BMW e30 318i K&N Filtercharger Cone Upgrade

Installation of the new K&N upgrade requires removal of the stock air box.  Removal of the box is pretty easy.  Undoing a few bolts and unplugging two sensors was all that was required.  Installation of the new cone was just as straightforward and convenient.  The bracket that was included with the kit is necessary to hold the AFM stationary because the AFM was previously supported by the air box.  The Bracket is bolted to the AFM on one side, uses the existing air box bracket on the other, and uses the old bolts and bushings from the air box as hardware.  With the AFM supported and bolted to the bracket, the two airflow sensors must be relocated.  The air temp. sensor that was attached to the ducting from behind the driver-side headlight was left in place with the sensor in its original location.  This tells the computer exactly the same thing it did before and the are no problems.  The second sensor is relocated to the AFM bracket.  Once the sensors are relocated, the K&N cone is easily sinched onto the plenum of the AFM with a hose clamp.  For ease of closing the hood, the cone has an angled base and should be adjusted so there is no interference. 
 
 

RESULT—

Everyone who sells these cone upgrades rave that you will see “A 10% gain in horsepower!”  I cannot say that I saw a huge power-band improvement, but I am very satisfied with the investment.

 First—It looks good…enough said.

 Second—Throttle Response.  After installing the cone upgrade, I immediately noticed a change in how snappy the throttle is.  There is no lag now when the pedal is depressed. 

 Third—Sound!  The cone upgrade does make a difference in the sound of the car when you step on it.  Juicing the throttle, it is evident that there is some serious suction into the AFM.  Accelerating onto the freeway is now music to your ears. 

 Fourth—Power.  The cone upgrade is definitely not an upgrade for the entire RPM range.  Because the air filter is open and exposed to the engine bay (because it was protected before by the air box), the filter is now exposed to engine heat.  Heat and horsepower do not go good together.  For more power, you need colder air for denser oxygen.  So, any performance gain will usually be seen traveling 35mph and up because the air is then getting into the engine and cooling it down.  Sitting at idle or city traffic, the K&N provides no gain, and most argue it robs horsepower because it is sucking in hot air.  I frankly don’t see any bad results when city driving.  I would say this is the greatest reason why people are against purchasing the upgrade because of the engine heat exposure.  Fortunately, the intake and the exhaust manifolds are on opposite sides of the car so any exposure is not direct. 

 Fifth—Million Mile Warranty.  K&N warranties their products for a million miles and they are reusable.  The reusability factor is great and reason enough to purchase the upgrade.  I clean mine quite often because it is so easy.  However, the element must be re-oiled so purchasing the Recharge kit is a good idea. 
 

Jobe Tichy