Suggestions for Velocity Stacks?

jcosta79 · 05-22-2014, 11:08 AM

Or you could just get the JWT Pop Chargers.

Jordo! · 05-22-2014, 01:17 PM

Quote:

Originally Posted by SouthArk370Z

The increase in velocity due to a narrowing of the duct doesn't do you any good. The velocity decreases as soon as the duct gets bigger again. It will actually reduce the flow.

Since the sensor is measuring mass flow, there shouldn't be any need for re-scaling.

The math for figuring the loss due to narrowing of the duct is pretty straightforward - it's just an orifice. Flowrate Calculation for an Orifice Flowmeter looks like a good place to start. You will probably need a manometer or other differential pressure measuring device.

Figuring loss due to turbulence is much too complicated for me.

Thanks for the link!

Yeah, I figured the restriction would only kill power... our meters aren't hotwires? If they are, flow rmass is based on flow rate over the wire, which is very much affected by diameter, although the section before the MAF wouldn't have changed, so voltage readings should still reflect OEM scaling.

Of course, abrupt transitions can throw things off... a problem I sort of hoped would not come up, but who knows until I try.

Anywho... I ordered a different set which should definitely have a smooth transition from bellmouth to the OEM diameter, so we'll see how that goes.

Quote:

Originally Posted by jcosta79

Or you could just get the JWT Pop Chargers.

That was the original plan -- I had a set! But, after deciding that fabricating decent airboxes for them would be too much of a PITA (I have zero experience working with fiberglass...), I sold them off and have started this new project using intact (but separated into F & R halves) OEM airboxes.

On that note, I have some fiberglass repair kits I should just probably sell off...

SouthArk370Z · 05-22-2014, 01:32 PM

Quote:

Originally Posted by Jordo!

... Yeah, I figured the restriction would only kill power... our meters aren't hotwires? If they are, flow rmass is based on flow rate over the wire, which is very much affected by diameter, although the section before the MAF wouldn't have changed, so voltage readings should still reflect OEM scaling.

When you have a restriction, the velocity goes up but the flow goes down. It's moving faster but has a smaller hole to go through.

As long as you don't change the duct size at the sensor (plus a diameter or two up- and down-stream) the sensor output should remain the same.

Jordo! · 06-25-2014, 05:14 PM

At long last, the new velocity stacks have arrived!

These have the right dimensions, so next step is to see what I need to do to fit them, in keeping with my plan to use the OEM airbox.

More details coming soon!

Jordo! · 06-25-2014, 10:27 PM

Test fit -- so far so good.

I might be able to just "snap" them in with some careful dremeling of the inside of the intake neck. If not, I'll have to make a bracket of some sort.

However, I'll have to have the filter sit forward a bit -- fits fine, so shouldn't be an issue; might make something to ensure it stays flush -- and figure out something for the top.

More soon...

Jordo! · 06-26-2014, 05:19 PM

After some additional thinking on this, I think my plan will be to bore out the inside of the OEM intake neck enough to have the v-stacks slide/snap in. Then I need to maybe drill in two flat head screws to secure it, or perhaps a thin layer of jbweld to keep it in place.

For the filter's slight relocation, all I should need are two thin strips of metal, similar to battery ties to ensure it doesn't pop out of position. Based on how snugly it fits, it should require much to secure it.

The top can simply be the OEM one, with the "frame" modified or removed so it just covers the opening. I might even simply bolt it to the front section to ensure that the OEM lid clamps will still keep it all together.

Essentially, the rear section would go in separately, then the modified front section plus filter would be locked down and sealed to the rear section. That should actually work, and make changing filters only moderately more challenging that it would have been on a totally OEM airbox.

So... question: What sort of hole saw like tool/accessory do I need to shave the inside of the neck precisely?

Also, is there something I could use that would create a slight tapering as I get to the desired depth to snap in the v-stack, and help ensure a smooth transition from V-stack to OEM intake neck?

Would I be better off taking this to a machine shop or something???

Looks like I need a tapered shell reamer -- something like this http://canadatool.ca/php/images/stor...rs%20taper.jpg ?

Anybody have any advice/relevant experience on this one?

