Cold air feed on a diesel?

[benj1989]

Saw on a readers ride someone put a plastic tube just under the mk2 leon grill and set up a cold air feed to his airbox. I was wondering if doing a cold air feed would help on my tdi? Are there any guides on how to do it and also could this ever cause problems. And finally would a new pannel filter(non oiled) help?
Thanks.

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[leero783]

I did mine on my bmc cda induction the weekend and noticed it was abit more responsive and sounds abit deeper . The old pipe was in the engine bay when i brought it 2 weeks ago , it should free up a couple of bhp at least ,

 

[leero783]

 

[benj1989]

You recon doing a cold air feed on the standard airbox is worth it or it worth removing the filter or a better one?

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[mk4 cupra]

Leroo783 why did u send the air intake to the lower grill and bend it like u have when u have a perfect grill up the top at the write place so there for no need to put a bend in the pipe and haveing less forced induction u would be a lot better off with it at the top grill

 

[Muttley]

The standard Mk.2 diesel has a large intake across the top of the front grill, above the radiator. I can't see the squashed tube pictured above being any better, and probably a lot worse, as well as obscuring part of the radiator.

The air isn't going to be any colder for being a few cm lower down, but you've increased the likelyhood of ingesting water in bad weather.

You're not going to get any worthwhile benefit from changing the induction feed or air filter in a turbocharged car in normal road use. You don't even have the dump valve excuse.

 

[cheshire cat]

, but you've increased the likelyhood of ingesting water in bad weather.

.

+1 you''ll only suck it up ONCE

 

[mrannikk0]

Have You thought any water methanol injection kit's?? Like Devil's Own!

 

[benj1989]

I imagine these will cost a lot??

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[leero783]

Leroo783 why did u send the air intake to the lower grill and bend it like u have when u have a perfect grill up the top at the write place so there for no need to put a bend in the pipe and haveing less forced induction u would be a lot better off with it at the top grill

The reason i have located it there is because if its in the top grill the air filter element gets caked in s"@t . Ive already tryed it and to be fair i carnt b bothered to clean it every couple of weeks . Like i said before it hasn't really made any difference and as for blocking the radiator i very much doubt it would cause it to overheat . There is no way water is gonna travel half a meter up and through the air element to the turbo unless i decide to drive trough a river. I also drilled 4 holes at the bottom of the feed to release and water held up in the very bottom . At the end of the day i dnt think and sort of cold air feed would help any diesel unless u are pushing 350 - 400 bhp which i doubt many of us do , petrol is anther subject as any cold air will help combustion and free the engine up . Hope this helps

 

[mrannikk0]

At the end of the day i dnt think and sort of cold air feed would help any diesel unless u are pushing 350 - 400 bhp which i doubt many of us do , petrol is anther subject as any cold air will help combustion and free the engine up .

That's what I thought too. My old Cordy had cold air feed but it had petrol engine. And it actually work!!

I don't know how much Water-Methanol kits cost in UK?? But here in Finland it cost around 300-400€ Not so much I think.

 

[BenG]

I'd have thought a diesel would intake more air per revolution than a petrol of similar capacity, as there is no throttle in a diesel intake and so the air taken in is always unimpeded as it would be in a petrol engine on full throttle.

If that's the case, then surely a diesel engine would benefit more from efforts to reduce inlet restrictions

 

[Muttley]

The performance gains from any aftermarket air filter/air feed system are minimal. The main difference from standard is an increase in induction noise.

There may be benefits for a highly tuned car in a competition environment. On the road, no noticable improvement. If you fit an aftermarket filter without feeding it cold air then you'll see a performance drop.

