GRUNT HUNT: BLOWN 7.3L GODZILLA

WITH ITS TVS SUPERCHARGER PROGRAM, HARROP ENGINEERING PROVES THE CAPABILITIES OF FORD’S 7.3L GODZILLA V8

Harrop Engineering combines its TVS blower with a Ford Godzilla V8, with spectacular results

STEP aside Barra, Mod Motor and LS fanboys, because the new king of the stock bottom end is here, and its name is Godzilla. Ford’s 445-cube small-block has been making news since it debuted under the bonnet of the medium-duty truck range back in 2019, with a tough, deep-skirted iron block, six-bolt mains, forged crank, and deepbreathing, pushrod heads.

Melbourne’s Harrop Engineering got together with Dandy Engines to test out what a TVS blower can make on a stock Godzilla long motor, and the answer is: serious steam! How does 800hp on 98 RON and 1015hp on E85 catch you – all through stock valve springs, stock cam and a totally Oe-spec bottom end? And this is just the first phase of the program’s development!

“Our Godzilla program started over 12 months ago, around April 2020, when we got our 7.3 motor from Harrop USA,” explains Harrop’s general manager, Heath Moore. “It’s a very impressive engine – a modern, old school-style engine – and Ford has clearly put a lot of work into refining the cam-in-block pushrod design. There will be so many trucks fitted with these, and in years to come there will be a huge supply of these engines both at the junkyard or parts distributors, so I foresee a very healthy aftermarket.”

The test engine was first fitted with an ATI balancer and an 87mm drive-by-wire throttlebody from an S550-generation GT350 Mustang, as it offers a 7mm-larger throat compared to the factory throttlebody. Frank Marchese and the Dandy Engines crew then plugged in a Fueltech FT600 ECU. The standalone computer was needed to control the Godzilla’s variable cam timing and variable-pressure oil pump, and it

expedited the testing process by making the engine’s cam syncing and crank triggering simpler to work out.

While the mill is rated at 430hp in production trim, once Frank had played with the variable cam timing and fuel trim, it made 550hp aspirated in the Dandy cell on 98 RON pump fuel. But then it was time for boost.

Frank and Harrop’s R&D manager, Clayton Stairmand, fitted Harrop’s all-new invertedstyle TVS2650 blower unit, where the intercooler sits above the Eaton four-lobe TVS rotor pack like in a factory-supercharged LS and LT. The locally developed blower features a sexy prototype billet lid, which does pump up the installed height of the Godzilla for those scared of cutting the bonnet, but we reckon the look of the new lid is worth it.

On the 8psi low-boost setting, the twisting force was reading around 750lb-ft, and Frank saw 780hp. With smaller pulleys stepping boost up to 12psi – fairly spicy on a stock production pick-up truck motor – the big-inch SBF stepped up to the challenge and threw down just over 800hp. Amazingly, Frank says he did 30 runs without lifting a

HARROP AND DANDY TESTED WHAT A TVS BLOWER CAN MAKE ON A STOCK GODZILLA LONG MOTOR, AND THE ANSWER IS: SERIOUS STEAM!

valve cover or having to pick up the rods off the dyno room floor, and he was running the donk to 6000rpm.

“The fundamentals of the engine are optimised for durability thanks to its life in commercial vehicles,” Heath explains. “That makes it a fantastic base for performance upgrades, which is always our goal.

“Compared to this new engine, a Coyote isn’t a great packaging solution for those who want a modern Ford V8 in their project vehicle,” he continues. “There is a degree of simplicity in the 7.3’s packaging and engineering, plus they are very accessible price-wise as a crate engine. This is also a far more capable engine out of the box for boost compared to a Windsor or a smallblock Chev. The block and cylinder casting process is more accurate and consistent compared to 40 years ago.”

Several days later, the 7.3 was back on the Dandy dyno and ready to rip with boostfriendly fuel in the tank. “We changed over to E85 and crept the boost up to 18psi over 30 dyno runs, to make 944hp with the 87mm throttle,” says Heath. “But we saw vacuum

WE CHANGED OVER TO E85, ADAPTED A 102MM THROTTLE AND PUSHED IT PAST FOUR DIGITS TO SEE 1015HP ON 20PSI

behind the throttle blade, so we adapted a 102mm throttle that Dandy had there, and it picked up around another 40hp seeing 19psi. Then we leaned on it a bit harder and pushed it past four digits to see 1015hp on 20psi.

“The head gaskets and head bolts must be something special from the factory, and the cam did well, too! There would be over 60 runs on this engine, and I thought we’d lift a head, pick a ring or throw a rod, but instead of the next stage of development being fixing this motor with upgrades, we’ll move to upgrading the valvetrain for boost.”

Despite having already upped the throttle size twice from the stock 80mm unit, Heath reckons there’s more potential in the Godzilla platform with a bigger-still throttle unit. “It needs more throttle blade diameter, so, like our LS 110mm and 115mm packages, we’ll be working on a specific large-diameter Harrop solution to maximise the blower potential,” he says. “Even with the 102mm throttle, we were seeing a decent amount of vacuum behind the blade, so these 7.3s definitely need a big throat. Working closely with Dandy Engines, we also have some development cams on the way from the USA to test, and we’re assessing a dedicated belt drive that can accommodate a wider belt for the seriouseffort engine packages, as this motor is still using the factory six-rib belt set-up.”

All in all, the Harrop crew are fairly stoked with how this new big-inch small-block has performed. “As a pure power-adder to a platform, we’re thrilled with the result,” Heath says.

As soon as Harrop and Dandy Engines start pushing their Godzilla, we’ll let you know just how hard this big lizard can stomp.

“We went with an inverted supercharger design to simplify the air path through the unit, with the large intercooler brick inside for efficiency,” Heath Moore says. “Eaton is still in the R&D phase of developing a larger rotor pack, but that is part of the plan in the future for really max-effort set-ups. We haven’t dug into the cylinder heads or valvetrain yet, so we’re looking at the huge potential there” RIGHT: One key upgrade made when the blower was bolted on was to the fuel injectors. “We ran 1000cc injectors on the engine dyno,” Heath says, “but we haven’t finished speccing out what we’ll fit in our kit yet, because a customer’s car can vary so much depending on what fuel they’ll run and the like” LEFT: “One of the good things about the Godzilla is that because it has been designed for a truck, you don’t have the space constraints you get in a Camaro or Mustang,” Heath says of the decision to run the high-profile billet blower lid. “We can get a great plenum volume in our kit, and it flows far more efficiently if you don’t have a low-profile lid. The intake temps were incredibly low during the first phase of tuning”

TOP RIGHT: “One technical hurdle is that there is no keyway on the crankshaft – a bit like an LS3,” says Heath. “We’re going to have to find a way to pin or keyway the balancer to the crank for long-term durability when we’re leaning on it” ABOVE: “The factory 7.3 throttlebody is fairly small [80mm], so for the max-effort combos we’re looking at 112mm-115mm throttlebody options,” Heath says. “We do have an integrated 115mm throttle for inverted 2650i kits and 110mm integrated throttles for the traditional-style 2650 set-ups, so we will consider how this throttle size works on the 7.3 down the track”