Engine Porn: Os Giken Tc24-b1z

Granted this is not the first time we have looked at the OS Giken’s TC24-B1Z, but seeing it’s further been refined from last year’s Nostalgic 2 Days show, I thought I’d dedicate a little post to it as it’s simply, a work of art. It was back in the late seventies that Okazaki-san from OS Giken decided to convert what was then one of Nissan’s most popular engines, into a true high performance powerplant. High power and high rpm were two of the main goals for the project, which was all based around an aluminum twin-cam head design. Combined with a reworked bottom end of their choosing, customers would really tap into the true potential of the L-series. Only 11 OS Giken TC24-B1 heads were created, demand was low due to the high cost but it was quickly regarded as the ultimate modification for Nissan’s popular straight six.

But seeing the continuous growth in popularity of the kyusha in the last few years, Okazaki-san was persuaded to offer a few more of these special heads to his most demanding customer. So from the middle of last year OS Giken began taking orders for the TC24-B1 head, except Okazaki-san was not exactly going to be recasting a design he created over thirty years ago. What he did was go back to the drawing board and refresh the whole design of the DOHC head, using better materials and modern technology.

One of the main changes are the cam caps. These 2-piece items used in the newer “Z-version” not only reduce friction, but are shorter than the bulky 1-piece round items that were implemented in the original design. Furthermore for 2013 the whole lower structure of the caps has been changed with a more complex and rigid design. Valve adjusters have also been changed from screw type to bucket & shim, helping lower mass and make the engine rev more freely.  And since the new head allows more revs now, cam and rocker lubrication has been altered for better performance at all engine speeds. One of the options that is being offered is the gear conversion that replaces the chain drive distribution system…

…with a series of cams. This has quite a few benefits, first of which it eliminates the slack chain systems have, as well as guaranteeing reliability at high rpm. Seeing this engine spins to 10,000 rpm, that’s a good thing. Cams not only sound nice but as you can see are actually quite compact and OS Giken offers a very nice billet aluminum cover that, to those in the know, will hint something very special has been done to this motor.

This particular engine is one of their development motors and runs the best components and options that OS Giken offers like a forged and counter balanced crankshaft, H-section connecting rods and oversized pistons. The increased stroke, 86 mm over the stock 79 mm and the bigger piston diameter of 89 mm, bump capacity to 3,208 cc. For those that opt for this complete engine OS Giken will also revise the oil circulation with better jets and fit a crank case reinforcement plate to keep the internals from torquing the vintage block. On this latest version of the complete TC24 engine, an ATI crank damper is also fitted to keep harmful crankshaft harmonics at bay.

Drive is sent to the transmission via one of OS Giken’s clutches and lightened flywheel.

This engine breathes through Weber carbs but can also be converted to fuel injection if the customer so requires.

The TC24-B1Z of course also comes with optimally designed intakes…

…although these stunning dry carbon trumpets are still a prototype part. As it stands this engine can churn out 420 HP at 9,000 rpm and 392 Nm (289 lb/ft) at 8,000 rpm thanks also to the increased compression (11.5:1 vs 11.0:1). With the improvements in design the red line has been raised 1,000 rpm to 10,000 rpm compared to the original TC24 head.

Here is a quick look at the equal length stainless steel headers the complete engine comes with…

…a six-into-two design. All of this makes the TC24-B1Z one of the best sounding straight-sixes of all times!

The complete package is topped off with a large billet aluminum oil sump and extended pick up. Nine of these wonderful motors have been built so far and since Okazaki-san can’t ever stop fiddling around with this beast I am sure this isn’t the last iteration of the engine we will see. Dry sump lubrication next maybe?

OS Giken

Nostalgic 2 Days 2013 coverage on Speedhunters

-Dino Dalle Carbonare

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113 comments
Zed Trev
Zed Trev

Yeah, great! HTF do I buy one??

rpmtapmpa
rpmtapmpa

love the idea! but im shure it would suck to adjust the clearance between the gears if you ever had to resurface the head or deck the block.

71Hako
71Hako

420hp !!!… any sound and / or vision of this ( the NEWER version) engineering artwork running in a an appropriate vehicle? This is just gorgeous !

JapCarVideos
JapCarVideos

That's very, very sexy. If I built that I don't think I'd ever be able to stop looking at it...

