TBI owners - Induction Noise/Improvements - Alfa Romeo Forum
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(Post Link) post #1 of 24 Old 07-04-19 Thread Starter
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TBI owners - Induction Noise/Improvements

Hi guys , I’m interested to hear if any TBI owners have sorted out an induction kit for the car I’ve had a look online and can’t find much info or anyone who’s done one , don’t really seem to be sold in a lot everywhere.

I’ve seen one from these guys but it’s for the Giulietta QV

https://www.torque7.co/product/giulietta_qv

Now this may mostly fit, but there’s a pipe leading from the engine into the induction that’s in a different position on the QV it’s just on the section before the turbo and on the 159 it’s closer to the MAF I think it might be an oil breather pipe? So it wouldn’t be a direct fit for this kit without modifications , other than that it might work?

The QV Giuletta also sounds little meaner our of the factory than the 159 and I think this is down to the induction set up particularly with the 159 containing a resonance chamber and the QV as far as I know being without one , it’s almost as if Alfa wanted to silence the 159 TBI and sell it as a corporate saloon and have the WV as the hot hatch and louder ...given it’s the same engine set up mostly I can’t believe that chamber has any other benefit in this car than sound reduction is the QV is without one.

The car sounds good as I have a wizard back section but I want to open up they engine note a little...interested in what others have done or if anyone knows of a kit.

Thanks lads!
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You’ve got the wizard straight pipes fitted? How are they? Loud? Drony on the motorway? Too subtle?
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(Post Link) post #3 of 24 Old 08-04-19 Thread Starter
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You’ve got the wizard straight pipes fitted? How are they? Loud? Drony on the motorway? Too subtle?
Yeah the straight pipes , I really like them...not too subtle for me they have a nice burble at idle and you get a few pops when accelerating, I don't find them too drony no at times in certain gears they can drone a little when decelerating but nothing that bothers me...the car is quite well insulated so the sound outside the car is superior but that's not to say it's bad inside they definatly give the car a much improved exhaust note and closer to what this engine should sound like.

I can take a quick video for you during the week if your thinking of getting them..
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Video would be much appreciated!
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Originally Posted by Lastbreath View Post
Yeah the straight pipes , I really like them...not too subtle for me they have a nice burble at idle and you get a few pops when accelerating, I don't find them too drony no at times in certain gears they can drone a little when decelerating but nothing that bothers me...the car is quite well insulated so the sound outside the car is superior but that's not to say it's bad inside they definatly give the car a much improved exhaust note and closer to what this engine should sound like.

I can take a quick video for you during the week if your thinking of getting them..
I would also be very interested in the video!

For the cold air intake, InCoGn1t0 has a video on that, it's in the steaky in this subforum.

Last edited by Daaristieweer; 16-04-19 at 11:21.
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Of course, removing the resonator will reduce the power because the inlet flow will be untuned. And the free flow exhaust will add even more air and weaken the mixture. So the plan is to make it sound powerful?
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V6 open induction has a comparison
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Of course, removing the resonator will reduce the power because the inlet flow will be untuned. And the free flow exhaust will add even more air and weaken the mixture. So the plan is to make it sound powerful?

Really? Well as far as I know the resonator is there purely to silence the intake and does not affect it's tuned length (Giuliettas don't have them on the same engine iirc) and fitting a free flow exhaust will only weaken the mixture if you remove all the upstream (of the cat) exhaust sensors when you fit it....as of course one of their jobs is to correct the mixture if it senses it's too weak or rich to protect the cat and keep the emissions within tolerances....
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(Post Link) post #9 of 24 Old 23-04-19 Thread Starter
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I would also be very interested in the video!

For the cold air intake, InCoGn1t0 has a video on that, it's in the steaky in this subforum.
Thank you , have spoken with him and he also sells a plug and play induction kit which I'm getting off him now so sorted!

Don't think removing the resonator will effect the airflow in a bad way , the Giulietta QV doesn't have one and has a better induction sound with the same engine. I reckon Alfa de-tuned the 159 and silenced it a little from factory as they wanted the GQV to be the sports model and be a bit more sporty than this car, the premium model as such this was aimed more as an exec car...but it hasn't panned out that way...either way yes I want a better induction sound and some Turbo chatter, losing 1-2 hp won't bother me much she has plenty...
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Quote:
Originally Posted by Lastbreath View Post
Don't think removing the resonator will effect the airflow in a bad way , the Giulietta QV doesn't have one and has a better induction sound with the same engine. I reckon Alfa de-tuned the 159 and silenced it a little from factory as they wanted the GQV to be the sports model and be a bit more sporty than this car, the premium model as such this was aimed more as an exec car...but it hasn't panned out that way...either way yes I want a better induction sound and some Turbo chatter, losing 1-2 hp won't bother me much she has plenty...
I don't think they de-tuned the 1750 engine in the 159 as such... I think it's fitted with a slightly different turbo to that in the GQV which accounts for the power difference. I think the engine itself is the same, although I'm sure that someone will correct me if I'm wrong..
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Thank you , have spoken with him and he also sells a plug and play induction kit which I'm getting off him now so sorted!

Don't think removing the resonator will effect the airflow in a bad way , the Giulietta QV doesn't have one and has a better induction sound with the same engine. I reckon Alfa de-tuned the 159 and silenced it a little from factory as they wanted the GQV to be the sports model and be a bit more sporty than this car, the premium model as such this was aimed more as an exec car...but it hasn't panned out that way...either way yes I want a better induction sound and some Turbo chatter, losing 1-2 hp won't bother me much she has plenty...
Could you tell me the price he is asking?
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The GQV is fitted with the larger K04 turbo and the 159 the K03 but he ECU map is also different , the K03 is well capable of reaching 240 HP stock and equaling the GQV, mine is remapped to this.

