C10 Shootout: The Big 10 Build from Start to Nearly Finished (Ep 3)

If you missed our epic LS vs Coyote 3 dyno test, let me give you the TLDR. Both the FFRE-built Coyote and the LME-built 5.3L LT struggled mightily to build boost because of crippling backpressure. While both did, in fact, eclipse 1,400 horsepower with the HPT 7680 turbochargers, for the C10 Shootout, presented by Summit Racing, we sent them back to HPT for a few modifications – namely a larger turbine wheel from the F5 lineup. The massive 103mm turbine wheel, combined with the larger housing meant we expected more RPM, more boost and as the result – more power. In the case of the aluminum L83 block that was going into the Big 10, we were worried that either the engine was already not the healthiest because of the backpressure issue and that the block could actually split. This is the reason we used an iron L8T block on our last high-boost build with Big 3 Racing and LME.

The solution to our challenge was, under the advice of LME, to send the 5.3L LT engine back to Houston for some fresh pistons from Diamond Racing. LME used the same specs, just slightly larger to clean up the bore. By lowering the compression it might buy us a little breathing room with the new turbo’s capabilities. The problem with this strategy is that it left Big 3 Racing without an engine for the Big 10 to use for proper weight and location for things like turbo system fabrication and chassis scaling. Big 3 had to soldier on with a junkyard L83 from Chuck Stefanski’s personal stash. This issue was only compounded by shipping complications.

Soldiering on with Big 10

With a mock-up engine secured and installed using some ICT Billet motor mounts (PN 5510-KIT553EM), Big 3 Racing turned its attention to completing the suspension, drivetrain, and chassis work. As mentioned in the last episode, the Big 10 will be using a bolt-in front suspension and leaf springs in the rear from Summit. The sliders on the leaf spring mounts were custom-designed and welded in by Big 3, along with a whole lot of 1-⅝-inch and 1-¼-inch chromoly tubing from Competition Engineering. The tubing was used for chassis reinforcement and a 6-point roll bar, going through the back window (replaced by lexan from Summit Racing).

The AFCO front coilovers and rear shocks were custom spec’d for this build, as were the Strange Evolution brakes and 9-inch rearend needed to complete the rolling chassis. The Evolution brakes, if you are not familiar, represent the latest technology in drag brakes suitable for not only dropping weight but handling the stopping demands of heavier vehicles like our C10s. The scalloped design of the stainless rotor is eye-catching, but it only hints at the trick Dynamic Drive Mount system that lies within. A billet aluminum hat attaches to the rotor with Spirolox fasteners to eliminate bolts and in the process unneeded weight and thermal stress. We used the ‘63-’70 Chevy C10 4-piston brake kit (PN B4165ECE) to mount to our aftermarket spindles on the ‘78. The Late Big Ford / Torino rear brakes (PN B1706WCM2) came fully installed on our 9-inch housing with a spool, 3.50 gears, and lightened 40-spline axles.

The transmissions, in case you are wondering, are virtually identical for both teams. ATI Racing put together both Turbo 400s, bellhousing to tail, and even included a flexplate and bolt-together converter. We went with a 2.10 First and 1.40 Second gear, second gear leave on the valve body, clean neutral, and the Stage 2 dump along with an SFI case and bellhousing. Having made more than its share of these for the new COPOs, ATI had everything we needed to fit up the trans to the Gen V engine. In case you are wondering, a clean neutral prevents the car from rolling by actually decoupling the engine and transmission hydraulically. The dump valve is essentially a tunable device to change the stall speed. To alter its characteristics at the starting line, Big 3 can manipulate the two-step rev limiter (what RPM the truck leaves), the stall speed via the dump valve, and the stator, which affects torque multiplication. Got all that? That’s essentially what makes the truck leave harder or softer, depending on how effectively the tire pressure, shock settings, spring rate, and instant center translate that into forward motion.

Speaking of tires, the spec tire for our little shindig is a very streetable Mickey Thompson ET Street S/S 295/55/15. Big 3 spec’d 15×12-inch 63 Pro Forged wheels from Race Star with a 4-inch back spacing and a double beadlock. If you are not familiar with Race Star, outside of their entry-level wheels, they do make some very nice, high-end wheels for Pro Stock, Top Fuel, Funny Car, and Pro Mod. The 63 Pro lineup is SFI 15.1 certified and made from forged aluminum. For the front, we opted for the Forged Stryker in 17×3.5-inches with a matching Mickey Thompson ET Street Radial in 27×6 inches.

