EvilDave83

True, but being a V8, I cant imagine the loss wpuld change much.

530dpower

Hi,

I'll try this in my 535d.

one question:

If we remove the tubes from the valve, it will not cause any error in cb?

Thanks

greetings

Gangplank

Saw a post somewhere that someone also used a bolt to keep the exhaust flap open. Does it open in increments or if you jumper it with this mid will it be open all the way when Car is running?

EvilDave83

I used the bolt. Some people said the little vacuum mod would open it all the way, but in my case, it wasnt true. It WAS open more, but not wide open, and I could open it by hand and it would sound far better. Depends on where the bolt is too. In my case its about halfway open at start, and opens all the way at throttle.

Gangplank

I got down and took a look at my e60 545 exhaust the other day and didn't see a flap at the outlet. Is it up further in the exhaust?

EvilDave83

Whats there is a small bell looking thing to the upper right of the right muffler. If you feel up there, there's a small rod that runs to the pipe. The valve cant be seen because of the bend in the tailpipe. If your cars cool, you can start it, and using your hand, you can open the valve some to hear it. Theres a stiff spring that'll make it bounce back though.

Ozi5Msport

I fitted a 2008-2010 BMW 535xi 528 E60 OEM REAR BOYSEN END DUAL EXHAUST MUFFLER to my 525i.


With the valve closed (default) it just a little deeper and maybe louder than standard but definitely has more power at least up to 3000RPM - hard to tell after that.


With the valve open its much deeper and a little boomie in the back seats but sounds great from the outside.


The downside is that there is definitely a power loss below 3000 RPM.


I am going to look at removing the main spring from inside the vacuum valve and see if I can open the valve with gas flow pushing against a week spring.


Anyone played with one of these ?

EvilDave83

[QUOTE=Ozi5Msport;1552122]I fitted a 2008-2010 BMW 535xi 528 E60 OEM REAR BOYSEN END DUAL EXHAUST MUFFLER to my 525i.
Theres a dude from the local BMW and German car group with the same car as mine, (545i sport, now almost a Dinan stage) and he put his on the dyno. I'll try to see if I can get a picture of his slip. Once he disabled his valve, the hp averaged the same rating, and varied 1-3 hp on 3 runs. One of the guys there is European mechanic, at a small performance shop here in michigan named Autowerks. He explained the back pressure theory to us, and said on a V8 the only thing that'll change is how fast your catalytic converter heats up. According to him (this is unverified, but his status as a Euro-car guru is verified) tha valve is on there due to noise, and emissions regulations in Germany, California, and a few other places. Apparently in Germany, if your under a certain speed, or in residential areas, your noise has to be under a certain decibel. Soothe valve is on there for that reason. Anyways, the other dudes 545i was at like 262 (I think, not positive) at the wheels before the mod, and 261-263 after. So that averages the same. Not sure about torque, but if I remember correctly, it was negligible either way. I would think if anything, you would lose horsepower with the valve in tact. Thats why when you install high performance exhaust systems like the Magnaflow, you end up with Hp and torque gains, even though they dont have the valve. The science supports that, the better the engine can inhale, and exhale, the higher horsepower you should make. The back pressure thing apparently doesnt apply on the 545i and 550i, or any of the V8 cars and trucks. Either way, Im just regurgitating info Ive heard, and my opinion. It is possible that this is all B.S. Where did you hear that you would make more horse with the valve intact?
On to the next thing; I did the vacuum valve mod first, in the trunk behind the drivers side tail light. It only opened the valve a bit more. So in order to test it, I ran it, and held it open by hand. Ultimately, before I removed it completely, the little bell housing you have pictured appeared to be key. So I took a 1/4-20 drill bit, and opens the small vent/vision hole on the bottom. Then held the valve open by hand, and pushed a 1/4-20 x 3.5" bolt through it, behind the vacuum or bladder or whatever the red thing is in the housing. That held the valve open, and allowed me to test it for the next few days, and was easy to remove if I decided, or if I decide to sell to upgrade to the M5.
So, thats my 2 cents. Let me know what you decide to do, and if you have any questions about mine. The best thing would be to do at least a cat back exhaust, but money isnt always in order lol.
Have a great one!

Ozi5Msport

EvilDave83 Thanks for your comments, Interesting, I am convinced that :-
1) The valve is necessary for peak engine performance (exhaust gas flow).
2) If there were no valve the booming noise at lower revs would cause customer complaints.
3) Heating of the cat to operating temp 350C is an important factor for manufactures, I
doubt if closing the flap helps this as the flow below 3000 RPM is basically minimal and
with the pipe size, friction from flow etc. there is little or no back pressure. Make a
water manometer and check. The idea sounds good but doesn’t add up with testing.

My comments about the valve closed and open are just based on my observation. It’s been 3
weeks now and the car sound great from outside, very "booming" below 3000 especially in
the back seats with the valve open - but it defiantly is down on torque which is sad
because I like the lower tone (but not the booming). I am driving with it closed and its
better than the original factory in power and sound.

I am using a cable tie or I think you guys call them zip ties to hold the valve open
after sucking on a vacuum line, I do like your bolt idea.

BMW aren’t stupid and the engineering work in their exhaust is brilliant. If you get the
chance to cut a rear exhaust open you will be amazed by the complexity, internal megaphone


and effort to get pipe length inside the box. The pipe length and pulse wave is as
important as pipe size and that is mostly overlooked in the design of exhaust in intake
systems.

Still thinking of how to have the valve closed and just open on flow - BMW do that opening


the vacuum valve on RPM and load via the computer. So really you shouldn’t play with it
except if you like the extra sound at lower RPM but I think you may loose power as well
only dyno can tell

For me I am not going to all the trouble to try and emulate what you have as standard and then see if the ECU is programed so I will have it closed as 90% of my driving is city and the torque is more important than absolute power between 5-7000

EvilDave83

Interesting point. I don't believe BMW engineers are stupid, in fact Im such a fan I'm a permanent owner. Like I said, this is all only what Ive heard, but like all manufacturers, they make their cars a certain way to meet standards and regulations. On cars that are exported they often make them in a way that covers regulations in several countries. So it was told to me (again, I don't know this) that the valve was there for the noise regulations. But you make a valid point. However, I must say that I find it interesting that Dinan, and Magnaflow both make exhaust for these cars, and when installed there are verified horsepower and torque gains. From my understanding neither has the valve. So that begs to argue that the performance exhaust, even cat-back without the valve makes more power. I know Dinan makes one, or they did with the valve, but their higher stage setups don't seem to have it.
Like the Corvette, it is by no means as exceptionally engineered as most BMW cars (though the new Vette is pretty incredible) but still, when you remove the stock exhaust, and install a Borla exhaust it makes more power. It is louder, so a manufacturer has to abide by laws, in several countries. A major part of the Dinan upgrade, thats even approved by BMW and wont mess with your warranty, is exhaust thats louder, larger, and doesn't have the flap.
Also, I was an ASE engine mechanic for a few years, so Ive looked into mufflers. The most incredible one Ive seen was from a Porche 911. The way it was shaped, the baffles, it was really neat. I couldn't tell you why their shaped like that, but it seemed a lot more intricate than what you'd find on a Honda. Im a Mechanical engineer and do electromechanical work in an Oil Refinery now. All Im saying, is that I do the work on my cars. That doesn't make me an expert by any means.
Also, I believe that when BMW engineered this car, they took into account fuel savings, and noise, comfort, etc.
So, no argument, but if you find anything out, or Dyno your car please keep me updated. Im curious as to what happens. Did you say you have the 545i?