Performance with 2.5i Sound Generator Mod

[Fanatic]

Hi all,

I recently retrofitted a sound generator to my 2004 Z4 2.5. Though the sound is phenomenal I have a slight feeling that I have lost a bit of power in the mid rpm's. Could it be that the larger boot from the 3.0 needed for the retrofit, plus the loss of air going to the SG are stealing a bit of power? :thumbsdown:

Has anyone else with this mod noticed something similar?

Cheers.

 

[Fanatic]

Nobody??

 

[pvr]

There is no relation between the SG and the air the engine gets ….

 

[inkey$]

There is no relation between the SG and the air the engine gets ….

+1
Its just a pipe filled with foam to dampen engine noise into the cabin. Removal of foam only increases noise levels.

 

[Fanatic]

Actually the sound generators one side is bolted on a tube that is leaving from the air intake, so some air does get redirected....its not just a pipe...its a system with a membrane that vibrates with the incoming air and engine vibration and that sound is directed inside the cabin.

I know what a sound genrator exactly is, I did the whole retrofit myself...

Nobody has done the mod on a 2.5????

 

[inkey$]

Actually the sound generators one side is bolted on a tube that is leaving from the air intake, so some air does get redirected....its not just a pipe...its a system with a membrane that vibrates with the incoming air and engine vibration and that sound is directed inside the cabin.

I know what a sound genrator exactly is, I did the whole retrofit

Sorry, then why ask the question?! I still think any power loss/gain is in your head.
Unless you have a head thats a dynomometer of course.

 

[danmiddle2]

It'd be hard to tell for sure without a before / after dyno.

It's possible that the "seat of your pants" dyno is getting skewed because of the additional noise (i.e. you are possibly not pushing it as hard because of the increased noise?) just a thought.

 

[Fanatic]

But I did not ask what a SG is, or how it works. I asked if someone else who has done the mod on a 2.5 has felt maybe the same as me. It's true that it could only be my sense and not reality.

BUT. We have two things in the mod. First of all a larger boot that is installed between the air filter and the induction and secondly we have SOME of the air that was normally going straight to the engine redirected to the sound generator. In any case these two ARE variations of the incoming air compared to before and COULD affect performance. And could means I am not sure and that is why I am looking for others to see if they have felt the same. Not people with the 3,0 because they have not felt their car without the SG.

 

[Fanatic]

PS With the SG I am pushing it much harder because I love the sound

 

[MrPT]

I've retrofitted a 2.5si. No perceivable performance impact, although without the foam in the performance doesn't match the noise level generated, particularly above 6k rpm!

Sent from my GT-I9100 using Tapatalk

 

[pokeybritches]

There is no change in engine performance. The engine sucks in air when a piston creates a vacuum... air isn't pressurized in the intake, so it doesn't blow out. The engine pulls air in.

If there was any loss in air, you would be running rich and likely see a check engine light, because the ECU uses the MAF sensor readings in conjunction with a few other sensors (like O2 sensors) to determine how much fuel to spray. If the MAF sensor measures a certain amount of air, and some of that air is lost along the way, and then it sprays the fuel it expected to spray... the O2 sensors will read that the engine is running rich. Usually any holes in the intake piping will result in unmetered air coming in, so a lean condition would result. In other words, the sound generator would be sucking in extra air, not blowing it out.

If you're really concerned, hook up an AFR gauge and weld in a wideband O2 sensor.

 

[pokeybritches]

All of what I described is for a naturally aspirated engine of course. On a forced induction emgine, holes in the intake piping WILL result in a loss of air, known as "boost leak", and you'll see a rich condition and power loss.

 

[Fanatic]

Ok thanks for the technical input. That is why I said I had the feeling and sure i could be wrong. Just wanted to hear if others with the same mod noticed anything.