He’s asking 120 plus delivery which is very reasonable considering he builds and sends a plug and play kit, nice chrome piping as well.
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That’s in Euros by the way...
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The GQV is fitted with the larger K04 turbo and the 159 the K03 but he ECU map is also different , the K03 is well capable of reaching 240 HP stock and equaling the GQV, mine is remapped to this.
..and the GQV maps to 280 HP.
Just fit the slightly larger GQV K04 turbo on the 159 TBi (direct fit), then you have 280-290 HP due the 159 TBi larger IC.
Only reason the 159 TBi have the smaller K03 turbo is for better low rpm torque for a more “executive sedan” feeling, and not to out perform the heavy 260 HP 3.2
The GQV have lower compression, stiffer valve springs, different ecu map and no intake resonator for the “GTI” feeling and sound.
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Oh, and the GQV engine apperently have different shaped piston to the 159. Compression is 9.25:1 which would allow for slightly higher boost compared to the 9.50:1 compression of the 159 TBi.
The boost level was then most likely kept "low" to avoid knocking if 92 octane pump gas is used.
As there will be need for higher octane fuel when boost pressures increase, it's nice that here in DK we have 100 octane pump gas
Even the GQV have lower compression (to allow higher boost level?) the 159 TBi have a larger IC which would also be beneficial for higher boost level.
The Giulietta Squadra Corse is stock 282 hp (safe limit) - have not seen many GQV mapped to +300HP
But more than a few Brera/159 Tbi out there with +300 hp (using K04 or K03 hybrid).

Of course all this have nothing to do with "induction sound" - a thing that most likely can't be changed easy on the TBi and in my opinion shouldn't.
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Quote:
Originally Posted by Lastbreath View Post
The GQV is fitted with the larger K04 turbo and the 159 the K03 but he ECU map is also different , the K03 is well capable of reaching 240 HP stock and equaling the GQV, mine is remapped to this.

He’s asking 120 plus delivery which is very reasonable considering he builds and sends a plug and play kit, nice chrome piping as well.
Could you post some pictures when it arrives?
I'm very interested in to see how the plug on one of the pipes has been fitted.(the one which goes to the engine)

Maybe it's also smart to look into a water repellent for the filter, because the filter will be placed so far down.
I know of one which is called Injen hydro shield.

Last edited by Daaristieweer; 25-04-19 at 08:22.
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Way ahead of you, that was my first concern I’ve already ordered a hydro shield for the filter to go in with it...and I had the same concern with the oil breather pipe for the engine apparently he has the tubing modified so that it plugs into the same position as the original intake but yes of course I’ll post some pictures once it arrives.
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Great!
I'll be waiting patiently.
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Most of the information is above. But to add some clarity - Noise is Energy. So when the resonator is tuned perfectly the byproduct is less noise. Taking it away changes the tuned length and reduces power.
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(Post Link) post #20 of 24 Old 25-04-19 Thread Starter
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Old Engineer - I think the majority of your posts on here are extremely informative and well understood and I don’t disagree with your reasoning , but if noise if wasted energy that’d mean a free flowing exhaust is also and we know that increases HP.
In this particular case for the 159 I agree with what has been said above on the reason the 159 was tuned this way vs other Alfa models on offer and I know that by opening the induction it’ll give the rasp I’m looking for and be more akin the GQV, maybe it will lose a small amount of HP maybe it won’t wel find out.

Either way it’s nothing a map wouldn’t sort out and she’s already remapped to 240 so can’t see me missing it much if I’d lose 1-2 HP. As said, the GQV is tuned without this resonator and it’s the same engine.
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Tuning the engine to recover the energy is one way of resolving the loss but it's not an Automotive Engineer's usual practice. I say that while knowing that several cars have launched with this compromise. A free flowing exhaust can be quiet; You just need a huge expansion box where the sound waves can blur and not build. The size of the interior of the car would do it! The sound waves you are pursuing are the regular beats that build into a sustained noise. If you consider tyre design you see that the block patterns are irregular to kill the sound build up. It's quite irritating when all our best work is dismissed with the idea that we somehow deliberately make cars worse. Many millions of pounds are expended in development so it should be quite obvious that a third party exhaust with a £50 margin can't hope to be better.
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...not a great argument. That factory exhaust has to pass lots of stiff noise and emissions tests the world over....be as quiet as as possible...be reasonably cheap to produce and produce a nice torque/power curve etc. In other wise its a big fat compromise.The aftermarket one can be tuned to just one requirement....such as intimate top end power....or a midrange torque boost....of just looking cooler! So its quiet easy to better the factory pipe in one or two areas....just not all of them!

Side note.
On my 2.0 JTDm I recently cut the old exhaust off to fit a new one. The child in me wanted to know what it would sound like with just a 2 foot straight tube as an exhaust!!!....the answer was exactly the same as with the silencer and all the tubing on!! The DPF and the turbo act as two very efficient silencers...pity!....now I have a car that has two straight thru race silencers instead of one factory box (i used a 2.4 centre pipe as the splitter).....and its quieter than it was before!!! LOL!

I dont see the resonator on the intake as affecting the tuned length...its just a silencer....and most silencers certainly dont help with power production...its just another compromise to make the car quieter. I would bet at least 50p that you could not measure the difference with it removed on the dyno.....maybe even a pound!
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(Post Link) post #23 of 24 Old 11-05-19 Thread Starter
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Sorry it took me a while to get this. Link below to the exhaust sound with the Wizard straight pipes installed.


<iframe width="560" height="315" src="https://www.youtube.com/embed/kTIojY3_9es" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
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Thank you! Sounds good!
Induction kit still has not arrived?
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