Intake Silencer Delete (540i, M62)

[E39 6spd]

I've made this mod and there were no sound difference on my 02' 540i/6.

I'm going to do this today, will post back.

[CBILL7]

I have a Dinan CAI, which I modified by bring the (K&N) filter up under the hood for much better sound. I think alot of the stuff about keeping down low for air temperature is a bunch of hooey. The main issue is unrestricted high volume airflow. That sound is a different sound than from modifying the silencer, which seems to be a lower frequency sound which I only here at about 3000 rpm when pushing it hard.

[ethirty9]

Is this the exact same process for a 2001 525i?

[ethirty9]

Ok so i took everything apart just to see if i can do this on my 525i, it's a 2001, and when i went to go look at the box and how it connects to the hose, the rubber part that connects the hose to the box is not just slip on and off. It looks like theres some kind of glue holding it and i don't just want to rip it off. any advice? ... anyone?

[Monty540]

I have done this mod and a few others today to my 540i late 98 build- it is non vanos but also no Idle control valve.

First up this is what I did-

Cleaned MAP with electronic circuit cleaner
Cleaned throttle body with throttle body cleaner
Removed the plastic and wire meshes from the MAP

I then got to removing the silencer which was integral with the tubing so I cut it and put in a cap with some Sikaflex sealant to smooth out the intake tubing.

Then I looked at the airbox filter side and decided I would keep the horn for now as the design should help with flow. However the matrix of plastic on the filter housing sure would slow down the flow- probably just for strength and maybe slow/quieten the intake. So I got out the die grinder and smoothed the airbox plenum flush.

Results-

Much nicer sound and a bit more throttle response.

Didn't take long and definately worth the effort.

Which part did the benefit? hard to tell as I did them all at once but much nicer and it does go a bit harder.

Sea of the pants dyno gives it a big plus.

Monty

Update after 1 day post deletes,

Definitely does goes a bit a better and much more responsive than before.

Will be doing the Exhaust I hope tomorrow and will see how it is then.

Monty

[Monty540]

Ok time to report back on my mods and some pics.

First up is the throttle body which was dirty and a now has been cleaned with Throttle Body cleaner. I held open the butterfly with a ragged screwdriver and cleaned both sides. Much cleaner and actually looks brand new! - pity the electronic throttle sucks.

2nd- The intake side of the airbox- all cleaned up with no more internal bracing. The bracing is on all sides and would have created a large decrease in flow. It would have also provided a dampening of the intake sound by bracing the lid and a extremely large boundary layer of air over the mesh slowing the flow.
I used a air-powered die grinder with aggressive carbide cutters to quickly remove the bracing, then a sanding drum to smooth it out.

Be careful not to remove to much and go through.

No bracing = more top end, growl and a little less torque off idle.

3rd- Here is the underside of the inlet tube, with the silencer removed, hacked off the silencer. I then added a cap.
I placed some heavy duty tape over the inside of the tube to cover the port leading into the silencer. Now I filled the port hole from the outside with black body sealant, then pushed the cap in and wiped off the excess sealant. When sealing I held down the tape flat against the hole with my hand. This made sure it would be fairly smooth flow over the hole once dry.

After a 3-4 hours it will be dry, and then I ground down the cap to be flush on the outside. I could have used a black cap but you don't see it, so I didn't bother. The result of all this is a smooth flow of air in place of the silencer. In great contrast to the silencer and its reduction in sound and thus flow rate.

The resulting mod adds a growl to the induction and better flow. I was quite pleased by this little mod combined with the air-box mod.

Silencer delete= improved flow, a growl to engine and bit less in bottom end.

4th- Here you can see the air-box with the intake horn replaced. Looks far different than before, and obviously looks like a better flowing design.

5th- Here is the Mass airflow sensor. I carefully removed the plastic grid at the filter side and the small alloy mesh- with a very small flat screwdriver. Again a mod for airflow improvement, the grid and mesh really reduces the area of the intake and slows everything down. Sure it does align the flow past the sensor and stop crap getting into the engine- which is a bit redundant with the airbox and filter.


