WoodyTX
12-13-2006, 03:43 PM
OK, some background first.
Most motors are designed with specific parameters in mind, and just bolting on parts may do little more than change the way something looks or sounds. New parts may also negatively affect the motor, resulting in a net loss of performance. Depending on how well they mesh with the original design, they may also increase performance.
A great example is headers, which are used to efficiently draw exhaust gasses away from the cylinder, reducing backpressure. This raises horsepower, especially at the high end. It also can reduce torque, especially at the low end. Most trucks and SUVs are built with torquey motors, and adding headers will reduce their greatest asset (torque) in pursuit of something they don't use that much (high end horsepower).
The 'brain' of a motor, and the central design element is the camshaft. Everything else is built around this. A torquey cam plus headers and a big carb will actually make a less efficent vehicle. But a racing cam and stock intake/exhaust/carb will also suck. Finding the proper synergies is critical to bolt on parts.
My other vehicle (i.e. project) is a 1970 International Scout 800. The IHC 304 motor redlines at 4400 rpm, and produces 140 HP and 240 lb-ft of torque. Yes, you read that right; a 5.0 V-8 produces under 150 HP, but it produces 200 lb-ft of torque at 1000 rpm. Getting more horsepower out of it is easy (headers, new valve springs, carb), but generally comes at the expense of torque. Not an option for an off-road vehicle.
With that in mind, what performance mods get the most bang for your buck with the Xterra? Does anyone have dyno charts, etc? (Absolute HP claims are just about useless, especially if you lose all your "grunt" to get "wind-out" in an SUV.)
In the few days I've owned my 07 Xterra, I don't think there's really much need more oomph, although "enough power" really isn't in my book. :)
So, who's actually dyno'd their headers? Chips? Intakes? What'd you get? Is it measurably faster, or does it just sound faster? (Not that there's anything wrong with a cool-sounding exhaust; I just want performance with it).
Anyone have linkage to tests of Xterra mods?
Woody, man of many questions...
Most motors are designed with specific parameters in mind, and just bolting on parts may do little more than change the way something looks or sounds. New parts may also negatively affect the motor, resulting in a net loss of performance. Depending on how well they mesh with the original design, they may also increase performance.
A great example is headers, which are used to efficiently draw exhaust gasses away from the cylinder, reducing backpressure. This raises horsepower, especially at the high end. It also can reduce torque, especially at the low end. Most trucks and SUVs are built with torquey motors, and adding headers will reduce their greatest asset (torque) in pursuit of something they don't use that much (high end horsepower).
The 'brain' of a motor, and the central design element is the camshaft. Everything else is built around this. A torquey cam plus headers and a big carb will actually make a less efficent vehicle. But a racing cam and stock intake/exhaust/carb will also suck. Finding the proper synergies is critical to bolt on parts.
My other vehicle (i.e. project) is a 1970 International Scout 800. The IHC 304 motor redlines at 4400 rpm, and produces 140 HP and 240 lb-ft of torque. Yes, you read that right; a 5.0 V-8 produces under 150 HP, but it produces 200 lb-ft of torque at 1000 rpm. Getting more horsepower out of it is easy (headers, new valve springs, carb), but generally comes at the expense of torque. Not an option for an off-road vehicle.
With that in mind, what performance mods get the most bang for your buck with the Xterra? Does anyone have dyno charts, etc? (Absolute HP claims are just about useless, especially if you lose all your "grunt" to get "wind-out" in an SUV.)
In the few days I've owned my 07 Xterra, I don't think there's really much need more oomph, although "enough power" really isn't in my book. :)
So, who's actually dyno'd their headers? Chips? Intakes? What'd you get? Is it measurably faster, or does it just sound faster? (Not that there's anything wrong with a cool-sounding exhaust; I just want performance with it).
Anyone have linkage to tests of Xterra mods?
Woody, man of many questions...