Monday, May 2, 2011

Spare Engine Rebuild Update: Tomei Poncams

The rebuild is going well and I've sent in my Tomei camshafts + Pulleys and a N1 Water Pump in for the final stage of the project. Looking forward to how the cams perform as not only will they improve response and overall performance but the poncams will also have a positive affect on the R33 GTR's exhaust sound.

And why Tomei? Tomei Poncam camshafts are designed as a "drop in application", so no dialling in required as the nock-pin has been pre-set. The Poncams are also designed to work with the standard valve springs and offer the best drop in performance gain for both street and track use. No machining is required at all.

Tomei manufactures several camshafts for the RB26 engine, the most mild being the Poncams. Designed as an upgrade when compared to stock cams, the Poncams fit all generations of the RB26 engine (R32, R33 and R34), and come in three types, Type A, Type B, and Type R. The differences between the Type A and Type B Poncams are limited, with the Type B version featuring 260° of lift on the exhaust, compared to 252°. This slight increase in duration means more air can enter the cylinders at higher RPM. The downside to additional duration is that low end power is sacrificed, as the turbochargers typically can not move enough air at lower engine speeds. The Type R Poncams were designed by Tomei to cater to those who wish to remain "street legal" by Japanese standards. This means decreased duration for better emissions, as well as compatibility with stock or aftermarket catalytic converters.

Type A camshafts are suitable for engines that will be using stock or larger bolt on turbochargers. Type B camshafts are for engines that will be running N1 turbo chargers or full aftermarket turbo kits. The Type R camshafts should only be used when a car retains the factory catalytic converter, or when you wish to upgrade to an aftermarket catalytic converter.

Tomei Pon Camshafts + Pulley Set: Nissan BNR32/BCNR33 RB26DETT Duration IN 260, EX 252, Lift 9.15 (Pon Cam + Cam Pulley IN & EX) 143036 A Type + 153027 Cam Pulley.

Excerpt from about the Tomei Poncams:

Tomei presents the popular poncams. Generally, engine tuning is to modify the torque characteristic of engine by changing cam duration timing and height of the cam lift, so as to gaining maximum torque and horse power. However, when tuning the engine strictly, it should be carried out with the idea of securing effective area of the valve not only by duration timing and height of the cam lift, but also by through improvement of its intake efficiency. High valve lift allows huge amount of air to flow in, yet it mechanically damages the system and gains friction loss. Also, wide cam duration will deriver great power at high RPM, but it gives rough engine character at low RPM too. Tomei have worked to get an ideal well-balanced profile of camshaft and succeeded to give it 1.3 to 1.5 times more effective area than regular camshafts.

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Exhaust Sound Control