Here at The Horsepower Monster, we love unique engine builds--and this one definitely qualifies.
We always enjoy visiting the shops of Keith Dorton, owner of Automotive Specialists in Concord, NC, because he's always building something cool. This particular engine came about when the Hotrod Hoodlums land speed racing team out of Texas asked Keith to help them set a new record in a class requiring a gasoline engine under 260 cubic inches in their '34 Ford roadster.
Instead of trying to take a small engine and soup it up, Dorton went against the grain and destroked an SB2 that in its former life had raced in NASCAR's Sprint Cup Series with Hendrick Motorsports. When you think about it, it makes sense: NASCAR Cup engines are some of the most efficient on the planet, and if you are trying to make maximum power from limited cubic inches, a very efficient engine is what you are going to need.
Keith had to purchase a new Chevy SB2 block to get a 4.030 bore (all the used Cup stuff is too big), but he was able to use the old cylinder heads, oil pump and a very cool billet aluminum dry sump oil pan (as well as a few other odds and ends). A custom Winberg crank with a tiny 2.454-inch stroke spins in the heart of the block, and 6.350-inch Carrillo rods with custom Mahle pistons provide the compression.
The valvetrain is almost all Cup stuff, except for a solid roller cam from Crane with approximately 0.800 valve lift. Dorton preferred to keep the duration and separation numbers to himself. Xceldyne titanium valves are sourced for the 2.180 intake valves, but the forced induction produces too much heat for the exhaust valves, so inconel units from Del West were sourced for the 1.580 exhausts.
Of course, even the most efficient engine will have trouble getting to triple figures in horsepower when you just have 260 naturally aspirated cubic inches burning gasoline. So a Procharger was bolted up front producing 10 pounds of boost. Of course NASCAR never actually allowed forced induction on its race engines, so the setup--including the intercooler--had to be designed and fabricated from scratch.
Controlling the one-of-a-kind setup at first seemed like a daunting task, but in the end it turned out not to be a very difficult hurdle at all. Keith says after a little research he found that an off-the-shelf Holley Dominator EFI ECU could do everything they needed-- including individual cylinder timing, boost control, individual bank O2 monitoring--and more.
Check out some of the photos below, and make sure to watch the video at the top of the post.