Measuring, cutting, trimming. All for the sake of finding the one correct answer.
The Fine Tuning Rebuilt Engine is born.

Tuned engines in the past were sometimes rough and dangerous, but they were a fascinating realm for car enthusiasts. Many of them were equipped with high-performance parts and prioritized power extraction. Ease of use was secondary, and a certain level of "resolve" was required from the user.
However, times have changed. Today, the precision of mass-produced engines has improved dramatically, and for the average user, they are already in the realm of perfection from the start. There is no room for doubt about the perfection of engines efficiently assembled on the production line.
However, no matter how much technology advances, there are tolerances and areas in the mass production process where effort cannot be expended. This is the fate of pre-made products, with production efficiency and cost being key considerations, and even the Roadster cannot completely escape these constraints.
That's where we tuners come in. Each of our new "fine-tuned rebuilt engines" has been painstakingly crafted by skilled craftsmen. The entire rotating system, from the crank to the flywheel, has been precisely tuned, as well as the weight balance of the pistons and connecting rods. Without using any special tuning parts, we have refined it to a smooth acceleration that makes you forget it's an in-line four-cylinder engine.
Of particular importance is the tuning of the cylinder head, which determines the engine's character. The valves and seats have been meticulously adjusted to equalize the combustion pressure in each cylinder and convert every bit of explosive energy into driving force. Furthermore, the volume of the combustion chamber is strictly controlled to within 0.1cc. The inner diameter of each cylinder is precisely machined down to the micron level to match the dimensions of each individual piston, and the clearance is maintained at an appropriate level, ensuring that all cylinders burn evenly and accurately, creating depth and tenacity in the torque characteristics.
Our consistent approach to tuning the Roadster is refinement in the realm of sensitivity. This engine may not have the flashiness of a turbocharger, but it embodies a meticulously refined "oneness between rider and horse" that is clearly different from mass-produced specifications.
After going through all these processes, only a handful of ND users will be able to receive this engine. That is why it has value. Freed from mass production, it is the answer we arrived at after single-mindedly pursuing the "ideal feel." This is a fine-tuned rebuilt engine assembled with passion, conviction, and the skill of a craftsman. We want to deliver this to you, the genuine article-seekers who share our commitment.

<Product features>

<Main work content>

Combustion chamber correction polishing, port polishing, valve seat cutting, valve refacing and chamfering, valve lapping
Precision honing with dummy head, piston and connecting rod static weight balance adjustment,
Crankshaft and flywheel dynamic balance adjustment, crankshaft lapping, precision clearance adjustment for each part

<Main new replacement parts>
■Uses the latest genuine Mazda parts

Piston set, piston ring set, connecting rod metal, main metal, thrust metal, timing chain, tubular pin, water pump, oil filter, pilot bearing, washer, various bolts, various seals, various gaskets

<Notes>

-This product requires a trade-in of an unmodified movable engine.In principle, please return the trade-in engine within 2 weeks after the engine arrives.
・If the trade-in engine is not working or has internal damage, the following parts costs will be charged additionally.
Cylinder head assembly / cylinder / connecting rod / crankshaft / oil pan, etc.
・ Depending on the stock status of the core engine, it may be possible to support OH, which will take care of your engine first.Please contact us for details.

<Recommended parts for simultaneous replacement after installing the engine>

Since the peripheral parts of the engine are expected to deteriorate over time, it is recommended to replace the following parts at the same time.
・Electrical parts: engine harnesses, ignition coils, spark plugs
・ Fuel system: Fuel injector ・ Fuel pump ・ Fuel filter
・ Others: Engine mount, differential mount, etc.

<Product compatibility table>

■ Fine Tuning Rebuilt Engine

　High-precision handmade rebuilt engine *Please note that due to the handmade nature of the product, it may take a long time for delivery.

Car name	適合 車 種	part number	Tax-included price (Price without tax)	Spec.	Codes
Roadster	ND5RE/ND5RC	NDA1 V5 300	657,800 JPY(TAX+) (¥ 598,000)	High-precision handmade Fully overhauled partial engine	F

■ A trade-in engine without modification is required at the time of purchase.In addition, additional costs may be incurred depending on the condition of the trade-in engine.
■ Please send your trade-in engine in partial engine condition (with all accessories removed).
■ The purchase price does not include the cost of removing and installing the engine or the cost of shipping the trade-in engine (return).

Description based on the Secondhand Goods Business Law Tokyo Metropolitan Public Safety Commission No. 307712005467 Autoexe Co., Ltd.