Diesel Exhaust Silencing.

[Dougal]

Quick question for those that have done it. This isn't a landrover, but it's a 2.something litre tdi so it all applies.

I want smooth flow with no droning. Car is going in for an exhaust upgrade on Monday.
It's currently a wastegated turbo, later it will get a VNT. Currently pushing 13psi, plan for 26psi if I can get enough fuel out of the pump. It's a build for mid-range torque, not high rpm power. I don't like noise either.

Currently it has the original non turbo exhuast kludged in, 1.75" with a centre resonator and a large end muffler.
The exhaust will be 2.5", crush bends because they are only minor angle changes. One flex joint.
Muffler on the end will likely be one of these Flowfast mufflers right by the bumper: Chase Flowfast (http://www.chase.co.nz/acatalog/Flow_fast.html)
http://www.chase.co.nz/acatalog/FlowfastPoster.gif

But will I need a centre box to keep it drone free or will the turbo do a good enough job of chopping up the exhaust pulses?

[rick130]

IMO you'll need a resonator on the back as well as a main muffler going from my experience with a 3" exhaust on a Tdi.

The resonator I have is just a perforated tube type, but it works well.

Without any silencing at all the resonance was horrific, the cab become a resonator :(
The noise was shocking too, it would have well and truly exceeded any noise test you'd care to name at WOT, including an F111 at take-off I'd reckon.

I'm going to try a Hooker Aero chambered muffler.
It's a straight through design but has a venturi section at the beginning followed by a larger, perforated chamber to slow the gas speed and hopefully break up the sound waves.

I have one, but the wrong one turned up (offset) and it's been a few months and the importer hasn't got any centred/centred's in yet (or as of December)

https://www.aulro.com/afvb/images/imported/2013/02/978.jpg

The other type I wanted to try was a Moroso spiral type, but they didn't have stocks of those either.

[justfishing]

Hello
I run a straight through exhaust 3 inch on my TD5 and get a bit of a drone with a VNT there was more of a drone with normal turbo, depends what you are looking for a nice note..........or something that makes it go better.
Ian

[Tank]

I run standard size pipe on my Disco 1 TDi, I replaced the original LR muffler with a same size straight pipe and left the original LR resonater on the rear, no droning, pleasant, non obtrusive sound and goes a bit better, esp. off the mark, cost $50 fitted, Regards Frank.

[PAT303]

^ thats what I've got on my Tdi,no drone at any time. Pat

[rick130]

I run standard size pipe on my Disco 1 TDi, I replaced the original LR muffler with a same size straight pipe and left the original LR resonater on the rear, no droning, pleasant, non obtrusive sound and goes a bit better, esp. off the mark, cost $50 fitted, Regards Frank.


^ thats what I've got on my Tdi,no drone at any time. Pat

When you go up in diameter from stock with a small displacement engine is when you start to have noise/drone problems.

[Johnno1969]

On this same topic....now, don't laugh - but what might be best for a 2.25D? I will be getting an exhaust in the next few months....

[rick130]

On this same topic....now, don't laugh - but what might be best for a 2.25D? I will be getting an exhaust in the next few months....

Nothing larger than 2" tube, mufflers of your choice.

[Dougal]

Thanks guys.

So just to be clear, perforated straight through resonator in the middle and a baffled muffler out the back?
As I understand it, you need to break the resonant frequencies in the middle of the pipe and then the muffler/silencer at the end is for taking out the residual pulsing?

I want this to be no noisier than any other standard diesel ute/4wd. It's a fully stickered work car.

[rick130]

Thanks guys.

So just to be clear, perforated straight through resonator in the middle and a baffled muffler out the back?
As I understand it, you need to break the resonant frequencies in the middle of the pipe and then the muffler/silencer at the end is for taking out the residual pulsing?

I want this to be no noisier than any other standard diesel ute/4wd. It's a fully stickered work car.

My understanding is the other way around.

Main silencer in the middle and the resonator at the rear ?

[Dougal]

My understanding is the other way around.

Main silencer in the middle and the resonator at the rear ?

So where do you put perforations and where do you put baffles?

[justinc]

Thanks guys.

So just to be clear, perforated straight through resonator in the middle and a baffled muffler out the back?
As I understand it, you need to break the resonant frequencies in the middle of the pipe and then the muffler/silencer at the end is for taking out the residual pulsing?

I want this to be no noisier than any other standard diesel ute/4wd. It's a fully sick work car.

There, I fixed it for you...:)

I would go baffled high flow main, and res at rear. OR no main and a high quality Res at rear only.

