K&N filters for CS
- Thread starter CHRIS
- Start date
not for my personal taste,
but if you insist on them, please place a long hose from the tube that comes out from the head cover, and thus send the gases and oil emulsion far away from the engine bay
but if you insist on them, please place a long hose from the tube that comes out from the head cover, and thus send the gases and oil emulsion far away from the engine bay
+1 not for me. Can you put the K&N inside the stock air cleaner box?
snj5
Well-Known Member
I went through this on a similar set up. While the K&Ns will flow more air, it is pretty warm air from the engine compartment. The original airbox as you know, is pretty much what you have but ducted around the radiator to take cool, denser air from outside to the engine. We did a couple of dyno tests on a 3.2 liter engine on another make of car and there is a measurable difference in horsepower; that denser air just has more oxygen molecules. So, on the other car I went back to a ducted airbox like stock with a K&N filter. I would bet that the stock airbox with K&Ns will actually outperform your (and it was mine as well) set up by a good margin at speed. That said, it sure is easier to tune with your set-up. 
Everything is a trade-off.
Best of luck with what ever you decide to do!
Everything is a trade-off.
Best of luck with what ever you decide to do!
I have searched for a K&N for my CSi. They don't seem to make a filter. Can any others be fitted and work? Steve
johanaxelson
Well-Known Member
O'neills - http://www.knfilters.com/search/appsearch.aspx?type=auto&year=1974&make=BMW&model=3.0CSi&engine=3.0L
There is a CSi filter, do not know your year though.
Open filters my look "cool" but I would be a little worried about the warm air intake as well.
BTW, the normal filter eats about 5HP at 5000 RPM. When tuning my engine some years back we tried with and without.
There is a CSi filter, do not know your year though.
Open filters my look "cool" but I would be a little worried about the warm air intake as well.
BTW, the normal filter eats about 5HP at 5000 RPM. When tuning my engine some years back we tried with and without.
DerSchwede
Well-Known Member
There are K&N-filters for the original air-cleaner. They are a little bit more noisy than stock filters and of course they require a clean-up every now and then.... it's your choise.
Mike Goble
Well-Known Member
We did some air cleaner dyno testing several years ago for a 2-bbl V-8 setup used in the Lacarrera Panamericana and found that the most effective device was not the style of air cleaner but the carb hat we put inside it. It was worth about 8-10 rwhp compared to running without it, while the brand of air cleaner made little difference.
CHRIS
Member
Thanks to everyone. I will try to put the K&N inside the stock air cleaner box.
Miscellaneous air filter musings.
A few things have changed since the design and production of E9s. All car manufacturers have improved air filtration so that oil bathed filters are far and few between. So too, the all metal filter housings have gone the way of the horse and buggy. If you wanted to improve the E9 filtration, you might be wise to look at current stock filtration.
Enclosed filter housings are typically better than their exposed counterparts at protecting the integrity of the intake air. They do this by excluding water and other contaminants capable of being flung about in any underhood environment. Actual air filtration and heat exclusion are separate considerations.
Results are mixed about whether oiled cloth is a more effective filter media than paper. Even if it is more effective at filtration, is it also more restrictive? (I recall advertising claims that certain media “combed” or “treated” the airflow so that it was more effective or efficient, but effective at what? Tornado? Twice the power with two inline filters???) Economically more effective, maybe. As part of this theory, I agree completely with M.Gobel regarding the internal contours of the filter or as he called it a carb hat. There is more than just a cosmetic reason for intake horns. Same logic applies to size and shape of plenum chambers. But of course, none of this makes much of a difference if the "combed" or "treated" air must traverse a throttle plate that is closed or partially closed. Simply stated, few street engines spend much of their time at wide open throttle.
