673-cube XY Falcon – FAT XY

John Saad's street-driven Ford XY Falcon combines elite-level build quality with a 1354hp Sonny's mountain motor!

Photographers: Chris Thorogood

John Saad’s Ford XY Falcon street car is a 1300hp mountain-motored monster!

This article on John’s XY Falcon was originally published in the November 2017 issue of Street Machine

JOHN Saad wanted a streetable car that had 1000hp naturally aspirated. “No blowers, no turbos,” he says. And that’s exactly what FAT XY is. With an engine bay filled to the brink with a massive 673ci Sonny Leonard, hemi-headed big-block Ford, this gorgeous black XY GT tribute exceeded John’s requirements with a bona fide 1354 98-octane-friendly horses. If you think 1354hp is stout, you’ll be blown away by the fact that John actually had the engine detuned to make that power.

FAT XY’s arrow-straight bodywork and unusual paint colour is thanks to Danny, Claude and the rest of the Custom Bodyworks team. “HOK tells us it’s the only black Kandy over black they know of,” John says

US-based Pro Stock/Pro Mod gurus Sonny’s Racing Engines originally built the Hemi-headed mountain motor for an Aussie drag racer who was looking to run sixes on C16. Unfortunately, the enormous mill was never fitted to a car and sat about languishing. John’s brother George was aware of its existence, and approached the owner about selling it. Although it wasn’t actually for sale at the time, a deal was struck.

“When Danny suggested gold Metajuls [HOK flake] in the paint, I was adamant I didn’t want it to look like some Auto Salon throwback. It had to be subtle.” John says. And subtle it is; you have to catch the light at just the right angle to see it

Unfortunately, with its alloy rods, sky-high compression and Mount Everest cam, the angry full-race engine was never going to be happy on the street. So it was packed into a crate and shipped back across the Pacific, to Sonny’s shop in Lynchburg, Virginia. They stripped and completely rebuilt it with different rods, pistons and a more streetable version of Sonny’s special 60mm camshafts.

The foundation for this extreme Ford is the aftermarket cast-iron Premier block by Eliminator Performance Products. Based on the factory 429/460ci (385-series) block, it has been significantly lightened by LSM Systems Engineering, who whittled around 32kg out of it. The casting features special high-flow water jackets to help the keep monster cool, along with a raised cam bore to clear the hefty Carrillo billet-steel rods and whopping 4.843-inch Bryant billet crank. If you punch the crank’s stroke along with the Diamond forged pistons’ 4.703-inch diameter into an engine capacity calculator, you’ll get a whopping 673ci!

The enormous hemispherical cylinder heads are just as capacious. They’re Sonny’s own design and have ports that look big enough to fit your fist into. The exotic heads are bridged by a mammoth sheet-metal intake manifold, topped with a pair of Holley’s legendary 1250cfm Dominators. Despite being nearly 60ci smaller than Sonny’s 729-cube Extreme Pump Gas Ford big-block, this donk is line-ball power-wise thanks to extensive CNC head work. Sonny’s Racing Engines is so happy with how it turned out, there’s a pic of FAT XY’s engine bay on the company’s website.

Despite the engine’s sheer power and physical weight, as well as being mounted almost solid via engine plates, it actually doesn’t shake the car all that much – John says it’s not in any way obnoxious.

As photographer Thorogood has noted, the sheer scale of the engine is epic – which is what you need when creating a 1000+hp, naturally aspirated street mill. And it didn’t stop there. While Sonny’s signature forward-facing, belt-driven (off the front of the cam) dizzy stayed, the drag-spec wet-sump set-up was swapped for a Moroso four-stage dry-sump system. This ensures vital oil pressure is maintained whenever John mashes the loud pedal for intervals somewhat longer than six seconds.

Underside points of interest include the dry-sump tank; massive PWR radiator; rear-mount VL rack; Wilwood six-piston calipers; strengthened front rails; hefty chassis connectors; billet gearbox sump; 4in exhaust and quad mufflers

“Todd at Sonny’s was massively helpful,” John says. “It was a scary proposition to stick the big-dollar engine in a wooden to box and send if off. But Todd looked after everything and made sure everything was right and it came back spot-on.”

The sight of those massive rocker covers simply takes your breath away. But it’s nothing like the punch in the guts you feel when you find out they’re sitting atop 673 cubes and 1354hp worth of Sonny Leonard hemi-headed, big-block Ford!

