I've been putting alot of thought in what I want to do to my car this year, I can't decide between getting a series 5 jdm t2 engine and swapping or going supercharger. I know what is needed for both and the engine swap is not that hard, I've helped with 3 this past year (sorry Ridge_Tech) My question is with the supercharger. In my thinking if I add a supercharger to my full exhaust NA it will make my car louder. Right? I already hit 110 db just from revving and I don't really want it much louder than that, my parents can hear me 3 miles away from my house.

Price wise I am leaning towards the t2 engine right now but If I can get some more info on https://www.rx7club.com/forum/showth...threadid=22131 I might go the other way.

 

I wouldn't expect a supercharger to make much of a noise difference other than the mechanical noise of the supercharger.

The T2 swap will run you about the same as adding a supercharger if you replace the drive train, but unless you've got a 'vert it is cheaper just to buy a T2, than to convert a NA to a T2.

 

my supercharger on my 5.0 mustang makes a lot more
noise when under full boost(more air through engine)
makes for more Db's(allthough it should apply to rotary engine)

 

(xentrix is using puppybear's account)

Well I looked for 7 months for a t2 before I got my NA, they are really hard to find around here. I have access to several parted out TII's so I can get all the extra parts for a decent price.

I still think it would make my car alot louder, I have an NA with a full exhaust and people here know that it is really loud, now with a turbo the exhaust is muffled because that is what spools the turbo, but with a supercharger the exhaust just goes straight out so in my thinking it would make my car alot louder.

 

More air in = more air out.
more air out = more noise.

 

Yes, but the noise is more related to the velocity rather than the volume or density. Most of the noise is created by the higher-velocity exhaust gas shearing with the ambient air. Mufflers work by slowing down the exhaust so that it mixes better with the ambient air. Under boost, the exhaust gas volume will increase, which increases the velocity if the exhaust pipe diameter remains constant (I assume yours will remain constant unless you have an F-16 variable exhaust nozzle. ). Therefore, unless you use larger diameter exhaust pipes and/or better mufflers to slow down the exhuast, your car will be much louder when boosted by the supercharger.

The nice thing about a turbocharger is that the turbine wheel's job is to soak up the high-velocity exhaust and turn it into rotating power for the compressor. Also, the turbine creates higher-frequency noise which is directional and more easily dissipated in the atmosphere, especially by obstructions like buildings or other cars. In contrast, the NA creates lower-frequency noise which tends to be more non-directional and resists dissipation, which is why your car can be heard for miles in all directons.