 

[cheshire cat]

The reason i have located it there is because if its in the top grill the air filter element gets caked in s"@t . Ive already tryed it and to be fair i carnt b bothered to clean it every couple of weeks . Like i said before it hasn't really made any difference and as for blocking the radiator i very much doubt it would cause it to overheat . There is no way water is gonna travel half a meter up and through the air element to the turbo unless i decide to drive trough a river. I also drilled 4 holes at the bottom of the feed to release and water held up in the very bottom . At the end of the day i dnt think and sort of cold air feed would help any diesel unless u are pushing 350 - 400 bhp which i doubt many of us do , petrol is anther subject as any cold air will help combustion and free the engine up . Hope this helps

howw's the weather in Brum'today

 

[leero783]

howw's the weather in Brum'today

Ha ha very funny . Yea its abit wet but nufink to worry my cold air feed . Certain parts of brum by the sounds of it i would tho , apparently its flooded certain parts completely out ( . Think i might raise it up a few inch )

 

[gdjohny]

http://autospeed.com/cms/title_PoweringUp-the-19-litre-TDI-Part-1/A_112210/article.html

 

[Muttley]

http://autospeed.com/cms/title_PoweringUp-the-19-litre-TDI-Part-5/A_112259/article.html

His conclusion - the remap made a huge difference. Changing the intake and the exhaust *on their own* made no difference.

The remap was performed after he'd changed the inlet and exhaust so took them into account. He never set out to compare the remap with changes to the remap on its own.

So the conclusion we can draw is, if planning changes, plan a remap to realise their potential as well.

 

[leero783]

Not being funny muttley but how can this pipe not be more restrictive than mine . The end of the pipe can only b open 15-20mm and my pipe doesnt go that thin anywhere along my air feed , also it a straight pipe so any crap that does get sucked in will clog ur air element . This is how my pipe was before and after cleaning it and checking it 2 weeks later it was caked in dust ,bits of leaf and i even found a tiny stone i had to clean it again and think of another air feed position .

 

[mrannikk0]

Here was My old Cordy SX cold air feed! Bigger is better!! But this was 2.0l 16v ABF!!
http://i509.photobucket.com/albums/s334/mrannikko/Projektit/Imuilmaputki2.jpg
and
http://i509.photobucket.com/albums/s334/mrannikko/Projektit/Imuilmaputki3.jpg

 

[Muttley]

leero783, which "this pipe" are you referring to? The one in the Australian guide on Autospeed was on a Škoda Roomster which has a different grill arrangement to your car, whatever it is (can't be the TDI sport in your profile as that has a picture of a Mk.1 accompanying it).

I've got two doubts about your corrugated tubing device.

1) The "cold air" myth. The standard feed is already coming from the front grill and will be no hotter than a feed taken from the lower grill. So there's no need for the messy tube in front of the radiator or the low location of the inlet. If you already had the aftermarket filter and it was sucking air in from the engine compartment, then any feed from the front will be an improvement. Taking it down low is not going to help though, and brings additional danger of water ingestion.

2)The "bigger is better" syndrome. Factors that affect the resistance of a duct include changes in cross-sectional area, changes in direction, length and the surface roughness of the duct. Comparing your duct to the standard arrangement, yours is longer, has more bends in it, is squashed and is corrugated. None of this is going to help.

And apart from that:

You can get the same mass of air through tubes of different cross-sectional area: all that happens is that the flow velocity goes up (and the static pressure goes down) as the duct area goes down. Provided the duct is large enough that surface effects are minimal, there really isn't any significant gain to be got in this application by making the duct larger. The biggest restriction before we get to the turbo is the air filter.

This is where Julian Edgar's Autospeed article makes a fundamental mistake. He says

"That is, if there’s a restriction to flow, not all the air available from the atmosphere will ‘get through’ – resulting in a pressure drop. "

By measuring only pressure and not velocity he's no idea what the real losses are. Losses come from changes in area, changes in direction, overall length and surface roughness of the duct, but you must measure pressure + velocity (preferably in the middle of the duct) or use a mass flow meter (like the MAF used by the injection system) to get the air mass.

Getting a sense of proportion here, the 14 inches of water he measures at his airbox tap is 0.5 psi. The improvement he makes is 10 inches of water, 0.36 psi. Standard air pressure at sea level, one atmosphere, is 14.7 psi or about 34 feet of water.