Suggestions for Velocity Stacks?

jcosta79 · 05-22-2014, 10:08 AM

Or you could just get the JWT Pop Chargers.

Jordo! · 05-22-2014, 12:17 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, 12:32 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.

05-22-2014, 10:08 AM	#1 (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

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