Fourth Vs Fifth Gear

There's a "gotcha" lurking in the new 5.0 Mustang's six-speed manual transmission. Unlike every previous manual, the new Ford gearbox uses a 1:1 ratio in Fifth gear, not the industry standard Fourth gear.

This is of no concern when driving, but it definitely skews chassis dynos, which assume a 1:1 transmission ratio. In other words, if you dyno a '11 Mustang in Fourth gear—all too easy for a dyno operator to do as he's always done it that way— and you'll get numbers lower than expected.

As you've already guessed, we fell into this trap during this article, and curious as to the effects, we base-lined the car in both Fourth and Fifth gears. We found horsepower was little affected, but torque was notice ably off. In our case, peak horsepower was 1.58hp less in Fourth gear (absolutely within the margin of error on this car/dyno combination, so statistically insignificant), and 11.62 Ib-ft of torque less in Fourth gear.

To save a whole day in the shop re-running tests, we've opted to present the short-tube header part of this test in Fourth gear and the long-tube header examination using Fifth. This

A Without having to worry about covering up the spark plugs, BBK's short-tube headers (PN 1632 chrome, $349.99; PN 16320 polished ceramic, $449.99; PN16325 stainless, $499.99) are free to roam along side the Coyote V-8. Like all the exhaust parts tested for this article, these near-production prototypes wear a polished ceramic coating. We expect to BBK to offer these headers chromed as well.

▲ Ford's Coyote headers are beautifully designed, well-built stainless-steel units. Craftily designed as short-tube Tri-Y designs, the Ford headers follow a different power philosophy than BBK's shortened four-into-one design. There's no way Ford could use the four-into-one layout—if for no other reason, access to the flange hardware would be impossible with bulky production-line tools.

▲ All BBK header flanges are stout, %-inch mild steel, plasma cut from sheet. The end bolt hole is slotted on this short-tube unit; it's one of several slotted holes found on all of the headers to aid installation. These beefy flanges should have no trouble lasting the life of the car.

▲ Ford's Coyote headers are beautifully designed, well-built stainless-steel units. Craftily designed as short-tube Tri-Y designs, the Ford headers follow a different power philosophy than BBK's shortened four-into-one design. There's no way Ford could use the four-into-one layout—if for no other reason, access to the flange hardware would be impossible with bulky production-line tools.

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