At the 2021 PRI Show, with the help of Late Model Engines, we assembled a 427 cubic-inch, all-aftermarket LS engine on the show floor with the sole intention of giving it away to a lucky winner (hence the name, “giveaway engine”). Once assembled, the engine went back to LME to be dyno-tested with the winner’s choice of Vortech supercharger.
As you might be able to tell from the timing of this article, the winner chose something other than what was on the engine, and the parts situation meant there was a delay in making everything happen. So, since it has been a minute since we covered this build, let’s recap what, exactly, went into this beast of an engine.
The Mighty Short-Block
We not only wanted this engine to make a big number on the dyno, but we wanted it to do it reliably at that power level. The easiest way to ensure longevity is to overbuild the foundation. For that, we turned to Dart and one of its SHP big-bore iron blocks. The SHP block will not only withstand all the power we want to throw at it, but thanks to the priority-main oiling, it should live at that power level for a long time.
LME did all the machine work to prep the block — including CNC deck surfacing, align honing, and finishing the bores at 4.125 inches — prior to the show. At the show, LME’s rockstar engine-builder, Vinnie Monighetti, made short work of the assembly. Starting off with dropping a set of coated Clevite bearings into the mains, Monighetti then grabbed the crank before torquing the ARP main stud kit.
For this project, we chose a 4.00-inch stroke, forged-steel unit from Callies. The Magnum series crankshaft is manufactured from 4340 steel that undergoes several heat treatments. With gun-drilled mains and fully profiled counterweights, the Magnum checks all the boxes, including having a full eight counterweights for extra smoothness at elevated RPM.
Attached to the crank are a set of Callies 6.125-inch Ultra Enforcer-series connecting rods. Forged from 4330V Timken Steel, the I-beam rods come fitted with L19 rod bolts and are rated for up to 250 horsepower each. A bit of quick math shows that 2,000 horsepower is no problem for these rods. Like the mains, the rods ride on a set of Clevite coated rod bearings.
Hanging off the end of those rods are a set of Diamond Racing’s “Ultra 2K” pistons, designed specifically for LME. With a 1.115-inch compression height for a zero-deck, 15cc dish, and lateral gas ports, these forged 2618 pistons are, as the “2K” name suggests, rated for 2,000-horsepower forced-induction applications and will definitely live in this environment. A set of LME-spec’d Total Seal piston rings in a unique 1.5mm top ring, .043-inch second ring, and 3.0mm oil ring configuration were fit to the slugs.
A Melling 10296 high-volume, high-pressure oil pump provides all of the needed lifeblood to the engine, while a Rollmaster double-roller 9-way adjustable timing set not only keeps everything in sync, but allows for up to eight degrees of adjustment, advanced or retarded. A Milodon “Low-Profile, Max Power” oil pan, designed with internal geometry to aid in scavenging was used, along with a Milodon windage tray.
A Monstrous Top End
Just like the bottom end, we need a good foundation upon which to build the top end. Of course that means a set of ARP2000 head studs. And besides the increased load-holding ability of the higher-grade alloy, there are two extra head studs per cylinder, thanks to the Dart SHP’s six-head-bolt configuration. The half-inch studs will achieve enough clamp load to surpass 2,000 horsepower. Similarly, a set of Cometic’s MLX multi-layer steel head gaskets will handle all of the boost that we throw at it. With a 4.150-inch bore size and a .052 compressed thickness, Monighetti added a quick spritz of copper gasket spray to ensure a leak-free seal.
Moving to the cylinder heads themselves, we went with a proven big-power combination. Brodix provided a set of their six-bolt BR7 12-degree cylinder head castings for LME to work their CNC magic on. The final pieces have custom CHE bronze valve guides holding Ferrea 2.200-inch titanium intake valves and Ferrea 1.615-inch Inconel exhaust valves. After being CNC-ported, hand-blended, and given a full competition valve job, the intake ports flow right at 400 cfm, while the exhaust ports flow a stout 280 cfm.
Controlling all of the valvetrain is a custom-ground COMP hydraulic-roller camshaft. With .651 inch of lift on the intake and .630 inch on the exhaust, the split-duration measures 248 degrees on the intake and 264 degrees on the exhaust side, at .050 inch. Riding on the cam lobes are a set of COMP’s short-travel hydraulic tie-bar roller lifters. Connecting the lifters to the rocker arms are a set of Manley 7.675-inch-long 3/8-inch diameter pushrods with .080-inch wall-thickness.
A set of COMP BSR shaft rocker arms translates the camshaft motion into valve motion with a 1.8:1 ratio. A set of COMP dual valvesprings with about 155 pounds of pressure on the seat and about 400 pounds of open pressure control the valves, while a set of titanium retainers and machined steel locks keep the overall valvetrain weight down.
With such a stout long-block, we couldn’t just use any old induction system. So we opted for one of FAST’s LSX HR polymer tunnel ram intake manifolds. Besides being more resistant to heat soak, the modular polymer design features interchangeable runner stacks, that can be tuned to the desired powerband. For this situation, we left the included “long” stacks fitted.
We also mounted one of FAST’s 102mm Big Mouth throttle bodies to the front of the intake in order to allow as much boost as possible into the intake as quickly as possible. We installed a set of Deatschwerks 1,500cc/min fuel injectors into the manifold, which should provide plenty of fuel without maxing out duty cycle. The injectors are fed by a set of FAST’s billet aluminum fuel rails.
