In the 2007 summer blockbuster comedy Superbad, Fogell is the lovable but truly helpless side character who ends up being the guy everyone likes. He earns his nickname “McLovin” from a hilariously bad fake ID with the same name, but redeems himself through a night of raising hell with two local cops he befriends and eventually hooking up with the cute redhead at the big end-of-year senior party. When we spotted our latest project, a 1976 Chevy LUV pickup, there was no contest on choosing the name “McLuvin” with its equally lovable and ugly looks. Now it’s time to show everyone what we’re made of, so let us sneak you into the cool kid’s party as our project McLuvin gets a Superbad Whipple supercharged 427 LS.

If you read the first article where we introduced our latest LS-swapped project, the build had a simple plan. Our ugly, but lovable, mini-truck was going to get absolutely zero attention to its rough two-tone green exterior. However, a monster power-plant under the hood and upgrades to the chassis and suspension underneath are definitely in store.

The original idea was to take a Gen-III, 5.3-liter LS block and bore the cylinders out to the LS1’s 3.898 bore with forged pistons, a forged stock-stroke crank, and aftermarket rods. This new 5.7 would serve only one purpose, to uphold a new Gen-5 Whipple supercharger and handle 1,000 horsepower with ease. As with most projects, we wanted more before we even got started and went bigger, way bigger.

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Weighing only a little more than a production LS7 block, the Concept Performance LSR block packages strength without the weight penalty of an iron block.

Bulletproof Bottom End

The idea of boring out a 5.3 block to a 5.7 was pushed aside. This is a proven method of getting extra cubes on the cheap that can still handle some abuse, so it’s not that we were worried about a 5.7 holding boost; just that “bigger is better” is always true when it comes to cubic inches. An LSR block from Concept Performance was chosen as the foundation for this Whipple supercharged monster. These are aftermarket blocks that take their inspiration from the Chevrolet Performance LSX blocks but are made out of aluminum instead of iron for weight savings. The LSR block’s design has undergone several improvements since its introduction almost a decade ago.

The LSR block has features like longer and thicker cylinder liners to handle longer strokes and higher cylinder pressures. A six-bolt deck design and deck surfaces that are 3/4-inch thick to hold all the boost, along with extra structural webbing and steel main caps to keep highly stressed rotating assemblies where they belong, inside the block.

The LSR block is cast and machined at Concept Performance’s foundry in Indianapolis from A356-T6 aluminum and utilizes spun ductile iron sleeves from PowerBore Cylinder Sleeves out of Ohio. All of this adds up to a block that’s stronger than any iron production block but roughly the same weight as an LS3 or LS7 block.

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After balancing the Scat crank, it was installed in the LSR block under the billet steel main caps and ARP studs. The crank and rods are riding on King XP tri-metal bearings that are designed to withstand the abuse.

A block this robust isn’t going to get a rotating assembly made out of the stock nodular iron crank and just any set of rods and pistons. Scat supplied the builder, Boostline Performance in Wichita Falls, Texas, with one of their forged 4340 steel 4.000-inch stroke crankshafts. Scat’s forged crankshafts feature lightening holes in all rod throws, like some of Chevrolet’s factory-performance LS engines like the LS7, and micro-polished and nitride-hardened journals for improved strength and wear resistance.

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Scat forged H-beam rods are fitted to the CP-Carillo pistons and then the Total Seal gapless and gas ported ringset is installed into the ring grooves.

Boostline Performance matched the Scat crank with a set of Scat’s forged H-beam connecting rods for our Whipple supercharged build. If you’re aiming for power past the four-digit mark, you can’t just grab any old connecting rod. These are made out of 4340 forgings and are designed to handle the rigors of power adders like nitrous or superchargers. Scat’s H-beam rods incorporate a special doweled cap design that locks in cap-to-rod alignment and keeps everything together with ARP 8740 7/16-inch-diamter rod bolts.

The aluminum slugs that fill the cylinders are CP-Carrillo’s Bullet series piston and ring set. When dealing with the high heat and load of a high-power stroker LS, piston selection can be crucial, or your engine will have a shorter-than-intended life. The Bullet Series pistons are made with power adders in mind, featuring a 2618 aluminum forging to handle the abuse and a special skirt design for low piston noise, which can be an issue on street engines with a long stroke and 2618 pistons. Boostline Performance ordered ours with an Atlantic Ocean-sized 25cc dish to keep the compression an E85 and big boost-friendly 9.0:1 for our Whipple supercharged 427.

