Big is a relative term, since it always requires some level of qualification or comparison to justify. For example, 496 ci sounds like a lot of engine, until it’s sitting next to a 572, which itself is smallish next to a 632ci, 10.2-inch deck Merlin-based big-block Chevy. And even that’s laughably miniscule when stacked against the offerings in the world of Pro Stock drag racing that soar up into the 700 to 900ci range. And we’re still talking about comparatively puny traditional pushrod-style automotive V-8s here. Plenty of military and industrial engines push more air in one cylinder than all of those engines combined.
When Sonny Leonard decided...
When Sonny Leonard decided to accept the challenge to build the world’s first 1,000-plus cubic-inch big-block, it necessitated going back to the drawing board, since there simply wasn’t a block in existence that could be safely stretched to the required bore. The behemoth SAR blocks are machined in-house and kept to extremely tight tolerances.
But in our world of hot rodding and racing, the limit for traditional-style blocks has always been in the three-digit range. That’s because the thing about creating more cubic inches is that you can only bore and stroke just so far before you bump up against the physical limitations of the block. Going for more means the block itself has to grow on every axis to accommodate bigger slugs, and in the cylinders more throw from the crank, and reach from the rods. Basically you have to design a bigger big-block. The only question is just how big do you want to go? Historically, the glass ceiling has always been the magical fourth digit. There just hasn’t been a traditional-style block that could package parts large enough that wouldn’t burst through. Until now, that is.
Sonny Leonard Racing Engines has always specialized in “big.” Their smallest offering comes in at around 611 ci and reached all the way up to 940 ci. Never satisfied and always looking to innovate and improve, Leonard decided it was time to create the biggest big-block on the planet: a 1,005.8ci behemoth with an unreal 5.220-inch bore and a 5.875-inch stroke. Leonard calls it the “Godfather,” and it’s hard to fault that bit of bravado since he can back it up with numbers like 2,150 hp at 8,000 rpm and 1,500 lb-ft of torque at 6,200 rpm on 112-octane fuel. That’s naturally aspirated, by the way.
The bigger the cubic inches,...
The bigger the cubic inches, the more the heads need to flow. The CNC-ported hemispherical heads for the Godfather dwarfs the Brodix big-block head in the foreground. The 680cc intake runner volume ports flow 740 cfm at 1.300-inch lift while the 240cc exhaust ports flow 475 cfm at 1.3 inches.
Previously, Leonard had always theorized that a 1,000-plus cube drag race engine just wasn’t feasible considering the criteria required to make it live and produce power that justified the all clean sheet design it would take. Prodding from CEO Racing’s Craig Olson is what finally pushed Leonard to accept the challenge. Olson, a loyal customer, wanted something bigger and badder than the Leonard-built 935ci engine he used to set the record in Top Sportsman with a 6.25 pass at 223 mph.
Please understand, calling the Godfather a “big-block” is little more than an aesthetic classification, since it shares absolutely nothing with traditional GM and aftermarket-based big-block Chevys, other than the main and rod journal sizes and bellhousing bolt pattern. Nevertheless, we just couldn’t resist the chance to take a peek at some of the specialized outsized components that make this engine possible. We feature a lot of really big, really powerful engines in PHR, but this bad boy takes the cake.
The standard big-block cam...
The standard big-block cam on the left has a healthy lift in the .700-inch range, but the Godfather’s cam on the right dwarfs it with a monstrous 1.300/1.315-inch valve lift and 290/319 degrees of duration at .050.
Surprisingly, it might. The Godfather is 34 inches wide at the valve covers’ outer edges, and from crank centerline to the top of the throttle body it’s 26.5 inches. Lengthwise, it is 32 inches from the flywheel flange to the crank bolt—that’s only 1.4 inches more than a stock big-block Chevy!
“Big is a relative term … 496 ci sounds like a lot of engine, until it’s sitting next to a 572…”
“Leonard decided it was time to create the biggest big-block on the planet: a 1,005.8ci behemoth…”
“…in our world of hot rodding and racing, the limit for traditional-style blocks has always been in the three-digit range.”
“Sonny calls it the ‘Godfather,’ and it’s hard to fault that bit of bravado since he can back it up with numbers like 2,150 hp at 8,000 rpm…”
Check out the “Godfather”...
