There is an age-old decision that high performance engine builders must make: hydraulic lifters, or solid lifters? Typically, (or more accurately, traditionally) the school of thought has been that hydraulic lifters were a better choice for street engines that accumulated a lot of miles at varying RPM, and solids were a better call for race engines that spent more time at high-RPM and were rebuilt regularly.
These opinions were created way back in the flat-tappet era, and followed the respective designs into the modern roller generation. Since hydraulic lifters did not require adjustment once they were set, they were a lower-maintenance item that street enthusiasts would appreciate. Setting hot lash was an art form reserved for the more hardcore race crowd. Certainly, the stability of a solid lifter offered consistency and strength to survive extended periods of high-RPM use, and by setting the lash at the minimum, every thousandth of an inch of precious lift and every degree of duration would be delivered to every valve.
At idle, the reduction in oil pressure would allow a bit more civilized idle in the hydraulic designs, while the solids would demand perfect adjustment to deliver a signature “crisp” lopey idle sound, and the requisite mechanical performance advantage to match.
Well race fans, it’s deep into the twenty-teen years now, and most of those ancient myths are busted. Modern technology and advanced engineering are blurring the line between hydraulics and solids. While both designs have seen durability increase over the years (mostly due to improved materials, tighter tolerances, and wider roller bearing surfaces), the real advances have been on the hydraulic side of the fence.
Modern engineering has led to more precise plunger, spring, and retainer systems. These have resulted in more consistent fluid control, both in and out of the lifters. Combined with the rest of the aforementioned advances, and with the benefit of decades of research on every part of the lifter design, the modern hydraulic roller lifter gives up little, if anything, to its solid counterpart. The benefits of the hydraulic design, especially that lack of a need to set lash or adjust anything once it’s set properly and locked down, brings plenty of benefit to enthusiasts whose valve covers aren’t easy to access.
The current trend toward turbocharging brings with it a commitment to relatively exotic plumbing. The deep engine setback of modern performance cars makes pulling valve covers a real challenge. Not having to do so between races (or, in extreme cases, between rounds) is a real gift. Certainly, improved poly lock designs have really helped minimize the need to set valve lash on a regular basis. Compared to the early parts racers had back ten or twenty years ago, things are much improved.