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Velocity Stack
Posted: Mon May 18, 2015 10:49 am
by Namreg Rac
Are you guys running a velocity stack on your custom I5 Intakes for flow stability to the MAF? Paul N. mentioned that he had a car that had "horrible stalling issues" which turned out to be the intake tract was to short between inlet and MAF. Getting ready to install Motronic on my 4K AAN and obviously I am running a custom intake.
Thanks!
Re: Velocity Stack
Posted: Mon May 18, 2015 1:07 pm
by deaner
I'm also a bit curious as well. I'm building the same thing and have been kicking around ideas. I'd thought about buying a $1400 "intake mod" purely because I hate MAF sensors lol. Have you started putting an intake together yet?
Re: Velocity Stack
Posted: Mon May 18, 2015 2:51 pm
by dalspaugh
Disclaimer: I've never installed a custom intake...
but yes, the flow of air needs some distance to become linear/non-turbulent between the filter and the MAF. A MAF only works on this principle assumption that the sample it is reading can be extrapolated across it's entire cross section.
for reference:
http://smile.amazon.com/dp/1932494421/r ... TTPN9A9NAJedit for the fact that I don't know what that distance needs to be but I'm sure there are some rules of thumb out there.
Re: Velocity Stack
Posted: Mon May 18, 2015 2:58 pm
by deaner
I'll take a read through your link later tonight. I'd imagine that replicating the stock dimensions would work just fine yeah?
Are planning on building your own intake from scratch or just putting an open filter where the box would normally be?
Re: Velocity Stack
Posted: Mon May 18, 2015 7:01 pm
by Namreg Rac
I am not to fond of placing a filter where the stock Airbox would sit for a multitude of reasons.
I wonder if a velocity stack would allow you to shorten the distance MAF and air filter. Every bit counts on these AAN 4K's.
Re: Velocity Stack
Posted: Mon May 18, 2015 11:19 pm
by Dutchbroracer
Install VEMS and throw your maf in a bucket!

Re: Velocity Stack
Posted: Mon May 18, 2015 11:30 pm
by Mcstiff
Re: Velocity Stack
Posted: Tue May 19, 2015 8:48 am
by bradyzq
If you leave the plastic or mesh grilles on the MAF and let them do do their job (they're called flow straighteners), this problem should diminish if not disappear completely.
This assumes that you have dialed in your MAF curve (voltage to mass flow) and that your injector data (flow and dead time) is correct.
Re: Velocity Stack
Posted: Tue May 19, 2015 10:07 am
by Namreg Rac
Yeah I plan on running the wire mesh. I'm not exactly sure the details as to Paul's issue.
This is going to be on a chip tuned Motronic ECU running a GT3071R with Hanks EM.
I would run the AAN air box but that is an impossibility in a 4000 with a header.
Thanks for the input, I'll give it a try and see if I have any issue.
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