Kindig-It Design 2024 Ridler Award-winning 1953 Corvette is a truly gobsmacking machine, and it required an equally impressive engine to suit – even if it had to come from the other side of the world.

Although it’s referred to as a ’53 Corvette, the car dubbed Twelve Air is really only a C1 in spirit, because the whole machine was handmade from the ground up for owners Dave and Tracy Maxwell. Not a single part is GM metal or came from a shelf – it’s based on Dave Kindig’s CF1 production cars, and takes design inspiration from the 1953 GM Motorama Corvair concept car.

Twelve Air took five years to complete, and as per Ridler Award rules, it was all done in total secrecy. Even a leaked rendering can see you disqualified from Ridler contention, which explains why nobody knew it would use an Australian-made V12 LS engine until its grand debut at the Detroit Autorama.

Dave Kindig initially got in touch with Matt and Shane Corish at Race Cast Engineering to buy one of their V12 LS engine-builder packages. After some correspondence, the Corish brothers realised the scale of the Kindig project, and instead offered to build a complete engine for Twelve Air.

The Corish boys have built a huge variety of cars over the years, including a V12-powered Kia Pregio van, a V12 Statesman, Matt’s own ’65 Mustang and even a Mazda 929 wagon that took out the Aspirated Four/Rotary dyno class at Street Machine Summernats 34. At this year’s Nats they thrashed a wicked, twin-turbo, Barra-swapped XB John Goss Special, proving they’re truly like us!

Before we get down to brass tacks with Twelve Air’s engine, it’s worth discussing how two Aussies became a world-renowned car-builder’s choice for an elongated LS. As the Race Cast Engineering name implies, the Corish brothers spend their time developing and manufacturing cast products, including entire engine blocks, race parts and loads more.

“We did our first V12 LS by cutting up two wrecker-yard LS1s, and basically seeing how possible it was,” Matt Corish says. While it was fairly simple, you can’t really go selling two blocks stuck together, so using 3D-printed sand, we cast the V12 block. This process is common in rapid prototyping because it eliminates the need to create traditional patterns, jumping straight to the sand mould to ready for pouring at the foundry. The castings for this project were poured in aluminium and heat-treated, before hitting the five-axis CNC machine to create parts ready for the machine shop.”

Plenty of Aussie innovation helped to make the concept a reality. The heads are LS7-based and made by Higgins, while the camshafts are specced to each owner’s individual power goals and made by Clive Cams. Dandy Engines line-bores every V12 LS that goes out into the world, while BNR Engines balanced, built and dyno’d the engine for Twelve Air.

A Haltech Nexus R5 VCU and IGN-1A coils are used, and GR Motorsport sorted Twelve Air’s hidden wiring loom. Ron Harrop even bucked retirement to make the camshaft blank, having created several custom parts for the Corish brothers when needed.

“We believe deeply in Aussie manufacturing, and there’s a lot of innovation here,” Matt says. “While we do use off-the-shelf parts for rods, pistons and the like from the US, we use as much Aussie business and parts as we can.”

The engine for Twelve Air differs in some ways from the other V12 LSs that leave Race Cast Engineering, conforming the aesthetic requirements for a Ridler-capable car.

The image above illustrates several parts that are unique to Twelve Air’s V12. The most obvious is the intake manifold, highlighted in dark blue. “Kindig sent us a CAD of their intake design; it was incredibly difficult to make,” Matt says.  “It’s sort of organic – not just twelve identical trumpets copied and pasted, but more like a sculpture that flows with the lines of the car.”

The front cover (highlighted in yellow) is also unique, performing several functions. It covers the rack-and-pinion parts of the steering and some of the suspension for Twelve Air, while also hosting a water passage from the water pump to the radiator. It’s a requirement that all Ridler Award qualifiers drive to and from their stand in the Detroit Autorama under their own power, so Twelve Air had to function as an actual car.

The rear cover is much the same story. Twelve Air uses a C7 Corvette rear transaxle, so the cover is used to hide the starter motor. Like the intake, the front and rear covers are one-off pieces cast by the Corish brothers.

All V12 LS mills are wet-sump, using a Melling high-volume pump and oil pan made in-house at Race Cast. “It’s a 10-litre capacity below the windage tray, which is about as low as you can make it,” Matt says. “Luckily, that pump flows 1.5 times more than standard LS, which is the basic math you use for an engine like this, so it works out well.”

Dave requested a relatively mild 600hp engine (these V12s can do up to 1000hp), and this one comes in at around 650hp. “Funnily enough, with the camshaft specs, if it ran the normal sheetmetal intake we sell with a V12, it would make 750hp,” Matt explains. “We told Dave that his intake robs 100hp, but it made over the 600 number, so it didn’t matter.”

That’s also why this engine is quoted to be making 650hp at just 5400rpm. It’s all that was required for Twelve Air, but Race Cast can spec engines that’ll scream to 7500rpm for the full 1000hp.

Another request from Dave was an exotic sound. As Matt explains, it wasn’t easy to achieve. “We tried to achieve that vintage F1 sound by playing with cylinder firing angles”, he says. “We went with a 15 degree split-pin crank, resulting in the equivalent of a 75-degree bank angle. Small-block Chevy rods were used to re-centre the little end in the bore.

“The anticipation to hear it rev was intense. Brett at BNR pushed the start button on the dyno and she fired into life, but it sounded the same!” laughs Matt. “In a nutshell, we learned that bore, stroke and RPM have a lot more to do with engine sound than cylinder firing angles. I’d say it sounds like a blend between a V8 and straight six.”

The engine was boxed up and sent to Kindig-It Design in April 2022, and it was another two years until Twelve Air was unveiled at the Detroit Autorama, where it won the Ridler Award. The Corish brothers are yet to see the engine in its final home with their own peepers, but are stoked with the outcome all the same.

“With Twelve Air, Kindig-It Design has raised the bar to a previously unimaginable levels, and we can be proud that so many Aussies helped make that happen,” Matt grins.

SPECS

Twelve Air V12 LS engine