NA Vibes With OS Giken

After seeing so many turbos sticking out of hoods and mounted low inside bumpers, and superchargers stacked on top of big block V8s, it’s always nice to get a breath of fresh air and a little normality. Well, at least in a SEMA sort of way.

Enter Z Car Garage and the car it brought out to the Vegas show this year, a beautifully restored Hakosuka finished off in a not-so-subtle shade of bright red. Despite the catchy color, it was the gaping hole in the hood that everyone was looking at, as it presented what is one of only two OS Giken ‘TC24′ cylinder heads that are currently fitted to engines in the US.


The original TC24-B1Z was a twin-cam head that OS Giken developed back in the ’70s for the L-series engines. Not many were produced, but they were revered as hands-down the best possible modification that could be made to that engine. It gave a big bump in power, torque and response, and completely changed the character of the straight six.


About 10 years ago, OS Giken decided to bring the TC24-B1Z back, albeit in a refreshed and evolved version. We’ve seen a few in Japan, but it’s always nice to see people abroad appreciating these sort of special parts.

In the case of this car, the OS Giken head is fitted on a LD28 diesel block from a Maxima, which has been fully upgraded with a Crower crankshaft, Molnar Technologies connecting rods and JE forged pistons and rings. Compression sits at 10.8:1.


On the intake side you’ll find a row of 50mm Jenvey throttle bodies run off an Adaptronic 420d engine management system, which with tuning has revealed peak power output of 470hp and 330lb-ft of torque on Californian 91 octane fuel. With a camshaft upgrade (currently in development) and a switch to race fuel, Z Car Garage is expecting even more out of this unique naturally aspirated package.


The Hakosuka is properly built to take some abuse at the track too, with a roll cage stiffening up the 40-plus-year-old chassis and a new HANS-compatible Bride seat to complete the ensemble.


Finally, the exterior has an authentic vintage race car look with the addition of fender flares, a deck spoiler, bumper delete and the all-important oil cooler mounted on the front grille.

Dino Dalle Carbonare
Instagram: speedhunters_dino



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jeeezus 470+ na hp out of a 6


Daaaang! Are there any other photos of this car from broader angles floating around? Looks like a rad paint scheme on the side of the car, I wanna see that in full effect.


i dig it


470hp / 350kw out of an NA straight 6!!
Even the 2JZ NA builds don't got that far. Damn son!




There is no way this thing puts down 470hp. I mean no way :)
Here we call these American ponies. I bet the reality is closer to 300hp


No way it's 470HP. Original TC24B1Z engine with 3.2l puts down 420 hp (i believe it's a crank number, so it's like 380-390 from wheels). 470 from this combination on a 91 gas - i don't believe it.


Love it! A great Hako!


I am inspired that someone able to earn $10230 

in 1 month on the internet ..............


326powah Why would you not believe it? This cylinder head was custom designed to create the maximum power possible out of an L28 based engine. With advances in CFD modeling which I am sure was used in the revamping of the head, I do not see why this is not feasible.


I believe its the american kind of horsepower..

Youtube is full of videos featuring "2000HP" Mustangs, "1500HP" Supras, etc.

It must be the same kind of 470 horsepower, running on BS.


i23sonny well making more than ~230hp with inline 6 isn't that hard..


asddasdsa i23sonny You can make 300whp out of n/a2JZ


Diesel block with a OS Giken head, but runs 91 octane? Can someone ELI5? Is the compression ratio altered by the crankshaft and pistons along with the new engine management?


Mustang dynos are getting more and more generous.



I dont belive this engine can put down 470 hp on 91 octane and 10.8 compression. and there is no way it can make around 330 lb.ft torque. on an engineering perspective the volumetric efficiency on N/A can not reach that value. but if you forget about the torque value and try to reach the mentioned numbers it should give about 240 lb.ft torque @ 140000 rpm . these are true engineering calculations, anyone can spend some time and study these online if interested.


AirLift_Lucas 326powah please read my comment above. i did some maths , then make your mind about believing or not. i tried to be very optimistic on numbers, do you think this can rev 14000 ?


Work of art, right guys?
★Signature: ™007-License-Plate-Hide-Gadgets by: ™★


That TC24 is the thing of dreams, it's weird what kind of effect a cylinder head can have on a man.


Chris Nuggets  Its a diesel BLOCK but using custom pistons and rods. Engine management will not change compression ratio. Only the physical components of the engine alter compression. The block design is almost identical between L28 and L28D. The only main difference is the strength of the main caps.


326powah Yea, hard to get another 50hp with the same displacement, the original cams were not exactly street cams either so they aren't leaving a ton of power on the table I imagine.

They've lowered the compression for the crappy gas, could the tune, lighter pistons, cams & crank add that much power? If anything it just goes to show the number OSG gave were legit! 

Even 420hp out of an NA 3.2l is impressive!


Hello Speedhunters!

My name is Alvin and I am a Datsun owner/fan. I also write for the shop blog over at

A little history on our first OS Giken TC24B1Z install into a Datsun 240z last year:

This build was based on a 3.3L block, 10:1 compression with triple 50mm Mikuni's running 91 octane.

It made 430hp on an engine dyno. On our chassis dyno, it put down 376hp/281tq to the wheels. 

You can see the dyno run and engine dyno in action in this (rather long) video documenting the build, direct links below:

Chassis Dyno:

Engine Dyno

This year we were super stoked to build another TC24 for a customer's Hakosuka and display it at the OS Giken booth at SEMA. 

It made 470hp on the same engine dyno. We have not run it on our chassis dyno yet. The Hako is now in LA for Auto Show and when it come back to San Jose we will post up the results. I will also do a full feature on the build with some video. 

For now, enjoy the sounds of the TC from the SEMA roll-out!


ps thanks for the feature Dino!


as Jeff said, I'm surprised that anyone can make $9248 

in 4 weeks on the computer ...............


I was totally writing the LA Auto Show off this year but now I am willing to go just to see this thing. Are you gonna have a booth or stand and which hall?


Andy always comes up with some crazy shots, must be the beard! =P
             see more detail


ZCarGarage the builds you have made are one of the very best out there. and your team are profesionals it can be understood. but ı can not make mind to belive this engine is capable of 130 hp/liter on 10:1 compression 91 octane gas @ 7750 rpm. these numbers can be seen on hillclimb builds but with higher compression and higher octane fuels. ı


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Now this is a amazing old picture of when Nissan made the engine before OSGiken


get paid $98 bucks every hour for work at home on my laptop.

I never thought I'd be able to do it but my good friend is earning 18k /monthly 

by doiing this job and she showed mee how.(Copy And Open This)


like Emily explained I can't believe that some one able to make $6869 in one month on computer see it.......



>>>>I'm surprised that anyone can make $9248 

in four weeks on the computer .

you could try here>>>>>>>>>


abezzegh87 ZCG come to their number via their own dyno and their work/dyno are trusted by none other than Canepa Motorsport among many other reputable race teams and privateers.


I cant believe that some one able to earn $8736 

in 2 weeks on the computer ..........




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I am inspired that anyone can earn $7391 in 4 weeks ..................


ZCarGarage the most important question is how much will this head cost and when is it available for sale in the U.S. ? I want to put one on my L28 that i have in my '79 620 Kingcab....


Those power figures are total bs. They claimed 376 HP at the wheels. 470hp at the crank would be over 25% drivetrain loss, Which doesn't even make sense. None the less, love the simplistic build. But that thing needs a muffler, way too loud.