Back when the earth was cooling, behemoths roamed the land. Scoggin-Dickey Parts Center’s latest creation is a record-setting, evolutionary tribute to the days when horsepower ruled the boulevard.
Known as the “Mastodon” for obvious reasons, this 6.6L (400 ci) offering from SDPC may look like a prehistoric creature, but thanks to today’s technology, it has leaped to the top of the horsepower food chain and still feeds off of the remnants of its siblings.
We spoke to SDPC’s Nick Adams at SEMA and got to the heart of how this behemoth makes so much power with such humble beginnings. The basis for this massive torque monster starts with GM’s L8T block. Those in the know with Chevy’s heavy haulers will instantly recognize this as the engine found in the Bowtie’s ¾-ton truck. Jeff Smith did a deep dive into the engine when it was first introduced. He surmised this engine could become a hot-rodder’s dream, but we’d venture even he couldn’t comprehend how big this engine could eventually grow.
With the right upbringing from the folks at SDPC, this L8T-based engine has just churned out an astonishing 2,077 horsepower on the SDPC dyno. You can hear this animal growl in the attached video, but we wanted to speak with Nick about those things under the surface that made all that power possible.
The project started when folks at SDPC started asking, “what if?” They approached the “mad scientists” within the confines of its race shop if they were interested in finding out how strong this late-model Mastodon might be. Their light-hearted response is the golden lubricant for all such endeavors, “If it’s not our money, we’ll blow it up!” To date, the monster’s heart has not stopped beating, mainly due to the fact it has good genes.
“We started with a stock L8T block casting,” Nick explained. “As it comes, the block is really stout. Our guys found it was within 12-pounds of GM’s LSx block. Then we added SDPC billet main caps and ARP studs.” From there, the guys in SDPC’s race shop added a stock, forged L8T crankshaft, which comes bearing center counterweights and is fully machined right out of the box. Topside, a CNC’d set of LT4 heads are clamped down to those factory LT4 head gaskets with another set of ARP fasteners.
The “tusky” creature features off-the-shelf aftermarket components to achieve its massive output. Topside, a factory Holley EFI intake and 103mm throttle body feed the beast, its diet on the dyno regulated with a Holley Dominator ECU. A pair of off-the-shelf, cast-iron Hooker “LS-swap” manifolds are plumbed to those Precision Turbo 8885 turbos which jam 32-pounds of boost down the engine’s throat for a tasty air/fuel ratio.
A solid-roller camshaft works well with the higher RPM, and the boost pressures kept under those LT4 heads. As it stands, this engine has churned out 2,077 horsepower on “only” 32-pounds of boost. The guys at SDPC are looking to go even larger on the throttle body bore size, as they were seeing a pressure differential between the two sides of the throttle blades at 6,500 rpm. Their hope is to increase boost to 40-pounds, as the mad scientists at SDPC “know there’s more in it.”
How much more can this late-model Mastodon handle? We’ll have to find out, but one thing is for sure, even with all this talk about electrification, this engine clearly shows that internal combustion horsepower is far from extinct.