X35d exhaust upgrade?

[leo95se]

The x5/x6 m models have the best sounding exhaust of any bmw. The growl and pop is truly amazing. While a lot of that is the motor I wonder how much is the muffler. Anyone do an upgrade on an x35d? I think an exhaust on a diesel could sound pretty unique.

[Kzang]

I would be interested to hear what the exhaust sounds like on a diesel!

[lowlevelhell]

Originally Posted by leo95se

The x5/x6 m models have the best sounding exhaust of any bmw. The growl and pop is truly amazing. While a lot of that is the motor I wonder how much is the muffler. Anyone do an upgrade on an x35d? I think an exhaust on a diesel could sound pretty unique.

An exhaust on a diesel, at its best, will sound like many of the large pickup trucks you hear with tricked out exhausts. Loud, growly, but none of the raspy baritone you get from a V8. The main reason is that diesels and gas engines burn fuel differently. A spark-ignition engine produces a smooth flame front in the cylinder, and the result is very predictable exhaust outlet pulse and pressures. These produce that smooth, even, booming sound we associate with a V8. Diesel fuel doesn't ignite with a spark. It explodes in a less predictable manner in the cylinder because it ignites with pressure and heat. This results in cavitation and the traditional "clatter" of a diesel motor.

More importantly, the X5M will always sound better because it has 8 cylinders set on a fully cross-plane crankshaft. Because internal combustion car engine run on a 4-stroke cycle, any multiple of 4 in the cylinders produces a more even, pleasing note. They also vibrate much less longitudinally and horizontally, but that's a different story altogether. Sixes just never sound as good as eights. It's a sad fact of life.

Long story short, a "loud" exhaust on a diesel would give you a clattery, truck-like sound, akin to what you hear out of the redneck fellas who juice their Cummins diesels up. You'd get more turbo noise, too. Probably not what you had in mind.

[JustAnotherGuy]

Well said.

Originally Posted by lowlevelhell

An exhaust on a diesel, at its best, will sound like many of the large pickup trucks you hear with tricked out exhausts. Loud, growly, but none of the raspy baritone you get from a V8. The main reason is that diesels and gas engines burn fuel differently. A spark-ignition engine produces a smooth flame front in the cylinder, and the result is very predictable exhaust outlet pulse and pressures. These produce that smooth, even, booming sound we associate with a V8. Diesel fuel doesn't ignite with a spark. It explodes in a less predictable manner in the cylinder because it ignites with pressure and heat. This results in cavitation and the traditional "clatter" of a diesel motor.

More importantly, the X5M will always sound better because it has 8 cylinders set on a fully cross-plane crankshaft. Because internal combustion car engine run on a 4-stroke cycle, any multiple of 4 in the cylinders produces a more even, pleasing note. They also vibrate much less longitudinally and horizontally, but that's a different story altogether. Sixes just never sound as good as eights. It's a sad fact of life.

Long story short, a "loud" exhaust on a diesel would give you a clattery, truck-like sound, akin to what you hear out of the redneck fellas who juice their Cummins diesels up. You'd get more turbo noise, too. Probably not what you had in mind.

[leo95se]

Nice explanation. Could be a fun experiment! Really through off the rednecks that I pass by. Haha

[Kzang]

OP, I've not heard any "pop" from a M car before.... or are you referring to the 35i with M Performance exhaust??? I also think some inline 6 gas engines sound better than certain V8's but this is all subjective of course..

[lowlevelhell]

Originally Posted by leo95se

Nice explanation. Could be a fun experiment! Really through off the rednecks that I pass by. Haha

Heck, you can pull your DPF while you're at it, add a smoke switch, and "roll coal" a bit.

[42pilot]

Originally Posted by lowlevelhell

An exhaust on a diesel, at its best, will sound like many of the large pickup trucks you hear with tricked out exhausts. Loud, growly, but none of the raspy baritone you get from a V8. The main reason is that diesels and gas engines burn fuel differently. A spark-ignition engine produces a smooth flame front in the cylinder, and the result is very predictable exhaust outlet pulse and pressures. These produce that smooth, even, booming sound we associate with a V8. Diesel fuel doesn't ignite with a spark. It explodes in a less predictable manner in the cylinder because it ignites with pressure and heat. This results in cavitation and the traditional "clatter" of a diesel motor.

