Engine Mods

Engine

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One of the Xterra's drawbacks is that the engine is a bit underpowered, so coaxing as much power out of the engine is a good idea. The engine is what makes you go, and is what gets out if you get stuck, do everything you can to keep it happy. Luckily the low gearing in the transfer case is pretty decent so offroad power isn't a problem but passing a semi on the freeway might be a little harder. The engine compartment is also a good place to put all the things you don't want taking up space or making noise in the passenger compartment.

	Optima Battery After I got back from Iraq and took the Xterra out of storage the stock battery was long gone. Since the stock battery is pretty weak anyway I was happy for a reason to upgrade, I had known for a long time that an Optima Yellow top battery was what I was going to get. Optima batteries use a paste instead of liquid electrolyte so that there's nothing to spill, so the Battery can be turned upside down or even cracked without spraying acid all over the place. Optima's come in two varieties, Red and Yellow, the Red has higher CCA's for starting in cold weather but can't be run down as many times as the Yellow. The Yellow is a deep cycle battery, that means that you can run it down and recharge it more times before it dies permanently. Since I plan on running lights and possibly later a winch the Yellow top was the best bet.
	Fuse Box I knew that adding alot of accessories was going to make the battery positive terminal a mess of wires so I set up my own auxiliary fuse box to run accessories. There is one wire coming off the positive terminal to a fuse on the firewall and from there to the fuse box on the driver side of the firewall. The power going to the fuse box runs through a 70 AMP relay that's switched so that the fuse box is only one when the ignition is on.
	K&N Fuel Injection Performance Kit I had a K&N Drop-In air filter since I bought the Xterra but I wanted to get as much power as I could from the engine. Since I had gotten the new BFG Mud Terrains there wasn't alot of power left for passing on the freeway, I hoped upgrading the intake would help. The K&N FIPK is a very complete setup and has passed California Emissions so it won't stop you from passing your safety and emissions checks every year. It would be a bit better if the engine heat shield had a bottom to it help keep more heat and mud out but it doesn't take much to create your own bottom and bolt it in. The included instructions are so complete they're nearly idiot proof.
	FIPK Mud Shield I really like the FIPK but when mud hits the cooling fan some of it has a tendency to get splashed up under the heat shield and get the underside of the filter dirty. And the mud is hard to rinse out. Many people do this to get more cool air from the fender instead of the hot engine air for more HP. But when the Xterra is going faster than 25 MPH the air in the engine compartment is about the same temp as the fender, besides the Xterra's little 170 HP engine doesn't have high enough performance for Cold Air intakes to make much of a difference.
	Sport Exhaust The new exhaust was an impromptu modification like the Optima battery and the TJM bumper, it was done out of necessity, my stock muffler had holes rusted in it and needed to be replaced to pass inspection. I took the opportunity to do an upgrade I was planning on doing anyway, the exhaust was replaced from the Y-Pipe back with stainless steel 2.5" exhaust (up from 2.25"), and the muffler was replaced with a Hooker Aero Chamber Muffler to reduce restriction.
	Hose Protectors To keep my radiator hoses in top shape I added a couple of cheap hose protectors I got at a local auto parts store. The protectors are oriented to protect the hoses from any debris flying from the vicinity of the cooling fan or fan belts. I don't think I'll ever have a problem with broken fan blades ripping my hoses open but I don't have to worry now.