Friday, December 28, 2018

The Eternal Engine Mechanic

Earlier this month I stopped by the Omori Factory stand at Nismo Festival to greet the staff when I ran into Nagatsuru-san, one of their top engine mechanics. Engines are built in a separate building from the main workshop area, so we don’t get the chance to talk often when I visit. After a brief chat he was adamant to introduce me to the man who was going to build the engine of my very own car, which is something that I hand’t thought about yet. Until I found myself shaking Kosaka-san’s hand: Omori Factory’s longest serving engine builder, also known within the family as eien-enginmekaniku, 永遠のエンジンメカニック (literally “eternal engine mechanic”) and revered as a true legend within the company.

Kosaka-san started his career at Nissan Motorsport International as a race mechanic and honed his skills on the circuit building and maintaining engines for Group A cars, starting with the FJ20 and then the RB26. In 1998 he was assigned to Omori Factory and over his career has built over 1,000 RB26 engines: the all time record within Nismo and most likely in the world. We live in the click-bait era, where superlatives are usually thrown around with little care, but there is no question that Kosaka-san’s experience building the RB26 is unrivaled and he single handedly wrote one of the chapters of Omori Factory history. So you might understand my excitement when I was told that not only he would build my engine, but that I was also welcome to come over and watch him at work. Christmas surely came early this year.

Few days later I paid my first visit to Omori Factory along with a fried who generously offered to let me drive his S1 BCNR33 to our destination. The 20 minutes drive from Tokyo to Daikokucho is a nice stretch of bends and bridges with elevation changes, which combined to the super smooth Japanese expressways tarmac makes it for a real treat and ideal environment to appreciate the lower end torque of the S1 engine.

The drive was nothing short of fantastic and reminded me how much I miss driving around Tokyo and its spectacular architecture. This wasn’t exactly a planned visit, so once I parked I realized the irony of the fact that I ended up at Omori Factory again, despite having visited every week for the past month and a half. Oh well, surely there are worse ways to spend a Saturday morning.

Once inside we passed through the main workshop area and then a small hallway filled with scale model prototypes of various race cars built for wind tunnel testing purposes (each costing in excess of ¥40,000,000). We then made our way through the customer racing area: this is where GT500 and GT3 cars are built and maintained, and also where Nismo historic racers (like the Pennzoil R34 or Group C prototypes) are restored and kept in perfect condition for Nismo Festival. No cameras allowed here, unfortunately.

We eventually made our way to the second building, which looks a lot more spartan and purpose-built than the shiny red and black showroom. Here, however, is where the true magic happens and state of the art competition race machines are built by artisans like Kosaka-san and Nagatsuru-san, who have perfected their craft hand building one engine at a time for years.

When we entered the main workshop room Kosaka-san was busy taking apart my engine and had kept a few elements on the side to show me. This might sound strange to some of you: why would they spend time dismantling my old engine if I had just ordered a new one? You might be surprised to know that all Nismo engines reuse at least a few parts of the old donor and that Omori Factory has never built an engine out of 100% brand new parts over its 20 plus years of operations, and yes, that includes Z-tune cars as well (hence they had to be under 30,000km in mileage). I apologize in advance for the lack of photos, but here I was standing in front of a man who dedicated a whole lifetime to his craft and I felt I should be respectful of his kindness and time and not be overly intrusive with my camera.

Kosaka-san started by taking us around my N1 block, which had clocked 80,000km without skipping a beat and had no cracks in sight to be seen. During a second visit a few days later, he explained how the GT500 JGTC racing engines were based on rebored N1 blocks, with the maximum displacement ever used in competition for a BNR34 being 2,708cc. The Falken team fielded their R34 GT-R at the Nürburgring 24 Hours for several years using an Omori Factory built RB26 based on a standard N1 block that at its peak developed 540ps at 6,800rpm. Although they encountered some reliability issues none of them was ever related to the block. 

Interestingly, the 2.8 liter RRR GT block developed for the Z-tune was never tested in competition; the higher displacement revealed to be the easiest way around the emission guidelines imposed by the authorities at the time, compared to using a highly boosted unit with smaller capacity as developed in real motorsport application. The bespoke IHI Z-tune turbines, on the other hand, were tested on the Falken car during one of its last outings on the Nordschleife in 2004. The takeaway is that this is an extremely strong block that can last a lifetime if not abused by reckless tuning in the quest of silly power figures.

One detail that he pointed out however was the presence of a slight surface corrosion, which he possibly attributed to the use of high pressure steam cleaning machines, perhaps by the previous owner (which might explain why my engine bay was in absolutely spotless condition when I bought it). Despite his reassurance that the block was still reusable and that in some cases they can even be rebored twice, I had already opted to go a different route and use new parts.

