posted on September 30, 2009 23:05
Project Pathfinder Part 5, Basic Engine
In the first few rounds of Project Pathfinders build up, we focused on getting the chassis and brakes sorted out. As you know SUV’s are notorious for poor handling and braking and that was something we could not tolerate. Now we set up to tackle the other negative attributes of an SUV, total sluggish lack of power and poor fuel economy.
To say that our Pathfinder sucked on power was an understatement. Our Pathfinder could not beat anything in any contest of speed, except for perhaps another SUV. Joggers and bicyclists gave it trouble. It guzzled fuel like a turbo car on boost as well turning in a miserable 15 MPG around town and 19 mpg on the highway. When attempting to tow, entering the freeway was a scary proposition and you had to depend on the mercy of other motorists and you all know that LA drivers basically have no mercy.
Things had to change. The first step was getting rid of the rusting and rotted 130,000 mile old exhaust. We wanted something with less backpressure, nice quality and not too loud for daily driving. We chose Nissan Motorsports cat back exhaust. Constructed of non-rusting high quality 304 stainless, it also had a free flowing Borla Muffler with Borla’s polished intercooled tip (this is just a cosmetic feature). The Nissan Motorsports exhaust is good for about 5-7 wheel hp and has a nice quiet note, hardly louder than stock from the inside of the car. It was an easy bolt in installing in about 20 minutes with simple hand tools. The exhaust noticeably improved power above 4500 rpm with no loss in bottom end power at all.
|Nissan Motorsports Cat Back Exhaust
Next we decided to uncork the intake. The VG30 engine breaths through a ridiculously small neck in the airbox, the hole is smaller than the MAF and throttle body. The air box and the filter element are on the small side as well. We figured that this was a restriction to the engines breathing and hampering power. We replaced the airbox and filter assembly with JWT’s POP Charger air cleaner assembly. The POP is an open-air cone type filter with a cast aluminum MAF adaptor that has a shape like a velocity stack to reduce the effects of MAF turbulence. The POP charger is good for 2-3 hp over the stock filter. The POP increases intake noise quite a bit and is pretty loud at wide-open throttle. At part throttle its only slightly louder than stock. The POP element is washable and reusable when it is treated with special oil after washing.
Finally we replaced the ECU with JWT’s POP tuned ECU. The JWT ECU has optimized maps for fuel and ignition timing. The closed loop operation envelope has been expanded so the car will cruse under closed loop at higher speeds on the freeway. This will help fuel economy. The JWT ECU greatly improved the Pathfinders sorely lacking throttle response and gave a 4-5 hp boost as well. A disadvantage to the ECU is the engine now requires 91 octane gas. We will be working with JWT on an ECU that also works with a lower grade of gas since gas is now so expensive. It will give up some peak power but who really cares, this is a tow vehicle, not a race car.
|JWT's Pop Charger
With our new mods, fuel economy has improved to 18 mpg around town and about 22 on the highway. The engine feels peppier and happier to rev. Just the gains in fuel economy are worth the expense of these mods. We would still like more power. Stay tuned, in the months to come, we will be adding more parts to our motor and will end up with a fully built monster tow motor.