Jon Kaase has announced his latest Boss Nine design, energized by an interesting new intake manifold with a hidden plenum below and stack injection above.
Four-time winner of the Engine Masters Challenge, Kaase has succeeded in investing this new stack injected Boss Nine engine with exceptional torque and tractability— qualities not usually associated with stack injection. But the hidden plenum on the underside of the Boss Nine intake manifold equalizes the pressures in all induction tracts and provides the engine with a clean, consistent idle, excellent part-throttle performance, and instantaneous throttle response. The plenum also provides for brake vacuum and empowers the MAP sensor, which has a major influence in the metering of the fuel.
Compared with a carbureted Boss Nine equivalent, the new stack injection system gives a surprisingly good account of itself. On a typical 520cu in engine with 9.8:1 compression ratio, hydraulic tappets, and running on pump fuel, the stack injection engine outpaced its carbureted rival by an extra 30ft lb torque.
Although 520cu in has been the most popular engine displacement, Boss Nines are available from 429 to 600cu in. So far the most desirable engines in Kaase’s Boss Nine series have been those producing between 500 and 1,000 horsepower. Constructed with either a cast iron or a cast aluminum engine block and topped with Kaase’s efficient hemi cylinder heads, Boss Nine engines were developed using four intake manifolds. These accept 4150 and 4500-style carburetors, as well as Keith Wilson’s EFI system, and various BDS blower units.
Pricing starts at $19,900 for a Dyno Tested ready to bolt in Kaase Boss Engine.