Making a 20 litre-1200ci V-12 completely from scratch seems beyond most all of our reach, so here’s a couple of hot rodders in San Diego that have done just that. Land speed racer, Pete Aardema, and offshore boat racer, Kevin Braun, have created a number of scratch-built engines, overhead cam conversions, and crazy combos of homemade and aftermarket components. But our dynamic duo didn’t just jump into making engines, but rather eased into it when Aardema’s interest was piqued after seeing some rather exotic Pontiac Iron Duke 4-banger “Super Duty” Cosworth heads. These were aftermarket 16-valve, double overhead cam (DOHC) aluminum heads. He and Braun reconfigured them for small-block Chevy applications, and Aardema Developments (AD) was born.
Their next step was creating cam boxes to mount on stock Chevy heads, creating a SOHC Chevy small-block. Belt-driven, there have been over 50 sets produced so far. The original cam is still kept to spin the oil pump and distributor. These also have been adapted to Mopar and Ford engines.
Soon AD was adapting Porsche 928 V8 single overhead cam (SOHC) heads onto Chevy big-block engines. This morphed into AD producing their own SOHC 4-valves-per-cylinder billet heads for various mutant small-block American engines, using bucket-type lifters from Volvo engines, and adapted Nissan belt-drive. The conversion was so adaptable that V2 versions were even made for Harleys.
From here things got weird. AD adapted Subaru flat-4 heads to ancient 1928-31 Ford Model A L-head blocks, netting 300hp naturally aspirated from an engine originally producing 40hp from 103ci. Aardema says, “If there’s an engine out there, and it’s an oddball, I want to mess with it.” If you’re impressed with the almost 8-times increase in horsepower, Aardema was not. An even more powerful twin-overhead cam head with 3-valves-per-cylinder was developed netting a 201ci displacement. Aardema says that 4-valves-per-cylinder was too much to cram into the smallish heads, and that a large exhaust valve does most of the work two smaller valves would provide. With turbo-supercharger induction and on racing fuel, the bad banger made over 500hp, launching a streamliner at Bonneville to a record 240mph in 2012. Yikes!
While designing and developing engines, Aardema has also built a number of hot rods with his exotic creations—he’s going ten different directions at any one time. When we asked him where the inspiration comes from, he says, “I like to build things and like to go fast, and if someone says I can’t do something, that’s when I will do it, so I’m off on another project.”
Next up was AD’s first completely scratch-built engine, one to replace the 500hp Model A engine in the streamliner. With 3-valves per cylinder, Chevy big-block bore spacing and reciprocating components, 4.375-inch bore and 3.00-inch stroke, they christened it the Sheet Metal Engine for it’s use of heavy sheet metal to encase the billet lower crankcase and steel tubes used for cylinders in the upper. HOT ROD did a story about it in 2014 . The dry- sump oil pump and twin-overhead camshafts were again belt driven. A crankcase girdle supports the block, while also incorporating one side of the five main-bearing journals. Port fuel injection with a little “100-shot” of nitrous helping the combustion, the banger is capable of 380hp spinning at 8500rpm. Numerous records at Bonneville in 2016 were set in F-Gas and F-Fuel classes.
All of these earlier developments and successes laid the groundwork for the V12. With Braun’s background in H1 Unlimited Hydroplane racing, where speeds exceed 160mph, the V12 was envisioned as a challenge to the Rolls Royce 27-liter V12 and 28-liter Allison V12. Since this is “unlimited” hydroplane racing, there are no limits to displacement or arrangement, thus Aardema and Braun had a really blank, blank sheet. Where do you start?
Interestingly, where to start came down to how long your crankshaft maker can make your crankshaft. Scat Crankshafts just down the street from HOT ROD, in Redondo Beach, was the crank manufacturer of choice, and their maximum length was 42-inches. That penciled out to be a 6.25-inch bore spacing and a 5.625-inch bore. With an estimated 7000rpm ceiling, a 4.00 stroke was deemed optimal. Why? Because the weight of 5-1/2-inch pistons is such that flinging them beyond 70-percent of the bore becomes too much inertia according to Aardema. A longer stroke could conceivably tear apart the engine.
All of this comes out to a displacement of 1192.8ci, or 19.55 liters. Though much less displacement than the popular Rolls Royce and Allison engines, their maximum rpm is around 3000rpm with a few blips hitting 4000rpm. Horsepower is much easier to produce at higher RPMs, so the AD 60-degree V12 with its higher rpm capabilities produces much more power at lower boost, provided by twin centrifugal superchargers. Scat manufactured a nitrided steel crankshaft with seven 3.0-inch diameter journals for Oldsmobile V8 main bearings. Connecting rod journals use bearings from a Chevy big-block.
Cam design was an initial problem. Says Aardema, “A V-type engine with rockers operating the titanium valves and cams rotating in the opposite directions is unfamiliar territory for cam grinders.” Eventually Schneider produced the gun-drilled hollow cam from 8620 alloy steel, actuated with convex faces acting in the same way as roller lifters in terms of valve lift profile, increasing valve-opening velocity over a conventional flat-tappet contact surface. Filing a lash cap to the desired clearance sets valve lash, much like Indy-type Offenhauser engines from the 1950s. Seven journals hold the cams, housed in a billet aluminum head with a top plate containing the valve train. An aluminum cam cover seals off the valve gear. Deck height is an even 12-inches.
Around the rear of the V12 are two crankshaft-driven Vortech superchargers, with planetary gearing that increases their rpm capabilities from conventional belt-driven configurations. One blower feeds into an intake plenum at the left while the second blower does the same at the right. Edelbrock throttle bodies are attached to each blower, with two 4.0-inch throttle bores opening together, while the cylinder heads flow 724cfm intake and 487cfm exhaust at 0.75-inch lift.
EFI West helped piece together an Adaptronics ECU to handle the engine management system. Detonation is controlled through the ECU’s vibration-type knock sensor located on each bank, retarding ignition if a knock is detected. Two 60-lb injectors per cylinder are fed constant fuel pressure by a Waterman mechanical fuel pump.
Essentially the makeup of the AD V12 is of two straight-six engines running together in both primary and secondary balance at 60-degree even-fire intervals. Total length of this monster is 59.5-inches, 35-inches high, and 30-inches wide.