Here's the major blurb on X51 from excellence. ENJOY! You did the right thing!



With the fluids properly warmed and a long onramp just ahead, it's time to put the X51 engine through its paces. In second gear and at full throttle, acceleration is strong - but then the same can be said for any Carrera S and even the 3.6-liter Carrera. The latest 3.8-liter 997s are powerful enough leave one wondering if there's much development potential left in the normally-aspirated flat six.

X51 answers that question convincingly, with a 997 Carrera S-like powerband that's as linear as it is strong. It offers good torque from just off idle all the way up to redline, but it can't match the GT3's top-end fervor. It feels slightly more "workhorse" to the high-strung GT3's thoroughbred. But, in a 911 more likely to be used every day than most GT3s will be, that's a good thing. The X51 3.8 offers tractable power everywhere, with plenty of good noises and enough zing to keep things interesting as it reaches for redline.

Does it feel faster than a plain Carrera S? Yes and no. No because it's tough to feel a seven percent power increase in a car that weighs more than 3,000 pounds and claims more than 350 horsepower. But informal roll-on tests in third and fourth gears later in the day saw the Club Coupe pull away from the 2005 997S slowly, but surely. It was exactly the difference you'd expect from a 26 hp/11 lb-ft advantage. Importantly, X51 gives up nothing across its powerband to the regular 3.8. Though its peak power and torque figures come 600 and 900 rpm later, the X51's powerband never dips below the 3.8's. Even from 1500-2000 rpm, it has a useful, 15 lb-ft advantage.

People after the best horsepower-per-dollar equation might be happier spending their $17,000 on the aftermarket, but X51 has two edges that must be considered: (1) it maintains the factory's full warranty and (2) there's a sweetness to this engine that can't be quantified. The throttle response in the X51-equipped 2006 997S was plain superior to the 2005 997S we tried. The revised motor sings through its powerband with an alacrity one wouldn't know the standard engine is missing - unless he or she tried an X51. Gear after gear, pull after pull to its 7300-rpm redline, the X51 engine is considerably more satisfying than the normal 3.8 - which itself is no slouch.