Have been searching online for a cold air intake kit for 1999 z3 2.5L engine. Have seen them for the 2.8L. Will the ones for the 2.8L fit in the 2.5L engine bay? If anyone has had a success with this, please advise.
Ordered a cold air intake from Cosmo Racing last week. They are located in Quebec, Canada. Just received it yesterday, It has a long tube that extends down and to the front of the car to draw air from just behind the grill. It came with a K & N filter. Cost was $180 including shipping ($160 + 20 shipping). Have not installed it yet as we have too much snow and I won't be driving it till April. First drive will be with the local BMWCCA when we take a spirited run down to Watkins Glen Racetrack for a few laps!
Installed CAI a couple of weeks ago. Installation was not hard. Had to buy spray oil for the filter. It did not come oiled. I have run the engine and throttle response is quicker. I have not driven my car yet, winter still has it's ugly grip where I live. I will be putting it on the road next week and hopefully driving it soon. It has been a long winter! I am pleased with the quality of the tubing, clamps, and installation instructions.
Just drove my car for the 1st time today after the Cosmos Racing CAI. Had absolutely no problems with anything. Engine ran perfect and could really notice and increase in throttle response and also more power throughout power range. Installed Magnaflow muffler last summer and I am very happy all around with some extra hp and sound! No problem with MAF as I was very careful not to over-oil the filter.
Independent, controlled studies have proven that oiled filters pass much more dirt than dry paper filters. http://www.nicoclub.com/archives/kn-vs-oem-filter.html
If trapping dirt is not a concern for you, why not just remove the filter entirely?
Many people with oiled filters claim "I've never had a problem." Is that really a standard to measure against? I've run paper filters and never had a problem, either. And many people DO have problems with oiled cotton filters, usually costing many times the cost of the filter, such as in the thread referenced above.
Every filter related problem I have encountered has been due to improper use. Every single filter related issue has been from excessive oil and/or a torn or perforated element. I'm well aware of how these filters work, and what they are capable of filtering. I spent many years building race engines for off-road and street/strip use as well as building and modifying diesel engines for pulling, towing, drag racing or mileage. I own several cars, presently one has 250k on it with an AFE filter since 100k. My 93 Cummins did 560k before I sold it, K&N on it since before the plates arrived. My 95 had almost 300k with a K&N too. Never saw a turbo failure or any other dirt related damage, and these were used in the Nevada desert constantly running between Reno, Ely and Las Vegas.
I sold my 04 Cummins with 180k on it, Airaid filter since 18k miles (when I purchased the truck used), and zero issues.
Then there's all the carbureted cars running them, wouldn't I see excessive dirt built up in the carbs if these filters were so horrible?
I'll let you fill in the blanks, I don't feel the need to post my whole resume and experience on this forum just for you.
The test you show compares filters for the same application, without consideration for cone style replacement filters (as used on the majority of CAI's on the market), not taking into account the very sizable increase in surface area on the cone filter in the OP's application.
And to the person that recommended the adapter from cosmoracing.com, you can get that same thing from your local Autozone. I don't recommend running the filter that close to the MAF, it creates turbulence and a length of pipe between the MAF and filter will often increase performance and improve drivability by reducing this turbulence at the MAF.
If you hold a K&N filter up to a light, you can see through it. You'll never find one on any of the engines I own, unless there's just no way around it (like limited options with a supsrcharger, for example).
I like the "smart fly" reference; probably more accurate than my description of "the only thing it keeps out is the cat!" I also can appreciate the shop owner that loves them, because they create more work for him! LOL!
Question - Has anyone seen a car or motorcycle manufacturer install an OEM oiled air filter on their OEM product, even one of their high-performance models?
Roush and Shelby install them on Mustangs and the warranty is still intact.
Dinan uses them and warranty is still intact.
Many of the OEM's offer them as options through the dealer or various performance packages.
Roush and Shelby install them on Mustangs and the warranty is still intact.