So, it did not take more than a hour to do except the drying time of the sealant. Overall result is a increase in flow and much better sound from the induction. She seems better in the top end but has lost a little down low. I am happy overall though as throttle response seems better and she just sounds better. I did all the mods at once so can only guess at the individual effects of each mod. But my seat of the pants says it feels faster.

Hope this helps explain what I did.

Next its off to get a muffler mod done.

Monty

[legitsnowe39]

did this on my 528i. took 15 mintues. the intake system is really simple. I just took out the big silencer box and put in a PVC cap backwards and clamped it extremely tight. It looks like the PVC cap is too big to go through the shutter flap of the intake, if it were to be sucked in. But I drove it right after and there is definitely a growl. I think if you have a stock exhaust you wont hear it, but anything other than stock you definitely will.

Now... M50 manifold is next

[jamesdc4]

I believe the silencer acts as a shock absorber for air waves going through the intake. It is like adding a length of tubing above a water faucet so when you shut the water off the column of water in the extra length of tube acts as a shock absorber and you don't get 'banging' in your water pipes. Removing this piece eliminates your 'shock absorber' function and may cause the air to be more turbulent going through the MAF and into the intake manifold. I don't see why removing it would give you any improvements at all. Once it fills with air, the air probably just sits there to dampen air turbulence and even out the flow above since air is compressible.

A lot of these mods are in the 'eye' of the beholder. I agree that BMW probably was paying someone much smarter than me to figure out they needed this part. Maybe it is only a consumer satisfaction item for 'ride' quality and quietness, I am not sure.

Have a great ride in your BMW.

I added this to the OP:

There seems to be LOTS of confusion/misunderstanding of how the intake systems on cars work. So instead of continuing to post things scattered in various threads, it'll all go here (hopefully).

Like most things, bigger isn't always better. Yet we see people try to put the biggest exhaust, largest intake, and widest tires on the car they can manage to fit. I blame a combination of marketing and stupidity for this, but perhaps it can be fixed.

This thread will focus on the basics of intake design BEFORE the throttle body. I think I've covered intake manifold design here on BF.C before. I'll make some reference to the intake manifold design here as well, but I'll leave it as something that BMW designed and nobody here will bother to change. If there are any of questions on its design, I'd be happy to start another thread for that as well.

So, onward. The intake manifold is designed to take advantage of resonances that occur naturally in the intake. These resonances are caused by the drawing of air into the cylinders. As the intake valves open/close, they create pressure waves. The mass of the air in the intake is accelerated torward the intake valves on the intake stroke, and when the intake valve closes, that mass + velocity has momentum. This creates a pressure wave that reflects off the closed valve and back out of the intake runner. The harnessing of this pressure wave, and tuning of its frequency, allows the engineers behind the intake manifold to take advantage of it. The reflection of that pressure wave off the back of the intake manifold, combined with other pressure waves from the other cylinders in harmony, will create a pressure wave torwards the intake valve that will arrive just as it opens at certain RPM's. This lets the pressure wave assist with the filling of the cylinder, effectively cramming the air in, instead of just the piston trying to suck in air.

These intake resonance pulses don't just stay confined to the intake though. With the throttle body open, they travel outward through the intake pipes until they find something else to reflect off of. Usually they work their way through the MAF and find themselves bouncing off of the air filter. From this, you can see that changing the length, diameter, or shape of the pipe between the TB and the air fliter will change this frequency. That in itself shouldn't be a problem, but usually these intake resonances can cause slight issues. Most common of which is giving bad readings from the MAF sensor.The MAF is counting on air flowing in only one direction over its sensor, and reversions of the air will greatly confuse its reading. It will be seeing more air "going into the engine" even though that air is actually going away from the engine. This means that small reversions, which should be subtracted from the "air into the engine" number are actually added. The ECU uses this value for fueling, and without knowing why, gets it wrong.

