Author: TOMEI USA

On the block side, in order to ensure that the angle installed on the machine is correct, the parallelism is thoroughly checked, and the angle of the machine and blade is adjusted.  Extremely high-level precision work is carried out by the hands of the ultimate super-skilled craftsmen. 

This figure demonstrates the gap if these tasks are neglected.  There are lot of experience in Japan and are aware of this kind of phenomenon and are improving upon it.  Overseas machining companies often neglect these tasks, resulting in many tuning engines with short engine life and loud engine noise.  At TOMEI USA, we have thoroughly verified and confirmed the deviation, and high-level short block is achieved by matching perfect machining with the high-precision pistons.

The order of process is boring to roughly enlarge the block, and then honing to determine the performance of the engine.  Detailed bore size and fine groove that also serves as a fine oil passage called crosshatch is achieved by honing. 

The craftsmen at Diamond Engineering take numerous measurements repeatedly to ensure the perfect finish without compromise.

This small groove is the crosshatch.  This angle and roughness are trade secrets, but they are important factors for reducing resistance and noise to the piston.  If it has a shiny mirror finish, oil will not enter and will seize and cause a failure.  There believed to be only a few machining companies in the world that can perfectly match the finish for the RB26. 

Regarding honing.  As for further information, Diamond Engineering uses a high-tech finish called plateau honing.  As shown in the figure, the finish that removes this apex greatly reduces aggressiveness to pistons and piston rings.  And this allows for quiet and smooth engine rotation. 

The engine is assembled at TOMEI USA headquarters in Japan by a veteran engine builder who has built RB26 engines for over 30 years.  First, burrs are carefully removed from the block after processing. 

After machining, metal shavings from the cutting machine remain in the water line and oil line.  We take the time to thoroughly wash these with a dedicated machine with the hands of an engine builder.  If the engine is started with such metal shavings remained in the engine, it will damage the bearings and pistons, and in the worst case it will lead to engine failure.  At TOMEI USA, engineers who cannot properly clean the engine are not allowed to assemble the engine, and we proceed carefully as we regard this step as the most important work of engine assembly. 

We measure the weight of each component such as pistons and connecting rods one by one in pursuit of appropriate weight balance arrangement. 

The crankshaft is balanced individually, and straightness is checked so that there is no bending, and the vibration is suppressed to its utmost state.  Combined with 12 full counterweights, amazing stability, and quietness even at high revolutions is achieved. 

High precision Mitutoyo measuring equipment is used to measure the bearing clearance with the utmost precision in a location that is well-controlled for temperature and air management. 

After measuring the weight of the piston and con-rod assembly, compatibility is balanced and matched.

When installing the piston ring to the piston, it is very important to adjust the piston ring gap.  Too tight of a gap will result in galling damage, and too wide of a gap may result in a blow-by.  TOMEI USA utilizes the skills of skilled craftsmen to achieve the highest level of sealing performance with tightest gap possible. 

A dedicated engine assembly lubricant is used for bearings and other components to suppress galling before the oil completely circulated upon engine installation. 

Next is the tightening of the main studs.  These are carefully assembled one by one taking equal amount of time with the specified torque in correct order.  Then crankshaft is rotated and checked.  As a result, smooth rotation is felt even when turned by hand.

And finally, the pistons/con-rods are inserted into the cylinder block and attached to the crankshaft.  TOMEI USA manufactures and uses special jigs and carefully incorporates them into the engine one by one. 

A laser marked serial number is engraved on each short block.  Also comes with serial plate with the same number packed separately.  The plate itself can be affixed to the vehicle such as the radiator core support and functions as proof.

The short block is also equipped with an owner’s book that authenticates the short block.  Detailed contents are listed, and serial number is marked.  By being able to authenticate the high level of quality, the next owner or car dealer can be informed at the time of sale of the vehicle, and possibly being assessed at a higher price.

Completed in a sturdy dedicated wooden crate with the TOMEI logo and serial number.  And we can ship all over the world.  We have completed two of each N1 block and standard block specifications, totaling four units have been completed and have already been transferred from Japan to the USA.  Currently, it is difficult to obtain new blocks from Nissan Motor, but TOMEI has secured several units, so we are able to produce more, but please understand that the quantity is limited.