help with a turbo diesel exhaust

[dunney]

hi this is my first post so please bare with me.(i did try to search this first too)

i have a 2000model mazda bravo 2.5TD and yes my gearbox is still the origional after 180 000km's(must have fluked a good one). and after a fair few mods its time for the exhaust.i will be doing it the whole way through from the turbo back but im only new to the whole diesel side of things as i come for a import scene wear i use to drift so this is a massive change in everyway.


i will most probably get 3' mandrel bent the whole way as it leaves me plenty of room for future mods if i chose to go that way (turbo change etc).is this correct thinking?comming from imports its usually just get a 3" exhaust to get the gas out of there the quickest.or with diesels is that wrong?

im after that really tuff truck sound but i am unsure how this is achieved?does this come naturally with a 3" axhaust with a muffler?my theory is that most of the cars that i have heard with this nice sound must be running 3'' with no muffler?


i have a mate with a 3L TD jackaroo and he has a 2.5' exhaust on it and it barely makes a sound (im assuming its because its a 2.5") so i dont really want that because thats half the reason i want an exhaust.

any help on achieving the sound im after is greatly appreciated.

[tweak'e]

power wise i doubt you will notice any difference from 2.5" to 3".
3" will be noiser, how much depends on mufflers etc. the only thing is some big straight through exaust systems sound like crap, not neccarly loud, just crappy. if your after tone i suggest having a trail of different mufflers.

i was at the exhaust shop the other day and they mentioned one thing to watch with big exhaust is some can be fairly tight going past the bell housing and chassi. they have had a few makes with 3" exhaust that bash the chassi when the motor flexs. tend to get a lot of broken exhausts that way. just something for you to check.

[Dzltec]

Use the same principal as petrol, more power = more fuel and air in equal amounts. A good sound can be had with just a straight thru system.


You may have to experiment a bit.




Andy

[dunney]

so you basically sayin that if its too shitty sounding with no muffler at all it might be better to mess about with different brands of mufflers?

seems very expensive way of getting the note i want??

but if thats whats needed then i suppose i will have to do it?

[tweak'e]

not really any more expence. while the guys are doing it just ge them to hold a muffler on it while you run the motor, simply swap mufflers to get one that sounds ok. takes a little bit of time and effort, nothing major.

[KiwiBacon]

3" sounds like overkill. How much boost are you running?

[chunks]

I'd go with a 2 3/4 system mandrel bent system.

[HotFourOk]

Sometimes, with turbo diesels, you can get away with running no muffler and just use a straight through pipe.

I have a 2.8TD Rocky and I installed a 2.5" system from turbo back (including new dump pipe), it goes a LOT better, but is not very loud. I used a lukey straight through hiflow muffler on it. When you are on the gas it has a nice low note which sounds grouse, but on the freeway you can't really hear it, which is good news, I hate the freeway drone on some cars!

Going by the size of your motor, try 2.5"... it should be big enough, especially if you are going to use mandrel bent rather than press bent. Also, get it without a muffler first off, then install one if its too loud for your liking.

[zagan]

I don't know about anyone else but I've never really heard of a diesel exhuast sounding all that great.

The induction nosie generally seems to drown it out anyway, when your outside the 4wd and inside the 4wd seems to be the same.

that and the banging of the pistions.

get a bigger exhuast if your after more power, this is the general reason why people even bother to upgrade the size of the exhuast (witin reason) as the diesel motor is all open ecept for when the valves are closed.

[chunks]

I dunno, my 60 series sounds pretty good to me spooling up through a 3" system with no mufflers!

[HotFourOk]

I don't know about anyone else but I've never really heard of a diesel exhuast sounding all that great.

Are you kidding? I've heard some trucks sounding bloody awesome!

[bazzle]

The diff muffler option is a good one. That motor prob 2 1/2 to 2 3/4 but ensure you get a short flexy joint up the front .

Bazzle

[LuxyBoy]

Legally a turbo system does not require a muffler so it is up to you if you want one of not.

If you want it loud put a cannon/resinator at the end; you know the barrel type things at the end that look like a step to access the roof

3" is overkill for that size motor and make sure you have a decent size dump pipe with a good flexy join.