FAT XY’s 1000hp-safe driveline includes an Al’s Race Glides TH400 complete with Reid case and billet internals. After dynoing the engine, Sonny’s sent all the specs to Neal Chance, who pieced together one of his bulletproof converters. Continuing rearwards, you’ll find a four-inch Mark Williams chrome-moly tailshaft and 40-spline Mark Williams diff with a sheet-metal housing by Red at Craft Diffs.

Notice the all the red and blue anodised fittings? “I didn’t go with all-black fittings like everyone expected me to,” John says. “I wanted that old-school pro street look. Same goes for the brushed-alloy and CAD-plated bolts instead of the usual stainless button heads”

As dominant as that hemi-headed big-block is, the rest of FAT XY is similarly grand. Michael and Chris from JT Performance are responsible for building a huge chunk of this ballistic Falcon. To make room for the massive donk, JT recessed and smoothed the firewall before carving out the factory shock towers to graft in a McDonald Bros Racing double A-arm front end, which utilises two-inch drop spindles. FAT XY weighs in at a hefty 1780kg, with most of its extra 200-odd kilos over the front end.

“The engine’s too heavy for an engine crane,” John says. “We have to take the carbs and intake off and lower it in with a forklift!”

To withstand all this extra weight, along with the engine’s brain-bending 988lb-ft of torque, JT reinforced the front rails and added beefy chassis connectors that tie into the full rear clip – which includes full tubs, four-link and coil-overs. Rounding out JT’s chassis reinforcement are two hefty crossbeams – one under the dash and another that runs across the rear, under the Falcon’s parcel tray.

The mile-wide PWR radiator is big enough to fit two 16in fans side-by-side. Note the remote reservoir for the Moroso dry-sump system sunken into the radiator support panel at the top right of this pic. A belt-driven, forward-facing dizzy is common to many of Sonny’s big-cube, big-horsepower donks

To accommodate those 22-inch Simmons FRs, JT stretched the rear wheel openings about 100mm. With John wanting the Falcon to be a no-hassle cruiser, JT had to raise everything up for decent ground clearance. There’s a taller, wider tunnel, while sections of the floor were also raised to accommodate the cavernous four-inch exhaust that runs the full length of the car.

With full tubs, Magnaflow 500 pump/filter and a 90L Aeroflow tank (the biggest they make), there’s not a whole lot of boot space left over. However, with that thumping great shiny bit at the other end, who cares!

The extractors are a good example of how serviceable Michael and Chris have made everything. Despite having massive 2.5-inch primaries and monstrous four-inch collectors, they can get the headers in, or out, in about 20 minutes. To keep everything sanitary, yet usable, mountains of drivetrain and suspension parts were given the powdercoat treatment by Oxytech.

John also ticked a lot of boxes on the Aeroflow order form. “I love their stuff and they really looked after me,” he says. “Every fitting, every line, every hose is Aeroflow. We plumbed the entire car, and not one leak!”

Unlike most projects that start out as basket cases, FAT XY was born from a very tidy Phase III tribute, which had been built with a number of genuine parts.

“In 2012, I saw it, loved it, bought it,” says John, who was looking for a cruiser while finishing his Summernats Grand Champion-winning Mazda RX-3 (SM, Jan ’17). “It was black with gold, 19-inch Simmons wheels and a 393 Clevo. Within a month, I changed the 19s for 20s. Then, after going to Powercruise I realised the 393 wasn’t going to cut it and had a 434 built. During the new engine’s first powerskid, it torched a piston. I had the new piston, the block was machined, it was all ready to go back together. But I said: ‘No, I want my 1000hp.’ That engine’s now in my brother’s XC Falcon.”

JT Performance had to heavily modify the rear seat to clear the huge tubs. While it may look factory-ish, it’s mostly for show. The angles are all wrong to be comfortable, there’s virtually no padding and you kinda need to be about 10 years old to fit in there

The fact that the interior looks like standard-issue GT belies the amount of effort that went into it. Daniel from Unique Marine & Auto Upholstery has done a remarkable job, rebuilding both front buckets, sorting out the rear seat (which JT had heavily modified to clear the tubs), then covering them in the correct, GT-patterned vinyl. Factory carpets were never going to fit, so Daniel fashioned individual floor panels that were covered in Mercedes carpet and press-fitted into place.

