2011 Ford Mustang GT BBK Headers Install - Nature Hunt
With that said, bolting on the BBK short-tubes showed they gave a substantial gain in torque below the torque peak, but at the midrange they lay down flat, before picking up 2 hp again around the horsepower peak. The dip is likely the engine management curtailing torque, but the short-tubes did worse than the long-tubes in the midrange, so there is something in the tube length as well.
A bigger, more established change came by adding BBK's X-shape crossover pipe to the end of the short-tube headers. This gave a gentle but definite lift up across the tach, but especially north of 3,500 rpm. The power peak reached 368 hp and 351 lb-ft of torque and in general the combination of short tubes, X-pipe seem to be worth 5 hp and 3 lb-ft over just the short-tubes in our test.
Header installation is essentially...
Header installation is essentially the same for either the short- or long-tubes. Disconnect the battery to avoid arcing your tools on the starter motor, remove as many nuts from the upper row of header studs as you can from the top of the engine compartment, along with the nuts securing the engine mount brackets to the engine mount cushions as shown. Long extensions, a universal joint wrapped in tape, and a socket are the hot setup.
Next, move under the car,...
Next, move under the car, remove the cross-car brace just aft of the engine, disconnect the oxygen sensors, and remove the catalytic converters. On the '11 GT, the H-pipe section is in three pieces: a right converter, a left converter, and the H-section behind them. This breaks the work into easily managed chunks, and with the great Ford hardware, there are no hassles with cheap, rusted connections.
Ford now places a plastic...
Ford now places a plastic grille over the steering rack; you need to open it (not remove it) by unthreading a couple of bolts. With the grille hanging down, you'll have just enough access to the front header flange hardware. The Electric Power Assist Steering sure bulks up the steering rack.
The final test in conjunction with the short-tube headers was BBK's prototype cold-air intake. This was definitely a happy rpm addition, building power starting at 3,500 rpm, but with authority from 5,000 rpm to the power peak, where it added a solid 7 hp to the party. And, as you'd expect, it gave a big throaty roar in the process.
All told, the combination of short-tube headers, catalytic X-shape crossover, and cold-air inlet was worth just shy of 12 hp and about 8 lb-ft of torque at the peak compared to the stock baseline. Remember, too, that this is measured with the transmission in Fourth gear; the same tests in Fifth gear would add a horsepower or two, and an easy 10 lb-ft of torque.
Remove and install the headers...
Remove and install the headers one side at a time by removing the engine mount and jacking up the engine. Here you can see Mike Briggs has installed a muffler stand under the center of the bellhousing to act as a jack. Here he's busy removing the four engine-mount-bracket-to-engine-block bolts.
Once all the engine-mount-bracket...
Once all the engine-mount-bracket hardware is out, the bracket is removed from the car. Then Mike raised the muffler stand, which both raised and slightly rocked the engine because the engine mount on the driver side was still attached. This gains the maximum amount of working room, which is required to both slip the BBK headers into position and give yourself working room to install the header flange hardware. With all this engine mount and flange hardware, you'll find 1/4-inch-drive tools are a real help; you'll use 13 and 15mm sockets on the flange and mount hardware.
With the engine-mount bracket...
With the engine-mount bracket removed and the engine raised as much as possible, the stock headers are easily removed. Because Mike had been putting headers in and out of the car for a couple of weeks during prototyping, he made it look easy. Compared to some old-school header installs, it is. The hardware is superb and assuming a hoist, access is good. As always, doing this with a floor jack and creeper would be a challenge.
* These are dyno results from tests conducted on BBK's in-house Dynojet chassis dyno. All tests with short-tube headers were run in Fourth gear; those with long-tube headers were run in Fifth gear. Therefore, figures from the two test series should not be directly compared.