How is a K&N on a X308? Does it really upgrade the performance as where you can feel it? And does the car sound different? And how bout MPG?

 

On every bike I've owned individual K&N's made a big difference. If you're keeping the stock intake plumbing though I wouldn't expect much. K&N's are also kind of a pain in that you have to clean and re-oil them to keep them filtering. On a bike in upstate NY that's a twice a year process for a car I would be doing that at least 4 times a year. As for mileage, anything that's flowing more air will use more fuel as well, as long as that's what you're asking it to do. If you take it easy there shouldn't be any difference.

 

I ran a K&N cone filter in a homemade air box shroud (similar to what the Mina Gallery box looks like). While I could certainly hear a difference, I'd say there was a little bit of a change in low-end pick-up, but as far as how much, I can't say. And it could just be placebo from the sound too. But what dw said is correct in that the main bottleneck that seems to be in place, isn't so much the filter and box, but rather the intake tube back to the throttle body.

I didn't notice much of a difference in mpg, maybe about 1/2 mpg if that, but then I also drive varying conditions and the gas up here varies so much from station to station, that it could've been anything.

People have also said that the oiled filters can play havoc with the MAF in the car, and truth be told, I did have it throw a code once or twice. Was another thing that I had a couple things happening, so I can't say definitely that it was the filter (I reverted back to the stock airbox at the same time I was fixing other things, but I haven't had a code since, either. Could be coincidence, could be not).

 

The codes thrown can be two fold as well as issues with the MAF. People "over oil" the K&N style filters which ends up getting on the MAF the another issue is people put one on and don't give the ECU time to acclimate but just start honking on the accelerator. If you put one on don't "saturate" it in oil. I also reccomend after a day of driving pulling the MAF and staying it with some approved MAF spray cleaner. Once installed let it idle for 10 mins or so and drive it around calmly while the ecu gets acclimated. A reset with the battery cables prior probably isn't a bad idea either to establish a new baseline.

 

Sound is different yes. HP increase/fuel consumption decrease? Absolutely not.

 

Even when well oiled, the filtering efficiency is really poor, meaning that more particulates get into the engine, increasing wear. No thanks.

 

What Mark SF said gives me a second thought, would I really want a air filter that would do damage to my engine?

 

Don't know what Mark SF said (he's on my ignor list for a reason) it isn't going to damage your engine. Been running K&N's on everything in my garage for years and years, never had issue one with anything on any of my engines. Put 199,000 miles on a 99 Explorer Limited with one on it since new and that vehicle is still with the guy I sold it to running fine 5 years later.

 

It's one of those things that is debated, like oil and wheel choices. Some vehicles are also more tolerant to changes, others are pickier, and I can't say what ones do or don't play nicer than others. I ran them on other cars just fine as well, and I can't swear that it did or didn't work well in mine, because I'm fairly sure I had other issues that were causing things. I can't just say the K&N cone filter totally screwed up my MAF. But, I do know that prior to changing it, I don't remember there being any codes other than a trans fault twice, and afterwards, I had other codes thrown. But I also did a hard reset and other things at the same time I went back to the stock airbox, so I won't point fingers because I just can't prove either way.

All I'm repeating is claims made by various other people on the boards, but again, it's debated both ways in every post. I personally wouldn't think it would affect it, and I wouldn't have a problem running it because of a risk of anything entering the engine, I know there are horror stories but they don't worry me as much. I'll likely switch to a drop-in style, with a smoothed air tube this spring, to split the difference. I liked the sound aggressiveness from the cone, but I think there's more actual gain (even though it'll be minimal) to be had by smoother airflow.

 

Im not getting the cone filter, just the regular K&N stick in oem air box.

 

They're perfectly able to cause trouble...

The days of biggish gains that way are gone, but it's your car.

 

No doubt there will be mixd opinions on this subject which is almost as
emotional as engine oil and spark plugs ;o)=)
Just my experiences.....I have run a standard K&N panel filter which replaces
the factory stock filter for the last six years.
I don't really notice any change except probably when i flatten it full throttle
but I don't venture that far up the rev scale very often in respect to the
engine which has covered 214,000klm ;o))
I think mpg has improved slightly.
As some one was complaining....I can't see that a filter clean every 40,000 is too difficult and over a period you are saving money on standard
filters and doing the planet a favour ;o))
Using the proper filter cleaning kit is easy and despite variopus comments about K&N filters clogging up MAF meters, I have had no problems along these lines.
Invariably it has been found that what problems do arise is usually down to people getting a bit too enthusiastic about re-oiling the filter!

 

How are the liquids chemicals required to clean and re-oil the filters doing the planet a favour?

 

 

It's easy to test the maximum gains a K&N filter could provide in the stock air filter housing. Just remove your existing air filter, close the filter box lid, and take a drive. You'll hear a little more induction noise and you'll have the sense that the engine revs very slightly more freely at mid to high revs, but that may be the increased air induction noise fooling you. The real difference in performance, if any, is probably so small as to be nearly immeasurable. And that's the maximum performance gain with no filter at all. Adding a K&N will of course decrease the "gains."

Then consider the indisputable fact that any air filter that can allow more air to pass can also allow larger-sized particles of airborne grit and debris into your engine, and you may decide a good quality paper filter is a better choice in a street car.

Cheers,

Don

 

I remember reading somewhere on the forums, a member who either owns a dyno or knew someone with a dyno went to test this. Don't remember if it was an x308 or x350 XJR... In any case, dynoing a paper filter in the factory airbox, vs a "lifetime" filter, produced no measureable differences. In fact, even taking out the filter completely for minimum restriction only produced a difference of about 2 hp.

 

I'll just stick to the paper air filter, haha.

 

Back in the dark days of needing to work for a living, I operated a variety of calibrated, certified accurate dynomometers. I can assure you that a 2HP variation from one run to another on a 300-500HP engine is well within the range of gauge/instrument error and not proof of any actual variation in performance.

 

Here's a fun thread read for the OP if he hasn't seen it yet:

https://www.jaguarforums.com/forum/x...results-74595/

 

Agreed, I probably should have mentioned that in my post.

Interesting to see that the big piping makes a difference, would be cool to hear a outside/inside driving sound clip to get an idea of how intrusive the noise is.