Patto
Patto

Anyone know where to get carbon trumpets like these from?

dalton
dalton

this is the kind of stuff i could read all day

KillerRaccoon
KillerRaccoon

Cams are the things driven by those gears. They're called "gear-driven cams"

 

Difference.

HeathvanderWaerden
HeathvanderWaerden

Water outlet manifold above the exhaust ports? These guys have done their homework. There is a lot of over-the-top fiddly stuff that is just mechanically impressive (engine porn) and doesn't really need to be there, but this is DAMN good none-the-less.

Nikhil_P
Nikhil_P

whats the advantage of having a all the headers an equal length apart from not only looking amazing and sounding great?

ive had many explanations but not a proper one!

milkplus
milkplus

Gorgeous... but all those tiny bits are terrifying.

apex_DNA
apex_DNA

What an engine! When you see a harmonic balancer especially an aftermarket unit you know whoever built this knew what they were doing...reliability is key.

Rbaez
Rbaez

Great shoot and article thumbs up! amazing engine.

MannyManiac
MannyManiac

Love, love, love the way you shoot man. It's decided, first chance I get I'll have to get another Z.

2222222
2222222

That thing is absolutely sexy! :)

I'd love to see more tech-related aritcles in the future :)Greetings from Germany!

 

shconer
shconer

I think you mean a series of gears instead of cams.

S30z
S30z

More HQ pics please

izzy_ortiz
izzy_ortiz

I believe the original TC24 engine was tested (one fitted to an S30) against a 911 and beat it in everything except top speed.  Which gearing was set low to begin with anyway.  I wonder why they didnt use O.E.R. carbs?

 

 

perpetualroad.wordpress.com

 

Fg2_FrAn
Fg2_FrAn

this. must. sound. Like heaven itself...Wow, that amazing work. I've heard of retrofits and restorations. But seeing new technology complimenting old technology is quite cool

econti
econti

So how many are they planning to make? And will the head be available as a standalone?

 

Jesus Christ that is awesome.

zamm333
zamm333

oh my lord. everything on this engine is just beautiful, the carbon stacks, the huge fuel rail, and by god those headers are so sweet.

hanablemoore
hanablemoore

What is the tooling cost to create your own head. I mean molds, foundry cost, the materials used, and even the prototype. I wonder how much did it cost him from the first 1 he made to the most recent version?

oneraceing
oneraceing

I want one of these! Birthday please!

 

FunctionFirst
FunctionFirst

I used to have a gear drive set-up in my 383 SB Chevy, sounded fantastic. I wonder if there's any whine or noise similar with this gear-driven set-up.

Ben Scales
Ben Scales

Perhaps i didnt read well enough, but is there a sump system that keeps the gears lubricated? id imagine theyd get pretty warm at 10k RPMs

Corey K
Corey K

Un-frickin'-believable. I'm almost glad I don't own a 240Z anymore; I always want the best for my cars, and I couldn't afford this in my wildest dreams! I'm glad they're building them again, and that it's a fresh new design to boot!

BeamsAE86
BeamsAE86

Guys what are the springs attached to the exhaust pipes for?

WIDEMR
WIDEMR

You wouldnt want to get your tie caught in in those gears when your leaning over checking the timing!

Sumo_Power
Sumo_Power

@SPEEDHUNTERS That's a different, smart feature. Like it.

hanablemoore
hanablemoore

Taking the valve cover off this beast is like removing the top off your favorite stripper. It just brightened up your day!

Zeus
Zeus

Curious as to why they didn't use a tri-y setup on the headers. What's the firing order of the motor?

scibO
scibO

tell them the price son!!!id pay just to hear this thing run , would sound amazing

RyanKuan
RyanKuan

Pinnacle of the L-Series right here. This is what I wish to have in a Hakosuka

JSequoia
JSequoia

so remember when you guys did the weekly survey of NA or Turbo...?         now THIS is NA!!!  :D      and that compression ratio is getting awefully close to modern sportbike ranges!

zackspeed333
zackspeed333

So are they planning on making more parts???  This and the twin cam L20 where amazing sounding engines.  

klarky75
klarky75

@butcher__51 Ez alul vezérelt felül szelepelt lenne?

mrcandyman
mrcandyman

I don't think I even want to know the cost of this beast. It's gorgeous.


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