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(Post Link) post #1 of 37 Old 01-02-09 Thread Starter
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Diesel Exhaust

I have a 1.9 JTD GT 2005, I know this may sound stupid, but what can I do to make it sound better ( apart from buying a petrol )!? I know it will never sound like a V6 but,I saw this vid on youtube " YouTube - Scarico Asso 1.9 JTD " of a diesel engine which didnt sound too bad.

What do guys do? Change the exhaust,free flow? Intake?

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Re: Diesel Exhaust

I think you should leave the exhaust alone..

The intake might be worth modding, but as its a turbo you tend not to get an intake roar, but more of a whistling sucking noise.
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Re: Diesel Exhaust

I dont have to do the exhaust, was just wondering what I can do to make it sound better. I was hoping to get it to sound more like this

YouTube - 147 1.9JTD Scarico Diretto Artigianale
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Re: Diesel Exhaust

tomorrow I will try to record the sound of my car...I have to do a few minors changes to the hardware but just for petrol fans I will record the sound of it.....
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Re: Diesel Exhaust

I ve changed the exhaust on a diesel before-you get a small but noticable improvement in performance and it does sound better
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Re: Diesel Exhaust

Has anyone replaced the cat converter on a 1.9JTDm?? Any power increase or sound difference?? any point??
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Re: Diesel Exhaust

whats a cat covnerter
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Re: Diesel Exhaust

Emissions equipment-precious metals act as catalysts to turn some of the sh*t in the exhaust gases into less harmful gases
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Re: Diesel Exhaust

oh that haha heard of it, cant see how it would help performance wise?
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Re: Diesel Exhaust

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Originally Posted by alfiGT View Post
oh that haha heard of it, cant see how it would help performance wise?

You have a turbo car, in simple words the faster the exhaust gasses leave the system the better for your turbo and your engine.

No obsticals (such as cat.converters) mean faster spool up times (meaning more responsive engine)...and less back-pressure to harm your turbo and your engine.

For N/A engines it is a bit more complicated and a bit different story.
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Re: Diesel Exhaust

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Originally Posted by kgb View Post
You have a turbo car, in simple words the faster the exhaust gasses leave the system the better for your turbo and your engine.

No obsticals (such as cat.converters) mean faster spool up times (meaning more responsive engine)...and less back-pressure to harm your turbo and your engine.

For N/A engines it is a bit more complicated and a bit different story.
Unless the turbo has special uprated seals the turbo does need a certain amount of back pressure.

Otherwise the oil in the turbo bearing will leak into the exhaust.


Diesel cars do have less energy in the exhaust gases than a petrol, and also the turbo vanes will cut up the gas pulses.

I think it would be pretty dificult to get a nice sound from a diesel exhaust, especially a 4 cylinder.

I can't say I like the one on the youtube link above TBH. I think it sounds pretty bad.

Last edited by symon; 04-02-09 at 17:37.
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Re: Diesel Exhaust

I'm looking at this:Secure UK tuning store Alfa, Ferrari, Fiat, Lamborghini, Lancia, Maserati

I don't think it'll change the exhaust note much but i'm not looking to make it sound 'better'(come on folks it's a derv) just wanting a little more power.

I want to FMIC it, sort the intake and then a re-map, should see around 200bhp safely??
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Re: Diesel Exhaust

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Originally Posted by symonh2000 View Post
Unless the turbo has special uprated seals the turbo does need a certain amount of back pressure.

Otherwise the oil in the turbo bearing will leak into the exhaust.


Diesel cars do have less energy in the exhaust gases than a petrol, and also the turbo vanes will cut up the gas pulses.

I think it would be pretty dificult to get a nice sound from a diesel exhaust, especially a 4 cylinder.

I can't say I like the one on the youtube link above TBH. I think it sounds pretty bad.
If the oil in the turbo leaks into the exhaust...I would have noticed it for the last 130 000km's of non-stop using the engine at more then 90% load.

And if it does so, that means that your turbo is a bit on the gone side... :-)

Aboout the sound....well untill I get a decent recording...cant say much :-)

The certain amount of back-pressure is good in order to keep the revs of the turbo between gear changes....but lets not go into such details....as we are talking about stock exhaus system and not uprated one.

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(Post Link) post #14 of 37 Old 05-02-09 Thread Starter
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Re: Diesel Exhaust

ah ok I see thanks for explaining
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Re: Diesel Exhaust

kgb, would you recommend a de-cat for the JTDm or is it a case of save you're money??
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Re: Diesel Exhaust

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Originally Posted by G5een View Post
kgb, would you recommend a de-cat for the JTDm or is it a case of save you're money??
On your car you have two of them...pre-cat which is just after the turbo and the main one.

Main one is easily replaced with straight pipe...and if you do it the right way, you can swap them..when you do your MOT for example.

Pre-cat is a bit more difficult for most mufler shops....the easy way is to cut it from one side and get ride of what inside by brute force...then weld the outer part back. Just be carefull with the sensor...best thing is to get it out then back on.

Have no idea how much that would cost where you live.

What you will get is a bit better sound and a little bit more responsive turbo.

If your car has been remapped then go for it, if not....just push the car more so the cat.s will stay clean.
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Re: Diesel Exhaust

It's a new car so I don't have to worry about mot's.

I'm looking to gow down the FMIC, new air filter and re-map route but not sure wether to bother with a de-cat (main cat). I'm thinking a combination of all the mods then a re-map would see most potential out of the engine??
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(Post Link) post #18 of 37 Old 14-02-09 Thread Starter
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Re: Diesel Exhaust

So wheres the sound clip kgb :P
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Re: Diesel Exhaust

Does anyone know if removing the main cat will cause engine managment problems??
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Re: Diesel Exhaust

of course it will.
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Re: Diesel Exhaust

Are there sensors in the cat or something??

Can you not put a resistor or something on to trick the ecu??
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Re: Diesel Exhaust

i am not an alfa expert so may be completely wrong here, but i imagine the cat will have at least 1, probably 2 lambda sensors (pre and post cat). These are needed and so if you decat it, you will still need these sensors to be there in the decat pipe. Generally speaking, on turbo'd cars, you want as free flowing an exhaust as possible, and so a decat would help. It may require mapping however, I'm sure someone on here has done a decat?
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Re: Diesel Exhaust

Dont think there are lambdas. They are for petrol cars with 3 way cats and diesels only have simple 1 way oxidation cats which dont have electronic control and therefore dont need lambda sensors
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Re: Diesel Exhaust

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Does anyone know if removing the main cat will cause engine managment problems??
If the car in question is GT JTD, then not....

(99% sure you don't have DPF....but just check to make sure)
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Re: Diesel Exhaust

I was assuming it didnt have dpf...
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