While the G-body offers tons of room in the engine bay for all sorts of activities, Midwest Mayhem opted for a compact LS engine. Not only is their bullet of choice physically compact, but it’s also the smallest-displacement engine of the competition.
While 75-percent of the teams in the competition have chosen the LS engine, Midwest Mayhem team-leader and engine-guy, Joe Hunt, opted for the smallest 4.8-liter variant. Not only is the team relying on their turbocharger to be the replacement for displacement, but they are taking the whole “stock bottom end” thing to the extreme.
The team has a good reason for going with the 4.8-liter. They didn’t just pick up any old LS engine out of a junkyard; instead, they scored a Gen-IV 4.8-liter for $200. The Gen-IV LS engines have improved connecting rods and the cast 4.8-liter cranks are documented to hold horsepower in the four-digit range.
With that in mind, the only thing Hunt touched in the OEM short-block, were the piston rings. For those, Hunt went with a set of Total Seal CR-series (Classic Race) rings, opened up a bit to account for the boost they will be shoving into the engine.
Team Midwest Mayhem is taking “stock bottom end” to the extreme, with the short-block of their 4.8-liter Gen-IV LS exactly the way it came out of the donor vehicle — except for new piston rings from Total Seal.
The Total Seal rings are a standard 1.5mm, 1.5mm, 3.0mm set. The top ring is a ductile-iron ring with a plasma-moly coating, while the second ring is a conventional cast-iron ring. A standard-tension, stainless-steel oil ring rounds out the only modifications made to Midwest Mayhem’s rotating assembly.
While OEM bearings were used in both the mains and rods, Hunt did opt for a set of ARP main studs to reassemble the engine with. For those of you counting, that means only two new parts used in the entirety of the bottom half of the team’s engine.
You’d think with all the saved budget from the short-block, Midwest Mayhem might be a little extravagant on the top half of the engine. Instead, the team’s frugality extends to the heads and intake as well, although, not quite as stringently as with the bottom-end.
Since the Gen-IV 4.8-liter engines came from the factory with what are regarded as the premier cathedral-port castings (799s) the team simply took a die-grinder to the intake and exhaust ports to give them a little extra airflow. The original 2.00-inch intake and 1.55-inch exhaust valves are also run as fitted from the factory.
However, Hunt and company did splurge a little on a Brian Tooley Racing Platinum Valvespring Kit. Composed of dual valvesprings with a combined spring rate of 409 lb/in, titanium retainers, and steel 7-degree locks, the kit also comes with locators for the stock valve-guides.
To fit the upgraded 3/8-inch pushrods, Joe Hunt had to clearance the factory 799 cylinder heads. An endmill chucked up in a cordless drill may not be the prettiest method of machining, but it was quick, and it worked.
Continuing the theme, the original rocker arms were used with no upgrades. A custom-ground COMP Cams bumpstick is used, as it was provided free of charge to all competitors. The team stuck with hydraulic-roller lifters, but upgraded to COMP’s short-travel race lifters. The new lifters are REM-finished to minimize friction and designed to limit internal travel to maximize high-RPM performance.
Connecting the lifters and the rocker arms are a set of upgraded Brian Tooley Racing 3/8-inch-diameter, 7.375-inch-long pushrods For the timing set, Midwest Mayhem simply opted for an upgraded Chevrolet Performance 58X timing sprocket and new Summit Racing LS2 single-roller timing chain.
ARP head studs were chosen to hold the heads in place for their superior clamping force, while a set of Brian Tooley Racing multi-layer steel head gaskets were used to seal the combination’s heads to the block.
While externally, the team’s stock, plastic 4.8-liter intake suggests more frugality, that notion ends once the other hardware comes to light. Fitted to the plastic intake is a set of DeatschWerks 1,000 cc/minute fuel injectors, along with a 92mm Holley Sniper EFI throttle body.
Providing fuel to the injectors is a used MagnaFuel ProTuner 750-series external pump the team scored for $175. Summit Racing fuel filters and pressure regulator, along with a Holley fuel rail kit, all plumbed together with Fragola hoses and fittings complete the fuel system.
For the ignition side of the equation, the team went with LS coil packs from E3 Spark Plugs, Summit Racing 8.5mm spark plug wires, and E3-108 spark plugs. Managing both the fuel and spark is one of Holley’s Terminator X engine-management systems designed to make an LS swap a plug-and-play affair, but with all the control of Holley’s more advanced ECU systems.
All of the LS engines in the competition are running E3 LS coils and E3 spark plugs to provide all of the spark energy they’ll need to keep the candles lit under the severe cylinder pressures they’ll see.
For Team Midwest Mayhem’s power-adder, they opted for a BorgWarner AirWerks SX400 80mm turbocharger, identical to the one chosen by Team Enemies Everywhere. The 80mm cast-aluminum compressor wheel is spun by a 96mm exhaust turbine wheel. The 1.32 A/R ratio provides a stout top end, but will potentially be a bit slow to spool on the smaller-displacement engine of Midwest Mayhem.
Also differing from the other team using the same turbocharger, Hunt opted for a Summit Racing universal aluminum air-to-air intercooler. It features 3-inch inlets and outlets, and a 31-inch by 12-inch core with a 4-inch core-thickness, plumbed with Spectre Performance aluminum tubing.
The team also opted for a blow-off valve on the inlet, in the form of a used eBay-special 50mm unit. To control the boost, a used, unknown-make 44mm wastegate was sourced for the princely sum of $55. The hot side was constructed using OEM 4.8-liter manifolds, and mandrel-bent steel tubing from Diamond Eye Performance.
While an unconventional engine build strategy, we’re curious to see how Team Midwest Mayhem’s plan of attack plays out on the racetrack.
Opting for an 80mm BorgWarner AirWerks SX400 turbo with a Summit Racing air-to-air intercooler, the team found an interesting mounting location in the G-body’s passenger-side headlight opening.
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