Ventilation Openings That Lower Friction
The 4B11 is fitted with many devices that eliminate friction in the assembly. The ventilation opening on the upper portion of the main journal is one of these. This was adopted from Porsche's race engines, which are known to fight pump loss. The blow-by gas is efficiently released and as a result lowers friction.
Two-Section Oil Pan And Low-Friction Oil Pump
The upper portion of the oil pan features ribs to keep the structure rigid. The oil pump is positioned at the lower end of the engine assembly, right below the upper oil pan to keep the suction of the pump at a minimal resistance. This setup is ideal during cornering and hard acceleration/deceleration. If the pan comes in contact with the ground, however, immediate oil pressure issues may come about. This gear type oil pump further minimizes friction than the conventional trochoid pumps seen on SR20s.
A Newly Designed Engine With No Balance Shafts
The pre-modern 4G63 was fitted with balance shafts, which were used to eliminate vibration. Many modified 4G63 engines had to have their balance shaft removed because it became a nuisance when tuning the engine. The new 4B11 doesn't come equipped with balance shafts. Overall, the engine itself is cleverly designed so that vibrations are nonexistent even without balance shafts.
Baffle Plate That Lowers Blow-By Gas
The oil pan is in two separated pieces and the upper aluminum oil pan is combined with a baffle plate. Six oil passes on each of the intake and exhaust sides on the cylinder head lead to exclusive oil return passages, where the oil drops down inside the oil pan. The amount of oil accumulated on the inner crankcase and crankshaft is decreased, which benefits by lowering the blow-by gases and improving oil pressure. On the 4G63, the level gauge tends to blow out when the engine is modified. The 4B11 already comes with a counter device that prevents the increased pressure of the blow-by gas from doing this type of damage. However, the area where the oil jets from the piston-cooling nozzle have the possibility of dropping straight below or at the wide clearance area between the crank weights and the baffle.
Forged Mahle Pistons For High-Power Output
Forged Mahle pistons with an 86mm bore and 23mm pin diameter are equipped in the 4B11. These pistons come with cooling channels with a different number of passages to the oil rings according to the intake and exhaust sides. The new piston pins were switched to a skirt-type, full-floating unit, replacing the ordinary forced pin oiler on the 4G63. Further inspection of the piston top reveals a rather shallow design suited for a forced-induction engine with an almost flat shape. Comparing it to an SR20DET, which is also 86mm, with an 8.5 compression configuration, the 4B has a slightly increased compression of 9.0. The top and secondary ring lands come thick in design, and along with the relatively high compression, this engine was made to withstand high horsepower. The piston pin and the rings weigh in at 546.2 grams. The 4G63 was engineered as a long stroke engine (85mm bore x 88mm stroke).
Improved Conrod Design
Once the 4G63 is heavily modified, the stock connecting rods cannot be used with full confidence. On the contrary, the 4B11 rods have beefier qualities with plenty of "meat" on the unit and great shoulder design. These rods also show indications of strength in design because of the lack of oil jet and bearing lubrication holes. Details of the connecting rods include M8 1.0 pitch-type rod bolts and the 4G63's dowel pin structure being replaced with a knock pin type. This part was designed with the bolt placement as center as possible. With the larger-sized crank pins, the bearing thickness was changed from 21mm to 17mm to contribute to less friction. The 4B11 rods are lighter, weighing in at 572.5 grams versus the 4G63 rods at 592 grams each. The slope ratio of the piston and connecting rod measures in at 3.34, advantageous criteria if the engine is going to be considered a 2.4-liter long stroke setup in the future. However, the torque-toyield connecting rod bolts that lack sufficient diameter may be an issue once the engine is modified to pump out more power.
Compact Design Crankshaft
The fully countered crankshaft has a 52mm main and crank pin area, which is skinnier than the 4G63's main pin but with thicker crank pins. This enables an overall strengthened crankshaft layout. The crank pick up sensor was moved to the rear area of the crankshaft. The flywheel position was relocated to the center of the entire assembly in order to create a more compact engine in terms of long-block height. The oil line that feeds lubrication to the crankshaft journals aren't the traditional "H" or "X" pattern, but a one of a kind design from Mitsubishi, presumably to supply plenty of oil to the bearings during high rpm. The concept of excessive oil supply related to extreme centrifugal force has been well balanced in this area. The crankshaft weighs in at 16.6kg.