This is where resonance control comes into play. Enter the Helmholtz resonator. The helmholtz resonator is there to attenuate the pulses that are outside of the intake plenum. A helmholtz resonator is a cavity and a duct connected to the intake pipe. Its the triangular thing hanging off the air box on the E36's. Its the gonzo nose looking thing on subarus and the likes. etc... Its the "random empty box" hanging off the intake pipe that most people look at and go "wtf?"
Yes, it has a purpose.

The diameter required for the intake duct is also an easily calculated bit. Its generally accepted that you want the intake velocities to not exceed 180 ft/sec. I'd be willing to bet that the factory was pretty damn spot on with the sizing of that stuff. So I'd be willing to "randomly guess" that somewhere around 3" is the right size for the intake pipes.

Next bit, Notice how straight and short the tract is from the stock airbox to the MAF? thats intentional. As is the air horn (velocity stack) inside the airbox. A bent piece of tube, even a mandrel bent one, will create turbulence. There is an exception to that though, and thats if you can get the air to swirl through the pipe, completing at least one full revolution through the bend. If one full revolution is completed, then all the air in the pipe has traveled the same distance and there is nothing to create a funk with the flow.

Hopefully this will prompt someone to actually "design" a proper intake pipe, as well as cut down on the random un-engineering of the intake system.

[540i6e39]

Ok so i bought a CAI intake and installed it yesterday.. and decided to do a silencer delete... so for months when i floor my car it sounds like my engine is screaming, i hear all the time.. you have a supercharger on there dont you! lol.. So when i lifted the silencer out i noticed it had a cut in it... so that is after the maf sensor so im wondering if that was why my dyno sheet kept saying i was running rich? Anyways it does sound alot better, the exhaust and Cai intake over the stock airbox.. my car feels way faster( mainly from fixing the air leak i had) but i seemed to have lost alot of low rpm throttle response but my car is crazy fast at higher rpms...

[jamesdc4]

Ok so i bought a CAI intake and installed it yesterday.. and decided to do a silencer delete... so for months when i floor my car it sounds like my engine is screaming, i hear all the time.. you have a supercharger on there dont you! lol.. So when i lifted the silencer out i noticed it had a cut in it... so that is after the maf sensor so im wondering if that was why my dyno sheet kept saying i was running rich? Anyways it does sound alot better, the exhaust and Cai intake over the stock airbox.. my car feels way faster( mainly from fixing the air leak i had) but i seemed to have lost alot of low rpm throttle response but my car is crazy fast at higher rpms...

All these impressions from the butt dyno?

[540i6e39]

All these impressions from the butt dyno?

I'm surprised that you didn't read what i actually wrote before you posted so i will copy and paste for you to read again.....

My car feels way faster(mainly from fixing the air leak i had)(after the MAF sensor)

Didn"t see any butt dyno comments in my post. I had a air leak after my MAF.

Edit: Also wanted to add that im thinking about putting my Silencer back on.. i actually will have to buy another one with a new elbow to the throttle body since mine was ripped... it does seem to make my exhaust growl a little more but the lack of throttle response is not worth this mod. IMO

[jamesdc4]

I'm surprised that you didn't read what i actually wrote before you posted so i will copy and paste for you to read again.....

My car feels way faster(mainly from fixing the air leak i had)(after the MAF sensor)

Didn"t see any butt dyno comments in my post. I had a air leak after my MAF.

Edit: Also wanted to add that im thinking about putting my Silencer back on.. i actually will have to buy another one with a new elbow to the throttle body since mine was ripped... it does seem to make my exhaust growl a little more but the lack of throttle response is not worth this mod. IMO

My apologies. What I said was in jest.
I read your post thoroughly. I just got back from work and let's just say I was in one of those moods.
If you look at the post before yours, read what I quoted.