More importantly, the X5M will always sound better because it has 8 cylinders set on a fully cross-plane crankshaft. Because internal combustion car engine run on a 4-stroke cycle, any multiple of 4 in the cylinders produces a more even, pleasing note. They also vibrate much less longitudinally and horizontally, but that's a different story altogether. Sixes just never sound as good as eights. It's a sad fact of life.

Long story short, a "loud" exhaust on a diesel would give you a clattery, truck-like sound, akin to what you hear out of the redneck fellas who juice their Cummins diesels up. You'd get more turbo noise, too. Probably not what you had in mind.

I agree with most of this, except the point diesels are "less predictable" ignition. This is completely wrong. In fact, some smaller training aircraft, including mutli-engine models use small diesel engines. If any part of the diesel cycle was unpredictable, it would not be used and the engine would come apart. The sound is different due to increased compression ratio, ignition (heat and pressure rather than spark), and fuel timing (whereas a gasser uses a spark for timing). The intake, injection, combustion and exhaust on a diesel is very predictable, precise and sustainable over hundreds of thousands of miles. If you don't believe my statement, talk to Audi and ask how they won 24 Hours of Le Mans in a diesel car, year after year.

In addition, the "clatter" is the injector solenoids firing, not the combustion. When I turn my Powerstroke to the "ON" position, it primes the injectors and you hear clatter - this is also a diagnostic advantage too: uneven clatter and you will melt a cylinder. Newer diesels are using different injection technology or strategies which lower the clatter to next to nothing. My 35d motor doesn't clatter but on a cool day, you can hear the combustion until it's warm. My 1995 3930 Ford New Holland tractor clatters though but the technology is slightly different.

Putting an after-market exhaust on a 35d will be tricky if you are looking for a throaty sound. It still has to go through the turbo (which muffles), the CAT, the DPF (all which muffle the sound or pressure waves) then to the muffler.

And I think a nice V8 diesel, like my 6.0L, with a turbo-back 3in free flow exhaust sounds awesome, especially at wide open throttle - it is a throaty roar even at 3500 rpm. An in-line 6 Cummins in a Dodge, not so much...

[lowlevelhell]

Perhaps I wasn't clear with "unpredictable." Instead of a flame front, you get an explosion that can technically start anywhere in the mix cloud, or at multiple points at once. Swirl effects in the combustion chamber based on engineering designs can reduce this, but you're still stuck with an air/fuel cloud that will ignite at whatever point gets hottest first, and not at the spark gap.

Diesels are certainly quite predictable systems overall, especially with modern injector technology.

Injector noise aside, my understanding is that much of the clattery sound comes from ignition and cavitation in the cylinder.

At any rate, I appreciate your insights and it sounds like we're getting to the same end....not much value in a crazy exhaust on the 35d.

[twelve535i]

I don't know anything about diesel predictability, but here's a vid of a 335d

It looks like the cars sounds good under load or heavy revving but no so much under light revving

[Kzang]

Every BMW turbo diesels I've heard on Youtube has that turbo whistling sound on the exhaust.. IMO doesn't sound very pleasing...

[wjbender]

Originally Posted by lowlevelhell

Perhaps I wasn't clear with "unpredictable." Instead of a flame front, you get an explosion that can technically start anywhere in the mix cloud, or at multiple points at once. Swirl effects in the combustion chamber based on engineering designs can reduce this, but you're still stuck with an air/fuel cloud that will ignite at whatever point gets hottest first, and not at the spark gap.

Diesels are certainly quite predictable systems overall, especially with modern injector technology.

Injector noise aside, my understanding is that much of the clattery sound comes from ignition and cavitation in the cylinder.

At any rate, I appreciate your insights and it sounds like we're getting to the same end....not much value in a crazy exhaust on the 35d.

The ignition in the diesel is more akin to detonation in a gasoline engine.

[stewy604]

I too have been researching something on this end...and to no avail. Typically an expensive endeavour to be a guinea pig. It would be nice to see an intake / exhaust upgrade for us diesel guys, mated with a tune...would defintely wake this vehicle up a little. I love the power delivery out of the box, but more is always better.

[lowlevelhell]

Originally Posted by wjbender

The ignition in the diesel is more akin to detonation in a gasoline engine.

Yep, which is why a carbed gas engine exhibiting run-on is said to be "dieseling."

By the by, I hate Hollywood always uses the sound of an engine dieseling to indicate a car dying.

