Article by Gary Rohrer.
Like all fellow Jeepers I am interested in the constant pursuit of improving my rig. Whether it’s suspension improvements, exterior modifications or engine improvements, we all have the drive to make our Jeeps a better vehicle.
If you an ZJ owner with a 5.2L V-8 there is one engine modification that is worth every penny of it’s price. It’s a K&N Filtercharger Injector Performance Kit or FIPK for short. This is a simple intake plenum and Air Filter that replaces your stock filter and intake. The performance gains are incredible! K&N claims to have dyno’d a Grand Cherokee and gained 26Hp with this kit. After installing one and feeling the results I believe this to be true.
I researched this kit at K&N web site and compared it to a similar product that Turbo City sells. Turbo City’s K&N intake for the 5.2L V-8, looks really sexy since it uses two K&N filters and it costs less than the K&N’s FIPK. I decided on the K&N kit since it creates an air baffle around the filter to separate the hot air in the engine compartment from the cooler air around the filter. Turbo City’s kit places the filter near the firewall above the heads and exhaust manifolds. K&N’s kit seems like it would have a better chance of drawing in cooler air than Turbo Cities kit. Cooler air of course provides better combustion.
I visited several on-line stores that carry this product. I finally settled on purchasing it from JC Whitney since they had the lowest price and free shipping at the time. I did have a bit of delay with the shipping since they used Airborne Express @ Home service. Airborne has partnered with the US Postal service for this service. Turns out the local carrier didn’t want to deliver a large 15-pound box to my address! After a call to Airborne it was promptly delivered.
Installation of the kit took about an hour and half, and that included taking pictures along the way and notes for this article. You’ll need a standard and metric wrench set along with metric sockets. K&N provides excellent instructions however some of the pictures are small and hard to make out.To begin with you’ll need to remove the stock airbox/filter and intake. Remove the nut that secures the intake to top of the throttle body and undo all the clamps around the air filter. You’ll also need to remove the crankcase vent hose that attaches to the top of the air box. The upper intake plenum should come right off.
Remove the air filer elements and remove the three bolts that hold the air box to the fender. This seemed simple but proved to be tricky since the nuts were located under the fender and were not secured in place. I turned the tires to the left and placed a wrench on the nut while loosening the bolt above with a ratchet. Once the three bolts are removed the lower half of the air box comes out leaving it’s puny intake hanging near the radiator.
There is a one plastic connector that holds this intake duct in the grill. I simply used an old hack saw bladed to cut the plastic connector. After this is removed it may be necessary to cut some of the rubber shash guard away to provide maximum airflow to the intake. This picture illustrates the shash guards removal. Basically you can see directly from the engine compartment to the outside through the grill.
Next it is necessary to remove the stud assembly from the top of the throttle body. This is easily accomplished with a 7/16″ ratchet. Be careful no parts or contaminates get into the intake.
With the removal of the stock equipment it is time to install the K&N parts. To begin you have to assemble some rubber isolators to the bottom of the K&N heat shield. Use the washers and nuts provided with the K&N kit. Before installing the heat shield into your Jeep I would install the rubber trim seal. K&N instructions said to do this after mounting the heat shield in the Jeep but think it would have been easier to manipulate the seal around the corners of the shield while it was off of the vehicle. Once this is done install the shield in two of the mounting holes that held the original air box. You will have to secure it in place underneath the fender using some of the provided washers and nuts. This image shows the heat shield installed with the trim seal on the upper edge.
Now it’s time to assemble the saddle bracket that supports the intake. K&N provides the necessary nuts & bolts. This bracket mounts to the heat shield and can allow for up or down adjustment of the intake. Before we install the intake, screw the provided stud into the throttle body where the stock bolt held the stud assembly. Be careful here since you are screwing this into soft aluminum. Also place the new gasket onto the throttle body and place the stand off on to the new stud.
Now it’s time to carefully place the large intake plenum into the heat shield and onto the throttle body. Again be mindful of the stud in the throttle body so you don’t bend it side to side. Use the original nut and a new washer to secure the plenum to the throttle body. Also adjust the saddle bracket on the heat shield to support the intake. Use a new hose clamp to hold the intake to the bracket. Be sure to inspect around the gasket to ensure you have a good seal between the intake and the throttle body.
Now is a good time to reconnect the crankcase breather to the fitting on the side of the new intake. I found my hose had a bind in it since the K&N fitting sits farther back than the factory setup. I simply cut 3/4″ off of the plastic tube between the hoses and the angle was back to normal. Your set up may vary.
Finally install the K&N Filtercharger and secure it in place with its hose clamp. Now go back and make sure everything is secure and fits properly.
Once you’re satisfied start up the engine and listen for any loose parts or vibrations. Also insect around the gasket for any leaks. Now you are ready for test drive! Be aware, your Jeep will now launch from stop. This is where I noticed the most improvement. Before the ZJ seemed like there just wasn’t enough get up and go. After installation the ZJ is ready to take off with no hesitation! It accelerates much more easily with this kit.
Under normal driving conditions I can tell no difference in sound from the new intake. Under hard acceleration I can hear the air flowing into the throttle body, but only with the radio turned down. The added noise is not significant. If you have ZJ with a V-8 you owe it to yourself to get this kit. The increase in power is substantial considering it’s easy installation and it cost.No comments