JC

[Dougal]

My only frames of reference at the moment are:

My 4BD1T has a large centrally mounted muffler (I have no idea of the internals, it's oval and offset in/out) and the only time it has ever droned was when I popped the wastegate to drop all boost while I was tuning the boost compensator.
The drone was quite impressive. 2.25" pipe (the next project).

This car has a small oval centred in/out centrally mounted and a big oval offset rear. It's very quiet, but at that restrictive, it has to be.

So, baffles centre and perforated rear? I am tight for room in the middle, it's a car so the driveshaft and muffler share the same tunnel.
In the rear off-set fits best, but centre-centre will also work.

[justinc]

Offset res at rear will be fine, as big as will fit and then will still 'look' factory. Try no middle first then, it may be just fine :)


JC

[Dougal]

Offset res at rear will be fine, as big as will fit and then will still 'look' factory. Try no middle first then, it may be just fine :)


JC

Thanks, that is plan A.
So what do you personally look for in a resonator?

[justinc]

I used a 3" Fibreglass packed straight through barrel res on the rear of my RRC, it was very quiet with the 4.7 V8 and I left it on there with the 4BD1t.

It performed fine, I was worried about sooting it up being glass packed, but it was still OK after 120K and then all got ditched for a complete Td5 Defender system when I fitted it all up to the 110.

I am not by any means a gasflow expert as much as some others here, but my idea centres around a large pulse absorbing cavern that offers little or no restriction to main flow. Whether it is material packed (F'glass etc), baffled/ chambered or louvred is the question for experts in the field.

Just in adition, the centre muffler in the 200Tdi disco is actually straight through, as in you can see daylight through it, I would say there would be very little advantage removing one of those except to generate more noise. Same with there rear resonator, it is pretty unrestrictive too. The 300 Tdi Disco has an offset rear resonator, but similar main muffler.

JC

[rick130]

Standard 300Tdi Deefer has a straight through, centre/centre glass pack main muffler (very large oval) and a straight through centre/centre glass pack resonator at the back.

The resonator that was recommended by a very experienced muffler/exhaust shop for the 3" system is a 5" round glass pack straight through centre/centre item and that took most of the sting and most resonance/drone out of the system.

I still have drone at cruising speed, but the 'main' muffler is a heavy wall 4" home made straight through glass pack and is inadequate.
Just no where near enough depth in the glass, but I had a 4" diameter oil separator and just put a hole saw through the ends, drilled a 3" pipe and wrapped/packed it.
I knew it wouldn't be enough, I've made mufflers before, but I had the material and I'm cheap :D

The big problem is the 3" pipe.
It acts as an amplifier.

At a guess a standard 60mm 300Tdi system would be quieter sans muffler/resonator.

Forgot to add, most systems I've played with have the resonator at the rear, but not all, eg dear old Dads ED falcon has a sort of small resonator/sonic box (which I removed as he'd bashed it so much) prior to the main muffler as well as a larger resonator at the rear of the system.

[justinc]

Standard 300Tdi Deefer has a straight through, centre/centre glass pack main muffler (very large oval) and a straight through centre/centre glass pack resonator at the back.

The resonator that was recommended by a very experienced muffler/exhaust shop for the 3" system is a 5" round glass pack straight through centre/centre item and that took most of the sting and most resonance/drone out of the system.

I still have drone at cruising speed, but the 'main' muffler is a heavy wall 4" home made straight through glass pack and is inadequate.
Just no where near enough depth in the glass, but I had a 4" diameter oil separator and just put a hole saw through the ends, drilled a 3" pipe and wrapped/packed it.
I knew it wouldn't be enough, I've made mufflers before, but I had the material and I'm cheap :D

The big problem is the 3" pipe.
It acts as an amplifier.

At a guess a standard 60mm 300Tdi system would be quieter sans muffler/resonator.

Forgot to add, most systems I've played with have the resonator at the rear, but not all, eg dear old Dads ED falcon has a sort of small resonator/sonic box (which I removed as he'd bashed it so much) prior to the main muffler as well as a larger resonator at the rear of the system.


i have a customer with a tdi 110 with no mufflers whatsoever, and a standard pipe diameter system. it sounds horrible and really intrudes. it would be fine with just a factory resonator at the rear imo.

the 6 cyl falcon from xd onward had the resonant chamber at the front, was quite effective but due to being hammered by rocks etc they generally get trashed.

dougal, are we allowed to ask for more info on the vehicle, or is it an embarrassment? :p

jc

[Dougal]

dougal, are we allowed to ask for more info on the vehicle, or is it an embarrassment? :p

jc

Yeah sure.
It's one of the japanese import freaks, that don't fit with any car actually sold new in NZ or Aus.
It's essentially a Nissan Wingroad (small pulsar based station wagon), but 4wd, manual and with a 2.2 diesel 16v twin cam engine in it (Nissan YD22)
Transverse fwd setup with a viscous 4wd to the rear axle. A bit like the Honda CRV in that front wheels always drive, back wheels push if the fronts slip.

