Nissan 240SX KA Header Install

Installing an aftermarket header on your 240SX is an excellent way to free up a few extra horsepower. Using a header, along with an aftermarket exhaust and a high flow cat, are going to yield positive results! Installation is straight forward and should be easily accomplished with a few simple hand tools.

This install will work with any 240SX from ’89 to ’98 (non-turbo of course!)

Tools Necessary:

  • Reliable socket set
  • Metric wrenches
  • Jack and jack stands or ramps
  • Penetrating oil
  • Hammer
  • Propane gas torch (maybe)

Start by Raising the front of the car and securing it with jack stands.

Spray the cat bolts with penetrating oil. Hopefully, your catalytic converter bolts are no where near as nasty as my 216,000 mile, salt belt rusty bolts.
Spray the cat bolts with penetrating oil. Hopefully, your catalytic converter bolts are no where near as nasty as my 216,000 mile, salt belt rusty bolts.  (That little stud is what’s left of the bolt FYI)
In my case, breaking the bolt was option. Your situation may vary.
Once the oil has had a chance to do its work, remove the two bolts that attach the cat to the down-pipe.  In my case, breaking the bolt was my only option. Your situation may vary.
Next, remove the three bolts that attach the primary catalytic converter to the manifold. Two will be accessible from above...
Next, remove the three bolts that attach the primary catalytic converter to the manifold. Two will be accessible from above…
...and one from below.
…and one from below.

Once you remove the bolts, you can pull out the down pipe and primary cat.

Take a moment to unplug the O2 Sensor.

Remove the stock heat shield. There are several bolts along the top and near the primary catalytic converter. Getting this cover off will be tricky just be patient and avoid breaking anything.
Remove the stock heat shield. There are several bolts along the top and near the primary catalytic converter. Getting this cover off will be tricky just be patient and avoid breaking anything.

With the shield off, you will need to remove The EGR tube located at the back of the manifold. It requires a 24mm box wrench in order to be removed.

Once the EGR tube is disconnected, you will need to remove all of the exhaust manifold bolts. Do not be alarmed if the stud comes out with the nut.
Once the EGR tube is disconnected, you will need to remove all of the exhaust manifold bolts. Do not be alarmed if the stud comes out with the nut.
Once you have all of the nuts/bolts removed, the manifold should slide off.
Once you have all of the nuts/bolts removed, the manifold should slide off.
With the manifold out of the way, you will need to clean off the original gasket material. I would take a moment and stuff the ports with paper towel so that you do not get any gasket material inside the engine.
With the manifold out of the way, you will need to clean off the original gasket material. I would take a moment and stuff the ports with paper towel so that you do not get any gasket material inside the engine.  Use a flat razor, a gasket prepping tool or sandpaper to prep the surface for the new gasket.
Prepped and ready for the new header!
Prepped and ready for the new header!
For my swap, I used an OBX header that I bought on eBay. It was $200 shipped. Other than hitting the bottom of the car, due to my Nismo mounts, it's an excellent solid stainless steel manifold.
For my swap, I used an OBX header that I bought on eBay. It was $200 shipped. Other than hitting the bottom of the car, due to my Nismo mounts, it’s an excellent solid stainless steel manifold.
The header appears has much smoother bends and helps separate exhaust pulses.
The header appears has much smoother bends and helps separate exhaust pulses.
Once you finish comparing the old with the new, carefully slide the header in from the top. It will be a tight fit, but with some effort, you will get it in. Slide on a new gasket, the header, and reinstall all of the manifold bolts.
Once you finish comparing the old with the new, carefully slide the header in from the top. It will be a tight fit, but with some effort, you will get it in. Slide on a new gasket, the header, and reinstall all of the manifold bolts.

Do not forget to reattach the EGR tube, and O2 sensors

Under the car, attach the new header to the lower cat and you’re ready to fire up the car and test for leaks.

As you can see, the new header looks great. Coupled with a new exhaust and catalytic converter, it made noticeable difference in power.
As you can see, the new header looks great. Coupled with a new exhaust and catalytic converter, it made noticeable difference in power.

Enjoy!

A quick video of the header and nothing else: