Postby Doctor X » October 26th, 2004, 11:02 pm
[QUOTE/]Nissan released a new Primera/Almera recently, what's interesting is that one of the engines used in this car is a 1.8l engine, somehow similar to the GA16DE since it also use Nissan's VTC technology, which optimize the timing of the intake cam, and is the reason why the Sentra has more torque most 1.6l engines around. However, the new 1.8l use VTC on BOTH cams. Which means ever more precise tuning for even better torque.
What makes us sure this is really the engine that will power the 2000 Sentra? Well, it's now a known fact: the base engine in the US/Canada 2000 Sentra will be a 1.8l (well, it's a rumor, but a strong rumor, visit (link no longer exists) for more info). If it's the same engine used in the Japanese version, it should be called the QG18DD. Notice it's not called "GA" anymore (the GA series has been used since 89 in Sentras), which means it's a completely new engine. Nemeth Laszlo has prepared a nice webpage which show the new engine, you can visit it at (link no longer exists). There's a nice drawing of a cutout of the new engine, on the intake cam you notice the familiar VTC system, and yes it's really there on the exhaust cam too.
What's less impressing are the torque and hp ratings of the European version of this engine. A mere 114hp at 5600RPM and 116lbs*ft of torque at just 2800RPM. But like Laszlo says, the GA16 engine was quite weak in Europe at first too, even dropping to 90hp at one point (that's with the 16-valve DOHC version). There is some hope. A good guess would be that the power would be in the 125-130hp range, considering all the technology use in this engine. 125hp or more would be just perfect. If they want to go to war against the Corolla, they need just that. The Corolla has a 1.8l 125hp but doesn't have VTC. What does that means? Even with the same hp ratings, the Sentra would be easier and more fun to drive because it would have more torque down low (notice the peak torque is at 2800RPM on the European version).
Variable Timing
Systems that change only timing are far simpler then either the VTEC or VVL systems. It is generally well known that adjusting cam timing with adjustable cam sprockets can yield significant gains at certain points in the powerband, but always at the expense of power somewhere else. If you are designing engines that have to meet LEV (Low Emissions Vehicle), ULEV (Ultra-Low Emissions Vehicle), or even SULEV (Super Ultra-Low Emissions Vehicle) standards, you have other concerns that can be affected by cam timing as well. Emissions, drivability, cold startability - the effects of cam timing are far reaching. A sophisticated cam sprocketthat can advance and retard intake and/or exhaust cams on the fly eliminates most of the compromises inherent in cam timing.
The number of engines equipped with some sort of adjust-on-the-fly cam sprocket is huge, and growing rapidly. nissan has used a system called VTC (Valve Timing Control) on the Infiniti Q45 and the turbocharged Nissan Silvia, among others. Toyota has begun using VVT-i (Variable Valve Timing with intelligence) extensively on their high end US models (most of which are under the Lexus badge), but as they refine the system and reduce the costs associated with it, VVT-i is bound to find it's way down to the four cylinder models very soon. Ford has already brought their variable valve timing down to the 2.0 liter Zetec engine, but unfortunately only on the exhaust cam where it improves emissions but does almost nothing for horsepower.
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What does Neo VVL stand for?
Nissan Ecology Orientated Variable Valve Lift and Timing
The VE (Neo VVL) series of engines is Nissan's answer to Honda's VTEC. The two systems are nearly identical. They use the same concept of multiple cam lobes to provide a low rpm cam ideal for torque and a high rpm cam optimized for hp. The only difference in the Nissan system is that the intake and exhaust cams are triggered indepedently for a flatter, more consistent power band.
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