Dinan uses them and warranty is still intact.
Many of the OEM's offer them as options through the dealer or various performance packages.
I agree... improperly/over oiling the filter will cause trouble but IMO done correctly there is no better filter medium for both trapping dirt and allowing maximum air flow.
The principle of how foam air filters work is simple: “Open Cell” Polyurethane Foam is wetted with specially developed filter oil. the inside looks like a honeycomb structure.
The “sticky” filter oil is suspended in the path of the dirty air on the strands of the web-like cell structure of the foam. This makes it impossible for dirt to pass through the depth of the filter without sticking to the strands.
As the outer strands become loaded with dirt particles, the wetted strands down stream start trapping dirt, allowing the entire thickness of the foam to be utilized. This prevents surface loading or air restriction for 80% of the service life of the air filter element. When the filter is sufficiently dirty, it can be easily washed, re-oiled, and re-used.
K&N filters are "oiled gauze" and while they do allow more airflow than a standard paper element they are not very good at filtering.... the gauze structure is much thinner than foam so there is only one chance for it to catch any dirt on the sticky oil wetted strands.
the worst part about the K&N is that once the strands finally do catch some dirt there is no way for it to catch anything else so then ALL the dirty air gets through. this is not good for an engine if you are wanting to get a long service life from it.
Paper, in dry conditions is a fantastic filter and is also capable of stopping very small particles like oiled foam but unlike oiled foam it is restrictive when setup to catch these small particles..... the reason paper filters are pleated is to give them enough surface area to catch dirt and still allow the engine to breath.... however even a new paper filter is not going to flow as much air as a properly oiled foam filter of the same dimensions.
I believe the reasons more OEMs use paper filters is just for the simplicity and availability of paper filters.... not because they are necessarily better than oiled foam.
...
I believe the reasons more OEMs use paper filters is just for the simplicity and availability of paper filters.... not because they are necessarily better than oiled foam.
IMHO, car manufacturers fall mainly into two groups. Those (ex., Ford and Toyota), who due to market forces and legal standards, care about low cost, fuel economy, low emissions, and low maintenance over all else. Those (ex., Porsche and Ferrari) who care about performance above all else.
OK, it is a little simplistic. Some manufacturers (ex., BMW) don't fail neatly into either group. And maximum profits is what all manufacturers ultimately care most about.
But both groups will use any technology that supports their goals. And both groups have rejected oiled filters.
As for simplicity, simplicity to BMW means replacing mechanical systems with electrical ones, "lifetime" fluids, and "no charge for the first four years or 50,000 miles" maintenance.
Any car manufacturer could easily source foam filters from some third world country.
the simplicity of paper is why the OEMs rejected oiled foam.... too easy for the average consumer to over oil the filter and then contaminate and ruin the MAF that is right downstream.
The average owner has never even seen an air filter, much less changed an air filter. At my former job (currently I'm retired), I was the only person who had ever changed their own oil.
Consider construction and farming equipment: they operate in extremely dusty environments and have little tolerance for maintenance down-time, failures, and limited engine life. They use nothing but paper filters.
At the other end of that spectrum are race cars, where maintenance and downtime are not a concern as long as they can complete a few hours. The tiniest margin of performance can help win a race, so often air filters are completely eliminated in that case.
Oiled filters seem to be an attempt to be between these two extremes.
I still don't understand the argument that "I've never had a problem with oiled filters." Millions of people can say that about paper filters, so it's not an argument.
I still don't understand the argument that "I've never had a problem with oiled filters." Millions of people can say that about paper filters, so it's not an argument.
^ This. Unless one really thinks they are going save money over the lifetime of their vehicle ownership between buying new paper air filters vs. cleaning and reoiling your oiled air filter, the only reason to use an oiled air filter seems to be if there is a real performance advantage in using an oiled air filter. I've just never seen real, independent proof that there is a real performance advantage.
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