Mike Kojima posted on May 13, 2009 19:03
During its production run, the North American SR20DE underwent 3 different major changes. The differences are listed below.
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| This SR20DE High Port engine lives in the engine bay of the world famous Dog Car, a NASA PTD Racer |
1990-1993 The High Port
SR20DE's made during this period have a racing type downdraft straight shot split intake port which is desired for all out performance in a highly modified engine. The high port was rated at 140 hp. The curving under intake manifold with the plenum and throttle bodies under the runner most readily identifies the engine. If you are building an all out turbo or naturally aspirated engine, this variant is the most desired. Fortunately this is also the most common SR20 out there. This engine is also plentiful and cheap from JDM used engine importers. This engine was redlined at 7700 rpm from the factory
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| Although the Low Port version of the SR20DE was designed to improve emissions, the engine still performs just as well as the High Port version once the restrictive 7000 rpm rev limiter is removed and the cams are changed |
1994-1999 The Low Port
In an effort to reduce emissions, Nissan shortened the SR20DE's intake port and placed the injectors closer to the intake valves by using a more conventional intake port design. This intake port makes a sharp turn inside the head and does not flow quite as well when ported although it flows nearly as well as the high port when stock. Due to the lower unsplit port configuration, the hydraulic lash adjuster also intrudes on the roof of the port. The Low Port engine has milder camshafts especially on the intake cam, which is about 10 degrees less duration than the high port. The intake manifold most easily identifies the Low Port motor with the plenum on top of the runners. The Low Port engine in the B14 Sentra has a really low 7100 rpm redline while the version found in the G20 retained the higher 7700 rpm redline of the High Port. Other than the rev limit in the ECU there are no differences in the engine and the low port can easily withstand having its rev limit raised.
In stock and modified form, once the cams are changed and the restrictively low 7100 rpm rev limiter is raised to 7700 rpm, the Low Port more than equals the power of the high port, usually producing more bottom end torque and the same amount of horsepower.
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| The B15 Sentra had a roller cam equiped SR20DE from 2000-2001. The famous Disco Potato pictured here is powered by a turbo version of the engine |
2000-2002 The Roller Motor
This version of the SR20DE was found in the 2000-2002 G20 and the 2000-2001 B15 Sentra SE. It had significant changes to improve emissions and to help power and response. The main cap girdle was deleted to reduce windage losses sacrificed by having the girdle so close to the rotating crank assembly. The pistons were lightened with a slipper skirt racing inspired design. The pistons are also coated with black organic coating to reduce friction. The pistons have thinner, lower tension rings for less friction. The top ring is moved higher on the piston, to improve emissions.
Although the connecting rods are unchanged, the crank is considerably lightened. Since the pistons are much lighter, Nissan was able to remove one counterweight from the crank. The bearing journals are micro polished. The most noticeable external feature of the motor is the new, taller valve cover to clear new friction reducing roller rockers. The head has valves with a 3mm shorter stem with springs and retainers to accommodate this shorter stem height. The roller SR has a revised intake manifold with shorter runners. The intake has a larger diameter, smoother pipe between the throttle body and a new larger airflow meter. The exhaust manifold has a close-coupled catalytic converter on a log type manifold, which probably sucks up a lot of the power gained from the other improvements. The roller SR has 145 hp.