Horsepower Graph You'll notice that we attenuated the horsepower graph to include just the power curve between 4,000 and 6,200 rpm. We did this to expand the scale to show the differences in power near peak horsepower. While the TFS head looks much stronger than the Edelbrock version above 5,500 rpm, the maximum differential is only 13 hp at 5,900 rpm. While that's significant, this is only at one rpm point. It is more important to evaluate the entire length of this horsepower graph. When you do that, you can see that the TFS head did substantially better than all the other heads from about 4,400 rpm and above. You will certainly feel that in the car. We should also mention that, while we didn't test a stock iron casting, it should be clear that even the heads on the lower end of our test would still be an improvement over stock factory castings. Cylinder Head Peak HP Peak TQ TFS 380 357 (1st) Edelbrock 371 346 (tie 3rd) RHS 364 352 (2nd) Ford 362 346 (tie 3rd) World 352 342 (6th) Flo-Tek/Speedway 349 347 (5th) The Ford heads require these net lash rockers. These rockers use a fulcrum placed underneath the rocker and a 5⁄16-inch bolt to position them. This system is not adjustable, except through shims under the fulcrum and by pushrod length. The Ford heads require these net lash rockers. These rockers use a fulcrum placed undernea Testing six different Ford heads required three different spark plugs. The Windsor, Jr. World Products heads require a tapered seat spark plug with a short thread while most of the other heads were machined for the common 0.750-thread-length, gasket-style spark plugs. The Ford Racing heads use a long thread but with a tapered seat. We used Autolite plugs throughout. Testing six different Ford heads required three different spark plugs. The Windsor, Jr. Wo Dollar Per Horsepower Peak power numbers are always fun to throw around, but car crafters are also very astute at determining what all that power will cost. To minimize the grief of doing the math yourself, we averaged the horsepower between 3,000–6,000 rpm and then divided that into the cost of a pair of heads. The winner in this evaluation is almost always the least expensive head just because of the way the math formula works. This particular evaluation only works, however, if lowest cost is the highest priority. If it is, then you know what you need to do. But for perhaps a majority of enthusiasts, this evaluation may be too simplistic. If this becomes a bit more subjective by adding in power (and why wouldn't you?), then the second least expensive heads—the Edelbrock E-Street heads—really begin to stand out. If we've muddied the waters a bit, it's only the result delivering more information on the way to a decision. Average Dollar Per Horsepower Flo-Tek / Speedway $2.61 Edelbrock $3.28 TFS $3.73 Ford $3.92 World $4.21 RHS $4.59 « | 1 | 2 | 3 | 4 | 5 | » | View Full Article By Jeff Smith Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!