[540i6e39]

My apologies. What I said was in jest.
I read your post thoroughly. I just got back from work and let's just say I was in one of those moods.
If you look at the post before yours, read what I quoted.

No problem... im seriously so glad i found that leak! If i have a air leak after the MAF that would cause me to run rich right?

[jamesdc4]

No problem... im seriously so glad i found that leak! If i have a air leak after the MAF that would cause me to run rich right?

I don't know about running rich, but I'm pretty sure it would cause issues.

[OldSkoolBMW]

I put in a 1 5/8" freeze plug with some seal retainer on it.. Fit snug on the rubber boot.. no chance of getting sucked in..

[540i6e39]

I put in a 1 5/8" freeze plug with some seal retainer on it.. Fit snug on the rubber boot.. no chance of getting sucked in..

99 and up 540i is different then 97/98... you cant just pull off the silencer.. its all one piece. I had a leak there... ended up putting a rubber gromet in the hole and putting a 3/8 cap on the inside. works great! just got my dinan stage 2 software installed today! car sounds great!

[topaz540i]

The a.f.e. C.a.i. Absolutely makes more power. Anyone that says it doesnt has never tried one. Simple physics. Better flow=more power. The a.f.e. Intake sits right in front of the ram air tubes comng out of the fender anyway.

[bondovw]

I was always told not to remove screens in air flow meter that they are there for a reason and afm will not work right without them?

[Xeniczone]

The a.f.e. C.a.i. Absolutely makes more power. Anyone that says it doesnt has never tried one. Simple physics. Better flow=more power. The a.f.e. Intake sits right in front of the ram air tubes comng out of the fender anyway.

How do you know you are getting better flow and more power? Your butt dyno must be more calibrated than mine.

That likes those people that kick tires to find out how much air is in them. *thump* *thump* "Yes sir, that be having 28 PSI in it there son."

[540i6e39]

How do you know you are getting better flow and more power? Your butt dyno must be more calibrated than mine.

That likes those people that kick tires to find out how much air is in them. *thump* *thump* "Yes sir, that be having 28 PSI in it there son."

Lmao

[AHay5]

Any feedback from I6 E39 drivers?

[540i6e39]

Any feedback from I6 E39 drivers?

Imo a simple k & n drop in filter will make more power then a cone filter sitting in the engine bay. I think a wheelwell mounted cone filter will make more power then both. The engine bay cone filter is sucking air mainly from the engine bay which is why they are called hot air intakes. The drop in filter is sucking outside air directed from the plastic ram air.

I would also imagine a v8 engine bay would be hotter then a v6 and a 4 would be cooler then both. Imo

Less room more heat, more engine bay room, cooler air.

[topaz540i]

the afe has a heat shield. It gets its air from the same two ports in the fender that the stock airbox gets it from.



i wish i had a better pic of the vents in the fender.

[540i6e39]

the afe has a heat shield. It gets its air from the same two ports in the fender that the stock airbox gets it from.

i wish i had a better pic of the vents in the fender.

And maybe it adds power, or maybe its still under the hood and in the hot engine bay, getting some hot air? You wouldnt know unless you did some dyno runs and tried a few different intakes and compared them. I have done them and seen gains on different cars I have owned growing up, but the stock airboxes werent like the airbox of a german cars. Also the stock airbox had a crappy cheap airfilter in it and not a k & n drop in , so of course u would see some gains with a cone filter.

[EditTim]

The a.f.e. C.a.i. Absolutely makes more power. Anyone that says it doesnt has never tried one. Simple physics. Better flow=more power. The a.f.e. Intake sits right in front of the ram air tubes comng out of the fender anyway.

Sound? Sure.
Power? Highly doubtful. Any dyno results from just a filter change?

Here's a couple:


https://www.youtube.com/watch?v=PAIxeQUSg-Q

...for the cone filter.

and

https://www.youtube.com/watch?v=gCi2...feature=relmfu

for the whole CAI.

There are others...