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VQ35HR

The VQ35HR update was first seen in the US in the 2007 G35 Sedan models, which debuted in August 2006. Nissan updated the VQ line with the addition of the 3.5 L VQ35HR (for "High Revolution" or "High Response"). It produces 315 PS (232 kW; 311 hp) (US market: 306HP due to new US federal measurement regulations) at 6,800 rpm and 37 kg·m (363 N·m; 268 ft·lbf) at 4,800 rpm, using a compression ratio of 10.6:1. As of 2009, the Infiniti EX35 produces 297 hp and the same torque presumably due to tighter regulations. It has NDIS (Nissan Direct Ignition System) and CVTC with hydraulic actuation on the intake cam and electromagnetic on the exhaust cam. Redline is 7,500 rpm. Reportedly over 80% of the internal components were redesigned or strengthened to handle an increased RPM range sporting a lofty 7,500 rpm redline. A new dual-path intake (two air cleaners, throttle bodies, etc.) lowers intake tract restriction by 18 percent and new equal-length exhaust manifolds lead into mufflers that are 25 percent more free-flowing for all around better airflow. The new intake is said to benefit from a ram-air effect adding three horsepower at 60 mph (not accounted for by SAE testing methods). The electrically actuated variable valve timing on the exhaust cams to broaden the torque curve is new over the "DE" engine. The new engine block retains the same bore and stroke, but the connecting rods were lengthened and the block deck was raised by 8.4 mm to reduce piston side-loads. This modification, along with the use of larger crank bearings with main bearing caps reinforced by a rigid ladder-type main cap girdle to allow the engine reliably rev to 7500 rpm. With an increase in compression ratio from 10.3:1 to 10.6:1 these changes add 6 more horsepower (306 total + 3 hp ram air effect not measured by SAE testing = 309 hp). Peak torque is up 8 pound-feet from the old "DE" engine (260 vs. 268) and the torque curve is higher and flatter across most of the rpm range, and especially in the lower rpm range.
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