performance air filter

sus

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k&n don't list them for 2012 C350cdi
does anyone know if they are the same as 2010 C320cdi as they list them for that
 

EmilysDad

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Save your money ;) 'performance' filters are generally no bettervthan OE, they just make more noise ...... the placebo effect :rolleyes:
 
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sus

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To see how well cars respond when the standard filter is replaced by a sports set-up, we took a Vauxhall Signum 1.9 CDTI diesel and a VW Golf GTI to tuning specialist Regal Autosport in Southampton.

Here, we hooked the models up to a rolling road and logged power data with a standard element in place, then with a sports filter and a full induction kit. We used K&N sports filters (£48) on both cars, a K&N Apollo induction kit (£190) on the Signum and an Evolution V-Flow (£249) on the Golf.

Vauxhall Signum CDTI
Standard*/Sports filter/Induction kit: 150bhp/152bhp/156bhp

VW Golf GTI
Standard*/Sports filter/Induction kit: 218bhp/219bhp/224.5bhp
THIS IS FROM AUTO EXPRESS
 
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LostKiwi

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OK so 152 hp against 150.
Statistically that's about 1.25%. That's within the realms of error from temperature changes and would not be felt by the driver. Even the induction kit wouldn't be felt. It takes a good driver to detect a 10% improvement 15hp on the first car and 21hp on the golf.
A remap on both would give far better results and more HP/ £.

And that's before we take into account wear caused by inferior filtering and shortened engine life or potential oil contamination of the MAF.
 
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sus

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cars already mapped:D,just thought id put k&n in as you can clean and re-oil so no need to buy filters again
 

V6Matty

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Afraid not, I had a BMC with my 270 and will admit I didn't get much extra induction noise but I did get a nice amount more waste gate chatter, and it may have been ever so slightly better on throttle response but it was only slight,

Oh I did also clean and oil mine every 5k any more and I think as the others say your running the risk of allowing more crap into the engine.
 

Craiglxviii

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cars already mapped:D,just thought id put k&n in as you can clean and re-oil so no need to buy filters again

Sus,

I work in automotive design and benchmarking. We test these things regularly. K&N filters make zero, say again zero impact on engine power. We have tested on dozens of cars over a decade and found no effect whatsoever. Put bluntly the OEMs are better and have more experience and money to spend on developing intrinsically-safe engine parts than aftermarket companies do.

What they do do however is contribute significantly to particulate buildup and associated wear patterns in the intake... :)
 

Yugguy

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The only time oiled filters are better than paper is when both are dirty. Just change paper regularly.
 

Craiglxviii

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In terms of noticing a difference in engine power, something else of interest is that human response feedback mechanisms are logarithmic. Hold a one kilo and a ten kilo mass each in different hands and you can obviously tell the difference. One and two kilo you can tell the difference. One kilo and 1.5 kilo and you can just tell the difference... as the differences between two things that you're comparing reduce down, your ability to perceive those differences reduces in sensitivity at a rate that very closely approximates a log curve.

So 150:152bhp, you would not be able to discern any difference at all. 150:160 you might, might just notice it, assuming that no-one had told you that there was a difference. The key here is that if you've been told about it, you'll go looking for it. And what is amusing is we find that people will swear down blindly that car XX is noticeably faster/ better performing etc than car YY even though there are no differences at all to them (except for the driver comparing them being told beforehand that XX has been uprated, tuned etc).

The placebo effect is responsible for a lot more in one's perceptions of how things perform/ handle than you might think!!!
 

LostKiwi

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In terms of noticing a difference in engine power, something else of interest is that human response feedback mechanisms are logarithmic. Hold a one kilo and a ten kilo mass each in different hands and you can obviously tell the difference. One and two kilo you can tell the difference. One kilo and 1.5 kilo and you can just tell the difference... as the differences between two things that you're comparing reduce down, your ability to perceive those differences reduces in sensitivity at a rate that very closely approximates a log curve.

So 150:152bhp, you would not be able to discern any difference at all. 150:160 you might, might just notice it, assuming that no-one had told you that there was a difference. The key here is that if you've been told about it, you'll go looking for it. And what is amusing is we find that people will swear down blindly that car XX is noticeably faster/ better performing etc than car YY even though there are no differences at all to them (except for the driver comparing them being told beforehand that XX has been uprated, tuned etc).

The placebo effect is responsible for a lot more in one's perceptions of how things perform/ handle than you might think!!!

The rule of thumb I found was 10%. Very few drivers will detect a 10% increase in power. Interestingly we are more attuned to when things get worse as almost all drivers will detect a 10% drop in power.
 

Yugguy

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I will say that back in the day on my Vec B V6 that had a badly-routed inlet to the airbox, replacing the airbox completely with a BMC CDA closed kit did help it rev more freely.

If I look at the Merc airbox though I don't see how even a closed aftermarket kit would improve it.

Although I do wonder why they route the inlet pipe across the front of the engine to the passanger side cutout instead of using the shorter route to the driver side cutout. I can only assume it's to do with noise reduction.
 

Craiglxviii

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The rule of thumb I found was 10%. Very few drivers will detect a 10% increase in power. Interestingly we are more attuned to when things get worse as almost all drivers will detect a 10% drop in power.

If you look at the natural log curve you'll see at 100 (1% of total) is where a change is just discernible, and 1000 (10%) is around the apex of the inflection point. Everyone is slightly different of course but this is a good approximation of the human ability to discern change in physical stimuli.

You are right though on things behaving worse than we are accustomed to! Odd one that, the curves when plotted together have a disctinct separation.
 

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