cold air intakes. any suggestion?

Pros an cons to a cold air intake on a 04 tdi jetta

First suggestion, read this thread: http://forums.tdiclub.com/showthread.php?t=290373
Second suggestion: Don't waste your money unless you have already done so many other serious modifications that you actually need more air than the stock cold air intake can deliver.

Have Fun!

Don

Patrick15 said:

Pros an cons to a cold air intake on a 04 tdi jetta

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Pros=0 except the looks cool factor
Cons=1 Costs money better spent on other mods.

MichaelB said:

Pros=0 except the looks cool factor
Cons=1 Costs money better spent on other mods.

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that's a pretty simpleton way to look at it.

now explain to me what 'average' means to you:

Fuel Economy: 46-48 mpg ave. Warm weather 38-42 cold weather. 35-38 extreme cold.

Perhaps there is a new 'average' formula in use I didn't get the memo for.

**thread hijack in progress**

stock can support what ? Around 400 hp? Don't waste your money.

bbarbulo said:

that's a pretty simpleton way to look at it.

now explain to me what 'average' means to you:

Fuel Economy: 46-48 mpg ave. Warm weather 38-42 cold weather. 35-38 extreme cold.

Perhaps there is a new 'average' formula in use I didn't get the memo for.

**thread hijack in progress**

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That really helped the OP out now didn't it?

Your TDI (regardless of model year) came with a "cold air intake" straight from the factory. An aftermarket one made of shiny bits isn't going to do anything that the stock air intake system won't do, and there's a good chance it will not be as good at keeping water out of the engine in case you drive in wet conditions.

The stock filter filters finer too, so it keeps the dust out of your turbo and cylinders.

Flow difference if any is minimal between stock and "performance" filters.

MichaelB said:

That really helped the OP out now didn't it?

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no more and no less than failing to 1. use search and 2. post in the correct forum.


however, a math lesson is always helpful to all

what in the world are you talking about?

bbarbulo said:

that's a pretty simpleton way to look at it.

now explain to me what 'average' means to you:

Fuel Economy: 46-48 mpg ave. Warm weather 38-42 cold weather. 35-38 extreme cold.

Perhaps there is a new 'average' formula in use I didn't get the memo for.

**thread hijack in progress**

Click to expand...

I that Micheil B's post was direct and to the point. Why can't something be simple and to the point to be valid.?

Read this.

http://forums.tdiclub.com/showthread.php?t=290373

Prompted by this thread, I did some instrumented testing today, on a car which is not a VW TDI, but for which there are all sorts of aftermarket blingy bits available including a number of aftermarket cold-air intakes.

Now, the advantage of this not being a VW TDI and being a non-turbo gas engine (in fact it is a Fiat 1.4 MultiAir), is that the intake air temperature is actually the intake air temperature ... not the post-turbo-compressor post-intercooler temperature, which is what you get with a TDI if you have a scangauge connected to it.

As with every VW, the air intake is coming through a duct which has its inlet in front of the radiator (before the heat source) and high up (to keep it away from potential water ingestion).

To make matters worse, on this particular car, the air filter is inside the plastic engine cover which is spread out across the top of the hot engine itself. So you'd think there would be heat going from the engine and soaking into the engine cover and then into the air stream. And, true, there is some evidence of this.

Outside air temp -5 C at time of test. Scangauge reported within one degree of that on cold engine start. Close enough.

After driving for about 15 km through the countryside, outside temp was still around -5 C, intake air temp was a whopping 3 degree C. So 8 degree C temperature rise from ambient, measured at the throttle body.

After sitting in a coffee shop for a wee bit, outside temp had risen to -2 C, and the heat-soaked intake air was now reported at 19 C. Over 4 or 5 km of driving, this dropped down pretty quickly, and after 10 or so km. it was now reporting 6 C intake air temperature. So aside from heat-soak conditions (which sorts itself out in a few minutes) it's safe to say that intake temperature is 8 degrees above ambient.

The difference in air density between 0 C (273 K) and 8 C (281 K) is ... 2.8 percent. If one were to construct a perfectly insulated intake system with absolutely zero heat transfer from the engine compartment, you could get air 2.8 percent more dense into the engine and maaaaaybe get 2.8 percent more power (probably less). In reality that (typically) metal air intake duct on your typical average "cold-air-intake" system conducts heat through it much faster than the plastic that the OEM cold-air-intake is made from. On the other hand, you wouldn't be stuck with having the air filter spread over the top of the engine. I think it's safe to say that the potential real world power improvement from the real world change in intake air temperature is pretty close to nil. Certainly not worth spending 300 bucks on.

Then there's the claim that stock air intakes are "restrictive".

Key-on engine-off the intake pressure sensor reports 98 bar. We'll take that as barometric pressure.

Going up a hill with the accelerator pedal located on the floor the intake pressure sensor reports 97 - 98 bar depending on RPM. I didn't test beyond 4000 rpm as there was no point. There is so little difference between barometric pressure and intake manifold pressure that the "restriction" of the stock air intake duct and generously-sized stock air filter element can safely be called "diddly-squat".

An interesting demonstration of the MultiAir system (variable intake valve timing and lift) is that even at part throttle, the intake manifold pressure remains high (it seems to like keeping it around 87 bar) under light load cruising conditions. It's using the variable intake system to manage how much air the engine is getting, not so much the throttle. Only at idle or shut-throttle coasting does the intake manifold pressure actually drop way down.

