For maximum low end torque, engine vacuum and fuel economy, you need a smaller, more efficient cam. But smaller cams rob mid and upper RPM power needed for fast acceleration. For more mid and upper RPM power, you need a larger, more powerful camshaft. But larger cams are murder on low-end torque, engine vacuum, fuel economy and idle quality. With Rhoads Lifters, you get both! Rhoads Lifters work automatically and give you a ''smaller'' cam at lower RPM and a ''larger'' cam at higher RPM for the best of both worlds. How you ask? At idle and lower RPM where lugging power and more torque are needed, Rhoads Lifters ''bleed down'' to make you cam seem smaller by about 10°. This really boosts low-end torque, engine vacuum, fuel economy and idle quality. At higher engine speeds where more cam boosts mid and upper RPM power, the Rhoads Lifters work to restore full lift and duration of your cam for maximum top-end power. As your engine revs higher, Rhoads Lifters bleed less because there is simply less time to bleed at higher engine speeds. Near 3500 RPM, the bleed action has virtually disappeared, shifting back to your full cam and maximum horsepower potential back into action. Here's an example:
Using a hydraulic cam with 280° duration and .450'' valve lift, here's approximately what the valve timing will look like inside the engine at various RPM using Rhoads Lifters vs. stock lifters:
|Rhoads Lifters||Stock Lifters|
|@ 2000 RPM||265°||.435''||270°||.450''|
|@ 3500 RPM||270°||.450''||270°||.450''|
Stock lifters don't vary the valve timing. Rhoads lifters do. Stock lifters can ''pump up'' at higher engine speed, drastically cutting power. But Rhoads Lifters actually help to eliminate pump up, adding as much as 500 more usable RPM on the top-end. You can even hear Rhoads Lifters work! They make a mild ticking sound at idle, which tells you they're working to boost low-end torque, vacuum and fuel economy. When the size of your cam is ''reduced'' for more low-end torque, the valves seat at a slightly faster rate, producing a mild, solid lifter sound. This sound gradually dissapears as your RPM increases, ''restoring'' your cam to its full size for maximum top-end power.