Ford Mustang Kenne Bell Supercharger 5.0 Coyote Vs. 5.4 Condor

We’re fond of saying there is no replacement for displacement, because, in the end, there isn’t. However, supercharging and refinement do much to overcome the advantage of large engine displacement, a fact brought to our attention by Jim Bell at Kenne Bell.

Clearly Jim is happy to tout the advantages of his popular twin-screw blowers, but we had to admit a comparison of his two most recent projects--adding a supercharger to the 5.0 Coyote engine in the Mustang GT and upgrading the Shelby GT500 to a Kenne Bell Twin Screw--illustrate how the smaller, lighter 5.0 ultimately makes more snort than the rip-roaring Shelby.

There is no new hardware involved in this story, as we recently introduced the 2.8 Kenne Bell Twin Screw blower on the new GT, and the 2.8 blower on the Shelby is well known at this point. What we haven’t mentioned, and why Kenne Bell just had an ’11 GT500 in its shop, is the current Shelby uses the same engine management system as the Coyote-powered GT. Thus, Kenne Bell was burning midnight oil getting its electronic tune on the ’11 Shelby, which is how the company got started comparing the Shelby and GT outputs.

To get right to the point, at just under the 9 pounds of boost, the stock GT500 was at 481 rwhp and the 5.0 Mustang GT with the KB blower hit 547 rwhp. This is an Eaton-to-Kenne Bell comparison, which accounts for some of the huge power differential, but it shows how eagerly the Coyote responds to boost. At 12 pounds of boost, the manual-transmission GT500 laid down 615 rwhp, while an automatic trans Mustang GT came in with 657 rwhp. At 15 pounds of boost, the same pair of cars were 654 rwhp for the Shelby and 720 rwhp for the GT. There was no higher GT boost pressure available at our deadline, but the Shelby was cranked up to 18 pounds of boost and 689 rwhp, where even with a manual transmission, 2 extra pounds of boost, and 400cc more displacement, it still came up about 30 rwhp shy of the GT. Hmmm...

Granted, the above summation is far over-simplified, if for no other reason because it compares just peak power figures, but the direction is clearthe smaller 5.0 makes more horsepower than a 5.4. Why is this? Shouldn’t Ford’s top-dog Mustang engine eclipse its smaller brother?

Now, with enough expensive parts, it’s possible to rev a 5.4 with Formula 1-like piston speed--witness the ’00 Mustang Cobra R. It redlines at 6,500 rpm with a fuel shut-off at 6,800 rpm, and if that doesn’t do it, the ignition cuts off at 7,000 rpm. Of course, this most exciting of Mustang engines was expensive and rare--only 300 produced. The Shelby GT500 on the other hand, is less exotic and redlines at 6,250 rpm.

Indeed, when looking at the horsepower and torque graphs, the 5.0 and 5.4 typically run near each other until 6,000 rpm, and then the 5.0 keeps on climbing another 1,000 rpm or more. Right there that will put the Coyote well ahead of the 5.4 Shelby.

Another Coyote advantage is compression ratio. The GT500 puffs up 8.4:1 compression, while the Coyote puts the squeeze on things with 11.0:1 compression. This is significant because compression is a fundamental aspect of power production. The whole idea in a piston engine is to build cylinder pressure, and higher compression puts more oomph into the power stroke.

Another Coyote advantage is breathing. We don’t have hard data comparing GT500 and Coyote heads, but the Coyote engineers have assured us that the 5.0 heads are some of the best-flowing V-8 castings ever to roll off a Ford assembly line. Thus they are clearly ahead of the GT500 units. We do have data on camming, where the GT500 valves lift about 12 mm and the Coyote’s 13 mm, so there’s a breathing advantage in favor of the Coyote as well. We’re not sure how much it really matters at streetable or pump-gas power levels, but the Coyote sports more sophisticated exhaust manifolding than the GT500 as well.

There is one thing you might consider a 5.0 advantage that isn’t directly in play during these dyno tests. That’s the 5.0’s sophisticated Twin Independent Variable Cam Timing. It is not important here because at wide-open throttle, the cams are adjusted to their maximum power setting and don’t vary during the run. Therefore the 5.0 has no particular cam-timing advantage over the less adjustable 5.4 engine.

Inevitably the 5.4 in the GT500 will go away, as it has in every other Ford application. Luckily the 5.0 is more than a worthy replacement, even if it is almost half a liter smaller in displacement. It certainly makes the prospect of an Ecoboosted version quite titillating, but that will remain speculative for the moment. What we do know now, is that there might just be a replacement for displacement after all-technology.

On The Dyno

Selected dyno runs from Kenne Bell’s voluminous testing regime are shown here. Careful attention to reducing variables makes this data accurate, but just the same, don’t bother picking one or two horsepower nits here. The trend to better power from the 5.0 at higher rpm is clear, and that’s the important point. Of course, the blown 5.4 looks pretty good in the midrange. Keep in mind that the first GT500 test was with the stock Eaton supercharger, while all the rest were with Kenne Bell’s 2.8H blower.

There is no 18 psi of boost run for the 5.0 because the two times the test car was tuned up that far, it blew up its oil pump. Yes, the oil pump. This happened because to get past 15 pounds of boost, a larger crankshaft pulley is needed, which means changing the integral harmonic dampener. Something in the aftermarket dampener and the oil pump didn’t get along, resulting in a shattered inner oil pump gear each time the larger aftermarket damper was tried. A stronger pump gear will soon be available to cure that problem.