Nerding Out at R's Meeting 2022 - NAPREC

 So I've been skimming some of the social media coverage of the R's meet lately, and one tuner/booth that seems to not get much attention is the one for NAPREC, short for Nagoya Precision.  Established in 1997 by Minoru Nagoya (yep, so the company is not named after the city), everyone in the aftermarket engine tuning world here in Japan knows about NAPREC.

It's no secret that, if you want your rebuilt engine to perform at its best for its specified usage, you get in line and send the cylinder head in to NAPREC to be machined properly, so as to allow for the use of bigger valves, ensuring the smoothest flow of fresh air into and exhaust out of each cylinder, and changing the shape of the combustion chamber, to give a few examples.  Check out their high-response menu. A not so well kept secret is that all the big name famous tuning houses send their engine heads into NAPREC - I recall Nakayama-san at Mine's telling me that he used to spend hours himself manually porting out the intake/exhaust ports for each engine he worked... but given the stuff that was included in the menu for my engine, I am pretty sure for the rest of the nifty bits added to my car's engine - strengthened valve guides,  intake valves, etc. - the head was sent into NAPREC.  In any case, for sure now, given how busy Mine's is, I am sure they outsource most of their cylinder head work to NAPREC (confirmed by Nagoya-san at his booth...)

Anyway, I wanted to share a few photos I took at his booth.

Just sitting pretty. Not even an RB26 head!

Anyone know what that gold ring is around each valve cutout?

Ok so this is an RB26 head, but check out how each cylinder combustion chamber is shaped differently in order to demonstrate what NAPREC can do.

Here are some close-ups, starting at the top.

OEM normal combustion chamber, with normal intake side valves of 34.5mm and exhaust side valves of 30.0mm, and normal seat rings.

This one (on bottom) shows "High Response Kit Machining" - normal combustion chamber, intake showing NAPREC forged big valves at 34.8mm (0.30mm more than oem); normal valves used on the exhaust side, except they have been refaced; and normal seat rings.

This one (on bottom) shows the "High Response Big Valve Spec" with the combustion chamber machined to "full squish", intake valves the NAPREC forged big valves at 34.8mm, exhaust valves the NAPREC forged big valves 1.00mm wider than OEM at 31.00mm, and normal seat rings. 

Bottom one here shows the "High Response Intake Drag Valve Spec" which differs from the "High Response Big Valve Spec" by having the combustion chamber machined to "Hemi Circle shape" and the intake valve is a NAPREC Drag spec forged big valve at a massive diameter of 36.00mm, 1.50mm wider than OEM!

Finally, this one on the bottom - sorry for the poor quality photo - shows the Drag Kit Machining, which adds to the High Response Intake Drag Valve Spec by incorporating a full circle machined combustion chamber, exhaust side NAPREC Drag Spec Forged Big Valve with a diameter of 1.50mm wider than OEM at 31.5mm, large diameter seat rings - beryllium ones shown here.

I guess the bigger valves make sense, but I was most curious about the different shaped combustion chambers.  Check out this NAPREC webpage for details.  Interesting that the OEM combustion chamber has a volume of 65cc, Full Squish is 69.5cc, Hemi circle is 70.3cc, and Full Circle is 71cc.  

From top to bottom - Full Circle, Hemi Circle, and Full Squish.

So even though the Full Squish looks pretty OEM, it actually provides the biggest step up in volume, with Hemi and Full Circles only being with 1.5cc of the Full Squish.  And yes I asked and my Mine's engine should have the Full Squish (and yes it seems that way in checking this old blog post).

Anyway, it was nice to learn something somewhat mechanical - and yes basic - but hey some of these things you have to get up close and personal to really appreciate the precision that is required to produce super smooth and responsive engines.  

In my next post, I am going to try to explain something very interesting I found... a possible future product which I am definitely interested in...

Thomas Mangum's Midnight Purple R33 GT-R - Spec Check and Driving Impression! (Part 1)

So recently my friend and fellow R33 GT-R fanatic Thomas Mangum invited me to drive his Midnight Purple machine.  I jumped at the chance – it would be a rare opportunity to drive a high spec car (and one with the HKS V Cam, too!) and compare against mine. 