SouthArk370Z · 06-26-2014, 05:43 PM

While I applaud your efforts and don't want to discourage you, I don't think that setup is going to do any good and may decrease performance. You are increasing the length of the "restricted" section between the box and MAF and the air to the right of the stack in the last pic will have to make a turn. You may also be affecting the tuning of the intake/manifold.

Jordo! · 06-26-2014, 08:44 PM

Quote:

Originally Posted by SouthArk370Z

While I applaud your efforts and don't want to discourage you, I don't think that setup is going to do any good and may decrease performance. You are increasing the length of the "restricted" section between the box and MAF and the air to the right of the stack in the last pic will have to make a turn. You may also be affecting the tuning of the intake/manifold.

I was a bit worried that it sticks out too far, but other OEM's have designs like that which work (see page 1), so it may or may not matter.

I'm hoping if I can ream out the intake neck enough, I can recess the v-stack further into it, which will minimize the degree its even an issue.

SouthArk370Z · 06-26-2014, 09:39 PM

The stacks shown in the second pic of the OP look like they might do some good. What you show in your last sets of pics looks like it would interfere with the flow. But I'm not an Aerodynamics Engineer (or Engineer of any sort). I'm looking forward to seeing your results and hope that my guesses are wrong.

A big dowel pin reamer may give you the taper you are looking for but not sure how it would work on plastic.

Jordo! · 06-26-2014, 09:56 PM

Quote:

Originally Posted by SouthArk370Z

The stacks shown in the second pic of the OP look like they might do some good. What you show in your last sets of pics looks like it would interfere with the flow. But I'm not an Aerodynamics Engineer (or Engineer of any sort). I'm looking forward to seeing your results and hope that my guesses are wrong.

A big dowel pin reamer may give you the taper you are looking for but not sure how it would work on plastic.

I think it all comes down to how much of a restriction is the filter. The lip of the bellmouth in it's current position just barely touches it. Otherwise, it has a direct path to the entry way on the airbox duct, maintaining the same "line of sight" as the OEM neck, just extended.

I'm hoping to recess the thing in by a few inches so it will be less of an issue. That might even give me enough room to just keep the OEM filter location, instead of having it sit a bit farther forward.

On that note, I'm not sure if filter position will make a difference either...

I'm committed to this experiment now, so win lose or draw, it will give me some useful info on what to do next (e.g., have even shorter v-stacks made) or whether to abandon the project entirely...

BTW, thanks for all of your input -- I very much appreciate it

SouthArk370Z · 06-26-2014, 10:12 PM

The portion of the airflow that is to the right of the stack in your pics doesn't look like it will have a straight shot to the stack unless the stack is a lot shorter. Can you cut the stack to make it shorter? That would avoid a lot of "machine" work on the plastic parts.

I don't think the position of the filter will have much effect on flow but it certainly would be a lot easier to R&R if it were in the original position.

Hang in there! This is one of the few time I'm hoping someone proves me wrong.

Jordo! · 07-06-2014, 09:03 PM

Minor update: After having NO luck finding a drill attachment that could smoothly bore the inside of the airbox intake tube to 2.625" (i.e., 2 5/8"), I attempted to bore it out manually with my dremmel...

Ehhhh... the short version is that it's too sloppy and needs more honing and, even worse, I cracked the outside of the tube trying to wedge my v-stacks in. D'OH!

So I am now considering a different route. If I just cut out the outer intake tube and cram the v-stack inside the hole, I can then simply use coupler to connect the intake tube to the v-stack, with the end of the v-stack poking through the hole in the airbox.

So long as I cut it right, it should be airtight (or easily fixed to make it so), connect perfectly to the OEM intake tube, take advantage of the OEM heat shielding as planned, and work almost identically to how I had originally envisioned the final version.

Moreover, it will allow me to recess the bellmouth further back, which may allow me to use OEM panel filter frame or at least minimize the likelihood of inadvertently losing part of the effective volume of the box because the v-stack protrudes too far.

More on this soon -- I may need a fresh set of airboxes... anyone willing to sell them to me on the cheap in the name of experimentation and adventure?