Being a cruiser, FAT XY needs cruising tunes. The faux-factory radio fascia hides a modern Bluetooth head unit. Unfortunately plans to mount speakers under the rear parcel tray had to be ditched due to the chassis-strengthening brace that runs directly underneath. Plan B is for a pair of boxed speakers up under the dash

The console, dash, door trims and many other mouldings are all repros from GT Ford Performance. However, the genuine FoMoCo rim-blow steering wheel had to be sent over to New Zealand for refurbishment – it looks absolutely mint!

The key to this very classy yet understated interior is how well it all fits together. A lot of time and effort went into getting everything to sit just right. XY GT Falcon interiors never looked this sweet when they rolled out of Broadmeadows in 1971.

In keeping with the traditional look, the steering column supports the obligatory Auto Meter tacho, along with water and trans temp gauges. But there’s no typical hose-clamp mounts here; instead the mounts have been welded to the column and neatly blended in

“Thanks to Mark from Ontrak Auto Electrical, everything in this car works,” says John. “He’s a genius. He completely rewired the whole car and looked after all the electrics. That’s why all the lights, wipers, gauges, even the speedo works.”

And the answer to the question on everybody’s lips: What’s it like to drive?

“I’m shocked at how well it drives,” John says. “Considering how heavy the car is, how much power it has and the fact it’s on 22s, I can’t believe how good it rides and how easy it is to drive.”

And for the doubters, FAT XY has already been snared in hardcore traffic, on a 32-degree day. It didn’t buck or carry on and the temp barely moved. With 500lb-ft of torque at 2000rpm, it pretty much cruises along at 100km/h on idle.

Mind you, stab the throttle and it’s next-level stuff. “I was cruising home after Justin from Horsepower Solutions tuned it up for me,” John recalls. “I gave it a fraction too much throttle and it fried the tyres so hard I had to pull over and open the front and rear doors to let all the smoke out. It’s everything I wanted!”


While the legendary 426 Chrysler Hemi is without doubt the most famous, it is far from the only Detroit V8 fitted with cylinder heads featuring hemispherical-style combustion chambers.

Developed to take on Chrysler’s famous 426 on the high-banked NASCAR ovals, FoMoCo’s effort was the Boss 429 – also known as the Shotgun, or Boss ’9. It is believed that less than 1400 were fitted to production cars – namely 1969 and 1970 Boss 429 Mustangs. Ford’s racing partners, Kar-Kraft, plus Holman & Moody, fitted Boss 429s to a few other cars, but these were mostly development mules or purpose-built race cars. Genuine Boss Mustangs are a worldwide collectible, with premium examples fetching in excess of US$400,000.

Given the engine’s scarcity due to low production numbers and the collector value of restored Boss-powered machines, factory engines are all but impossible to find. But aftermarket companies like Ford Racing, Eliminator, Kaase and Sonny’s have all tooled up to churn out reproduction blocks and/or cylinder heads – much to the delight of Ford fans the world over.


Colour: HOK Kandy Black

Engine: Sonny’s Racing Engines 673ci
Block: Eliminator/LSM big-block Ford
Heads: Sonny hemi-Ford, billet, CNC-ported
Intake: Sheet-metal
Carbs: Dual 1250cfm Holley Dominators
Cam/lifters: SAR 60mm, Isky 1.062in
Crank: Bryant billet
Rods: Carrillo billet-steel
Pistons: Diamond forged
Oiling: Moroso four-stage dry-sump system
Ignition: MSD Grid/SAR
Water pump: Electric
Radiator: PWR custom
Cooling: Twin 16in thermo fans
Exhaust: 2.5in primaries, 4in system
Pref fuel: 98 PULP
Power: 1354fwhp

Gearbox: Reid-case TH400, billet internals
Converter: Neal Chance 3800rpm
Diff: Mark Williams 40-spline, sheet-metal housing
Tailshaft: Mark Williams chrome-moly

Front suspension: McDonald Bros IFS
Rear suspension: JT Performance four-link
Springs/shocks: Strange coil-overs (f & r)
Brakes: Wilwood two-piece rotors with six-piston calipers (f), Wilwood two-piece rotors with four-piston calipers (r)

Rims: Simmons FR; 22×7 (f), 22×12 (r)
Rubber: 225/30R22 (f), 335/25R22 (r)