Yes, the new Edelbrock Performer RPM heads are good. On our 2006 5.7L-based test engine, we picked up 49 hp and 28 lb-ft of torque by simply bolting them on. The heads are available with three different combustion chamber sizes including 67cc, 73cc, and 83cc. The difference in chamber volume allows users to tailor the heads to the desired combination of displacement, compression, and piston design. The Edelbrock heads also offered several other desirable features, including 202cc intake ports, 75cc exhaust ports, and a 2.165/1.650 valve package. The assembled heads also included a valve-spring package that offered 130 pounds of seat pressure, 285 pounds of open pressure (at 0.500 lift), and allow cams with up to 0.690 lift. We liked the fact that the heads also accepted much of the factory hardware, including head gaskets, valve covers, and rocker assemblies. The Edelbrock heads did feature 6.4L intake ports but were compatible with 5.7L Eagle, 6.1L, and 6.2L Hellcat manifolds.
For our 5.7L 392 test motor, we chose the 73cc chamber heads that, combined with the dished Wiseco pistons, produced a static compression ratio of just under 10.0:1 with the Edelbrock heads, or 9.0:1 with the stock, 85cc early Hemi heads. According to Edelbrock, not only would these RPM heads improve the static compression ratio on our test mule, but they also flowed better than any of the production heads, including the Eagle and Apache variants. It goes without saying that the Edelbrock heads handily outflowed our early Hemi heads (by as much as 87 cfm at 0.700 lift, if anyone is keeping score).
The intake of choice for our stroker was the carbureted, single-plane, Drag Pak manifold. More than just the intake, the whole motor was better suited to take advantage of the Edelbrock heads. The test motor started out life as a 5.7L but had been previously upgraded with a stroker kit that included a 4.080-inch-stroke crank from K1, a matching set of rods, and Wiseco forged, dished pistons. The extra stroke combined with the 3.93-inch bore to produce a finished displacement of 392 cubic inches, matching the displacement of the factory 6.4L.
As good as they were, the stock (early) 5.7L Hemi heads were not designed for this displacement, but that didn’t stop us from running them to get a baseline. Equipped with the stock 5.7L heads, Hooker 1-7/8-inch, long-tube headers, and a Holley 850 Ultra HP carb, the carbureted 392 stroker produced 469 hp and 441 lb-ft of torque. Naturally, we dialed in the carb and added timing with the MSD controller until it stopped making any more power.
After installation of the Edelbrock Performer RPM Hemi heads, the peak numbers jumped to an impressive 508 hp and 469 lb-ft of torque. The Edelbrock heads were worth 49 hp and 28 lb-ft of torque, with gains increasing past the power peak. Best of all, the head swap improved the power output through the entire rev range. If you combine the impressive power gains with the fact that you don’t have to worry about valve seats falling out, isn’t it time you gave your Hemi a new pair of heads?
500HP 5.7/6.4L Hemi Build: What Parts Do I Need?
- 2006 5.7L Hemi long block
- 32-tooth reluctor wheel, Wiseco/K1, TR-32
- 727/5.7L starter NP 280-0331
- Balancer bolt, ARP,147-2501
- Belt tensioner, Gates,38323
- Camshaft, Crane Cams,1989521
- Cam bearings, JMS, PD31B
- Chevrolet rod bearings, Wiseco/K1, CB-745HN
- Denso alternator, eBay,13796N
- EGR block-off, Mopar,53032739AA
- EGR plug, Mopar,4891312AA
- Engine gasket set, Fel Pro, CS262841
- Fuel Rails, Aeromotive,14146
- Head Gaskets, Fel Pro, HS6284PT1
- Head stud kit, ARP,244-4300
- LSX 92mm adapter, Comp Cams, 112001
- Main bearings, Wiseco/K1, MS-2220H
- Main stud kit, ARP, 244-5400
- MDS plugs, Mopar, 53032221AA
- Non MDS lifters (4), Elgin/JMS, HL7013K
- Oil anilido, 31002
- Oil pan gasket, Milodon, 40750
- Oil pan bolts, Milodon, 85025
- Oil pump, Melling/eBay, M342
- Oil pan pickup, Milodon, 18334
- Rotating assembly, Wiseco/K1, R-KD20246
- Street strip tray, Milodon, 32010
- Thrust washers, MS
- Valve springs, Crane Cams, 99831-16
- Water pump, JMS, CP7170
- OIL Filter, RAM, PH16
- Filter Nipple TRD-1034
Edelbrock Hemi Heads: How Much Power Do They Make?
- 2006 5.7/6.4L Hemi Stroker: 469 hp and 441 lb-ft of torque
- 2006 5.7/6.4L Hemi stroker with Edelbrock 73cc Hemi heads: 508 hp and 469 lb-ft of torque
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