Like the pistons, the rings and wrist pins CP-Carillo included with the set are up to the task as well. The pins are 0.180-inch-wall chromoly as standard, and the rings are gapless gas-ported Total Seal ring set. The set features a 1.5mm gas-nitrided steel top ring, 1.5mm Napier second ring, and 3.0mm oil ring.

Heat and oil control are paramount for piston rings when you’re pumping out big dyno numbers underneath a Whipple supercharger. Your more common moly-faced iron top ring cannot transfer the heat to the cylinder wall efficiently, which can lead to scoring and potential failure under abuse, and Boostline Performance knew McLuvin wasn’t going to be your typical trailer queen with a big dyno sheet for show.

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The LSR block can't use production-style roller lifters, as there is no boss machined for the factory plastic lifter retainer trays. We went with Johnson Lifters ST2116LSR link-bar hydraulic-roller lifters. After a quick dip in engine oil, they were slid into place.

The bottom end is buttoned up with ARP main studs, King XP bearings, and an Aviaid dry sump oil system. The XP series of bearings from King, dubbed pMax Black bearings, is a tri-metal design with performance and racing applications in mind. The bi-metal style rod and main bearings you find in factory LS engines are designed to last well over 100 thousand miles if maintained properly while still being equally durable in an OEM performance application. A tri-metal bearing takes the performance capability further because it can handle a much higher load in our Whipple supercharged LS and won’t crumble under the cylinder pressure.

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Both the LSR block and AFR heads feature a 6-bolt design and 3/4-inch thick deck surfaces. We took full advantage of this for our high-psi needs and went with SCE's Athena head gaskets with their Vulcan rings. the rings have ridges that "bite" into the block and head to hold extreme cylinder pressures.

The factory oil pump design is a massive improvement over the Gen-1 small blocks of old, but with this much power in a truck that will see excessive use of the driver’s right foot, we needed something more. A dry-sump system won’t suffer from sustained high-RPM cavitation or oil starvation when this lightweight truck sees some corners or donuts in the shop parking lot. The Aviaid dry-sump system features a sheet metal aluminum reservoir tank, a baffled low-profile pan, and a belt-driven external pump. We’ll actually be diving deeper into the Aviaid kit in a future article.

High Flow Heads And Race-Spec Valvetrain

Boost or not, airflow can make or break your horsepower goals. Think of trying to run a mile, but you can only breathe through a thin straw. Having an air pump helping force extra air in would help, but you still wouldn’t run very well. The same thought process goes for our Superbad 427 here, so a stock rectangular port casting wouldn’t cut it. This is where Air Flow Reasearch steps in with a pair of their CNC cylinder heads.

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These heads are based on the LS3 design, but are AFR's casting. They feature CNC-machined chambers, intake runners, and exhaust runners. Once some ARP Ultra-Torque is wiped on every thread and washer, the studs are torqued to ARP's specs.

These heads do not start life as factory castings, but as AFR’s unique casting design, so they aren’t constrained to the factory port shape. They are cast out of the same A356-T6 aluminum as the LSR block they’re mounted to with equally thick 3/4-inch decks. They feature a 6-bolt design, providing extra clamping force with ARP head studs. The SCE Athena head gaskets with their Vulcan cut-ring keep the boost contained to the chamber. The intake runners, exhaust runners, and combustion chambers are CNC-machined so there is no variance in flow or volume between each other.

The 260cc intake ports flow 384cfm at 0.700-inch lift through a 2.165-inch stainless intake valve. The exhaust flows 255cfm at the same lift through a 95cc port with a 1.600-inch exhaust valve. These heads came assembled with PAC dual valve springs and titanium retainers to hold the valves closed. With 155 lbs of seat pressure, they are made for hydraulic-roller applications and match our BTR PDS Stage 4 cam perfectly. This off-the-shelf cam specs out at 229 and 25x degrees of duration on the intake and exhaust lobes with 0.636 lift and a 117 lobe separation angle.

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Once the cylinder heads were torqued down, we just couldn't wait, we had to see what our fresh candy green Gen-5 3.0-liter Whipple looked like mounted between the heads.

The large spread between the intake and exhaust duration combined with the wide LSA will help our screw-blown 7.0 liter make power. A postitive-dispalcement-supercharged engine needs extra exhaust duration to evacuate all the exhaust gas it just created, and the wider LSA keeps boost-leaking valve overlap to a minimum. Not to worry though; even in a big cube engine like ours, the Whipple supercharged Superbad 427 has enough chop at idle to impress all the cool kids.

