Stock vs. JPC/RGR CNC Heads
|Stock Heads||JPC Heads|
|Stock Heads||JPC heads|
12 The crank sprockets (from...
12 The crank sprockets (from and rear) also featured a timing mark, which was used to line up the cam and crank sprockets. Just visible on the right was one of the off-color links on the chain that line up with the respective marks on the sprockets during assembly.
13 After sprocket and chain...
13 After sprocket and chain removal, it was necessary to swap over the tensioner assemblies from the stock heads to the JPC/RGR heads. A small clip located at the bottom is all that secured the plunger assembly.
14 We marked the cams to...
14 We marked the cams to ensure proper installation on the new heads, but the sprockets will not go on if the intake and exhaust cams are in the wrong position.
15 After removing the factory...
15 After removing the factory head bolts, off came the stock heads.
16 The stock head bolts were...
16 The stock head bolts were replaced with a set of ARP head studs. These will be beneficial when we retest the engine under boost. The stock head gaskets were reused.
17 On went the CNC-ported...
17 On went the CNC-ported heads from JPC. Not shown are the cam and ECT sensors swapped over from the stock heads.
18 With the heads torqued...
18 With the heads torqued in place, we installed the Comp cams taking care to position them properly for installation of the cam sprockets.
19 On hand to ensure adequate...
19 On hand to ensure adequate fuel delivery was an Aeromotive A1000 fuel system.
20 Once everything on the...
20 Once everything on the Coyote was buttoned up, Ken Christley from Kenne Bell dialed in the tune using SCT software. Equipped with the new heads from JPC, the Killer Coyote produced 545 hp at 6,600 rpm and an amazing 475 lb-ft of torque at 5,300 rpm.
21 In anticipation of the...
21 In anticipation of the head swap, we ran the engine with the stock heads and Boss intake. This way we could gauge the power gains offered with the stock and Boss intakes. As it turned out, the gains were almost identical for both manifolds.
22 Both intakes were tested...
22 Both intakes were tested with stock and Ford Racing throttle bodies.
23 Run with the Boss intake,...
23 Run with the Boss intake, the peak power jumped to 571 hp at 7,400 rpm, but torque dropped to 449 lb-ft at 5,300 rpm. The Boss was definitely better suited to high-rpm power, as the stock intake offered more power from 3,000 rpm to 6,500 rpm. For the next 1,000 rpm (and beyond), the Boss is the way to go.