Another consideration is heat exclusion affected by air filtration housing composition and placement. There is no doubt that colder/denser air is desirable, but with the large stock “metal” housings, one wonders if they do not act like glorified heat sinks and still contribute to a warming of incoming air. Even if the housing is not directly behind the radiator or above the exhaust, it still absorbs underhood radiant energy. A lightweight plastic or heat resistant filter housing placed away from the radiator and/or exhaust would make the most sense, but for obvious reasons, can pose a logistical issue, just as with a turbo heat exchanger. Of course, at speed there is probably enough omni directed underhood air flow that heat absorption becomes less of a concern. But that begets another consideration, designing the intake for stop and go traffic and/or autobahn. The stock offerings are a compromise for both, with room for improvement. I am guessing that unless you are driving in the foulest of off road conditions, fording rivers, snow banks and jungle terrain, the exposed filters would work almost as well as anythings else. To say the least, they save weight and improve the view.
A few things have changed since the design and production of E9s. All car manufacturers have improved air filtration so that oil bathed filters are far and few between. So too, the all metal filter housings have gone the way of the horse and buggy. If you wanted to improve the E9 filtration, you might be wise to look at current stock filtration.
Enclosed filter housings are typically better than their exposed counterparts at protecting the integrity of the intake air. They do this by excluding water and other contaminants capable of being flung about in any underhood environment. Actual air filtration and heat exclusion are separate considerations.
Results are mixed about whether oiled cloth is a more effective filter media than paper. Even if it is more effective at filtration, is it also more restrictive? (I recall advertising claims that certain media “combed” or “treated” the airflow so that it was more effective or efficient, but effective at what? Tornado? Twice the power with two inline filters???) Economically more effective, maybe. As part of this theory, I agree completely with M.Gobel regarding the internal contours of the filter or as he called it a carb hat. There is more than just a cosmetic reason for intake horns. Same logic applies to size and shape of plenum chambers. But of course, none of this makes much of a difference if the "combed" or "treated" air must traverse a throttle plate that is closed or partially closed. Simply stated, few street engines spend much of their time at wide open throttle.
Another consideration is heat exclusion affected by air filtration housing composition and placement. There is no doubt that colder/denser air is desirable, but with the large stock “metal” housings, one wonders if they do not act like glorified heat sinks and still contribute to a warming of incoming air. Even if the housing is not directly behind the radiator or above the exhaust, it still absorbs underhood radiant energy. A lightweight plastic or heat resistant filter housing placed away from the radiator and/or exhaust would make the most sense, but for obvious reasons, can pose a logistical issue, just as with a turbo heat exchanger. Of course, at speed there is probably enough omni directed underhood air flow that heat absorption becomes less of a concern. But that begets another consideration, designing the intake for stop and go traffic and/or autobahn. The stock offerings are a compromise for both, with room for improvement.
I am guessing that unless you are driving in the foulest of off road conditions, fording rivers, snow banks and jungle terrain, the exposed filters would work almost as well as anythings else. To say the least, they save weight and improve the view.
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gwittman
Well-Known Member
I have been running K&N filters in the stock air cleaner housing of my Coupe since around 1981. I have never had a problem with them. I did install a foam ring on the top part of the filters to get a more secure seal. Other than that they have been great.
Odd that this topic should come up, as I was just looking into this for my commuter V70R Volvo. From what I've read, flow is inversely proportional to filtration. That is, more flow = more dirt no matter how much hype the manufacturer may proclaim. Additionally, the K&N flow degrades dramatically as it gets dirtier.
About 15 yrs ago I did some 60-80 runs with some K&N filters versus some comparable filters I got from JCWhitner(don't scoff). The JCWhitney filters were measurably quicker and I returned them as they didn't meet their claims.
These days as well as then, I drive in pretty dust and dirt free environments (Hey, it's Vermont!), so filtration isn't so much an issue. The filters on there now are Redline, comparable to K&N.
My net assessment is to stay with a good paper filter unless you're driving mega miles. Then get a K&N and you'll save a few bucks over the life of the car.
IMHO as always.
About 15 yrs ago I did some 60-80 runs with some K&N filters versus some comparable filters I got from JCWhitner(don't scoff). The JCWhitney filters were measurably quicker and I returned them as they didn't meet their claims.
These days as well as then, I drive in pretty dust and dirt free environments (Hey, it's Vermont!), so filtration isn't so much an issue. The filters on there now are Redline, comparable to K&N.
My net assessment is to stay with a good paper filter unless you're driving mega miles. Then get a K&N and you'll save a few bucks over the life of the car.
IMHO as always.