Through the years, Nissan's SR20DE engine proved a willing participant when it comes to building horsepower. The normally aspirated SR20DE 2.0-liter four boasts 140 hp and 132 lb-ft of torque in stock trim, which is more than enough to properly propel any of the NX 2000s, SE-R Sentras, 200SXs and Infiniti G20s it appears in.
Stock trim is fine, but here in the Dyno Cell, it's all about power. The SR20 has a number of pluses. It's fairly light, thanks to its aluminum block, aluminum head design. The block's closed deck configuration means there is no need for sleeves or block guards. Everything in the SR20 is stout (especially the rods) because the powerplant is turbocharged in Japan where the engine powers the Silvia sport coupe.
Beyond the internals, the SR20 runs a very stout valvetrain in stock trim. The head features a mechanical lifter assembly that incorporates one rocker arm per two valves which means one cam lobe per two valves. Since the rocker arms are floating and the lifters are hydraulic, no valve adjustments are needed for the Tomei units. Rather than using a timing belt, Nissan has paired the timing chain with a hydraulic chain tensioner. This system tends to out-last belt systems, but can sometimes complicate matters during installation of cams or making adjustments to engines equipped with cam sprockets. In this cam story, we have used a different installation method than that found in the factory service manual.
With the Sentra strapped to...
With the Sentra strapped to the Dynamic Autosports dyno, we laid a foundation of 133 hp and 125.0 lb-ft of torque. With the Tomei cams installed, the SR20DE engine pumped out 141.9 hp and 127.0 lb-ft of torque. A peak of 8.9 was realized, but 10 to 15 hp was found in the high-rpm range from 6000 rpm to redline.
Remove the valve cover by...
Remove the valve cover by loosening the 10mm bolts that fasten the cover to the head.
The Tomei cams are considered direct replacements. They utilize the same size base circles as the factory units, which helps in eliminating harsh rocker arm angles. The cam sprocket dowel pin for the intake sprocket is within factory spec but the exhaust sprocket dowel comes in a much longer length. This is done to accommodate rear-drive SR20 engines that run cam sensors on the sprocket. If these Tomei units are to be installed in front-drive vehicles, either the dowel needs to be cut to the proper size or the sprocket bolt washer needs to be grooved to accept the protruding dowel.
Our test vehicle is one that has been through grueling tests in the past. From being a turbocharged guinea pig with a full-blown, race-ready engine to an all-motor SR20 test bench, Project SER-ious Sentra has been tortured tested on many a Dynojet dyno.
Currently, the engine is stock with a few basic bolt-on upgrades. Although the engine is tired, the baseline figures show that even an SR20 with miles can produce good power. A baseline figure of 133.0 ponies were present and 125 lb-ft of torque was still plenty to motivate the Sentra. To futher view the process of installing SR20 cams and resulting power, follow along as we show you the easiest and least time consuming way to make bolt-on power. Let the boogie begin.
It is necessary to loosen,...
It is necessary to loosen, but not remove, the 24mm bolts that attach the sprockets to the cams before cranking the engine to its TDC (top dead center) mark. Placing an adjustable open-end wrench on one of the cam's lobe will keep the cam from moving while you loosen the bolts. To ensure the timing does not fall off its original mark, use two wire ties to lock the chain to each sprocket.