GoldTypeS_RENAMED

Okay... by doing a search I've determined that it's normal for an intake to make a hissing sound at light throttle when the engine is cold. And there's also the "whoosh" sound that happens when you shut the engine off.

My question is... what exactly is going on here? I take it the hissing is the sound of the engine sucking air through the intake? Why is it so much more noticeable when the engine is cold? And what's the "whoosh"? Is that the sound of the air leaving the intake after the engine stops sucking air??

TIA

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2001 Acura 3.2CL Type S
Comptech Springs
Comptech Sway Bars
Comptech Headers
AEM CAI
PIAA 19169

Nashua_Night_Hawk

My theory is this:

1) The hissing sound when the engine is cold or better I describe it as sound of unbalanced rotating flywheel: This is sound is comming from the Throtle body. When the engine is cold, the Fast Idle will partially open the throtle the sound coming from the throtle is used to be muffled by the resonator box that you removed when you installed the CAI. When the egine fast idle is shut down, the sound will go away. Still you can hear the sound of sucking air when you push on the gas pedal.

2) The whosshing sound when you shut off the engine: is the sound of equaliztion of persuure after the engine is shut off. When the engine is running, there is a net flow a air comming from the outside to the inside of the CAI. And, the pressure is stablized by the constatnt flow of air. When the engine is shut off, the air that was going at constant flow has to come to a stop, i,e, building presure inside the CAI and the building of this air presure inside the CAI is the source of whosshing sound.

If I am wrong, I welcome any better explaination.

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Black, Ebony, 3.2 CL Type-S, NAV.
- 3M clear bra, by Stonguard (full front bumper, and side mirrors, and partial hood)
- Acura Spoiler, Moonroof visor
- Splash guards, Winter mats, Trunk liner
- Valentine V1 Radar Locator
- HELMS Service Manual
- PIAA 19169 road lamps
- 03/19/01: Injen Polished CAI
- 04/13/01: 235/40/18 NITTO 555 on 18x7.5, +45 offset, Koing Imagine in Silver with wheels locks

[This message has been edited by Nashua_Night_Hawk (edited 04-24-2001).]

silverESS

IMO both sounds suck-i feel really stupid after a cold start making all that hissing racket-it sounds like my new acura is a POS-wish we could figure out how to remedy the noise
...but they only last briefly and it's well worth what you get out of the thing-and the growl under WOT more than makes up for it. really the sounds are just minor annoyances-you won't notice them most of the time

IMO,POS,WOT,WTF? LOL

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you are not your fukking signature.

Shawn S

It’s really not that bad.
It only lasts a few seconds when you first start the car in the morning.
You can definitely hear it from outside, but with the windows up, you have to really listen to hear anything inside the cabin.

That short 10-second HISS is worth it to hear the HELLA SWEET sounds at 5,000+ RPM.

Shawn S


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Speed limits are for CARS and DRIVERS whose limits are easily exceeded !!!!!

2001 CL Type S - NAV - San Marino RED / Parchment - Spoiler - 35% Tint - Roof Visor - PIAA Lamps
GOLD Emblems & Grill - V1 w/remote - KICKER AMP w/(2) 10" Alumapro Subs - Xephyr CAI - Shine by ZAINO
For Photos see: PAGE 1 PAGE 2 PAGE 3 PAGE 4 V1 & SUBS

Jens H.

Nashua Nighthawk has got it right.These are normal sounds that are in a stock car muffled by the stock airbox and it's attendant sound suppression equipment.I have to date not seen any aftermarket intakes that can suppress this type of sound however these are minor things and not harmful in any way.We just started retailing Xephyr intake systems and one really cool thing about these that they do not emit that droning sound at an idle that other systems have such as the AEM do.Jens

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1992 mazda Miata lowered with Eibach springs KYB AGX adjustable struts Sparco racing buckets 4 point safety harnesses Momo steering wheel lo profile headlite system with PIAA superwhite bulbs Custom audio system Custom gauges Jackson racing supercharger with header and Greddy cat back exhaust and a ton of other stuff 2000 Honda Civic on APEX coilovers Full Alpine Audio system factory fogs with Piaa bulbs Catz ZETA high beam headlamp system H.I.D. Xenon low beam tinted, custom taillites and on and on

silverESS

hey H-town boy,
waddayamean a few seconds? mine hisses until the car warms up
...which results in embarassment for at least a couple of stoplights
are you having diff results? i'm wearin a xephry too

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you are not your fukking signature.

Shawn S

I don’t know….I only hear it when I start the car and back out of my garage.
As I pull out onto the road I hear it a little bit more.
By the time I get to the stop sign about 1/8 mile up the road, I don’t hear anything.

Shawn S


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Speed limits are for CARS and DRIVERS whose limits are easily exceeded !!!!!

2001 CL Type S - NAV - San Marino RED / Parchment - Spoiler - 35% Tint - Roof Visor - PIAA Lamps
GOLD Emblems & Grill - V1 w/remote - KICKER AMP w/(2) 10" Alumapro Subs - Xephyr CAI - Shine by ZAINO
For Photos see: PAGE 1 PAGE 2 PAGE 3 PAGE 4 V1 & SUBS

[This message has been edited by Shawn S (edited 04-24-2001).]

silverESS

mine isn't too loud until i have to step on the gas-then it sounds really dumb. it increases and decreases depending on the pedal. it does NOT sound right
prolly lasts for a minute or two

sure that i'm scarin goldtypes now-sorry.
really, it's okay-i'm just a pissy freak, i can't stand squeaks or rattles either

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you are not your fukking signature.

silverESS

maybe it's just warmer in pennsylvania

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you are not your fukking signature.

Ult

Hey Night_Hawk,

wow. at first I discounted you as a young teen based on your avatar... but sheesh! well written explanation. I tip my hat to ya, man.

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-Ult

EricL

1. People are already bitching about the price of these units. (If you haven't, please excuse me.)

2. The original system had a Helmholtz resonator to: a. reduce the intake roar b. to silence the hiss.

3. If you have ever seen a good pistol silencer or a "glass pack", then it would be possible to build a "pistol type" silencer for the CAIs that would eliminate the hiss and only remove a small fraction of a HP.

The end of the CAI would look like a glass pack muffler and would have a foam like material in the "outer" casing vs. the fiberglass typically put in a exhaust muffler.

If enough people complain, it can be eliminated...

Note: any noise emanating from the tube itself NOT the K&N would need to be eliminated by damping materials.


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Silver 2001 CL-S with NAVI

• Mud guards
• Wheel locks
• Toyo T1S 235/45ZR17-97W* Proxies on 17x8" SSR Competition wheels (48lbs less than stock)
• Kevlar/SS Brake lines ordered
• Comptech headers & sways ready
• Silver AEM CAI ready
• 8 coats of Zaino magic

GoldTypeS_RENAMED

don't worry... you're not scaring me. I have the intake already and am living with the sound. It was a little disconcerting at first, but like anything else... I'm sure I'll get used to it!!