TrevorS

iTrader: (1)

I understand the purpose of the black plastic box on the engine side of the OE intake hose (between the filter box and TB) is to reduce engine noise.

I'm told it does this by adding turbulence (presumably tuned) to the air flow. What I'm wondering is exactly what the impact is of that box on engine behavior. I would think that adding turbulence to the air flow would have the effect of reducing air velocity as well as disrupting the sound waves. If so, then I would think the TB would breath better without it.

Somebody also said that mpg drops with it removed. Presuming that tends to be true, the only way I can interpret it is if indeed the engine breaths better and hence can perform more strongly (leading to reduced gas mileage if the throttle is aggressively exercised).

Anybody know what the real deal is with that box and its impact on our engines?

FromTheOld

It's called a Helmholtz resonator. According to theory, they are tuned for a certain frequency and they cancel out the oscillations from the airflow. This reduces the sound and reduces the turbulence in a way, which means it doesn't really impose a restriction and in some cases, it helps with airflow. No point in removing it unless you want to hear the intake. If it helps by removing it....it shouldn't be noticeable.

TrevorS

iTrader: (1)

Thanks !

So naturally, I decided to search a little on car intake Helmholtz Resonator:

http://blog.autospeed.com/2003/11/30...-into-intakes/

http://www.rexresearch.com/helmholtz...resonators.htm

http://books.google.com/books?id=eL6...page&q&f=false

http://www.mx6.com/forums/mazda-626/...ml#post2036640

Lots more out there too. Thing that's especially interesting to me is not only are they used to cancel out noise frequencies, but also to improve air charging for engine torque improvement. I wonder if that second part is an explanation for MPG decline due to reduced intake efficiency? Maybe our xB2s actually get a bit of intake ram charge from those resonators! Think I'll keep mine installed !

FromTheOld

Well, a lot of people with xBs (or most common cars in general) don't really understand cars that well and just enjoy having noisy cars when it's not really helping them at all. It's the same as people who slam their cars without even realizing that the certain suspension geometries get worse as you lower it more. But it's not really their fault.....so many people are just uninformed and you've got people who just repeat the same garbage as other people do. I mean, you've even got people who think Throttle Body Spacers are useful on EFI cars....LOL.

TrevorS

iTrader: (1)

Yeah, I'm not really expecting too much from my smooth bore TBS project -- heck, it might even screw up the tuning of my intake resonator ram charge ! But hey, it's just an experiment !

FromTheOld

Hah. I wasn't poking fun at you, but there was this guy who insisted that his TBS had drastic effects, and he was actually on here. Sad stuff

pyroman131

Ha ha ha! Awesome.

sexby

lol might have been in my thread too!

ScionFred

iTrader: (1)

If those resonators help at all, it can't help much when independent dyno tests show a typical gain of ~10whp/wtq with a CAI. As for a change in MPG, the effect of adding or removing a noise-cancelling resonator assembly from the intake tract should be obvious.