Jordo! · 07-11-2014, 12:44 AM

Quote:

Originally Posted by Jordo!

So I am now considering a different route. If I just cut out the outer intake tube and cram the v-stack inside the hole, I can then simply use coupler to connect the intake tube to the v-stack, with the end of the v-stack poking through the hole in the airbox.

So long as I cut it right, it should be airtight (or easily fixed to make it so), connect perfectly to the OEM intake tube, take advantage of the OEM heat shielding as planned, and work almost identically to how I had originally envisioned the final version.

Moreover, it will allow me to recess the bellmouth further back, which may allow me to use OEM panel filter frame or at least minimize the likelihood of inadvertently losing part of the effective volume of the box because the v-stack protrudes too far.

More on this soon -- I may need a fresh set of airboxes... anyone willing to sell them to me on the cheap in the name of experimentation and adventure?

I'm leaving town tomorrow and will be gone for a week -- BUT, the above method worked beautifully! I should even be able to keep the filters in the OEM frame without any issues!

I will post pics when I get back, and in due course, dyno test -- but this will all have to wait until at least the end of July.

More details coming soon

Jordo! · 08-31-2014, 06:59 AM

Update: I am within days of bolting everything together and within a week of doing testing.

Tons of pics and dynos coming very soon -- finally! (or a sad report of failure devoid of worthless pics... hoping on the former, obviously.)

It will have the V-stacks recessed in box, coupled to OEM MAF holder and neck, make use of a modified OEM filter bracket and lid, and should all snap in and bolt down just like OEM, but with a nice V-stack, exactly as planned.

We'll see... report on success or failure soon... to be continued....

SouthArk370Z · 08-31-2014, 07:32 AM

Good luck. I've got my fingers crossed.

05-22-2014, 11:08 AM	#46 (permalink)
jcosta79 A True Z Fanatic Join Date: Jul 2012 Location: N/A Posts: 1,430 Drives: N/A Rep Power: 15	Or you could just get the JWT Pop Chargers. __________________ 2012 PW NISMO #0559 - GT Spec Brace Kit - Swift Springs - ARK TP & Invidia CBE K&N Intake - UpRev Tune - 15mm Z1 Spacers & Studs - StopTech Slotted Rotors & SS Lines - ZSpeed CMAK with Stage 2 Clutch and Lightweight Flywheel

06-25-2014, 05:14 PM	#49 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 418	At long last, the new velocity stacks have arrived! These have the right dimensions, so next step is to see what I need to do to fit them, in keeping with my plan to use the OEM airbox. More details coming soon! megalapagas and merkil like this. __________________ Enjoy it. Destroy it.

06-25-2014, 10:27 PM	#50 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 418	Test fit -- so far so good. I might be able to just "snap" them in with some careful dremeling of the inside of the intake neck. If not, I'll have to make a bracket of some sort. However, I'll have to have the filter sit forward a bit -- fits fine, so shouldn't be an issue; might make something to ensure it stays flush -- and figure out something for the top. More soon... madwi and megalapagas like this. __________________ Enjoy it. Destroy it.

06-26-2014, 05:19 PM	#51 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 418	After some additional thinking on this, I think my plan will be to bore out the inside of the OEM intake neck enough to have the v-stacks slide/snap in. Then I need to maybe drill in two flat head screws to secure it, or perhaps a thin layer of jbweld to keep it in place. For the filter's slight relocation, all I should need are two thin strips of metal, similar to battery ties to ensure it doesn't pop out of position. Based on how snugly it fits, it should require much to secure it. The top can simply be the OEM one, with the "frame" modified or removed so it just covers the opening. I might even simply bolt it to the front section to ensure that the OEM lid clamps will still keep it all together. Essentially, the rear section would go in separately, then the modified front section plus filter would be locked down and sealed to the rear section. That should actually work, and make changing filters only moderately more challenging that it would have been on a totally OEM airbox. So... question: What sort of hole saw like tool/accessory do I need to shave the inside of the neck precisely? Also, is there something I could use that would create a slight tapering as I get to the desired depth to snap in the v-stack, and help ensure a smooth transition from V-stack to OEM intake neck? Would I be better off taking this to a machine shop or something??? Looks like I need a tapered shell reamer -- something like this http://canadatool.ca/php/images/stor...rs%20taper.jpg ? Anybody have any advice/relevant experience on this one? __________________ Enjoy it. Destroy it. Last edited by Jordo!; 06-26-2014 at 08:42 PM.

