The small block Chevy, or LS series of engines, is one of the most commonly used engines for conversions thanks to its simple, durable design, affordability, commonality and aftermarket support that is simply unrivalled.
One thing it often cops a lot of flack for, however, is its pushrod valvetrain. Many modern engine makers utilise double overhead cams with variable valve timing as the established valvetrain type, leaving pushrod/overhead valve designs in the past. With most of the valvetrain deep down in the engine block, including the camshaft, pushrods offer a lower centre of gravity and are generally cheaper to make, which is why GM and Chrysler still use this layout for their V8s.
With this in mind, EFI University teamed up with Comp Cams to develop a package capable of taking the LS7 7.0-litre V8 to a stratospheric 11,000rpm. To put that in perspective, the Porsche 911 GT3 RS has a redline of 9000rpm, as does the Ferrari 458 Speciale. The only road-going car that comes close is the upcoming Mercedes-AMG Project One, that features a detuned Formula One engine.
Since the number 11 features prominently in the goal of the project, calling it “Spinal Tap” only seemed natural. The collaboration has focused on cylinder head, compression ratio, valve springs and bearings. The pushrod configuration threw up some unique challenges however, with the movement of the rocker arms in particular causing a headache. EFI University’s Ben Strader explains:
“The issue this presents for the LS is that the cylinder head itself is very narrow, so Jesel came up with the idea to twist the intake rocker in order to move the pushrod away from the port. Then we also had to come up with a custom titanium valve that was long enough for one inch of lift but wouldn’t make contact with the seals. But once we got those roadblocks figured out, then we really started to focus on the stability of the valvetrain and how we were going to make it survive. And not just the rocker arms, but the pushrods, lifters and camshaft too.”
Check out the video below to see the team’s progress, and head over to the enginelabs website for more info.