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April 3, 1997

Dyno Testing Headers for the 32V Cobra

The introduction of the new 32V Cobra engine was at first met with much skepticism by the majority of the aftermarket and Mustang enthusiasts. People feared that the engine was largely un-modifiable and that OBD II made things even worse. Well, now that we've been working on these engines for awhile all our fears have been laid to rest. It is truly a powerful engine that responds well to modifications and as more parts become available it will only get better.

Enter the new long tube stainless steel headers from Watson Engineering. Watson has long been known for their quality exhaust systems and are one of the major vendors that Ford Motorsport uses to design and build their performance headers. Our plan was to install these new headers along with the matching h-pipe on a `97 Cobra that we installed a Vortech Supercharger on a month earlier, and dyno the car before and after the header installation. For information on the Vortech install, check out the Water Box Archives.

We made our way to Paul's High Performance in Jackson, Michigan to strap the Cobra to his DynoJet Chassis dyno for some baseline numbers. We made several pulls all with very close results. There really isn't much tuning you can do with these engines, Ford's origional calibration in conjunction with Vortech's FMU raising fuel pressure under boost is pretty much on the money. We experimented with several different timing profiles (you get a chip with the Vortech to pull timing out), anymore timing or less octane (Sunoco 94 with octane boost) and it knocked, and the air/fuel ratio was slightly rich but not worth tampering with. With race fuel we could have gotten a little more aggressive and nervously added timing and found some power, but the results wouldn't have warranted running race fuel on a full time basis, it's a very optimized package. Then it was back to the shop for the header install.

The headers are extremely high quality, look aggressive and feature an 1 5/8" slip tube race header design, all the tubes are individual and slip into the collector. At first we weren't too happy with this feature on a street car (it's common to have exhaust leaks) but we quickly realized that it was the only way to get the headers to fit properly, Ford didn't leave us too much room. And testament to Watson quality, there were no exhaust leaks. The 2.5" h-pipe that comes with the headers eliminates the primary catalytic converters, so it's intended for off-road use only. Hopefully Watson will offer an h-pipe with high flow converters for emissions legality. Both the headers and h-pipe are stainless steel and feature all mandrel bends, they truly are nice pieces.

The installation went smoothly and the fit was excellent. Having finished the installation a little early, we still had a day before our scheduled trip back to the dyno, so we decided to do the next best thing, take it for a drive. Much to our dismay, the car didn't feel like it picked up that much, Watson claimed 25 hp on a naturally aspirated engine so we were hoping for even more. The car felt a little better in the mid-range, but not what we expected. Let this be a good lesson that "Seat of the Pants" is a pretty unscientific measurement, even for people who drive 3 or 4 different Mustangs before and after modifications everyday. The dyno showed a different story, the engine started gaining horsepower and torque at 2100 rpm and kept gaining it all the way to 7000 rpm where the factory rev-limiter kicks in and we had to lift. Horsepower kept climbing, with no drop off, as soon as we burn a custom chip to eliminate the rev-limiter we expect to see even more power all the way to 7500 rpm.

The air/fuel ratio after the header install still appeared to be slightly on the rich side but not excessively. Any leaner and detonation would have been a definite problem. This package turned out extremely well and with pump gas there really wasn't any room to experiment with timing or fuel. The Vortech makes almost 10 psi and the Cobra's owner experienced spark knock when he used a fuel with one less octane (92 vs. 93). We used Sunoco 94 octane with Super 104 octane boost as added insurance against detonation.

We set out to see if Watson's headers and h-pipe were worth the money for the 32V Cobra, at $850 for the system they're a little pricey. But they're extremely high quality pieces, actually not a bad deal for stainless, and did what they were supposed to, make more power. When all was said and done we gained 46.6 ft lbs of peak torque and 48.8 peak hp, both at 5500 rpm. But the real story was in the curves, both horsepower and torque were significantly improved from 3000 rpm on up. The bottom line is "Would we recommend them to other Cobra owners?", Hell Yes.

The accompanying charts and graphs tell the rest of the story and show the specific curves and gains.