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How To: Remove Intake Restrictors SDI

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Hi Guys,

Just removed the intake restrictors from my SDI so I thought I would post up a how to.

Tools needed:

Socket Set incl

10mm socket

Extension Bar

6mm Allen key

Mole Grips

Fist of all remove the engine cover.

Then remove the wiring loom that clips over the edge of the intake box (The blue lines)

Then remove the Intake Box by undoing the five bolts, 10mm socket on extension, (Circled in red) holding it to the manifold and undo the oil breather pipe (Also in red). Also remove the Air Intake Pipe from the box.

iiotn3.jpg

You’ll then have to slide the Intake box backward so you can get to the bolts holding the restrictors in place.

intakeoffqi1.jpg

The bolts take a 6mm Allen key and need quite a bit of force to get them to move so I used mole grips to get a bit more leverage.

I worked from left to right as when you remove the first restrictor you can move the intake box out of the way.

When you have removed the restrictor you will have to remove a large washer from the restrictor and re-use it when you put the bolts back.

dsc00348eo4.jpg

And then replace everything the way you took it off.

And there you have it a free-er revving engine.

Cheers,

Ben

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hi,

thanks Ben for this post.

i recently took my car into hi q in wolverhampton to align the front wheels. the guy said that the air box was leaking, and that it was full of soot and needed cleaning out. he said it might cost £70, so i decided to do it myself, and bought a mini socket set from halfords for £10.

i took the cover off and removed the air restrictors as described above. my lupo was made in 2000, and i suspect that this was the first time the cover had been opened since then. there was black gunge everywhere, especially in the restrictors. even after they were removed, the air intake chambers were thick with gunge.

i scraped out as much gunge as i could with a screwdriver. some of it fell back into the chambers, as they point down at a steep angle. when i replaced the cover, the engine wouldn't start. the next day, i had to get towed to a garage, where they discovered that the engine had seized due to gunge falling into the engine. they had to take the engine apart and decarbonize it, machining the engine head and the valves, and sending the injectors away to be cleaned. all in all it cost £630, at an independent garage.

i just post this to warn sdi owners of the dangers of cleaning the air intakes. i thought that diesel engines were pretty robust, but it seems they can't handle a small amount of gunge falling into the air intakes. i'm seriously considering getting a petrol engine next time, as i suspect they don't have the same issues. please advise if you have any related experiences.

james

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I recently cleaned mine out, i think once you remove the restictors there's only two bolts holding the manifold on so i don't see why people just take of the manifold and clean that too. needless to say mine were pretty bunged up and after some time and a lot of Black mess i put it all back on and took it for a spin. The car felt much much much more responsive. Id recommend people with SDI'S go and get this done if its needed. If you don't have much confidence in doing this yourself then i think its well worth the £70 to get it done professionally.

Also Jeb75, Did you drive it at all after you cleaned the restrictors or did you wait a day? i would have tried it then and there it might not have seized then. But you never know

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When I had my TDI apart a while ago there was so much gunge in the intake and EGR it was unreal, whole thing had to come off and then the inside of the head had to be cleaned out the best I could as well.

Used an entire blue roll (stolen) to get rid of it all.

Now I keep an eye on it all. Paying £630 to get it all cleaned, I'd have been tempted to bang a can of easy start in it and let it burn itself clean.

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Could you not use brake cleaner to get most of the oily stuff to disintegrate and just come away easier?

Unfortunately i was at home when i did mine and did not have any to hand. so i did the best i could with some warm soapy water and a little brush. Needless to say if i was doing it in college i would a chucked it in the parts washer. Probably would a been less messy and annoying, and yielded better results.

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A parts washer would have been awesome for doing it.

I did have a can of carb cleaner but it didn't last that long and didn't really work for breaking down the gunk, I found that it was better to use it after the majority of the crap had been taken out.

Then I used the carb crap just to kinda get rid of the remnants and restore everything to a nice shiny finish.

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I only did mine as i just did the exhaust from underneath as it put it on the ramps for that, then it was blowing so i thought screw this and took all the intake off on the drive to get to the exhaust, to tighten and decided i may as well clean em out while there off. so yeah, if your getting your exhaust done you may as well get these cleaned too, they have to come off for you to get the exhaust on properly anyway

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Bump

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Hi people I just asked the moderator to unlock this thread as it is technically incorrect.

Let me explain briefly as I can. There's a lot of science to this.

On a normally aspirated engine, you rely on the ambient air pressure to push air into the engine. Technically speaking, the engine doesn't actually suck air in, but allows ambient air to fill the cylinders as they descend. So the idea is that you make it as easy as possible for the air to get in. This means you reduce turbulence in the inlet path and try to keep the air flow as laminar as poss. More air means more power. Turbulence decreases the the amount of air you can push through the pipe. Air doesn't like going around sharp corners.

It was discovered back in the 1930's that by gradually tapering the pipe radius and smoothing the openings on the inlet ducts actually gave an increase in horsepower. So the radiused inlet was born. It is still used.

Then another discovery was found which meant that the length of the tube can affect the power curve of the engine, and consequently the torque curve. Air weighs something. If you imagine a really long pipe, say 1000m long and get the air to move at high speed through the pipe, it will naturally have inertia, like a train on a track. If you suddenly block the end of that 1000m pipe where the air is coming out, you'll get a build up of high pressure just behind the blockage as the air down the pipe backs up. Open that blockage and the air suddenly rushes out. There is a relationship between pipe length, air pressure, air velocity and the timing and duration of the opening and closing of the blockage to increase air flow.

In an engine, the inlet valve is the blockage. The length of the inlet duct (often called a trumpet or ram tube) can be adjusted to give the engine up to an 8% increase in torque OR power. Short tubes work best for gains at high revs, giving high end power and longer tubes work best for increasing low end torque. Somewhere in the middle is a good compromise to make the car easy to drive.

Many modern normally aspirated engines have variable inlet paths, to give gains at different revs. Some have variable inlet paths and variable cam timing to give maximum effect.

On a pressurised engine (turbine charged or compressor charged), the effects of duct length and sharp edges are not as critical since the air is forcefully pushed in.

The classic Lupo SDI engine has tuned ram tubes (or trumpets) to give good low down torque and top end power. Removing the trumpets reduces engine power and torque. It also affects the way the air swirls around the cylinders creating an uneven fuel air mix, further reducing efficiency. The trumpets really should not be removed (unless you're cleaning them or altering the EGR system).

I don't understand where the idea that they are 'intake restrictors' comes from. Removing them is far more harmful than leaving them alone.

Here is a nice pic of a classic F1 engine with it's engine ram tubes.induction-system.jpg

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I assume it sounds louder and revs higher, but no actual performance gain lol.

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The same principal also goes for exhausts. Often called exhaust headers or extractors. You can tune them to create a 'suction' just behind the exhaust valve, to help suck out the exhaust gas more efficiently.

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