Tech Tips
Restrictive Exhaust
A restrictive exhaust creates back pressure in the exhaust system that hurts your vehicle's performance in two ways:
- The engine has to work harder to force exhaust gases out of the cylinders.
- Engines cannot scavenge burned exhaust gases out of the cylinder efficiently. This leaves exhaust gases in the cylinder to dilute incoming air/fuel mixtures and rob your engine of horsepower.
Contrary to popular belief no modern engine requires back pressure!
Pipe Diameter
A common misconception is that the larger the diameter, the better the system. But bigger isn't always better. Systems that are too large in diameter can actually hurt performance.
As a general rule, switching to a performance system that is 1/4" to 1/2" inch larger than std will provide you with the best power increases. To determine which pipe diameter will be best for your system, decide what RPM range your engine will operate at, most of the time. Smaller diameter pipes will produce low- to mid-RPM torque. Larger diameters produce mid- to high-RPM torque.
Horsepower Depends on Flow not Pipe Diameter Alone
Bigger isn't always better. Systems that are too large in diameter can actually hurt performance. Improved flow is what you need.
How Springs & Shocks Work Together
Have you ever wondered about spring rates, shock rates and damping? Here's a look at what they mean and how they affect your vehicle.
"Simply stated, shock absorbers convert the kinetic energy of the spring movements into heat," says Bilstein (www.bilstein.com). "This heat is then dissipated into the air through the shock tube or body. In practical application, shock absorbers are necessary to maintain maximum tyre contact to the road as the car corners and negotiate irregularities on the road surface.
"Spring rates determine how far your chassis rolls, pitches or squats. Shock rates determine the length of time it takes for each of these movements to occur.
"Rebound damping controls the movement of that part of the car's sprung mass that is stored in a compressed spring. The rebound damping rate determines how long it takes for the compressed spring to return to the static ride height. The stiffer the rebound value, the more the shock resists the compressed spring's effort to rebound, and the longer it takes for the chassis to return to the static ride height.
"Compression damping controls only the oscillation of the car's unsprung weight (road wheel, brakes & a proportion of the suspension arms). Therefore, it is normal to use less compression damping than rebound damping. The exception occurs in racing when we choose to slow the downward movement of the car to mimic the effect of a stiffer spring during initial cornering."