Then the peace de resistance, the big-boy supercharger. Vortech supplied one of its V-30 105A superchargers for the giveaway. The 105mm (as the name implies) centrifugal supercharger is capable of making 1,700 horsepower at full boogie, thanks to a cogged belt drive and the aggressive step-up ratio inside the V-30 race transmission.
Putting It On The Pump
When we pulled the winner’s name, Celeste Haskins got the phone call so many of you were hoping for. In fact, we actually interrupted her in the garage, as she was preparing her street/strip project car — a 1991 Buick Roadmaster Estate wagon (who doesn’t love a longroof?!). As we advertised, she was given the choice of superchargers and surprised all of us by choosing the smaller option, since she plans on actually driving her car to and from the racetrack.
That necessitated having LME remove the V-30 105A supercharger and cog-drive, and instead install a smaller Vortech YSi-B supercharger. Featuring both a smaller volute and a smaller 94mm billet impeller, the YSi-B blower is rated at a maximum output of 1,400 horsepower — 300 less than the 105A. Besides the size and power difference, the V-7 supercharger transmission is much more suited to the street than the V-30, with a less-aggressive step-up ratio.
Additionally, Celeste opted for a C5/C6 Corvette Front Engine Accessory Drive, which keeps the supercharger in about the same location as the 105A setup, but flips the blower around and tucks it in behind the front line of the engine. This necessitates the use of a reverse-rotation blower, and allows for a factory-style 10-rib serpentine belt setup to drive not only the blower but all of the engine accessories.
That switch also necessitated a water pump change. Originally, we were utilizing one of Meziere‘s 55 gpm remote-mount electric water pumps. Even with the race-oriented remote-mount, the pump still has provisions for a thermostat and bypass for use on the street. However, with the Corvette front-drive setup, we needed to swap to one of Meziere’s more traditional 55 gpm pumps. They have one designed specifically for late-model Corvettes, so that works perfectly with the new front-drive.
With a pulley setup designed for only about 11psi of boost from the smaller blower, we had to revamp our original 1,500-horsepower goal. After a quick break-in run on the Superflow engine dyno, LME made the final adjustments to the Holley Terminator X ECU and let the engine eat all the way up to 7,500 rpm. There it made peak power of 1,182 horsepower (with power continuing to increase according to the graph), and peak torque of 856 lb-ft at 6,100 rpm.
All in all, not a bad result with a blower rated at 300 horsepower less, and significantly less boost pressure than we would have been running with a cog setup. If Celeste decides she wants to take a run at the YSi-B’s max output, there is an available cog-drive upgrade that will allow her to run more boost without worrying about belt slip.
We’re excited to see the engine going to such a passionate enthusiast, and we’d like to personally thank the companies involved for helping us make Celeste’s journey a whole lot more powerful. It certainly wouldn’t have been possible without Late Model Engines, Vortech Superchargers, ATI Performance Products, Cometic Gaskets, Edelbrock Group, Ferrea Racing Components, Fuel Air Spark Technology, Holley, MAHLE, Manley, Melling Engine Parts, Meziere Enterprises, Milodon, Trend Performance, Dart Machinery, Diamond Racing Pistons, Wrenchers, LTA Manufacturing, Ryno Classifieds, SCT, and VP Racing Fuel.
EngineLabs Giveaway Engine Spec Sheet
Engine: LS7-based LSX
Builder: Late Model Engines
Total Displacement: 427 cubic inches
Bore x Stroke: 4.125 inches x 4.000 inches
Block: Dart SHP iron block
Main Fasteners: ARP2000 main-stud kit
Crankshaft: Callies Magnum, forged 4340, 8-counterweight
Bearings: Clevite coated main and rod bearings
Rods: Callies Ultra Enforcer, forged 4330V, I-beam
Pistons: Diamond Racing LME-spec “2K”, forged 2618
Wrist Pins: Trend Performance .927-inch H-13 tool-steel
Rings: Total Seal, 1.5mm, .043 inch, 3.0mm
Oil Pump: Melling 10296
Oil Pan: Milodon low-profile “Max Power” with windage tray
Timing Set: Rollmaster
Balancer: ATI Performance
Head Gaskets: Cometic MLX .052-inch
Head Fasteners: ARP2000 6-bolt head-stud kit
Cylinder Heads: Brodix BR7 castings
Port Work: LME CNC program
Valves: Ferrea; 2.200-inch titanium intake, 1.615-inch Inconel exhaust
Flow numbers: 400 cfm intake, 280cfm exhaust
Camshaft: Custom COMP; .651/.630 lift, 248/264 duration at .050 inch
Valve Springs: COMP/LME dual LS7 with titanium retainers
Lifters: COMP short-travel tie bar
Rockers: COMP LS7 BSR shaft rockers
Pushrods: Manley 3/8-inch, .080-inch wall-thickness, 7.675-inch length
EFI System: Holley Terminator X
Injectors: Deatschwerks 1,500 cc/min
Throttle Body: FAST 102mm Big Mouth
Intake Manifold: FAST LSXhr, “long” runners
Power Adder: Vortech YSi-B, 10-rib serpentine drive for C5/C6 Corvette
Ignition System: Holley Smart Coils
Water Pump: Meziere electric; late-model Corvette
Fuel System: FAST fuel rails
Fuel: VP Racing