Oct 132011
 

At peace and at ease is the feeling of home. Driving the Sentra is being so for us.

Being a big fan of Nissan, we proudly owned or had intimate relationships with no fewer than fifteen of these fine specimens ranging from 1973 to 2011. Interacting with them had been our seemingly first nature; next to eating and breathing. It is a phenomenon that it doesn’t take us any time to get familiar and be confident driving a Nissan. It doesn’t matter if it is a race-prep Datsun 510, sporty 350Z, entry-level Versa or even the all-new Juke. They all make us feel like home.

It is hard to illustrate the at-home emotion in words. Everything there just falls in place per your preference and taste. Everything is just the way it is supposed to be. It doesn’t mean you don’t go out do something exciting like a camping or vacation trip. To us Sentra is the home and it doesn’t mean we don’t want to drive the 370Z or GT-R.

A testdrive review themed around our own home doesn’t sound very attractive, but an article on the stuff in the crawl space might sound more interesting. Let’s crawl into this black hole, turn over each and every ratsnest and reveal what the Sentra is made out of inside-out.

Background – All You Need to Know About the Past & Present of the Sentra

The first Nissan Sentra (B11) appeared in the U.S. market in 1982 as the entry level compact that replaced the rear-wheel drive Datsun 210 and began the front-wheel drive era. The B11 was powered by Nissan’s E15 1.5L inline-4 carbureted engine generating 67 hp and 85 Ib-ft. It might not sound much but it was sufficient to power the B11’s less than 1,900 Ibs curb weight. The EPA fuel economy at the time was rated at 48 mpg combined. The B11 was diversified by different body styles; sedan, hatchback and wagon. The frugality and reliability of the B11 contributed to its instant success as reflected by the sales figure.

Carrying the momentum of the B11, the 2nd gen Sentra (B12) was introduced to the U.S. market in 1985. It had a completely redesigned four-wheel independent suspension and a 1.6L E16 engine. The later B12 models came with a new GA16i 12-valve throttle-body injection inline-4 engine pumping out 90 hp and 96 Ib-ft of torque.

The B13 was available to the U.S. market in 1991 including the granddaddy of all Sentra, the SE-R. The SE-R was equipped with Nissan’s state-of-the-art SR20DE engine and a slick 5-speed Viscous Limited Slip Differential (VLSD) transaxle. The SR20 was internally balanced with forged connecting rods, 7,500rpm redline. The 2,400 Ibs curb weight was propelled by 140 hp @ 6,400rpm and 132 Ib-ft @ 4,800rpm of fun inducting power. The SR20 responded extremely well to aftermarket modifications, the SE-R, along with its SR20 equipped siblings, the Infiniti G20 and Nissan NX2000, gained tremendous followers even today – 20 plus years later. From the fact that we had owned both Infiniti G20, and Nissan NX2000, we could write a book on them. The B13 is still in production today in Mexico as the Nissan Tsuru for the South American markets; proven its superior reliability, durability, dependability, frugality and owner loyalty. The B13 was also the last Sentra in the U.S. market received a fully independent rear suspension.

In 1994, Nissan rolled out the 4th generation Sentra (B14). The rear suspension received Nissan’s multi-link beam setup that shared with the 2nd generation Infiniti G20 (P11). The GA16DE was the default engine. The 2-door version evolved into a separate model line, the 200SX. The SE-R version was only available as the 200SX.

The B15 came out at the turn of the millennium. Detailed information from our previous Testdrive Review on the B15 is available HERE.

Bringing the timescale back to the present, our tester (B16) is the sixth generation of the series, competing in the compact sedan segment. It was debuted in 2006 North America International Auto Show and went on sale for the 2007 model year. In 2010, the B16 received mild aesthetic refresh. It received Altima-derived front end including revisions to both head and tail lights. Gauge cluster are illuminated in red instead of orange.

The 2010MY comes in six trim levels: 2.0 [base], S, SR, SL, SE-R and SE-R Spec V. All non-SE-R models equip with a 2.0L engine and standard Continuously Variable Transmission (CVT) except the 6-speed manual is standard in the base model. The SE-R and SE-R Spec V equip with a 2.5L engine (QR25DE) that produces 177 hp, 172 Ib-ft in the CVT equipped SE-R and 200 hp, 180 Ib-ft of in Spec V with 6-speed manual.

The tester in Super Black paint is the 2.0S model with standard Anti-lock Braking System (ABS) and Electronic Brake Force Distribution (EBD). It has the MSRP of $17,160 and is assembled in Aguascalientes, Mexico along side with Nissan Versa.

Powerplant – MR20DE

The inline-4 powerplant [engine code: MR20DE] consists of 16-valve DOHC aluminum head and block, producing 140 hp @ 5,100 rpm and 147 Ib-ft of torque @ 4,800 rpm. In PZEV states, like California, the outputs are lowered to 135 and 142, respectively. It has 84 x 90.1 mm bore and stroke undersquare layout with 9.7:1 compression ratio.

Introduced with the Versa and Sentra in 2006/2007, the MR series replaced its inline-4 predecessors, the QG18DE and our beloved SR20DE last found in the B15 Sentra SE. The MR carries and emphasizes Nissan’s healthy low-end torque heritage. Ninety percent of maximum torque is available at 2,000 rpm with linear increase to the 6,400 rpm redline. The MR is jointly developed with Renault for use in their volume-selling models. The SR series’ unique characteristics are gone in history.