[zagan]

I don't know about anyone else but I've never really heard of a diesel exhuast sounding all that great.

Are you kidding? I've heard some trucks sounding bloody awesome!

Well no, compared to a petrol car or a bike they don't have much of a sound really.

Semis, trucks etc have the big exhuast sound but on the small diesel engines, I wouldn't say have much of a exhuast sound.

it's more the turbo spool/induction sound, I think that is more of a head turner than a exhuast sound as it's quite different.

[tweak'e]

I don't know about anyone else but I've never really heard of a diesel exhuast sounding all that great.

The induction nosie generally seems to drown it out anyway, when your outside the 4wd and inside the 4wd seems to be the same.

that and the banging of the pistions.

yes/no modern diesel are fairly quiet, don't have so much diesel knock noise or induction noise (unless modded intake).

generally turbo diesels sound fine while on boost, its just they tend to sound poor offboost. local guy has nissan 2.7 turbo with just a coby resonator (i think) and it sucks untill boost comes on. had tractors sound better!

[dunney]

i didnt think it really mattered what size exhaust u got on a turbo diesel or any turbo for that matter?i understand that 2.5" is probably large enough but 3" wont rob me of power will it?
i just thought the theory with turbo's was "get the exhaust gas out of there"? is this wrong?
the 2.5 inch systems doesnt seem to get the good sound from what i've herd in my experience with my friends cars.

its a pity the mazda's arnt modified a bit more but thats life.

the exhaust i will get will be 3" mandrell bent for the dump pipe and the rest will be 3" press bent with any bends over 30degrees being mandrell.oh and yeah i requested a flex join

its booked in for wed next week to get the above 3" work done unless someone here seriously thinks this will make me lose power?

BTW car runs 12psi (stock) and i will also get the car dyno tuned and tweaked a little by specialists when the system is done.

will be very interesting to see what power i end up with compared to hilux/rodeo/patroll/cruiser etc..

[macca81]

I don't know about anyone else but I've never really heard of a diesel exhuast sounding all that great.

Are you kidding? I've heard some trucks sounding bloody awesome!

Well no, compared to a petrol car or a bike they don't have much of a sound really.

Semis, trucks etc have the big exhuast sound but on the small diesel engines, I wouldn't say have much of a exhuast sound.

it's more the turbo spool/induction sound, I think that is more of a head turner than a exhuast sound as it's quite different.

my MQ qith a n/a SD33 had an awsome note, with stock everything. it was a real headturner. that was by no means a bigdiesel engine, had no turbo spool, and i am fairly sure it wasnt induction noise as when i put a huge hole in the zorst the note changed dramatically

[KiwiBacon]

i didnt think it really mattered what size exhaust u got on a turbo diesel or any turbo for that matter?i understand that 2.5" is probably large enough but 3" wont rob me of power will it?

No it won't rob you of power, but a bigger pipe will radiate more heat, emit more noise and be a lot harder to fit in.
As well as costing you more for absolutely no gain.

[coxy321]

Time for my 2c worth!!!

I reckon 3" is too big. Go with a 2.5" mandrel bent system, make it yourself (save $$$$). Reason: no huge advantage stepping up to 3", 3" will cost more, 3" is physically harder to route/run than the smaller 2.5" system, hotdogs/resonators/mufflers are cheaper with a 2.5" inlet/outlet, PLUS you wont get labelled as a complete gagger by the local 4x4 enthusiasts.

Turbo diesels are generally very quiet as the motors generally only do lower rpm's, and the exhaust turbine makes a MASSIVE difference (heaps quieter). The only real issue i have with big exhausts is having a completely ridiculous amount of turbo whistle. This can be rectified with a slimline hotdog or a resonator. A young bloke down the street from me has this problem, i can hear his truck (stocker) from 3 blocks away, and thats when he's poking around slowly. He must wear earplugs.

The noisiest turbo diesels that i've heard are all comp trucks, and as Zagan said, all the noise generally comes from the induction when they come on boost like a jet engine winding up. Very nice........

Coxy