Ive been experiencing this sort of grinding hiss that seems to be coming from under the front passenger-side. It usually occurs from a stop when I lightly accelerate and then again around like 40 mph when Im accelerating hard. When I lightly accerlate from a stop I can hold the hissing noise if I hold the rpms at about 2200.

Ive found via the search about Y Pipes making a hiss and also some intakes. I guess Im just trying to make sure something else isnt wrong.

I have a 96 Auto - Popcharger/Cattman Y/RT Cat. I also started to notice this more after I added the JWT ECU.

Im thinking: loose exhaust manifold bolt, exhaust leak, or Im just crazy and it's the infamous Y Pipe hiss.

Any ideas?

 

my first thought is that your alternator bearings are going bad. Im saying this because just today, my alternator is staring to act up(see my post in general forum) and I did a searched and read up on topics and the most problems that came up are grinding, whining, noises that come from the engine compartment on the passenger side of the car. Perfect matchup to what your describing. Do a search and you would be amazed at how many ppl have this problem

 

Hmmm. I dont know, the difference between the noise you are experiencing and the one I am is that you said the whine continues as the rpms climb. For me, when I accelerate from a stop or a slow roll, I get the hiss and then after a second it goes away. It's almost as if the hiss happens when the throttle "gasps" for air.

 

I think I've got the same thing, but mines at 3K rpm intermittently.

 

Do you have a Y Pipe. Im starting to think it's just Y Pipe hiss.