06-26-2014, 05:43 PM	#52 (permalink)
SouthArk370Z Premium Member Join Date: Nov 2010 Location: South Arkansas Posts: 8,435 Drives: 2014 Challenger Rep Power: 324198	While I applaud your efforts and don't want to discourage you, I don't think that setup is going to do any good and may decrease performance. You are increasing the length of the "restricted" section between the box and MAF and the air to the right of the stack in the last pic will have to make a turn. You may also be affecting the tuning of the intake/manifold. __________________ Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

06-26-2014, 09:39 PM	#54 (permalink)
SouthArk370Z Premium Member Join Date: Nov 2010 Location: South Arkansas Posts: 8,435 Drives: 2014 Challenger Rep Power: 324198	The stacks shown in the second pic of the OP look like they might do some good. What you show in your last sets of pics looks like it would interfere with the flow. But I'm not an Aerodynamics Engineer (or Engineer of any sort). I'm looking forward to seeing your results and hope that my guesses are wrong. A big dowel pin reamer may give you the taper you are looking for but not sure how it would work on plastic. __________________ Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

06-26-2014, 10:12 PM	#56 (permalink)
SouthArk370Z Premium Member Join Date: Nov 2010 Location: South Arkansas Posts: 8,435 Drives: 2014 Challenger Rep Power: 324198	The portion of the airflow that is to the right of the stack in your pics doesn't look like it will have a straight shot to the stack unless the stack is a lot shorter. Can you cut the stack to make it shorter? That would avoid a lot of "machine" work on the plastic parts. I don't think the position of the filter will have much effect on flow but it certainly would be a lot easier to R&R if it were in the original position. Hang in there! This is one of the few time I'm hoping someone proves me wrong. __________________ Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

07-06-2014, 09:03 PM	#57 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 418	Minor update: After having NO luck finding a drill attachment that could smoothly bore the inside of the airbox intake tube to 2.625" (i.e., 2 5/8"), I attempted to bore it out manually with my dremmel... Ehhhh... the short version is that it's too sloppy and needs more honing and, even worse, I cracked the outside of the tube trying to wedge my v-stacks in. D'OH! So I am now considering a different route. If I just cut out the outer intake tube and cram the v-stack inside the hole, I can then simply use coupler to connect the intake tube to the v-stack, with the end of the v-stack poking through the hole in the airbox. So long as I cut it right, it should be airtight (or easily fixed to make it so), connect perfectly to the OEM intake tube, take advantage of the OEM heat shielding as planned, and work almost identically to how I had originally envisioned the final version. Moreover, it will allow me to recess the bellmouth further back, which may allow me to use OEM panel filter frame or at least minimize the likelihood of inadvertently losing part of the effective volume of the box because the v-stack protrudes too far. More on this soon -- I may need a fresh set of airboxes... anyone willing to sell them to me on the cheap in the name of experimentation and adventure? __________________ Enjoy it. Destroy it. Last edited by Jordo!; 07-06-2014 at 09:05 PM.

08-31-2014, 06:59 AM	#59 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 418	Update: I am within days of bolting everything together and within a week of doing testing. Tons of pics and dynos coming very soon -- finally! (or a sad report of failure devoid of worthless pics... hoping on the former, obviously.) It will have the V-stacks recessed in box, coupled to OEM MAF holder and neck, make use of a modified OEM filter bracket and lid, and should all snap in and bolt down just like OEM, but with a nice V-stack, exactly as planned. We'll see... report on success or failure soon... to be continued.... __________________ Enjoy it. Destroy it.

08-31-2014, 07:32 AM	#60 (permalink)
SouthArk370Z Premium Member Join Date: Nov 2010 Location: South Arkansas Posts: 8,435 Drives: 2014 Challenger Rep Power: 324198	Good luck. I've got my fingers crossed. __________________ Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

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