Diesel Exhaust Silencing.

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/im...013/02/915.jpg

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.

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

Quote:

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Originally Posted by 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.
[snip]

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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..

Quote:

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Originally Posted by rick130

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..

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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.

I found a boost gauge with enough numbers:

http://www.aulro.com/afvb/attachment...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.

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.