Cutting out a restrictor

[Chris017]

yes well i think this is a important topic to all JTD stilo`s as this alone can save money and get better performance. and i came across it buy accident haha.

well i am just about to put the car in the garage start working on fitting a new pipe. i will upload photos as soon as im done. it will just be a bodge job to start and try it out for a few days and if it works then i will do it correct then buy replacing the whole pipe.

 

[dave]

Air now passes through the radiator into the engine bay, then straight down and out under the car.

hot air don't travel down it goes up and is kept there by the air passing from under the car

 

[Davren]

I suspect the inlet of the pipe's current location is purely because of design considerations. i.e. "Where else can we put it?". It needs to be in a cold air location and somewhere that water can't get into it (especially for diesel engined vehicles). Early Peugeot diesels suffered because they put the air inlet low down and directly behind the grille facing forwards.

It's not just the depth of standing water the designer has to consider, but the "bow" wave that's created and creeps up the front of a car when driving through even shallow water. Peugeot forgot about this and many of their diesel engines were ruined because of it. I seem to remember that the issue with Peugeots was highlighted on Watchdog years ago forcing a redesign and numerous payouts for replacement engines.

 

[Shadeyman]

hot air don't travel down it goes up and is kept there by the air passing from under the car

Surely when the car is moving the air being forced through the grill/radiator and into the engine bay would over come the air trying to raise up due to convection and force it out under the car? Doesn't the shape of the front skirt create a low pressure area under the car?

I suspect the inlet of the pipe's current location is purely because of design considerations. i.e. "Where else can we put it?". It needs to be in a cold air location and somewhere that water can't get into it (especially for diesel engined vehicles). Early Peugeot diesels suffered because they put the air inlet low down and directly behind the grille facing forwards.

It's not just the depth of standing water the designer has to consider, but the "bow" wave that's created and creeps up the front of a car when driving through even shallow water. Peugeot forgot about this and many of their diesel engines were ruined because of it. I seem to remember that the issue with Peugeots was highlighted on Watchdog years ago forcing a redesign and numerous payouts for replacement engines.

I understand having it high up is important but why so restricted? When the bonnet is closed the gap from inlet to bonnet is less than an inch so air must be drawn through the slots in the bonnet. I think thats a really odd way to get cool air into an enegine. I looks quite restrictive too?

 

[Chris017]

rite then iv done what i can but i have to say its a pig of a job.

NOT A GREAT JOB AND ABIT MESSY BUT IT WILL DO FOR NOW UNTILL I GET SANDPAPER FOR MY SMALL ELECTRIC SANDER TO SMOOTH IT DOWN, THEN WILL LOOK REALLY GOOD

to connect a new pipe is awkward. you would have to completley remove the oval one and somehow place it somewhere god knows where.

so now i have just cut more out and made it much better

1- looking down onto the pipe i have cut out all the plastic bit to make it more direct, it's really fiddly job and patience, plus pull the grill off it makes it much much easier


2- after putting the grill back on and looking into it before and after



so that is how i got on and think it is much better and also a pic of my tuning box

 

[Shadeyman]

Now if Fiat had done what you've just done I could understand why.

Its as high as possible to help avoid taking in water.

Its open to atmosphere to take in the cleanest and coolest air.

So why didn't they?

 

[Chris017]

dont have a clue, its the same on all cars. there all restricted in some way or another, but just buy little things like this one.

and bloody hell does it make a better difference now that i have opened it up even more.

no restriction just straight inn

Highly recommend people with a JTD to do this !!!!!! its like having a cone air filter without the stupid noise.

 

[Shadeyman]

and bloody hell does it make a better difference now that i have opened it up even more.

I would have expected a difference at higher revs when the engine is taking in more air but does it really make that much of a difference?


Edit
This thread might be better placed in the new Tuning section as it now contains info on a tuning box and induction modification?

