The battle of the bump sticks: Solid vs. Hydraulic lifters

Solid roller lifters are the most popular type of lifter for automotive applications. They’re reliable, easy to replace and have a longer lifespan than hydraulic lifters. One downside of solid roller lifters is that they don’t have as much torque as hydraulic lifters. This means that they can’t lift as much weight. Solid cams are known for their higher rpm power and, to some, the image of a race-only piece. Solids require periodic adjustment, produce noise, and are slightly different from what the average person is using. For some, that is reason enough to start one.

We, on the other hand, were more interested in seeing what differences there were in power output. First, we explain the differences between solid and hydraulic lifters, as well as why there may be power to be gained.

For performance, should you use hydraulics or solids?

When hydraulic lifters were invented, all-out racing performance was never on the agenda. The vast majority of performance cams sold, on the other hand, are unquestionably hydraulic grinds. Some of the same attributes that made them a favourite with Detroit hold favor with many enthusiasts. Because hydraulic cams were originally installed in most engines, hydraulic performance cams are usually the most cost-effective replacement option. Making the switch to a solid grind can quickly add up, usually necessitating the purchase of adjustable rockers and compatible pushrods. Along with the lower cost, the quieter operation and no need to adjust the valves make hydraulics an appealing choice for dual-purpose applications.

Hydraulics perform exceptionally well at moderate RPMs, which is the range of most mildly modified street engines. When the performance is increased, the hydraulic mechanism that makes them so sweet in a milder application can cause issues. Why? Under the stresses of high rpm, the hydraulic piston, which normally serves to zero out the clearances, can either pump up or bleed down. These are two distinct phenomena that can both impair hydraulic-lifter performance.

Through fluid bleeding past the lifter’s plunger piston during the life cycle, all hydraulic lifters can absorb a small portion of the cams lift profile while running. Absorption is most likely negligible in stock or mild street applications. In a radical street or racing application, highly aggressive cam profiles and spring loads can strain the hydraulic lifter’s mechanism to the point where some performance potential is lost due to absorption. Lifters with tight internal clearances and valving closely follow the cam profile and are referred to as stiff.

Hydraulic lifters are generally considered to be more reliable than solid lifters, but there are some advantages to using a solid roller lifter. A solid roller lifter is less likely to wear out over time, which can lead to a longer life for the vehicle. It is also less noisy than a hydraulic lifter, which can make it a better choice for vehicles that are used in noisy environments.

As the automotive world moves towards more advanced and fuel-efficient cars, some manufacturers are looking to replace traditional mechanical lifters with solid roller lifters. The main advantage of using solid roller lifters is that they are much quieter than hydraulic lifters. This is important because it can improve the overall driving experience for customers. Additionally, solid roller lifters do not require maintenance, which makes them a more long-term investment.