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 a 347 stroker short-block, machined by L&R Automotive and asse
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 includes a forged-steel 3.40-inch stroker crank and 4340 forged
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 forged flat-top pistons. Note the dual valve reliefs, for use wi
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 RPM is internally balanced, so we secured a neutral-balance damp
Our 347 stroker received an XFI stroker cam from Comp Cams. The XFI236HR-14 cam featured 0
Both the factory and Brodix heads were secured using ARP head studs and Fel Pro 1011-2 hea
The stock 5.0L heads were modified to accept screw-in studs. The modifications allow us to
Feeding the 347 is a Holley 750 HP-series carburetor. The Percy's Adjust-a-Jet system allo
Originally we installed ProComp billet distributor and matching plug wires on the 347. The
Naturally we ran long-tube headers on our 347. These Hooker Super Comp 13/4-inch headers w
Once we had the baseline numbers, it was time for the head swap. Off came the stockers and on went the aluminum Brodix 195 castings. From a weight standpoint, aluminum heads have it all over their iron counterparts. That the Brodix heads also offered 195cc intake ports that flowed 300 cfm at 0.700-inch lift was icing on the cake. The Brodix heads also feature CNC-porting, the aforementioned 17-degree valve angle, and ductile iron seats for use with unleaded fuel.
Like the stockers, the Brodix heads were drilled for accessories holes so they can be run with A/C and power steering. The CNC-ported Brodix heads also feature 60cc combustion chambers, a 2.02/1.60 stainless steel valve package, and competition valve job. In short, the Brodix heads were everything the stock heads weren't. The only change required for the swap was replacing the stock 6.25-inch pushrods with a slightly longer 6.50-inch set from Comp Cams. We also replaced the self-guided rockers with Ultra Pro Magnum rockers from Comp Cams (retaining the 1.6 ratio).
Run on the dyno with the stock E7TE heads, the 347 produced peak number of 351 hp and 395
After installation, the 347 came alive. The Brodix heads were run with the same dual-plane intake and Holley carb employed with the stock heads. No longer did the 347 struggle to produce 400 lb-ft of torque. In fact, the Brodix 195 heads transformed the 347 into a serious street/strip performer.
The power output jumped from 351 hp and 395 lb-ft of torque to 462 hp at 6,200 rpm and 435 lb-ft of torque at 4,400 rpm. The simple head swap improved peak power output by over 110 hp, but the gains were even greater higher in the rev range, where the power curve fell off dramatically with the stock heads.
Next up were the KC LH 17 195 heads from Brodix. From a weight-savings standpoint alone, t
Whereas torque production with the stock heads failed to reach 400 lb-ft, the 347 exceeded 400 from 3,500 rpm to 6,000 rpm. Don't be tempted to think the stock heads offered better low-speed power, as the Brodix heads improved the power output from as low as 3,000 rpm (our lowest test speed) to 6,800. The Brodix head swap improved the specific output of our test motor from a touch over 1 hp per cubic inch to a more street-worthy 1.33 hp per cubic inch. Add to that the significant reduction in curb weight and you have the reason why performance aluminum head upgrades are so popular on 5.0L motors.
It came as no surprise that the Brodix KC LH17 heads offered huge power gains over the wimpy factory heads, but we weren't finished with our Brodix-headed 347 test mule.
Full CNC-porting applied to the 195 heads produced impressive flow numbers. The intake por
Since we had it on the dyno, we decided to swap out the dual-plane for a single-plane design. The funnel-web intake has always proven powerful, and this design is now available from ProComp as well. The only downside is possible hood clearance, as the high-rise intake will not fit under a stock 5.0L hood. Since our motor was not hood-clearance challenged, we opted to install the FunnelWeb intake on our 347.
The intake proved to be every bit as deadly as its eight-legged namesake, as power increased to an even 500 hp at 6,600 rpm. The peak torque was up slightly, to 441 lb-ft, but at a much higher 5,300 rpm. As expected, the single-plane traded a loss in low-rpm torque for all that wonderful top-end power. The dual-plane intake offered more torque and horsepower up to 4,800 rpm, but then it was all FunnelWeb up to our self-imposed ceiling of 6,800 rpm. The extra 40 hp offered by the FunnelWeb is certainly a compelling argument for a cowl hood!
The exhaust flow was equally impressive, as the porting unearthed 214 cfm at 0.700 lift an
The Brodix heads featured 17-degree valve angles, 60cc combustion chambers, and a 2.02/1.6
Brodix offers the 195 heads with a 987 spring package (135/345) designed for hydraulic-rol
5.0L Head ShootOut
Stock vs. Brodix KC LH17 195 (347 Ford)
The true test of any perform
Single vs. Dual Plane (347 Ford)
Looking at the XFI cam specs on our 34
Installation of the Brodix heads required longer pushrods. The 6.25-inch pushrods used wit
After the head swap, the 347 stroker really came into its own. The Brodix heads improved t
After running the stock and Brodix heads with the ProComp dual-plane intake, we decided th
Run on the dyno with the funnel-web, the 347 produced an even 500 hp and equally impressiv