Obviously, you watched the latest running of the Engine Performance Expo (if you didn’t, go back here and check it out), which means you saw multiple segments featuring different parts of this engine’s build. So now, we’re going to take a look at the engine as a whole.
Designed from the outset to be a living, evolving project, this is just the first iteration of the engine. We’ll likely see changes made in future installments of the Engine Performance Expo in order to explain various concepts and explore areas of potential improvement. This version was intended to be a “typical 1,000-horsepower” build.
Right off the bat, this build faced the same challenges that all of us are currently experiencing — parts availability. Again, like all of us, the team at the Engine Performance Expo made a few deviations from the original plan in the name of being able to use a part that was available. Fortunately, the team has enough talent that a few parts changes didn’t phase them one bit. One thing to note, is that you can see the components being worked on, thanks to the Expo’s coverage, so we’ll be listing timestamps for you to go back into the On-Demand Expo footage and check it out in more detail.
Starting At The Core
Starting with a Dart LS Next iron engine block (Day 3, 1:37:00), the original plan was to go with a typical 4.125-inch bore. However, the 4.125-inch MAHLE pistons were on backorder, while a set of otherwise identical 4.155 pistons were sitting on the shelf. A little more bore never hurt, especially when the largest recommended bore for the LS Next is 4.200 inches, per Dart. It was no problem for Straub Technologies’ CNC Blockworks team to add an extra .030-inch to the cylinders after they had already completely finish-machined the block.
While the block comes ready for up to 4.100 inches of stroke, the team chose a stock-stroke forged 4340-steel crankshaft from Dart. As an added benefit, the crankshaft comes with center-counterweights added, making for eight total counterweights instead of the O.E. six-counterweight design. The center counterweights provide extra stability at elevated RPM, but do require extra clearancing with the LS Next block — no problem at all for the CNC Block Works team. Just like it was no problem for them to install keyway lifter bushings in the block.
The crankshaft rides in a set of Clevite coated H-series main bearings inside the LS Next’s splayed-bolt main caps. Attached to the crank are another one of the “this part is available” components — Bill Miller Engineering aluminum rods. While BME aluminum rods might seem like an incredibly high-end race part, and they are, they were available in the custom length needed in the timeline that was in place. Aluminum rods are more than capable of handling the power. Certainly, aluminum rods wouldn’t be the right choice for a street engine, but they aren’t a hindrance to this engine.
Hanging off the ends of the aluminum rods are the aforementioned MAHLE pistons. The LSX Combo flat-top pistons have MAHLEs new “multiple geometry” valve pockets, designed to fit a variety of cylinder head configurations. Made from 2618 aluminum, with Mahle’s Grafal skirt coating and recognizable Phosphate coating, the valve pockets only cost 5.8cc of volume.
The 1.0mm top and second ring grooves are filled with Total Seal’s impressive gas-ported Gapless ring set (which is an off-the-shelf combination, these days). The top ring is a stainless steel, PVD-coated gas-ported ring, while the second ring is a ductile iron gapless design, with a standard-tension 2.0mm oil ring. (Day 3, 4:16:00)
Providing the lifeblood of the engine is a Melling high-performance oil pump designed specifically for aftermarket blocks with priority-main oiling systems. A Robert Yates Racing 11-quart wet-sump road race oil pan provides extra oil volume without any extra windage thanks to the pan’s baffling and windage tray. The whole short-block was assembled by Robert Yates Racing’s expert assembler Jimmy Barton.
A Powerhouse Top End
The short-block is topped off by a set of Straub Technologies’ VEPR 12XS LS3-style cylinder heads. Straub’s VEPR (Velocity Enhanced Port Range) program is available as a porting program on customer-supplied castings, or as a ready-to-go set of heads. After the trip through the CNC machines, the heads have a 260cc intake port, 92cc exhaust port, and a 68cc combustion chamber. (Day 3, 20:00 and 56:30)
Inside those combustion chambers are a set of Victory stainless-steel valves — 2.165 inches on the intake, 1.600 inches on the exhaust side — set at a 12-degree angle, as the “12XS” name suggests. As supplied, the heads flow 384cfm at .700-inch of lift on the intake side, and 262cfm at .700 on the exhaust side.
The brain of the operation is a custom camshaft spec’d by Straub Technologies. A set of Morel keyway solid roller lifters translate the camshaft’s lobes into vertical motion. A set of Trend Performance pushrods connect the lifters to the 1.7:1 Harland Sharp aluminum roller rocker arms. Controlling the valve motion is a set of PAC dual valvesprings. (Day 3, 6:18:00)
Topping off the long-block is the ubiquitous Holley Hi-Ram cast aluminum intake manifold. Fitted with the forward-facing inlet, it’s fitted with a 102mm throttle body. Schoenfeld headers efficiently scavenge the exhaust gasses, while a Holley Dominator ECU and Holley Smart Coils control the fuel and keep the fires burning. The break-in process was done naturally/aspirated and saw some decent numbers produced, which you can see in the Day 4 Expo footage, at 22:00.
Adding the unnatural aspiration to the combo is a ProCharger F-1A-94. This supercharger tops ProCharger’s “Street” supercharger lineup. With a 9-inch volute diameter, The F-1A-94 shares its external dimensions with a number of other ProCharger’s street blowers, but beyond that, it stands on its own. Rated at a maximum of 1,300 horsepower from its 1,620-cfm output, it has a billet-aluminum compressor wheel capable of 74,000 rpm and an aggressive 5.40:1 step-up ratio. To reliably drive the unit, a cog-belt setup is utilized. (Day 4, 2:44:00)
After some tweaking and playing around with fuels by EFI University’s Ben Strader, naturally aspirated, the engine made 650 horsepower at 6,780 rpm and 531 lb-ft of torque at 5,040 rpm. Not bad for a blower engine without a blower. With the ProCharger attached and fresh VP Q16 oxygenated fuel in the cell, the engine peaked at 1,046 horsepower at 7,920 rpm and 711 lb-ft at 5,280 rpm. Not bad at all for an engine that was put together with a bunch of available parts. However, there is plenty of room for the engine combination to be optimized, which we’ll see in upcoming iterations of the Engine Performance Expo. (Day 4, 5:32:00)