Stock for this turbo is ~13psi boost which is ~250Nm and 81kw. I have a custom built GT1856V turbo for it which if I can get enough fuel can provide 26psi of intercooled goodness. I have an injection pump from the Navara YD25 engine which can provide enough fuel for ~450Nm and a good honest 200hp. But it's an EFI diesel, I'm the only one in the world tuning them and it's putting up the occasional fight.

It's the work hack that does pickups, deliveries and gets used for sampling work offroad around mine sites.

[justinc]

actually should be a fun project. BIL made a 1982 holden rodeo 2.2 ute sloth into a firebreathing weapon.(well not really, but it was pretty quick) by using a saab turbo from a 9000CS,and the intercooler, some home made diesel gas fumigation and 18psi of boost, made his own exhaust manifold etc , all on a C223 isuzu...:p

fun times, keep us in the loop :)

jc

[goingbush]

I changed the center muffler on my Td5 110 for a 3" hotdog the other day,
no other mufflers, It dosen't drone at all but is noticeably louder and more throaty, and the EGT is at least 50 degrees lower at the same speed / same hill. Now with the Allisport intercooler and free flowing exhaust I can not get the EGT over 700 ;) , I'd rather it wasn't louder because its a tourer, but if thats as cost of lower EGT's then its a no brainer. (when its cruising the noise is no more, only when I put my foot down)

https://www.aulro.com/afvb/images/imported/2013/02/915.jpg

[rick130]

The point I was trying to make is that a larger pipe definitely amplifies noise.

Too long ago a mate and I made a series of dyno pipes for a 1600 to test pipe sizes on the dyno, ranging from 2" (which is what everyone standardised on) up to 3".

The noise from the 3" pipe had to be heard to be believed :blink:

Power and torque were really poor, but it sounded fast :lol2:

Actually, it sounded awful, what threw us was the amplification over the open 2, 2.25, 2.5 and even 2.75" dumps.

[redrovertdi]

110 300tdi, fitted a 3inch exhaust with large center muffler only, a little bit deeper sounding but not noisy at all, engine now revs a lot faster and higher and turbo[mitsubishi t04] spools up faster, climbs hills a bit better and water temp is cooler on those hills, also picked up nearly 100ks more to the tank since fitting exhaust 2 weeks ago and heat wrapping turbo and manifold.
Richard

[rick130]

I changed the center muffler on my Td5 110 for a 3" hotdog the other day,
no other mufflers, It dosen't drone at all but is noticeably louder and more throaty, and the EGT is at least 50 degrees lower at the same speed / same hill.
[snip]


That's a huge drop. :o

I only ever measured around 25*K difference between a stock Tdi system and my 3" one on a 2.5km/150m climb..

[goingbush]

That's a huge drop. :o

I only ever measured around 25*K difference between a stock Tdi system and my 3" one on a 2.5km/150m climb..


Thats about the same grade as my 1.3 klm test hill, EGT is actually cooler if I let it hang on in 5th, gets to 695, WOT @ 88 kmh on the crest, in 4th it will go over 700 but back off to crest @96kmh (measured by GPS)

before the hotdog I had to change back to 4th half way up and back off to keep EGT's down.

the differance is really noticeable.

the only part of the system that is 3" is the hotdog section, Engine pipe is 2.5" and after hotdog 3" tapers back to 2.5" for the tail section.

[Dougal]

I found a boost gauge with enough numbers:

http://www.aulro.com/afvb/attachment.php?attachmentid=56559&stc=1&d=1360451877

So plan at this stage.
Perforated straight through muffler in the middle, flow-fast in the back and see how it goes.

[Dougal]

This job is done, I haven't got the bill yet but I'm very happy with the result.

It's got a slight burble at idle, no noticable noise at 100km/h, no drone at all and it pulls smoothly from idle to the 5,000rpm rev limit. It now does 80km/h in second without running out of puff. :D

No change in cruise EGT, high rpm EGT's have dropped further (now 550C worst case) as peak boost went from 14 to 15psi.
I need to get more fuel into this.