What is it that cause's the hissing noise on some cars when you shut them off? I notice that the RA doesn't do it. I was just curious as to why. Thanks,

 

I was freaked out the first time i put ym intake on my accord. when i would shut it off it sounded like it took a hugh gasp of air before it died. but its completely normal, I forget what cause's it but my mechanic explaned it to me once

 

Oh I know its normal. My RSX used to do it....I notice that the RA doesn't do it though w/ my SRI

 

So nobody knows what cause's this? Or why our car doesn't??

 

I don't know what actually causes the noise, but when you put an intake on it you can hear the hissing noise because there is no air box to muffle it.

 

This is what i was told.....on some engines (depends on how the valve timeing is set up) when you kill the ignition and there is no more cumbustion happening but the momentum of the flywheel keeps the crank moving for a split second you get a slight kick back on the crank from a cylinder in combustion stroke; and that sends a quick pulse of air from a cylinder that is on intake stroke back though the intake manafold and with out the muffleing capasity of a air box it travles down the intake and creates a gasp. Now this might all be crap for all I know, but it's what someone told me. If anyone knows this is wrong let me know....but it makes sence to me.

 

Well, it makes sense....I think it also may have to do w/ compression too. Come to think of it...I've never heard of a car that was below 10:1 make that sound. My RSX did and thats 10.1:1 i believe...

 

My base model made that noise. It's still making that noise in car heaven.

The compression for RSX's

Base is 9.8:1
Type S is : 11.0:1

 

think of it like this... take a big metal pipe, and make a noise into it... it will echo A LOT. the car has always made this noise, you just couldn't ever hear it before because the stock air box is more restricting and muffles the sound. no worries man, its completely normal.

 

I don't have the stock airbox....I have the SRI and I'm not worried, just curious is all. I actually like that sound...hehe