 

[Chris017]

well i have a heavy foot and have a problem with it haha. i find it hard to drive slow even when the old bill are behind me lol, but i have to say it does make a difference.

like you know 1st gear is pants on a diesel but after that its look out.

for instance joining a duel carridge way and your in 3rd and really put your foot down like iv just done then you go from 40 mph to stupid amount and straight through the gears with no problem.

it does help as your getting more air, and that is always good.

this is my first diesel car and all my other cars had a cone air filter directly into the grill and that was a hell of a difference from when they were standard.

so its the same principle with what i have done on the stilo but without the cone

 

[Chris017]

I have to say, I have been out for a real spin and put it to go uswel and o my god it has made a massive massive difference to my car. it pulls much harder than before in a big way.

 

[dave]

Surely when the car is moving the air being forced through the grill/radiator and into the engine bay would over come the air trying to raise up due to convection and force it out under the car? Doesn't the shape of the front skirt create a low pressure area under the car?

shakespear country raceway next year will give you the answer, do a run then remove all the rubber, then do another

 

[Davren]

I understand having it high up is important but why so restricted? When the bonnet is closed the gap from inlet to bonnet is less than an inch so air must be drawn through the slots in the bonnet. I think thats a really odd way to get cool air into an enegine. I looks quite restrictive too?

Yeah... Just been out to look at mine. As you say, the gap under the bonnet when closed is about 2cm but it stretches the width of the grille (apart from the area of the bonnet catch) which is about 80cm. 160cm² is more than the cross sectional area if the inlet pipe, so from airflow design point of view is more than adequate. Of course, almost any manufacturer design can be improved upon though, as Chris has already said.

 

[rattystilo]

Chris,

you will never get a diesel car to sound like a petrol one. Ther DPF is like a cat but is right after the turbo. this is the biggest restriction, there is also another cat in front of the rear box.

I bought a front cat replacement from jstuning in Holland, then got a Powerflow s/s full system with one box in it. At tick over it is louder at the exhaust end and sounds more purposeful. When you boot it you get a nice thrum through the midrange but nothing intrusive. It just sounds more purposeful.

 

[sussexa]

Do the 8v jtds have a snorkel fed from the back of this recess?
I did pressure test on clean side of filter and readings were quite low so not really restrictive.
http://www.alfaowner.com/Forum/tuni...3-refresh-airbox-or-get-an-induction-kit.html
If yours don't have them I'd sugest a snorkel off the 16v pic near bottom of thread above.

 

[Chris017]

Yes I know it wouldn't sound like a petrol but wasn't sure if it would make a noise on a diesel.

Ok well sorry if I'm abit thick here but how do I get rid of the dpf on my car, where is it as the turbo is mounted directly on the front of the engine isnt it? I was under the car the other day and checked the turbo hoses again as one was loose.

 

[rattystilo]

get under your car and look up at the turbo. See that first bend? That is your diesel particulate filter.

http://www.js-tuning.nl/downpipe-8v16v-euro-p-128.html

this is what i have on my 2003 jtd.

 

[Chris017]

Cheers for that, I didn't even know about it.
So would I get a big power increase and performance buy just changing that and leaving the exhaust how it is?

 

[Davren]

Chris,

you will never get a diesel car to sound like a petrol one. Ther DPF is like a cat but is right after the turbo. this is the biggest restriction, there is also another cat in front of the rear box.

I bought a front cat replacement from jstuning in Holland, then got a Powerflow s/s full system with one box in it. At tick over it is louder at the exhaust end and sounds more purposeful. When you boot it you get a nice thrum through the midrange but nothing intrusive. It just sounds more purposeful.

When you refer to the DPF, do you mean the normal cat that all Stilo JTDs have (Item 1 in the first picture) or the actual DPF (Item 4 in the second picture) that very few late model Stilos have under the car?

I didn't think any Stilos have a DPF before reading your post and checking.
.

 

[dave]

don't the car need a different map to run with no DPF? i thought i read that on here some where

 

[Davren]

I would think so, or it would be constantly trying to regenerate something that's not there.