On the spec sheet, the power output of the MR20DE is nothing but ordinary. But internally the MR contains the following enhancement and technology upgrades to increase fuel economy and maximize efficiency by reducing friction:

Friction reduction is achieved with bore circularity machining; a technique used in ultra-high performance engines to diminish deformation of the cylinder bore due to axial forces from the cylinder head bolts. It ensures a symmetrical bore diameter in the length of the cylinder. Energy sipping friction and ozone thinning blow-by gas are minimized.

Furthermore, lateral pressure acting on the cylinder walls by the pistons and particularly during the downward stroke at top dead center is reduced by offsetting the center axis of the cylinders and connection rods. Rotational components such as the crankshaft and camshaft journals are polished to mirror-like finishing reducing resistance in the bearings.

Combustion efficiency is enhanced by utilizing lightweight composite equal length manifold runner that contains swirl valve to create vortex in the fresh air. The 12-hole injector nozzles ejaculate fine mist of fuel to ensure each and every fuel molecule is bond with the oxygen rich intake charge in the specially shaped combustion chamber. This homogeneous air-to-fuel mixture is ignited by long duration ignition coils for complete combustion. No questions in the latter part since Nissan ignition system is well known for its potency. The stock ignition system on the SR20DE engine can provide reliable spark even under 20-pound of boost pressure.

For volumetric efficiency, the intake manifold is located behind the radiator to make room for the firewall facing exhaust manifold. This layout reduces pumping loss by straightening the exhaust system. Intake valve timing is enhanced by Nissan’s Continuously Valve Timing Control (C-VTC).

Lastly, engine weigh-reduction, acoustic, noise, vibration and harshness improvements are achieved by the use of silent timing chain. For decades, Nissan always in favor the use of chain over belt. Built-in coolant pipe is now cast-in-to-the-block instead of an external pipe connecting from thermostat housing to external mounted water pump used in a KA24DE engine.

Drivetrain – Xtronic CVT

The transversely mounted engine is mated to a Jatco supplied CVT [transmission code: RE0F10A] which is also used in Nissan X-trail, Mitsubishi Outlander, Suzuki Kizashi and Dodge Caliber variances (i.e. Jeep Compass).

What is a CVT?
Although CVT made its U.S. debut in the Subaru Justy subcompact in 1987, not too many were aware of its existence. This pushbelt type CVT was employed for both FWD and AWD models powered by a 1.2L 3-cylinder engine. Due to immaturity of the material technology on the pushbelt, the CVT was deemed unreliable. With the discontinuation of the Justy in 1994, the use of CVT in the U.S. market was ceased.

In the islands that are surrounded by open seas, the CVT technology started to mature thanks to Nissan’s dedication on the research and development. To a degree, the CVT to Nissan resembles the rotary engine to Mazda. With Nissan’s subsidiary, JATCO, Nissan solely designed a CVT system that could handle higher torque, was being the first and still the only company confident enough in the CVT technology to completely switch out the conventional automatic transaxle (AT), making their XTronic CVT mainstream.

The first debut of the Xtronic CVT in North America was in a 2003 Murano CUV powered by a 240 hp 3.5L V-6 engine. Since then CVT became Nissan’s standard clutchless transmission. It was found in every transversely mounted engine in Nissan’s North America model lineup. With the separation between Nissan and JATCO, the CVT has been gaining popularity among other makers.

How CVT Works?
The fundamental principle of the CVT is quite simple. In the CVT box (lingo, derived from the term gear box), the engine’s crankshaft is connected to a torque converter. The converter disengages during idle and at very low engine speed to prevent stalling. Work from the engine is transmitted through the converter like a conventional AT but instead of connecting to the gears, it is driving the cone shape drive pulley which is similar to the input shaft in the manual transaxle (MT). On the other side of the box, situates the driven pulley, output shaft in MT lingo, connecting to the driveaxles. A steel belt is riding on these cone-shape pulleys transmitting work between the engine and the drive wheels.

Gear ratios change by varying the spacing between the cones in each pulley by hydraulic pressure. The steel belt rides on a larger diameter when the pulley spacing is less. Widen the spacing, smaller the diameter. This enables the CVT to infinitely deviate gear ratios within the high and low limits. For example, when the drive pulley is at the widest spacing and driven pulley is at its tightest, lowest gear ratio is set. The opposite will allow for highest gear ratio.

The benefits of this infinite gear ratio are: 1) stepless shifting which eliminates shift shock, 2) avoid the peaks and dips in engine output, 3) earlier torque convertor lockup to reduce torque loss in the convertor and enhance efficiency, 4) reduce energy loss during shifting, 5) compact and lightweight design without a bunch of gears and clutch packs.

Nissan has further enhanced their CVT by: 1) improving both electronic and hydraulic system responsiveness for quicker response to throttle input and selection for optimal gear ratio, 2) changing CVT mapping to offer driving experience similar to conventional AT. The vehicle speed increases with rise of engine speed without the “Rubber Band” feel, 3) mapping also corresponds to road condition, such as, uphill, or to provide engine braking.

Sorry, the comment form is closed at this time.