We then moved onto my N1 pistons which, despite having reached the end of their lives, Kosaka-san had neatly arranged for me to see with their individual conrod cap and bearing metals. Talk about attention to detail.

Both Kosaka-san and Ochiai-san asked if I had been generous with the application of my right foot on the accelerator, explaining that racing DNA of the RB26 demands that its clearances must be revved out properly for it to stay in good shape. Apparently I had done a good job in such department, although credit goes to the first owner, who had put most of the mileage on the car.

Tell tale sign of a well used RB is the absence of carbon residual below the piston rings area, as Kosaka-san proceeded to point out by grabbing on of them.

A closer look and I realized what he meant as there was a very stark contrasts between the top portion of the piston and the almost spotless area below the oil ring groove.

I then started wondering around and couldn’t help but soak in all the details of a room so simple yet filled with so much history, like Kosaka-san’s very personal Snap-on toolbox that he has carried with him throughout his career. The photo on top was taken at Fuji Speedway over 30 years ago during the Group C era (Kosaka-san is the second from the left in the front row and Aguri Suzuki is the third from the right in the rear row): at the time I was 4 years old and Kosaka-san was already building engines. He then explained how Nissan and Nismo had their own garage and development facilities just right trackside, down the main straight.

During a following visit I was able to tour the state of the art engine test bench facility where 8 custom made bench rooms, each costing in excess of $1,000,000, are used to test and develop both race and road car engines. Half of them are for motorsport application while the others are divided between VR, VQ and RB engines. The RB room is one of its kind and is completely tailored to its dedicated application. The engines are mounted to the rig and connected to a Nissan transmission that goes straight into a dynamo capable of withstanding over 1,000ps. A custom ECU pre-programmed with every Nismo engine setting (S1/2, R1/2, F-sport, Z2, etc) is plugged in and the engine is then connected to a radiator and a custom intercooler. Finally, an air-conditioning system can feed hot or cold air into the airbox as well as different humidity levels to simulate winter and summer conditions. Different exhausts set-ups are available and a complex diagnostic system can pretty much simulate every single possible scenario, including running the engine through a lap of Fuji Speedway or other circuits. Each customer engine goes through a day of tests in this room before being fitted to the car and then subsequently road tested again.

Earlier in the post I mentioned how my engine was assigned to Kosaka-san; the reason behind my choice of words is that, after over 30 years of service the “eternal engine mechanic” will finally hang his Omori Factory apron for good in summer 2019 and retire. With each engine taking between 3 weeks to one month to build he has very few units left to assemble in his career; Nismo decided to assign his last months of work to selected projects only, which so far included building the 1,000th customer engine and overhauling the Z2 of Z-tune #15. I have recently been revealed the serial number of my engine and construction will undergo shortly.

I consider myself extremely fortunate: for a kid who grew up consuming his eyes on low resolution Best Motoring videos and that in 2001 used to wake up at 3:00am to check JGTC races results using a 56K modem, to find myself today having visited these places more times than I can recollect and developed with some of these people what I can now call a friendship is something that I would have never, ever imagined. After all these years and visits during which I’ve been lucky to touch, see and hear almost every single race car, prototype and special BNR34 ever made I thought I had seen it all, but meeting Kosaka-san and watch him at work has been the experience of a lifetime and an humbling one at that. I cannot think of a better embodiment of Japanese craftsmanship and dedication and I’m beyond honored that they decided to let me have one of his final works.

This is the final post for 2018: a huge thanks to all of you who stopped by this year. Wish you a great holiday season and see you in 2019.

Until next time.


  1. Great Read! Ive been to Omori 3x for the 3 Nismo Festival visits i attended everytime we fly to Japan every year. But i only see the front of the showroom. I wish i live in Japan and have my GT-R tuned to the Mother Heafquarters of Nismo. :)

  2. Two Questions:
    1) What did Kosaka-san say about a driving style where you bang up against the rev limiter several times?
    2) Did your friend's BCNR33 survive the trip back, assuming you were driving back?

    1. 1) Highly recommended driving technique, especially effective for hand built Mine’s engines.
      2) It did.

    2. Last I checked the rev limiter behavior on the RB26 is not conducive to long oil pump life...

  3. Wow, incredible post and indeed a great honor to have one of Kosaka-san's last engines ever built in your car and also see him work first hand.
    Much appreciate the sharing of these moments with us!

  4. Absolutely fantastic, you are truly a very lucky man and most of us can only dream about doing what you are doing. I am extremely fortunate myself that I purchased my R34 GT-R in 2011 before the price hike but what you are doing is on another level! All the very best and Happy New Year!

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