Vacuum/breather lines on t-jet air intake?

Hi,

I'm thinking of replacing the stock airbox+ducting of my Doblo T-Jet with a much simpler setup involving a pod airfilter.

I attached a picture of the stock pipe between the airbox and the turbo.
This pipe has to be replaced for my plans to work, so it is important I understand what's going on before I can design a replacement part in the shape I need.

Apart from the obvious airbox at one end and turbo at the other end I see 3 connections going to this pipe:
1. On the right there is a medium sized line which I think is part of the crankcase ventilation.
2. The smallest line on the bottom left goes to what I think is the boost controller
3. The slightly bigger line goes to the back of the engine.
(The boost recirculation valve goes to a connection on the airbox itself)

What are lines 2 and 3 for?

Edit: my theory after some research, confirmation/correction wanted:
2: recirculation of the leaked air from the boost controller? (If so I guess it's safe to just let the boostcontroller "leak" into the engine bay?)
3: fuel evap?

Greetings from Belgium,
Isabelle

Nobody?

Reason I need to fabricate a custom intake myself is because a part of the LPG conversion is in the way to fit a Punto/Bravo intake kit, and the height between the head and the bonnet is to low to fit an A500 intake kit

Why would you replace a perfect balanced, stock air intake set up...??

Because we can!

Fish

It brings absolutely nothing but noise and loss of power...

Peter Pick-Up:
I wonder what the discussion about stock vs custom adds to this particular topic. The thumbs-down icon in your second reply even implies you condemn this modification despite not knowing why nor how I'll change the intake.
I dare to say I'd expect better from a moderator!

I will answer the semi-off-topic question though:
- The intake setup of my Doblò is very similar to that of the A500 where it makes sense due to space restrictions.
Logic tells me an airbox sitting on top of a hot engine isn't great for performance. Fiat obviously agrees with me as they use a different setup with the airbox next to the engine in most of their T-Jet powered models.
- A stock intake setup is always a compromise between performance, ease of maintenance and acoustics. Personally I like some induction sound and a Doblò van without a bulkhead isn't a silent automobile anyways. I also don't mind spending a little time cleaning a pod airfilter once a year, and actually prefer this over chucking away a piece of paper and plastic origami to replace it with more disposable paper and plastic.
- Even IF (big if!) the stock setup were optimal and impossible to better for the needs of the stock engine, I plan to tune the engine in the future (partly when the warranty ends, partly when the cambelt needs replacement) to a power level exceeding that of the most powerful A500 delivered with this intake setup, so this setup obviously isn't designed to meet my engine's future needs.
- The intake setup I have in mind will draw its air from the same spot as the stock setup, maybe even a little further away from the engine, will be heat-shielded (unlike the stock setup), and will feed the air to the turbocharger more directly and without passing over top of the hot engine, much like the stock intake setup of a Punto/Bravo.

Greetings,
Isabelle

It's just so funny, that every now and then, somebody thinks he/she can improve something that is already designed and tested over and over again by skilled factory engineers.
But hey, go ahead and do what you want, turn your Doblo into an HP monster....!!

Please read my previous reply again.
TLDR version:
- Doblo T-Jet 120 uses the A500 setup despite not facing the same space constraints.
Fiat obviously agrees it's not an ideal setup as they use a different setup in Punto/Bravo, although the A500 setup would fit.
- My plans are heavily inspired on what is designed and tested over and over again by skilled engine tuners, in combination with other modifications designed and tested over and over again by those same skilled engine tuners.

I don't think ca. 225hp/300Nm (eventually) at the crank in a close to 2000kg vehicle that is sometimes loaded close to 2500kg is "an HP monster" these days.
If anything, I'll just be getting the real world 1.5-3.5k rpm performance of most average modern diesel cars, but with the advantage of more top-end reserve.

Get rid of the emission crap, and fit a larger turbo, together with a decent remap of the ECU.
Than we're talking real HP gains...

The only emissions regulating "crap" on the T-Jet I know off is the catalytic converter.
Unfortunately Belgium is very strict when it comes to modifications and emissions, so I'm affraid the cat and cat-back have to stay original.
An air intake is pretty much the only thing allowed as an air intake in itself rarely improves performance and is even more likely to reduce performance when badly engineered (see, we actually agree on this).

However...
The guys at the inspection see all kinds of vehicles and don't have the time nor the means to check if f.e. a turbocharger is the correct type for that car. They also aren't allowed to remove a heatshield to check behind it.

So these are my plans on the engine:

When the warranty period (2y, 1y3m left) is over:
- TD04 + necessary adapting on the exhaust manifold and downpipe
- remap
- recalibration of the LPG conversion if needed

When the cambelt needs replacement (maybe I'll do this a bit prematurely):
- NA camshafts
- 380cc injectors (kinda dumb as they're only used for starting, but the LPG conversion follows the petrol mapping)
- remap
- LPG injectors if needed
- LPG recalibration if needed

As you see, the stock intake setup will probably become asthmatic in the forseeable future and I like the sound anyways, so why not do it in advance?

How about the infamous EGR...??

http://www.jtd-performance.com/nl/?Itemid=121

I thought the T-Jet didn't have EGR?

I'm sorry, thought it was a Diesel...
(I'm in the middle of a birthday party...)

It's a 1.4l 16v turbocharged petrol (+lpg conversion)

I compared it to a diesel as the torque of the T-Jet heavily tuned to 200-250hp will still be pretty average compared to that of a diesel with 100 less horses, making it far from a rocket in average driving situations, but having the luxury of more power when needed by shifting down a gear or two.

I'm considering changing the end-ratio of the gearbox to a slightly taller one too after tuning, as first gear is ridiculously short, but turbolag (which will only worsen with a larger turbo) makes "launching" in 2nd impossible.
Changing the gear ratio so all gears have a higher top speed, but the new total gearing in 1st still being way shorter than the original total gearing in 2nd would make more sense and also improve fuel economy on the motorways (I now drive 90-110km/h as it makes a huge difference compared to 120-130km/h).

Other plans are improving the front brakes, but I'll have to put some more research in the possibilities for that as I want to keep compatibility with 16" wheels.

I know of Squadra and I'll definitely contact them when the time comes as my dealer also recommends them.
However their website only mentions chiptuning of stock engines and that better results can be achieved with Colombo Bariani camshafts, but nothing about customisation, non-oem turbochargers, injectors...

I also found HS-Corse, which is where I found out there is more to achieve with the T-Jet engine when using a TD04, 380cc injectors...

Update: to avoid having to build a complex arrangment of silicon hose, aluminium piping and a bunch of connections, I ordered an OEM airbox-to-turbo pipe for a Bravo T-Jet.
This option provides all the connections I need (I might have to reroute or replace a few hoses though) and should help me a long way to mounting a pod air filter where I want to.

I will keep you guys updated in my "Members Motors" thread where I recently posted a few small mods I did during the past few months.

Greetings,
Isabelle

Despite using some OEM parts, it still took a costly while thanks to the LPG evaporator being in the way, but the new intake is installed!

Check out my Members Motors page:
https://www.fiatforum.com/members-motors/437147-candisas-doblo-t-jet-lpg.html?p=4248384
(If I did this right, it should jump straight to the first post about the intake.)