Company: Jon Kaase Racing Engines
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Blown Boss Nine Engine
Popular Ford Boss 429 Engine Available in A Variety of Configurations, Including Supercharged
The Boss 429 was available as a NASCAR homologation special in 1969-70 Mustangs (and two special Cougars) and the Ford faithful have been lusting for the Blue Crescent/Shotgun engines ever since. While others dreamed, the die-hard Ford junkies at Jon Kaase Racing Engines worked, and brought the Boss 429 back to life on its 40th anniversary.
Constructed with either a cast iron or cast aluminum block it was developed using five intake manifolds. These suit 4150- 4500- and Tunnel Ram-style carburetors, Keith Wilson’s EFI conversion, and Hilborn’s stack injection. Additionally, it is available in a blown version.
Fitted with heavy-duty bearings and special double-lipped Teflon seals for prolonged life, the BDS 871 series three-lobe standard helix blower is used. In its naturally aspirated form the engine typically produces between 700 and 1000 horsepower on pump gasoline. Add to this the displacement of the BDS Roots-style supercharger (416 c.i.d.) and the 40-50 percent additional horsepower its makers claim.
Though a variety of engine capacities can be specified, from 429 to 600 cid, the company says the most popular displacement is 520 c.i.d. And so it is with the blower version. By using a 429 passenger car block with a .030˝ overbore (4.390˝) and a 4.300˝ stroke ensures that engine parts are readily available, making this a cost-effective unit to build.
Like its naturally aspirated forerunner, the 520 c.i.d. blown engine uses either a forged crankshaft or the Bryant billet creation.
The pistons, however, in the blower engine are very different to those of the naturally aspirated. With compression ratios of 8 to 8.5:1 Diamond’s low-compression pistons allow higher blower boost, producing lots of low-end and mid-range torque. Similarly, the camshaft was designed to eradicate any jerking and bucking at off-idle and part throttle in the low gears
Additional features of the engine include intricate work on the cylinder heads and timing gear, the full-race roller-tipped billet rockers by WW Engineering, the race-bred 3/8˝ thick-wall Trend pushrods, or the nostalgic Kaase Boss Nine valve covers.