[twelve535i]

Originally Posted by stewy604

I too have been researching something on this end...and to no avail. Typically an expensive endeavour to be a guinea pig. It would be nice to see an intake / exhaust upgrade for us diesel guys, mated with a tune...would defintely wake this vehicle up a little. I love the power delivery out of the box, but more is always better.

If you like anything you see on a youtube vid of a 335d, you can most likely modified the exhaust to fit your car

[XxBBVTMxX]

Fairly new to the forums. Was reading up on your comments last night gentlemen. I personally do not like my EOM exhaust on my 35d M Sport. So I am hoping my project turns out well..

-Vibrant 10632 Street Power Oval Muffler
-MMI Motorsport Dual Wall, Staggered, 3.5" Dual Tips
-New Piping from DPF to Muffler

All 304 stainless steel, but thinking if I want to do some powder or ceramic coating. Talked to the manufacturer and they said the muffler is free flow, safe on diesel applications, and sounds a bit higher than stock but not ridiculous. I'm not looking for ridiculous sound, I just want more free flow exhaust. Waiting on the parts, more to follow I guess..



UPDATE:


Alright, so muffler and tips are put in on my 35d.  Pretty happy with the setup and look, although I had to got through two separate shops because the shop that did my muffler did not want to do the tips after they began the work. Apparently, because of the heat shields being so close to the back of the tips.  I ended up finding another shop that could modify the back of the tips a bit and get it done 🤷🏽.

Drove through some rough streets to ensure there is no banging or metal clanking coming from under the vehicle.  It is as quiet as OEM.

PROS;
-The muffler is straight through and safe for Diesel applications
-Perfect size, not as long as the OEM muffle and does not touch the heat shield
-It setup sounds just like OEM
-Tips stick out less than half an inch which was my preferred goal
-No more D.Pedal delay / I can feel the difference now when pressing the D.Pedal as the vehicle just takes off on comfort mode.  Before it had a slow lag to the pedal response

CONS;
-It sounds just like OEM (no ricer sound)
-Heavier muffler (does not affect anything on the vehicle from what I've seen and experienced)

The OEM Muffler is baffled (I did not know this) so it stays pretty quiet.  I do not know why they would do this when the CAT and the DPF is doing most of the work 🤷🏽. Happy with the setup and look, and glad it does not have a ridiculous metal clanking sound which was what I was worried about.

[F15GorDe]

Originally Posted by XxBBVTMxX

Fairly new to the forums. Was reading up on your comments last night gentlemen. I personally do not like my EOM exhaust on my 35d M Sport. So I am hoping my project turns out well..

-Vibrant 10632 Street Power Oval Muffler
-MMI Motorsport Dual Wall, Staggered, 3.5" Dual Tips
-New Piping from DPF to Muffler

All 304 stainless steel, but thinking of I wanna do some powder or ceramic coating. Talked to the manufacturer and they said the muffler is free flow, safe on diesel applications, and sounds a bit higher than stock but not ridiculous. I'm not looking for ridiculous sound, I just want more free flow exhaust. Waiting on the parts, more to follow I guess..

Following this. Good luck.

[XxBBVTMxX]

So finally all done. Used 2Kdf flat black to paint the piping and protect the welds.

-Simple green scrubbed
-Sanded
-Prepped
-Sprayed

Now you can't see the heat shield nor any piping from the bumper exhaust hole and I get added protection to the metal 🤙🏽

[RED_Y_]

How does it sound now? Mind recording a short video?

[XxBBVTMxX]

Originally Posted by RED_Y_

How does it sound now? Mind recording a short video?

Here you go. It is still pretty quiet, I do like that I can feel it pick up faster.

[Dr. Anthony]

Originally Posted by XxBBVTMxX

Here you go. It is still pretty quiet, I do like that I can feel it pick up faster.

Its been a little bit, hows it holding up?

I have a completely deleted F15 diesel including a muffler delete, however its a bit loud for my liking. Thinking of quieting it down a bit and going with a similar setup since I no longer have a factory muffler to swap back in.

[///d]

Originally Posted by Dr. Anthony

Its been a little bit, hows it holding up?

I have a completely deleted F15 diesel including a muffler delete, however its a bit loud for my liking. Thinking of quieting it down a bit and going with a similar setup since I no longer have a factory muffler to swap back in.

Curious as well. I was thinking of taking this route, or running a T to a 8x6 (or similar size) oval for each side, similar to how the Supersprint design is. The Vibrant would be way easier thou.