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Discussion Starter · #1 · (Edited)

like many of you guys did on this Forum, i too decided to disconnect the ByPass Valve Hose from the Air Intake Tube so that the Tube would Vent in the Air, but after a couple of days, i got tired of that Sound... it missed something, it sounded like an Old Man Coughing, and you only had to be mumbling something while driving, and you couldn't hear it anymore.

Nah, in my view, if i have a Blow Off, it needs to have a Sound that says:
"Puffff... yeah, i just wasted 80Hp, but i don't care: i have much more to come" basically like a high roller that goes to Vegas and plays with $50k chips.


Those Loud and expensive Blow Off Valves are generally built by making an obstruction to the exit of the Tube, but by leaving some more small exits spots before the Obstruction itself so that the pressure is still released properly.

Well, in my head that sounds like a Filter with a Hole in it!


- a Drill with some Small Drill Bits (i used a Dremel)

- a Small Grinding Tool (i used a Dremel)

- a Hose Cap;

- a Breather Cone Filter;

- some High Strength Silicon;

First of all, let's Open the Hood and Identify the "Area of Action":

Land vehicle Vehicle Engine Car Auto part

That 'Y' junction is where we will be working: the smaller Tube is the ByPass Valve Connector that recirculates the Blown Away Air into the Air Intake again.


1) Disconnect the Smaller Tube from the Main Intake... simply press with 2 fingers the Locking Clip and slide it backwards, then twist Left and Right the small Tube while pulling it away until it pops away;

{{{ sorry i forgot to take a Picture of the Disconnected Hose Before Capping Off the Intake... }}}

2) Close the opening on the Intake Tube by placing a Cap on the Hole... you may use a Rubber Cap and Clamp it with a Hose Clamp, or you may use Tape (although i don't suggest it in the long term) or you can use a hard cap and glue it... i mean, anything that closes this opening will work:

Auto part Engine Hand Fuel line Automotive fuel system

OK, don't ask where i found that perfect fitting Cap, it happened to appear in one of my tool boxes and it looked like it was designed to close the BPV Opening... at the beginning, i have temporarily held it with Tape and went for a Test Drive, after i Soliconed it in position and it look sit came from the Factory like that.

~~~ ~~~ ~~~


any Car has to have an "Air Intake Sensor" that tells the ECU how much Air is entering in the Engine so that the Injectors inject the proper quantity of Fuel to obtain the best combustion and ultimately efficiency.

In the Air Intake Port there are 2 Sensors: IAT (Intake Air Temperature) and a MAF or MAP sensor... if the Veloster Turbo used a MAF Sensor, this modification could cause a Slight Problem:

MAF Sensor (Mass Air Flow): this is a Sensor that Calculates the Flow of Air entering in the Intake, once it's in, it's in the Memory of the ECU until it is Burned by the Engine... if we threw away the Air by Disconnecting the Hose, the ECU wouldn't be aware of the fact that that Air has been Lost, it actually expects it back soon, meaning that it will Inject more Fuel into the Motor, Fuel that won't be able to Burn Properly due to the Lack of Air... that air that we Vented out, so basically every time you release the Throttle, the Car would run Rich of Fuel for a second... no biggy, but not the best thing on the long run.

Luckily for us, the Veloster Turbo uses a MAP Sensor which reads a pretty different kind of Data:

MAP Sensor (Manifold Absolute Pressure): this is basically a Sensor that measures the Density of the Air, the ECU has to calculate how much Air Mass is entering in the Engine by considering the RPM's of the Motor...

ECU Thinks: "With this Air Mass at this Engine Speed the Engine is taking in this Much Air so the Injectors will have to Inject this much Fuel"

this should answer the Question that i have seen appearing many times OnLine of people asking if this Modification on the Veloster Turbo will cause any harm to the Motor... No Worries, the Engine will keep working like if nothing happened

NOTE: this Modification will not increase any kind of Performance on the Car, there is not advantage or disadvantage in venting the Excess Turbo Pressure in the Air, the Car will perform exactly as it did before the Modification, the only difference is the Nice Sound that you will Obtain

~~~ ~~~ ~~~

At this point, many were already happy with the Result... and YES, the sound is Audible and it's always a Pleasure to hear the Turbo Blowing when you release the Throttle, BUT there were 2 things bugging me:

a) the Sound was kinda weak, it didn't transmit any energy, it was an: "empty sound";

b) i didn't like the idea of having a big whole hose ending in the Air, although it blows outward quite a bit of Air, there are several moments in which stuff could get in... (in my mind i was imagining a huge Hornet Crawling to my Turbo and once i turn everything on, the squashed body would have ruined everything inside... i know it's impossible, but this gives an idea)


You will have to BUY a Breather Filter:

Auto part Muffler Wheel

The problem if this Breather Filter is that the Attachment Hose is too Small to work with what we want to do... technically speaking, the Hose on the Bottom goes entirely inside the Blow Hose, and we definitely do not want to do that because we need to not have any Obstructions to the exit of the Excess Pressure Hose, so... we need to get our Hose inside the Filter... and here is how:

3) Take off the Connecting Fitting Hose from the Breather Filter by bending it and pulling it away from the Filter itself... make sure not to press too much on the Filtering part itself, otherwise you might bend it... the result should be this:

{{{ sorry i forgot to take a Picture of Filter Fitting Before and After the Fitting Removal... i downloaded a Pic and Photo-Shopped it }}}

[[if you want to feel how little is the Air Flow Obstruction of these kind of Filters... try to Breath through it... as a Breathing Filter, it basically doesn't slow down Air Flow AT ALL]]

NOW: Remember what i said before about how those Loud Blow Off Valves make the Loud Noise?

Well, let's make sure we do the same... so:

4) Drill a Hole on the top of the Cone:

there is not a Specific Measure, i did a Hole about 1/3 to 1/2 of an Inch Diameter... just about.

Now we have our outlet Blowing Hole smaller than the Blow Off Hose, this will create a sort of Whistle effect, BUT no pressure will build up inside the Cone because of the Filter all around it.

the Problem now is that this little Filter, doesn't have an opening Large Enough to let the Blow Off Hose get inside him from the back (F... that sounded so wrong... ;-), so we need to make sure the Hose can go in, but needs to remain kinda tight.

5) patiently Grind out the Bottom opening of the Cone Filter until you make it just a bit smaller than the Rubber Blow off Hose;
(i used my Dremel Tool and a Grinding Wheel... some Grinding, then test... some more grinding, and re-test, grinding again... and so on until i was able to Easily Squeeze in the Rubber Hose).

Eye Font Circle Logo

{{{ sorry i forgot to take a Picture of Filter Fitting Before and After Hole Enlargement... so i recycled another Pic and Photo-Shopped it }}}

You don't have to Force the Hose through the opening, BUT the Opening doesn't have to be bigger than the Hose itself... you have to be able to just apply some pressure onto the Hose and insert it in the Back of the Filter.

At this Point, we are almost ready, the only issue is that the next step will require you to leave the Car parked for about 12 Hours.

6) with a High Grade Silicon, create a Gasket around the Large Opening in the Back of the Cone:

This image has been resized. Click this bar to view the full image. The original image is sized 1103x827.

I decided to use Silicone because of it's Properties:

- It is elastic and so not bothered by Vibrations;

- it's a Strong Glue once Dried;

- it resits perfectly to heat and cold stress;

- It can be removed with no Damages by applying the correct forces to it;

7) Carefully insert the Blow Off Hose into the Hole, make sure you push it in straight so that the Silicone Smears outside the Hose evenly sticking to the Cone Flaps

Do not worry, the Hose will go in no more than a Half on an Inch into the Cone, meaning that all the rest of the Filter will remain Untouched and Free to Breath

8) Carefully, without bending the Hose in the Filter, look inside the little Hole on top of the Cone and verify that the Silicone is not obstructing the Hose, if it is, grab a Thin & Long object and go inside the Filter to Push outward the Obstructing Silicone

Personally i used a 3" long Screw and cleaned off all the inside of the Hose frm the Little Hole on top of the Cone... REMEMBER it is mandatory that the Hose is not obstructed in any way: it has to Vent Freely into the Cone Filter.

Auto part Pipe Vehicle Fuel line Car

Land vehicle Vehicle Car Engine Auto part

9) let the Silicone Dry for at least 12 Hours... do not Drive Hardly 24 hours, time in which the Silicone will Dry Completely: you don't wanna shoot the Filter away after all this work

The Concept behind this Simple design is the Following:

Diagram Line Text Plot Slope

BURGUNDY = Filter | BLUE = Silicone | TURQUOISE = Pressure Air | RED = Noisy Air | GREEN = Filtered Air | BLACK = Hose

The Blow Off Pressure come Straight out of the Tube, right on front of the Tube there is the Drilled Hole on top of the Cone that creates the "Whistle Effect" while the rest of the Filter allows the Pressure to be Freely released on the Sides without creating Return Pressure that could Defy the purpose of the Blow off Valve.

10) Go Drive and... ENJOY

OK, it is not as loud as a Trumpet Blow Off Valve, but the sound you obtain is quite similar to what you would get by purchasing one of those High Dollars Blow Off Valves, and in reality, they are not much different inside than what this little job is.


P.S.: as of this Month, it has been 2 years and over 40k miles driven that i had this thing installed this way, and it still sounds awesome ;-)

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In b4 people say "This is a bad idea dont obstruct the BOV"

This does seem ok....but somewhat dicey...theres that risk of obstructing too much air, which is why I still cannot recommend that anyone try this.

Buy a $15 charge pipe, some silicone couplers, and a knock off ssqv if you want that sound done right on the cheap. Yeah, it may be a knock off but it will sound right and hold better boost than stock (until it wears out) and wont break your turbo
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