Gibbons Motorsports Builds An 800 Horsepower, Pump Gas Beast Of A Big-Block

15 min read

Gibbons Motorsports Builds An 800 Horsepower, Pump Gas Beast Of A Big-Block

15 min read

There is just something special about a well-built big block engine. All those cubic inches, truckloads of horsepower and torque, and the way a big block just has a presence and fills an engine bay in a way that’s hard for any small block to duplicate.

So when brothers Jake and Pete Gibbons decided it was time to start screwing together a new engine for Jake’s personal C10 hot rod pickup, they knew it had to be a big block.

But not just any big block. Gibbons Motorsports is based out of Mooresville, NC, and is all about performance. Although they build plenty of hot street engines, their bread and butter is oval track racing – Late Models, Modifieds, you name it. And you don’t last long in the racing business if you can’t build winners.

Gibbons big block Block

The baseline for our build is a new aluminum big block casting from Brodix. This casting is a big reason why the completed build, even with eight quarts of oil in the oil pan, weighs in at just 529 pounds.

So even though the engine needed to be dependable as a daily driver, the Gibbons brothers couldn’t help but pack in plenty of performance. It started with an all-aluminum Brodix block with 4.600 cylinder bores. The crank is a stroker from Callies with 4.500-inches of swing, and together that makes the total displacement 598 cubic inches.

Bolted on top of the block are a pair of big Brodix aluminum cylinder head castings. These heads are fully CNC cut with 119 cc combustion chambers and 365 cc intake ports that can flow absolute tons of air and fuel – over 460 cfm!

An engine like that requires a lot of air and fuel, so Gibbons decided to go with one of Holley’s new Sniper Stealth 4500 EFI systems to provide it. The Sniper Stealth 4500 looks almost exactly like a big Dominator carb, and it has that same presence sitting on top of a big block, but it also brings with it so many more capabilities.

Gibbons Brodix

The Callies forged crank bumps the stroke out to 4.500 inches. Gibbons had the counterweights coated to help sling off oil and help reduce horsepower robbing windage.

First of all, the Sniper Stealth is capable of keeping this hungry big block fed with its 1,440 cfm rating. Eight 100 lb/hr fuel injectors means the unit can provide enough fuel for 800 to 1,500 horsepower in naturally aspirated applications. Plus, the ECU makes for easy tuning for a variety of environments and applications. The ECU is all contained inside the throttle body, but somehow it can handle multiple functions. It is self-learning, can handle blow-through boost with a 2.5 bar MAP sensor, nitrous controls –both wet or dry– ignition controls, basic datalogging, and even launch control.

But when you are packing in a ton of air and fuel, you’ve also got to have a strong spark. For this, Gibbons decided to try something new. Instead of a traditional distributor and a single coil, Gibbons went with MSD’s new Direct Ignition System (or DIS for short), which eliminates the wear-prone distributor cap for a low-profile dual-sync distributor and provides a coil to every cylinder. The result is a system that provides maximum spark to each cylinder with maximum dwell time, is easily programmable and even allows individual cylinder timing to the ultimate in tunability.

Gibbons Brodix pistons

Flat-top pistons help keep the compression down to 10.1:1 so that we can safely run pump gas safely.

On the dyno we saw some pretty interesting results. The ECU’s self-learning capabilities did all the work and after a short break-in the big 598 was making peaks of 742.6 foot-pounds of torque at 5,200 rpm and 802.7 horsepower at 6,200 rpm. But best of all, we absolutely love the torque output. The torque exceeded 600 foot-pounds by 4,000 rpm and never dropped below that point by the end of the pull at 6,600 rpm.

What’s interesting, however, is Gibbons felt the cam was probably a bit too small. The cam we used is ground with 256 degrees of duration for the intakes at 263 for the exhausts –both at 0.050 tappet lift. Gross valve lift with the 1.7:1 ratio rocker arms is 0.724 and 0.731 for the intakes and exhausts, respectively. The brothers feel the combo is capable of at least 100 more horsepower with a new cam with about 15/20 degrees more duration and a tad more lift. So we’ll make sure to check back in and update you with the new numbers when they are able to stab in a new camshaft and head back over to the dyno.

Gibbons Brodix camshaft

The big 55mm cam is a solid roller from Comp Cams. It has 256/263 degrees of duration at 0.050 lift with gross valve lift of 0.724/0.731 inches on a 110-degree lobe separation angle. Interestingly, Gibbons did a firing order swap that mimics a modern LS.

Gibbons Brodix timing belt

A timing belt drive system from Xceldyne is basically the same thing running in NASCAR’s Cup Series and Gibbons Motorsports installs on their big-bucks Dirt Late Model engines. It is super accurate, and the belt helps dampen harmonic vibrations that can disrupt the valvetrain.

Gibbons Brodix

The heads are aluminum castings from Brodix designed to move huge amounts of air and fuel. The combustion chambers are 119 cc’s, and the valves are sized at 2.350 for the intakes and 1.880 for the exhausts.

Gibbons Brodix valves

Big, fully ported intakes are sized at 365 cc’s and can flow over 460 cfm

Gibbons Brodix rockers

The Jesel shaft-mount rocker arms keep the stock 1.7:1 ratio but are much more stable than the stock pedestal mount system.

Gibbons Brodix Sniper Stealth 4500

The cherry on top of this build is one of Holley’s new Sniper Stealth 4500 EFI systems. It flows over 1400 cfm, includes eight 100 pound-per-hour injectors and includes a highly tune-able, self-learning ECU built into the body.

Gibbons Brodix Sniper Tuning

You can use a laptop, but we tested the viability of the Sniper system by setting everything up exclusively on the hand-held controller. It worked flawlessly.

Gibbons Brodix Sniper Stealth ECU

If you use a more traditional ignition setup, the Sniper Stealth 4500 ECU can control it, and you can make all tuning adjustments through the handheld. Because the DIS will be handling all ignition controls, we simply turned off the ignition options on the Sniper.

Gibbons Brodix Sniper Top-Down

Check out the fuel being injected into the venturi of the Sniper. The big 4500 unit can handle up to 1,500 horsepower in naturally aspirated engines and 1,250 when adding boost.


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