The new VQ37VHR engine, as it's called, is the first V-6 sold in the USA to use infinitely variable valve timing in place of a throttle. This system, called VVEL, is the second such system on the market -- BMW's Valvetronic was the first.
We discussed the new engine in depth in previous articles on the G37 (see related links below) so let's cut right to the chase: The new 3.7-liter is only 5.6 percent larger than the old engine, but made almost 22 percent more power on a chassis dynamometer.
We tested the 2007 G35 Coupe 6MT on the same dyno a few months back. When attached to the six-speed manual transmission, its 3.5-liter is rated at 293 hp @ 6400 rpm and 258 lb-ft @ 4800 rpm. Its power peak is very close to the 6600-rpm fuel cutoff - this is an engine that loves to rev. Looking at the dyno chart, you can see that it comes alive just over 2000 rpm and produces a fairly constant amount of torque until just over 5000 rpm. Torque (and the corresponding push in your rear) drops off only slightly, as the engine is still producing over 85% of its peak torque at redline. Impressive indeed.
The G37's engine, however, blows that performance away. It's rated 37 horsepower higher, but the G37 we tested put 51 more horses to the rear wheels. Since this was measured on a chassis dyno, we can't know for sure how much of that increase is due to higher engine output versus lower driveline losses. However, since the drivelines are similar, we'd guess nearly all of this increase is brute force from the new motor. Think about it this way: If frictional losses are a constant percentage, you'd have to add 63 horsepower to the G35's engine to make it put 51 more to its wheels. This is a big, big jump in power.
The best news is that Infiniti wasn't exaggerating about its other claims: the new 3.7-liter is stronger than the 3.5 both at low revs and high revs.
Its torque curve is flatter, too. Throttle response (if you can say that about a car without a throttle) is instantaneous, the 3.5's coarseness has been tamed, and I got an indicated 27 mpg - with the air conditioning switched on at 80 mph - on the way back from the dyno shop. So if there's any drawback to VVEL, we haven't seen it.
See the dyno charts for more information, and be sure to check out the videos to hear the G37 at full bore.
2008 Infiniti G37 Coupe - Dyno Videos - Multimedia - Automobile Magazine