When I pulled up to his house, I initially took some photos before jumping into the driver’s seat.   Thomas seemed embarrassed by how dirty his car was, but that couldn’t be helped as it’s parked outside and as a daily driver a car cover doesn’t make sense (for most people...).   Nevertheless the car was in good shape, nothing a nice wash and wax wouldn’t fix.

Purple disc rotor caps to match the Midnight Purple car. Nice touch. F50 Brembos with Biot 2 piece rotors!
Wheels are ENKEI RS05RR in 18x11J(!!!) with offset of 16.

A bit of trivia about these wheels - these were one of, if not THE first, sets of the RS055RR that Enkei made for the Skyline GT-Rs. How do we know? Because when Thomas and I went to Tokyo Auto Salon  that year, we noticed that the displayed wheels had some stickers that these wheels did not have. When we inquired, we were told that the first batch did not have the stickers, and further all the ENKEI reps there said they had never seen or known of a GT-R with them before! (ENKEI later mailed him the missing stickers!)

Essentially this is a custom made front bumper - I've never seen another quite like this.

I recall when Thomas asked me if I had ever seen this front bumper before when it came up for sale on Yahoo Auctions a few years back... obviously the answer was no. It seems to be a very clever design, incorporating cooling abilities along with the front canard aerodynamic effect.  It apparently was a one-off design for one of the JUN Auto racing cars [thanks to our friend Matt Rearick who remembered seeing the same item on Yahoo, and the description!] which meant that Thomas had to get clever to incorporate turn signals in order to make it street legal.

AutoSelect Tower Bar. ARC Cooling panel (no longer made).
Aluminum catch tank and UK GTROC Aluminum fuse box cover

I'm proud to say I did my bit to contribute to this engine, as the fuse box cover was something I gave Thomas a long time ago... Note also the relocated power steering pump fluid reservoir.

Aha! V Cam. I can only dream at this point. With a NISMO surge tank too!

Yep. I was eagerly looking forward to how differently this car would drive with the V Cam, given the HKS 2530kai turbos the car is running.

Carbon fiber hood (or bonnet in the Commonwealth?)

He has some interesting custom mods so I took photos of those. For example:

Custom carbon piece to direct air towards the intercooler. If well done, stuff like this adds to a car's allure and personality.

I've already pointed out the clever use of side turn signals used upfront. Here's another custom application:

Another interesting tidbit - oil cooler located here!

Due to the design of the bumper, Thomas couldn't place an engine oil cooler in the usual place (that is, under the left front lights in the front bumper). So naturally, he put this Greddy one up front behind the grill to ensure lots of airflow. Reminds me of the old NISMO set up (albeit that was underneath and behind the front lip spoiler).

Speaking of spoilers:

Genuine NISMO dry carbon 2 piece blade. Looks like the previous owner liked to advertise that fact.

For the back, he found a used NISMO 2 piece dry carbon spoiler blade.  He restored it best he could but you can still make out where someone had applied a NISMO sticker. (and yes, the blue car in the back ground is the ISF I'm slowly modifying...lol)

90mm AMUSE titanium exhaust. 

Thomas' car is equipped with this Amuse R1 titanium exhaust, which obviously maximizes exhaust flow and doesn't even pretend to really have any "muffling" capacities. This thing is LOUD!

Thomas later sent me a list of the specs of his car. For example, some highlights of the engine/powertrain are:
- N1 block bored to 86.5, N1 oil pump, N1 water pump
- Carrillo rods, Mahle pistons (both save weight)
- balanced and straightened crank by NAPREC
- NISMO crank and conrod bearings
- NAPREC high response head kit (ported, etc.)
- NISMO 600cc injectors/NISMO fuel pump
- R35 AFMs
- Tomei Powered oil pan baffle/metal head gasket (1.2mm)/timing belt
- Trust/Greddy Type R intercooler
- Okada Plasma Direct ignition coils
- HKS hard piping kit
- Advance 130A alternator

This is all managed by a custom flashed ROM that piggybacks on top of the OEM ECU. Thomas estimates about 600 horsepower. 

So how does this all add up, really? I’ll give my honest (good and bad) impressions on how the car drove, as well as photos of some interesting interior bits, in my next post...