Turbo performance guru, Josh Straub, holds the answer with his rare-and-fast, 1991 GMC Syclone. Under the hood of this mini beast, the original 4.3 V6 sat and ran for up to about 130k miles, but finally spun a bearing at around 140k.

Once that was done, the original block was replaced by a short block from RPM, along with a 4-bolt crank, forged SRP pistons with Eagle H-Beam rods, a 67-mm, PT6780H turbo, Vortec heads, a Comp cam and a trick, air-to-air intercooler.

The most common problems that Straub has encountered with the radical turbo setup are issues of air/fuel mixture; at boost ranges between 19-23psi, Straub’s AFR, as recorded in DataMaster’s dyno test, ran relatively lean at a ratio of around 14:1.

These readings were also caused, in part, by faulty wiring when hooking-up the dyno, so the exact ratios are unknown, though minor engine knock could be heard under certain running conditions.

Motors with radical turbos are usually prone to be finicky, especially past the 20psi threshold, but don’t think that Josh’ quarter-mile times still aren’t impressive. So far, Straub has run a best time of 11.39 @ 116, and while he was running-against this ’03 Cobra in this drag race video, he ran a best time for the day of 11.45 @ 117.8, obliterating the late-model Mustang.

Turbo-6 performance is making an aggressive comeback, and if that’s true, then Josh Straub is their chief pioneer.