred bucks a pop -- x2 + dyno time makes for a pretty pricey experiment, especially since they may or may not fit...

My have found an option (though still very open to working something out with AZspeng)

58m ID shorty bellmouth stacks here (need to remove that screen) http://www.dimecitycycles.com/vintag...-pos-shrt.html

Rubber flanges that I believe (need to double check...) will fit here Genuine Mikuni Carburetor Mounting Flange VM36 VM38 | eBay

Worth a try?

First link is broken. Delete the "\" from the end of the URL and it works. (Fixed in the quote above)


Which air boxes are you using? I took a look at my spare set and they don't look anything like what's in the pic in your first post.

^^^ Thanks :tup:

OEM airboxes split in half -- the front pries away from the rear without any structural damage with a bit of firm but gentle coaxing with a flathead.

The other ones I posted a pic of, which already have stacks installed, are ones from a 35DE motor I think.

Ah. I took a closer look at your pic and what I thought was a plastic "grille" was just reinforcements molded into the case. Doh!

I still don't see you getting much out of a velocity stack. I can see where it might help a little bit on the 350 box but the walls/throat of the 370 outlet look pretty aerodynamic to me. But I hope you prove me wrong. ;)

Honestly, I'm only expecting 5 or so and maybe a little snappier response. But, that, plus K&N + smooth tubes would mean like 15+ whp with the OEM airbox, which is pretty nice.

I'm hoping that if this works, I can figure out a way to at least offer a good DIY or, hell, maybe people can send me their airbox to mod for a small service charge.

Anyway, phase 1 is find stacks that fit, phase 2 is test ;)

Okay, I said **** it and ordered the velocity stacks -- now I just need a way to mount them... looking for some of those rubber flanges -- AZspeng still interested in collaborating on this if possible as these stacks may not work out...

Ah, the allure of tinkering on car projects...

ebay might be your best bet

I can't find any rubber flanges specifically for stacks with an ID of 58 mm... I may have to get creative -- I'll figure something out.

Maybe a silicone reducer and some hose clamps will work?

I think there may be holes for some small flathead bolts to fasten in directly to the inside of the airbox -- I can make a gasket out of rubber easily enough.

Failing that, yeah, I'll have to experiment with something along the lines you are describing.

First thing I need to do is see what's involved in removing the screen -- hopefully easy to pop out -- no need for that there.

Somebody on here mounted bellmouth velocity stacks on the end of his G3's and claimed he picked up an extra 8 whp. Seems reasonable -- and I am expecting at least 5, but we'll see... no harm in trying :D