We completed the valvetrain with BTR shaft-mounted rocker arms, pushrods, and Johnson lifters. The Johnson lifters are a linkbar design, which are required when using an LSR block. The one-piece pushrods are 5/16-inch-diameter, 0.080-inch wall-thickness chromoly that keeps horsepower-robing deflection to a minimum. The BTR shaft-mounted rocker arm system significantly reduces deflection compared to the stock single-bolt trunnion design, thereby improving performance and durability. Each shaft is precision machined out of billet 52100 bearing steel. We optioned ours with BTR’s unique LS3-style rocker arms that differ from the factory units; they’re stiffer and keep the weight closer to the center of the body to keep high-RPM valvetrain stability in check.

Controlling The Fuel And Spark

For several years now in the LS world, the Holley Terminator-X EFI units have been the go-to for custom builds wanting to control ad fine-tune the fuel and spark on big power LS builds. The Holley ECU offers more tuning control in a simpler package than trying to adapt the OEM computer to work on its own. The harness comes in a simple standalone fashion and is pre-terminated to plug directly into whatever LS application you might have – like our 7.0 liter LS that has a massive 3.0 Whipple between the cylinder heads – and only needs a few external wires to hook up to run. This makes it easy and simple for engine swaps, like McLuvin here that started life with a 1.8-liter 4-cylinder that will end up in the dumpster to make room for this Superbad 427.

When going for four-digit power numbers on E85, you can’t skimp on fuel delivery. You need injectors and a pump, or three, that can flow enough fuel while still proving to be reliable and durable enough for street duty, which is where Project McLuvin will spend most of its life. Each port under that bright green supercharger received a DeatschWerks 1,250cc/min injector and all eight injectors are fed by a trio of DeatschWerks 810 fuel pumps in the dyno cell. The triple-pump setup would be overkill for McLuvin’s needs, but it was already wired and plumbed for the dyno cell at KPE Racing, so that’s what we used.

Fuel delivery is critical, and the spark is just as important. We’re filling 7.0 liters full of compressed air and ethanol; the risk of blowing out the spark and losing power – or worse, causing detonation and hurting our Whipple supercharged LS – is real. Performance Distributors Sultans-Of-Spark ignition coils are made for LS and LT applications that need extra volts to keep the spark plug lit under extreme cylinder pressures.

The SOS coils produce 28,000 volts under load, which is 7,000 more than the stock GM units. This means in total, you will have 56,000 more volts on tap when compared to the stock GM LS coils. Transmitting that extra spark to each cylinder is a set of Scott’s Performance Wires custom spark plug wires. We ordered our set with 10mm thick wire for minimum resistance to make the most of the SOS coils and in a lime green finish to match the color theme of the build.

 

Big Boost For Such A Little Pickup

The Gen-5 3.0-liter Whipple supercharger sits on top of our LS small block like an adult-sized helmet on top of a determined 5-year-old pee-wee football player; it looks as ludicrous as it does menacing. “Sleeper” is not in our vocabulary for Project McLovin, so cutting a hole in the sheet metal of the original hood is no problem to show off the candy-green finish of our Hotrod-Series blower. Whipple will powder coat your supercharger any color you want, and our Whipple supercharged Superbad 427 received its new 3.0-liter blower with a two-part powder coat finish consisting of a metallic silver base and “Shocker Yellow” over it to produce this candy-green result that just pops in the sunlight.

The 5th generation 3.0-liter Whipple supercharger is a big leap in performance and efficiency over the previous generation. The 4×3 rotor pack inside the housing is more efficient over the previous generation’s 5×3 design, so much so, that Whipple states that the Gen-5 3.0-liter outperforms their previous-generation 4.5-liter. A supercharger that can provide the airflow of a larger displacement blower, but in a smaller package, translates to power and torque across the entire RPM range, not just the top end. We went with a Wegner accessory drive with a 10-rib belt to drive our new candy-green air pump and a Granatelli 112mm throttle body to flow enough air. On the engine dyno at KPE Racing, our Whipple supercharged 427 flexed all it could on E85 to the tune of 1,142 horsepower at 6,600 rpm and 1,018 pound-feet of torque at 5,700 rpm, topping 17.1 psi of boost when the pull ended at 7,000rpm. That’s more than fifteen times more than what the original 1.8-liter four-banger could muster!

We still haven’t landed on what transmission Project McLuvin will end up with, maybe a Tremec Magnum 6-speed or maybe a built 6L80E. Regardless of what ends up behind the 1,100-plus-horsepower Superbad 427, it will also need to be able to handle four-digit torque in this tiny Whipple supercharged 2,500-pound classic American mini-truck.