Experiment concluded. Not worth buying a cold-air-intake for that car, either. (I didn't expect anything different.)

Why waste your time, the OP is an obvious troll...

You get more induction noise with an intake, at least on gasser cars, so you have to making more power, right?

Another factor completely ignored is the fact that engine computers are adaptable and will adapt to any changes and erase any benefits of the increased flow, if there is any benefit at all.

A lot of intakes draw air from underhood so they are actually bringing in warmer air. That coupled with the fact that the filters are porous prompts my relabeling them as "Hot air dirt injection systems."

1854sailor said:

Why waste your time, the OP is an obvious troll...

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Why would you say that? Maybe he just plain old doesn't know. He probably sits around and wonders how he can get more power out of his TDI so he goes out and buys Diesel World and gets sucked in by the predatory advertising.

Yeah, I think the ubiquitous CAI ads with false claims, combined with the ease of installation, make them attractive to many. Just like many folks fall prey to Slick50, miracle fuel magnets, etc..

pdq import repair said:

You get more induction noise with an intake, at least on gasser cars, so you have to making more power, right?
Another factor completely ignored is the fact that engine computers are adaptable and will adapt to any changes and erase any benefits of the increased flow, if there is any benefit at all.
A lot of intakes draw air from underhood so they are actually bringing in warmer air. That coupled with the fact that the filters are porous prompts my relabeling them as "Hot air dirt injection systems."

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More noise does not necessarily equal more power.

VWs have a well designed cold air intake system and it's already way oversized for our cars to not be restrictive at all and for the air filter to have a 40k mile change interval. The ECU controls boost from the turbo in a closed loop manner such that the engine always gets the amount of air the ECU says it should get under any given set of conditions. The intake setup is not the source of any major restriction in the first place so opening it up any further won't help. Aftermarket CAI setups are actually warm air intakes (WAIs) in reality compared to OEM and may hurt performance aside from allowing for more noise.

I'm curious to know what the OP doesn't like about the well designed and already oversized ram-air cold air intake system the car came with from the FACTORY. "It just HAS to be better than the stock setup!" OK, based on WHAT?? I recommend the OP should do some back to back dyno runs on the same dyno on the same day and the cold air intake setup is the only change made between dyno runs. I look forward to seeing the results.

Have fun!

Now that these cars are aging, more and more kids are getting their hands on them easily and cheaply. Questions like this are going to become more and more frequent.

CAI and Straight pipes... the kids love them for looks and sound.

belome said:

Now that these cars are aging, more and more kids are getting their hands on them easily and cheaply. Questions like this are going to become more and more frequent.

CAI and Straight pipes... the kids love them for looks and sound.

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We all know how fast it makes the ricers go, and how good it makes them sound.

I am thinking of putting a 5 inch outlet on my tailpipe, how much horsepower do you think that will add?

Cool air intake any good?

I have a 2012 jetta tdi and been considering getting a cool air intake would really like to know any pros and cons to doing so. Thanks.

In preparation for my RC Stage 2 tune, I let my mechanic talk me into a 3 inch exhaust pipe from right after the turbocharger on back. We did put a resonator at the end just in case to prevent droning noise.


Tdidre - didn't you read the previous posts ? ZERO benefit to you , minus - dollars to the vendor.

At least he did some searching even if he didn't read what he found.

And to be fair, the OP was asking about an '04.

pdq import repair said:

We all know how fast it makes the ricers go, and how good it makes them sound.
I am thinking of putting a 5 inch outlet on my tailpipe, how much horsepower do you think that will add?

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I have a 2 1/2" Cat back straight pipe. My goal was to improve flow through the entire system - start to finish. The sounds is not loud at all but a little droney (sp) at times.

This is what I was shooting for:


Just kidding

Tdidre said:

I have a 2012 jetta tdi and been considering getting a cool air intake would really like to know any pros and cons to doing so. Thanks.

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read this thread: http://forums.tdiclub.com/showthread.php?t=290373
and then don't waste your money.


Have Fun!


Don

OH LORD NOT AGAIN
HAAAAHAHAHAHA
lol newbs

would swapping to a K&N filter be good?

DmaxjonTDI said:

would swapping to a K&N filter be good?

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If you want to keep changing out MAF sensors at $100 US a pop .....


A K&N will, for most people, just put excess oil on the MAF thus messing it up. And even for those few that don't overoil them - the K&N doesn't catch as much of the bad stuff that an air filter is there for as compared to the stock air filter that already has more than enough air flowing capacity.

scooperhsd said:

If you want to keep changing out MAF sensors at $100 US a pop .....


A K&N will, for most people, just put excess oil on the MAF thus messing it up. And even for those few that don't overoil them - the K&N doesn't catch as much of the bad stuff that an air filter is there for as compared to the stock air filter that already has more than enough air flowing capacity.

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Thanks for the input how about AFE dry filters I can see them being Worst than stock

Leave it alone. You need to be making well over 250hp more like 300 to be even remotely concerned with air flow as a restriction on a tdi as well as 99.9999998% of cars built after 1990. That's clearly an exaggeration but not really.

Leave it alone and put a quality filter in like a MANN.

DmaxjonTDI said:

Thanks for the input how about AFE dry filters I can see them being Worst than stock

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On turbo diesels that do not have a CCV going in the intake, it's obvious that the AFE doesn't filter as well as paper. A turbo that has been under the watch of a properly sealed paper filter will have a clean looking compressor wheel after a hundred thousand miles; the ones with an AFE filter look like they've been through hell and back.