Check out the “Godfather” versus a standard GM big-block; the crank centerline stands at 12.225 inches from the deck while the big-block checks in at 9.80. It’s also about 8 inches wider at the top of the valve covers and the cam bore is raised nearly 2 inches to make room for the crank’s massive throw. Options include water jackets, stock big-block water pump mounts, and side engine-mount lugs. Shown here is the full-race block with no water jacket.
Lift numbers like that require...
Lift numbers like that require a stronger cam core. Here’s a closer look at the drastic difference in base circle versus a standard big-block cam (left). The practically rectangular lobes are ground on a 121-degree lobe-separation angle with a 118-degree centerline. The intake is advanced 3 degrees.
You can’t use standard GM...
You can’t use standard GM paired guide bar roller lifters with their wee little 0.842-inch body to transmit 1-inch-plus lift, so Leonard relies upon burly keyed Cam Effects or Jesel roller lifters with 0.950-inch wheels in a 1.095-inch body that could practically double as small casters.
Coming in just a bit under...
Coming in just a bit under 6 inches, the 5.875-inch stroke of the Godfather’s billet steel crank (left) is comically larger than a common 4.25-inch-stroke 454 unit (right).
The valves will never see...
The valves will never see all that lift if the pushrods buckle under pressure, so rather than ⅜-inch pushrods, the Godfather uses ⅝-inch pushrods—11.300 inch on the intake, and 12.735 inch on the exhaust.
Every part of the Godfather’s...
Every part of the Godfather’s crank (right) grew except the bearing surfaces; it still uses big-block Chevy main and rod bearings.
Most 540ci big-block strokers...
Most 540ci big-block strokers use a 6.385-inch rod (bottom). To create 1,005 cubes, the Godfather requires rods in the 8-inch range. The GRP aluminum rod shown here is only for full-race versions; the aforementioned street versions will get billet steel rods.
Pondering how much work it...
Pondering how much work it would take to get one in a muscle car? If you’re up to the challenge, Leonard’s got you covered. Godfather number two was actually built as a slightly less radical pump-gas version intended to go in a street car down in Australia. That one “only” makes 1,650 hp at 7,000 rpm, and 1,400 lb-ft at 5,700. Why? “For the bragging rights,” was the response.
Redefining the concept of...
Redefining the concept of “big bore,” the Godfather’s piston measures 5.220 inches in diameter. For comparison, the bore on a standard 454 big-blocks measures 4.251 inches.
The fabricated sheetmetal...
The fabricated sheetmetal intake mounts four 2.750-inch (id) two-barrel Accufab throttle-bodies that flow 924 cfm each for a total of 7,392 cfm from all eight. Eight 65-lb/hr main injectors and eight 35-lb/hr supplemental injectors are used to fuel the Godfather. The supplemental injectors only come on under WOT.
By The Numbers
1,005ci Big-Block Chevy
| Block: |
Sonny’s Automotive Racing (SAR) billet with 2-inch raised cam |
| Crank: |
Sonny Bryant billet crankshaft |
| Rods: |
GRP billet aluminum |
| Pistons: |
SAR custom pistons |
| Balancer: |
ATI Super Damper |
| Timing set: |
Jesel beltdrive |
| Oil pan: |
custom Dailey Engineering |
| Oil pump: |
custom Dailey Engineering 7-stage
lightweight dry-sump system |
| Cylinder heads: |
Sonny Leonard CNC-ported Special Edition hemispherical heads |
| Rocker arms: |
SAR/T&D/Jesel shaft-mounted rocker system |
| Intake: |
SAR sheetmetal Pro Stock intake with SAR/Accufab throttle bodies |
| Engine management: |
BigStuff3 EFI |
| Ignition: |
MSD Performance |
| Cam: |
custom 70mm camshaft with 121 LSA, 1.300-/1.315-inch valve lift and 290/319 degrees duration at .050 |
| Lifters: |
keyed Cam Effects roller lifters with 0.950-inch wheels in a 1.095-inch body |
| Pushrods: |
⅝-inch diameter; 11.300-inch intake, 12.735-inch exhaust |
| Distributor: |
custom MSD beltdrive |
| Plug wires: |
MSD Performance |
| Valve covers: |
Sonny’s billet valve covers |