Can a head swap really be...
Can a head swap really be worth 100 hp or more?
When we last checked, there were about 37 million 5.0L head combinations offered through the various manufactures, which begs the question, does the market really need any more Windsor heads? The answer is an unequivocal "yes."
Having been with the 5.0L program since the days when the only option was a set of ported stock or 351W heads, there is no such thing as too many aftermarket heads. Each combination, no matter how small the differences, can respond to a different cylinder head configuration. Given the great many different combinations, it's a wonder we don't have even more too choose from.
Our test motor consisted of...
Our test motor consisted of a 347 stroker short-block, machined by L&R Automotive and assembled by Demon Engines.
With this in mind, Brodix now offers its part number KC LH17 195 heads, and as always, we had to get our hands on a set. Would the 17-degree valve angle improve flow and power?
The stock E7TE iron heads will support just over 300 hp, despite the lackluster flow numbers that top out at 155 cfm on the intake and 112 cfm on the exhaust. These compare to 300 cfm on the intake and 214 cfm on the exhaust for the Brodix KC LH 17 195 heads (which we will refer to as "195 heads" from this point forward).
The reciprocating assembly...
The reciprocating assembly includes a forged-steel 3.40-inch stroker crank and 4340 forged 5.40-inch connecting rods from RPM.
Understanding that a stock 5.0L wasn't going to be sufficient, we decided on a popular stroker version, supplied by L&R Automotive and Demon Engines. The 347 featured a 3.4-inch steel crank and matching 5.4-inch forged-steel rods from the stroker folks at RPM. Probe Racing supplied the flat-top pistons and Demon Engines put it all together.
In fact, the weakest link in the whole combination was the production 5.0L block, but it was more than sufficient for our testing needs. The 347 now required a host of additional components for our cylinder-head shootout. Starting from the bottom, we first installed an XFI stroker cam from Comp Cams. The XFI cam offered 0.579 lift, a 236/248 duration split (at 0.050), and a 114-degreee lobe separation angle. The XFI cam was installed with a set of Comp hydraulic-roller lifters and double-roller timing chain.
Probe Racing supplied the...
Probe Racing supplied the forged flat-top pistons. Note the dual valve reliefs, for use with both inline and Twisted Wedge heads.
After installation of the cam, a new front cover, and an HV oil pump from ProComp, the bottom end was buttoned up using a factory 5.0L oil pan and pick up. ProComp also supplied a set of fabricated valve covers, a dual-plane intake, and a billet distributor with matching plug wires. We also took ProComp up on its offer to run a single-plane (FunnelWeb) intake as well. Rounding out the components was a set of Hooker Super Comp headers, a Holley 750 HP carburetor, and a Meziere electric water pump. The distributor was configured to provide 36 degrees of total timing, while the HP-series Holley was equipped with Percy's external Adjust-a-Jet system (making dialing in the air/fuel curve a snap).
Our stock iron heads were already modified to accept the high-lift values supplied by our XFI cam. No changes were made to the flow rate of the stock heads, we simply machined the spring pads to accept proper valvesprings; then drilled and tapped the heads for use with rocker studs and self guided rockers. Given the short installed height and wimpy stock valvesprings, it would be near impossible to run the XFI cam with the stock heads without these modifications. Our modified stock heads represented a known quantity to properly compare the Brodix 195 heads. To ensure proper sealing, both the stock E7TE and Brodix heads were installed using Fel Pro 1011-2 head gaskets and ARP head studs. Run with the stock heads, the stroker produced peak numbers of 351 hp at 5,300 rpm and 395 lb-ft of torque at 4,100 rpm. Though the stock heads limited peak power numbers, torque production exceeded 375 lb-ft from 3,500 rpm to 4,700 rpm.
 The 347 crank supplied by...  The 347 crank supplied by RPM is internally balanced, so we secured a neutral-balance damper from ProComp. The damper was essentially adjustable, thanks to a removable balance weight (28 ounce or neutral). Unbolting the balance weight resulted in a neutral-balanced damper for our internally balanced 347. |  Our 347 stroker received an...  Our 347 stroker received an XFI stroker cam from Comp Cams. The XFI236HR-14 cam featured 0.579 lift, a 236/248 duration split, and a 114-degree lobe-separation angle. Comp Cams also supplied the matching hydraulic-roller lifters to work with the XFI cam profile. |  Both the factory and Brodix...  Both the factory and Brodix heads were secured using ARP head studs and Fel Pro 1011-2 head gaskets. |
 The stock 5.0L heads were...  The stock 5.0L heads were modified to accept screw-in studs. The modifications allow us to run a set of self-guided roller rockers on the stock heads. Both the stock and Brodix heads were tested with a ProComp dual-plane, high-rise intake manifold. The dual-plane, air-gap-style intake is an ideal (and affordable) choice for most performance street motors. |  Feeding the 347 is a Holley...  Feeding the 347 is a Holley 750 HP-series carburetor. The Percy's Adjust-a-Jet system allowed quick adjustments to dial in the fuel curve without removing the float bowls for jet changes. |  Originally we installed ProComp...  Originally we installed ProComp billet distributor and matching plug wires on the 347. The ProComp distributor was run with an MSD ignition amplifier. To speed up testing, we later swapped to an MSD distributor with the timing curved locked. |