Turbo System Fabrication

Rick Trunkett was hard at work on the turbo system using the mock-up engine. He started with 1.75-inch 304 stainless steel tubing for the primaries from Vibrant, which snaked their way into a 2.5-inch crossover to the HPT 76103 turbo, mounted on the passenger side front and exiting below with a 5-inch downpipe. Big 3 ordered a series of 180-degree bends and UJ bends, plus 2.5-inch slip joints helped round out the bunch. For the header flanges, Summit Racing had these in stock for the LT (PN SUM-670207-SS). 

The cold side is where things really got interesting. Rick used aluminum in 3.50 and 4.00 inch diameters to go directly from the turbo compressor outlet to the Holley 105mm billet throttle body that already had a 4-inch HD Clamp flange welded to it. Vibrant’s Pinless HD Clamps are trick, if you are not familiar. It locks with a push-button, so you don’t need any tools to install, but they hold a ridiculous amount of boost. At 30+psi a worm clamp isn’t going to hold, and your traditional VanJen clamps usually require special tools, which can be problematic in the staging lanes or the burnout box if it busts loose.

VS Racing provided two Gen3 50mm wastegates (PN VSR50WGD) and a 50mm Blow Off Valve to complete the system. The Gen3 wastegates have a revised piston design for better stability with CO2 providing dome pressure, which is exactly what we’ll be doing to control boost through the Holley EFI system. The input in the bottom port will be teed in, which comes from the pressure source and the other port will be capped. The wastegate has a 2-inch inlet and outlet that Rick built with the Vibrant stainless steel.

Fluid Movement

Remembering that Big 3 is employing the Keep It Simple approach, not only was the turbo mounted to one side of the engine bay, but the radiator would be mounted right up front as normal. Since it’s a drag-and-drive build, the radiator needed to be pretty substantial. Thankfully, Big 3 was able to pull this straight from the catalog, using AFCO Racing Bolt-In Direct-Fit Aluminum Radiator, complemented by SPAL Plus Series 16-inch Brushless 500-watt, 2,430 Peak CFM Puller Fans, AFCO Asphalt Oil Cooler, and an AFCO heat exchanger for a ‘99-’04 Ford Lightning. A Rhodes intercooler tank would sit in the bed, with fluid pumped by a Meziere WP728 intercooler pump.

The complete fuel system was provided by Radium Engineering, a 14-gallon racing fuel cell with an SFI bladder, three surge pumps, and a lift pump. The fuel cell is designed to mount flush to a surface using the weld-in cage that it fits inside with a direct-mount fill neck. A fuel pressure regulator and gauge, 10 Micron fuel filter, fuel level sender, and a subharness kit were all included. I’m not sure if we are building Time Attack trucks, or drag n drive builds – but if something fails, it won’t be something in the fuel system. And the safety of the SFI-rated system makes us feel all the more safe about putting 1,400 horsepower in these well-built, but still sketchy old trucks.

The Last 10% or So

Normally, it’s the last 10% of the build that seems to take the longest, but if we are being honest, Big 3 is a bit further from that because they are still waiting on the engine from LME. We’ve got shelves full of Earl’s fuel line and fittings to plumb the truck, the wiring hasn’t even been touched yet to get the Holley EFI system to talk to the rest of the vehicle, and all the little odds and ends needed to make the truck safe on the track and the street. To give you an idea, Summit provided $7,500 in gift cards to get the truck to the starting line – there are so many things like a battery shut off, CO2 bottle and mount, engine diaper, throttle linkage…the list goes on. But, we knew Big 3 could do it… Stay tuned as the truck gets wrapped up in time for the dyno and hopefully track testing. But first, Team Bigun and the Coyote 10.

Horsepower Wars C10 Shootout would like to thanks its sponsors for making this possible including Summit Racing, Holley (Holley EFI, Simpson, etc), Manley Performance, Diamond Racing Pistons, COMP Cams, Moroso Performance Products, Total Seal, Automotive Racing Products (ARP), Cometic Gaskets, AMSOIL, Vibrant Performance, HPT Turbochargers, ICT Billet, ATI Performance, Meziere Enterprises, AFCO Racing, Optima Batteries, Old World Industries/Peak, Strange Engineering, SPAL, Auto Metal Direct, and Wiles Driveshaft.