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Installing an exhaust header is one of the few external things you can do to add a few horsepower to a normally-aspirated car. Cost can run $150.00 to $400.00 for a 8-10 hp increase. This is generally considered a good investment. Installation is mechanical stuff that just requires basic hand tools.

This page details the installation of Archer Racing headers on a '93 Eclipse. Depending on whoose headers you buy, your procedure may be different in some areas, but the main steps should be the same.

Before you start, be sure you have an exhaust manifold gasket appropriate to the model year of your car. The gasket was changed along the way. Also, do you have gaskets for the other joints? What about bolts to connect the pieces, if your header set is multi-piece? Be prepared as the BSA motto says. Study the instructions and your existing exhaust system.

The Archer header is one piece from the cylinder head to the collector flange, and extends under the engine past the oil pan. Then the short flex-section goes between the collector flange and the catalytic converter. Other headers may have 2 or 3 pieces joined differently, but they all accomplish the same thing.

Archer put the O2 sensor fitting on the driver's side of the collector, which means the O2 sensor wiring harness must be lengthened about 4 feet to route the wires away from all the hot exhaust and engine parts. The one-piece design also means the radiator has to be removed to get the header into the engine compartment. If you bought another brand of headers, you may not have to do these steps and can skip them when the time comes.

If you didn't skip the first part and haven't started already, let's begin. References to right and left are as you face the engine

Off With The Old

• Raise the front of the car about 8 - 10 in. using jackstands or ramps of some sort. This is the only way to get to most of the bolts that must be detached.

• Put some penetrating oil on the bolts at each joint: exhaust manifold to head, heat shield to manifold, O2 sensor, manifold to downpipe and downpipe to cat-con.

• Disconnect the O2 wiring connector at the left end of the engine and remove the O2 sensor from the exhaust manifold.
  I used a large adjustable wrench, because I didn't know better, and it broke loose easily. If yours doesn't want to come out, you may need to get a special O2 sensor socket. These are available at most parts stores.

• Remove the exhaust manifold heat shield.
  There are 2 bolts on top, one on each side down low (not easy to get to), one in front and one behind the exhaust manifold. This last one can be reached better from below.

• Remove the down-pipe with flex-section.
  Unbolt the 2 bolts at the cat, then the bottom bolt of the rubber biscuit hanger a foot or so in front of the cat and the ground strap near this same point. Then remove the 3 nuts at the down-pipe/exhaust manifold joint. Don't let if fall on you.

• Remove the power-steering heat-shield
  This is bolted to the power-steering pump mounting bracket. Removing it gives you more room to get to the lower right manifold nut so you don't have to remove the power-steering pump. There is a bolt that parallels the engine and a small one between the power-steering pump mounting bracket and the pump itself.

• Remove the exhaust manifold and gasket
  There are 9 nuts to remove. The lower right nut is hard to get to, but mine was so loose, I could spin it off with my fingers.

• The gasket is metal, so there shouldn't be any gasket material stuck to the head, but there will probably be carbon around the edge of the ports. Scrape it off and clean the mating surface with solvent. Now would be a good time to check the studs and replace any broken or damaged ones.

• Disconnect the fan motors at both fans and a sensor connection at the bottom of the left fan.
• Remove both fans.
  There are 2 bolts at the top and 1 at the bottom of each fan. The bottom ones don't have to be completely removed.

• Open the petcock at the bottom right of the radiator and drain the coolant into a clean container, because you can reuse it if you keep it clean.

• Disconnect the upper and lower radiator hoses.
  I found it easier to disconnect the lower hose at the engine end. There will be some coolant spillage here, so have a catch-pan handy.

• Disconnect the transmission coolant lines, if you have an automatic.

• Remove the 2 upper brackets that hold the radiator to the frame.

• Lift the radiator straight up and out of the car.
  Do this carefully and set it aside in a protected spot. You don't want to stick something through it. Notice how thin it is. Seems like it should be twice as thick.

On With The New

• Place the new exhaust manifold gasket on the studs with the side marked "out" facing away from the head.

• Put the header on the studs and tighten the nuts.
  Torque them to 18 - 22 lb/ft. Start in the middle and tighten the nuts alternately towards each end. That lower right one may be difficult to torque. Just get it as tight as you can with whatever wrench you can get on it. You can leave off the engine hanger bracket, which is the sort-of triangular-shaped bracket that came off with the manifold. My header flange hit the power-steering pump bracket and I had to grind some material off to get it to fit, and I also had to ream out a couple of stud holes in the flange.

• Bolt the flex-section to the header collector flange and to the cat-con.
  Don't forget the gaskets. Here is a tip from my muffler man. Use clear silicon bathtub caulking on the flanges before bolting a joint together and wipe off any excess that squeezes out.

• Attach the rubber biscuit and the ground strap to the flex-section.
  I had to drill a hole in the flex-section mounting bracket to attach the ground strap. And the ground strap must be re-attached.

• Put the radiator in, connect all the hoses and replace the coolant.

• Replace the fans and plug in the electrical connectors and sensor.

• Replace the power-steering pump heat shield.
  The little bolt that goes inside the bracket can be left off. I also had to bend the dip-stick tube slightly, to clear one of the header pipes.

• Replace the O2 sensor in its fitting on the new header and connect the other end.

• Cut the 4 wires somewhere in the middle.
  You will want to stagger the cuts by a couple of inches so the 4 connectors at each end won't be bunched together.

• Connect a 4 ft. piece of 18 gauge wire to each of the 4 wires.
  Check the wire colors to be sure you are reconnecting the same wire. Do them one at a time and you should be OK. Try to get the overall lengths the same. I got a package with 4 colors of wire plus crimp connectors (8) from Radio Shack for about $5.

• Connect the O2 sensor to the fitting on the header collector.

• Run the wires out to and then along the edge of the side splash shield, forward past the oil filter, across the bottom of the radiator, and up to the connector at the left of the engine and reconnect. I covered the wires with some flexible split plastic tubing and tied it down at a few strategic places. It looks like it came from the factory that way.

• Start your engine and let it get up to operating temperature and check for leaks.

• Turn off the engine and re-torque the header nuts.
  Start in the middle and worktowards the ends as you did before you started the engine. Check the other joints also.

Your engine will probably sound different and may be noisier because steel tube doesn't muffle sound as well as cast iron. But I think the performance improvement is worth it.

Last updated on Jan. 31, 2000