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Quieting the intake?
by
Gizmoman
on 22 Apr, 2014 05:30
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Now that I have the turbo sorted (K-14 to Holset HE200) and am drawing in a bunch more air, my intake is louder than the engine
I built a new filter housing and am drawing air in through the right pillar
I've done some reading but don't have a clear idea of the best solution - hoping for something simple. My first thought would be to get some dryer vent hose, form it around the square intake and run it up the pillar a foot or so. It will be tough to get the hose to stay in place but I'll figure something out. Maybe if I put a few bends in it on the way, it will deaden the sound a bit. I could also drill some small holes in the end of the housing around the edge (outside the sealing surface of the filter itself). Possibly bringing the air in several places will cancel out the in-rush through the single port I have now.
Any suggestions appreciated.
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#1
by
theman53
on 22 Apr, 2014 05:37
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The turbo that moves the air well also makes a lot of noise. Mine is in a lexan box and it is still louder than the engine. The car sounds like it has a turbo though. Probably like the intake, longer tubes make lower frequency so you may not hear it as much? Good luck
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#2
by
TylerDurden
on 22 Apr, 2014 05:48
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AIUI...
Generally, sound waves travel straight, so curved or serpentine ducting is effective if the inner surfaces are non-reflective (soft).
Heavy materials generally absorb sound better than thin or light, e.g.: metal castings vs. thermoformed plastic. Dynamat type wrap on all the thin surfaces can help absorb resonance.
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#3
by
carrizog60
on 22 Apr, 2014 13:45
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cant you try a OEM airbox?with the snorkel inside?
if nor maybe you can locate the intake on another side,farther from the cabin...
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#4
by
Rock3tman
on 22 Apr, 2014 14:01
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FWIW I'd try something like Dynamat on the outside and this: Auralex 2SF22CHA 2 x 2 Wedge StudioFoam 2" Foam
lining both the inside of what you have existing + an extension from the intake port.
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#5
by
745 turbogreasel
on 22 Apr, 2014 15:05
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are you wanting to go after whistle or resonance?
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#6
by
Gizmoman
on 22 Apr, 2014 17:45
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The turbo that moves the air well also makes a lot of noise. Mine is in a lexan box and it is still louder than the engine. The car sounds like it has a turbo though. Probably like the intake, longer tubes make lower frequency so you may not hear it as much? Good luck
Thanks, While the whistle is fine (actually less than the K-14), its the drone of the intake itself that gets to you over time and I'd rather not hear that at all.
FWIW I'd try something like Dynamat on the outside and this: Auralex 2SF22CHA 2 x 2 Wedge StudioFoam 2" Foam
lining both the inside of what you have existing + an extension from the intake port.
AIUI...
Generally, sound waves travel straight, so curved or serpentine ducting is effective if the inner surfaces are non-reflective (soft).
Heavy materials generally absorb sound better than thin or light, e.g.: metal castings vs. thermoformed plastic. Dynamat type wrap on all the thin surfaces can help absorb resonance.
Both great ideas. I'll see what I can rig up in the limited space. Possibly a tall thin box with baffles all lined with foam (if I can get it in the pillar)
cant you try a OEM airbox?with the snorkel inside? if nor maybe you can locate the intake on another side,farther from the cabin...
I don't have the stock intake (never did) and I doubt it could flow enough air. The other side is filled with my WAIC.
Thanks for the feedback!!
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#7
by
Toby
on 22 Apr, 2014 17:50
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I suspect part of your problem is turbulence in the transition from the small hose to that tin drum and from the drum to the square inlet to the outside air. I suspect that you will need to smooth up these transitions to have any chance of quieting it down. Pointing the inlet forward instead of at your feet may be the most important step, however.
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#8
by
Gizmoman
on 22 Apr, 2014 18:18
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I suspect part of your problem is turbulence in the transition from the small hose to that tin drum and from the drum to the square inlet to the outside air. I suspect that you will need to smooth up these transitions to have any chance of quieting it down. Pointing the inlet forward instead of at your feet may be the most important step, however.
Good point about the "tin drum" - that's about what it sounds like - a big bass drum on max reverb.
Hmm. . .I may have to spend the weekend making an entirely different intake - possibly rectangular with plenty of baffles. Wife's gonna love hearing that
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#9
by
745 turbogreasel
on 22 Apr, 2014 19:51
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Add a 1/4 wave dead end passage off your intake tube. Same diameter, departing at 90 degrees.
start around 26" the total length of your intake path will have a big effect as well. An experiment with dryer duct might get you in the ballpark pretty quick.
Wrinkle coating the inside of your can might also help break up the boom.
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#10
by
TimpanogosSlim
on 22 Apr, 2014 21:01
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I think turbogreasel has the right idea. It could also be a tube that goes to a chamber off the side.
Dunno about wrinkle coating. bed liner type material probably damps the heck out of vibration tho.
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#11
by
carrizog60
on 23 Apr, 2014 11:55
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i see high HP buils using stock airbox(the larger,square one), why do you think it may not flow enough?
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#12
by
Gizmoman
on 23 Apr, 2014 18:52
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i see high HP buils using stock airbox(the larger,square one), why do you think it may not flow enough?
Interesting thought, maybe I should have kept the 1.6 exhaust as well
Kidding aside, typically automotive engineers who design stuff like this don't design them for three times the capacity required - just a guess though.
I ran a quick calc (keep in mind, I am math challenged) and came up with 322 CFM for my engine at 3200 RPM @20 psi. In comparison, the 1.6 NA runs about 90.4 CFM@ 3200.
Granted the numbers are rough, but that's nearly a 256% increase in air volume over the stock engine.
A stock 2.1 gasser vanagon intake box (as you suggested) would be designed to flow approximately 119 CFM @ 3200 - still 170% less than required for my engine.
If anyone want's to take a stab how many CFM's I may be running at 20 PSI/3200 RPM, that would be very interesting. Turbo is an HE200, medium head porting and short 2-1/2" exhaust.
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#13
by
410
on 23 Apr, 2014 19:47
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A quick test using the factory air box and a sensitive vacuum gauge in the intake tract might answer your question. As long as you're seeing less than 15" water column you should be fine.
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#14
by
Gizmoman
on 23 Apr, 2014 20:07
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A quick test using the factory air box and a sensitive vacuum gauge in the intake tract might answer your question. As long as you're seeing less than 15" water column you should be fine.
Interesting concept, although I don't have a stock box to try your suggestion.
If you wouldn't mind explaining (in layman's terms) how that 15"w.c. relates to my engine's ability to receive all the air it can, that would be sweet.