How to make a Datsun 240Z rev like a Honda S2000 (and not blow up)

Colin
By Colin Wood
Aug 5, 2021 | Datsun, Nissan, 240Z, Z-Car Garage, Datsunworks, KN20

Photography Courtesy Z Car Garage

Yes, you can make a Datsun 240Z rev past 8000 rpm without detonating it. No, you don't need witchcraft to do so.

Instead, start by mating a custom head based on Honda K-series technology to a Datsun L-series bottom end.

Besides the improved flow rate offered by a modern valvetrain, this unique piece of engineering effectively transforms the single-overhead-cam L-series into a high-revving, dual-overhead-cam engine.


The head was built by Datsunworks and further developed with help from Z Car Garage.

Only 10 of these kits currently exist–there's confirmation that more are on the way–with one of them installed in a 240Z known as the Behemoth.

Although the Behemoth is “still in the tuning phase” and running a conservative tune, Z Car Garage was already able to extract 350 horsepower at the wheels using 91-octane fuel.

More of these KN20 kits are on the way, with a lead time of about three or four months. In the long term, the shop wants to offer a bolt-on setup for customers looking to add power to their L-series engines. It also hopes to offer customers with a dedicated shop car for test drives. 

Price for a basic kit–head, timing cover, valve cover, valve guide and seats–starts at $9000, and plenty of optional extras are available for purchase, including Honda OEM cam bolts, a DCOE intake manifold and an aluminum upper tensioner.

Visit the Datsunworks website for a full breakdown on parts and pricing for the KN20 kit. Head to Z Car Garage for further updates and information on the kit's development.

Besides the 240Z, what other L-series-powered cars would you put this kit in?

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Comments
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MadScientistMatt
MadScientistMatt UltimaDork
8/4/21 8:09 a.m.

I had clicked on this expecting to see it was a 240Z with a Honda motor swapped in. That could be interesting, but this is WAY more impressive.

APEowner
APEowner GRM+ Memberand SuperDork
8/4/21 8:17 a.m.

This is incredibly cool but in today's world I don't know that there's really a market for $9,000.00 engine upgrades that only deliver 350 HP to the wheels.  I just don't know if there's enough people who are willing to drop that kind of coin on cool.  I hope I'm wrong though.

tuna55
tuna55 MegaDork
8/4/21 8:56 a.m.

I am going back and forth. $9K seems like a lot for a cylinder head and some parts, but then again an engine swap is going to cost you a bunch if you ditch the L.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
8/4/21 9:22 a.m.
APEowner said:

This is incredibly cool but in today's world I don't know that there's really a market for $9,000.00 engine upgrades that only deliver 350 HP to the wheels.  I just don't know if there's enough people who are willing to drop that kind of coin on cool.  I hope I'm wrong though.

You might be amazed at what some people will spend.  I was told that a certain Fiat shop was getting $10k for X1/9 engine rebuilds.  That's a lot of money for 100hp or so.

Subject takes me back to when I was interested in 240Zs because a friend had bought one.  Someone found a Japanese company that made a setup that eliminated the timing chain guides in favor of one or two idler sprockets, making the chain drive good up to 14,000rpm, or at least, so they claimed.  Commentary on 240Z forum:  "So all I need is this to allow me to rev that high?"  No, you need a lot more than that, but this is one of the things that will help you get there.

 

I mean, personally, the first thing I'd do would be to get the heavy, high-friction chain out of there and install a belt drive, but what do I know?

Mr. Peabody
Mr. Peabody UltimaDork
8/4/21 9:30 a.m.

You'd be surprised at what some people will spend on a Swift GT engine. And while it will rev and make fun noises, it will never make any meaningful power.

Is $9k too much? Yes.

Will hard cores spend it? Yes.

Robbie (Forum Supporter)
Robbie (Forum Supporter) GRM+ Memberand MegaDork
8/4/21 9:35 a.m.

Mr Asa - you have a bogey. 

stylngle2003
stylngle2003 GRM+ Memberand Reader
8/4/21 9:43 a.m.

dude kind of drives like an shiny happy person, but it sounds wonderful.

Streetwiseguy
Streetwiseguy MegaDork
8/4/21 9:45 a.m.

It's not terribly hard to build an L24 that will run 8,000rpm...

iansane
iansane HalfDork
8/4/21 9:54 a.m.

Hubba, hubba.

A modern crossflow head is always what that L series needed. It's so bloody expensive but probably worth it for the improvement. Obviously not for max hp numbers but I think I'm starting to get to the age where I don't just want to swap the biggest/most hp engine into a car but meddle around with a weird swap or mod to see what it can achieve.

Rodan
Rodan SuperDork
8/4/21 10:00 a.m.

I remember looking through the Nismo catalogs back in the 80s and drooling over the OS Giken head for the L24-28s back then.  Good to know there's at least one other super expensive, unobtanium head for the Z... cheeky

Datsun310Guy
Datsun310Guy MegaDork
8/4/21 10:55 a.m.

I starting to think $9000 isn't much these days.  After this video I'd rock it.  

I also have the OS Giken brochure and it's sweet.  
 

 

wspohn
wspohn SuperDork
8/4/21 11:04 a.m.

Saw the title and figured I'd see a 240Z with an S54 engine in it, maybe with a turbo.  Or perhaps  2JZ engine.

Impressed that the bottom end holds up well to that sort of rpm use, though.

j_tso
j_tso GRM+ Memberand Reader
8/4/21 11:45 a.m.
Pete. (l33t FS) said:

Subject takes me back to when I was interested in 240Zs because a friend had bought one.  Someone found a Japanese company that made a setup that eliminated the timing chain guides in favor of one or two idler sprockets, making the chain drive good up to 14,000rpm, or at least, so they claimed. 

Was it this setup from OS Giken? I think they made a single cam version as well.

 

thatsnowinnebago
thatsnowinnebago GRM+ Memberand UltraDork
8/4/21 11:59 a.m.

That sounds so good

Tom1200
Tom1200 SuperDork
8/4/21 12:47 p.m.

Datsun guys are spending more for less horsepower now; mostly on vintage race engines but in this realm that's not a lot of money.

noddaz
noddaz GRM+ Memberand UberDork
8/4/21 12:57 p.m.

Wow.

Spendy, but wow.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
8/4/21 1:00 p.m.
j_tso said:
Pete. (l33t FS) said:

Subject takes me back to when I was interested in 240Zs because a friend had bought one.  Someone found a Japanese company that made a setup that eliminated the timing chain guides in favor of one or two idler sprockets, making the chain drive good up to 14,000rpm, or at least, so they claimed. 

Was it this setup from OS Giken? I think they made a single cam version as well.

 

Cool, but no.  The link was to a Japanese website (and you know how awesome those were 20 years ago!) and it was not a geardrive, it was idler sprocket(s) for the existing chain, to eliminate the guides.

I would think that you NEED the guides to prevent the chain from resonating all over the place, you know?

 

Edit:  Or... I could just start searching around for L24 cam chain idler and see what happens.

 

KAMEARI Twin Idler Gear Setup

Eliminates the timing chain tensioner in favor of a manually adjustable setup.

 

There's a hack for Ecotec timing chain tensioners that converts them to a manually adjusted unit with an external screw, and something similar for Duratecs, for the same problem this company is solving.

Countingcrowbars
Countingcrowbars UltraDork
8/4/21 1:24 p.m.

Pff. My entire rebello L28 engine revved to 9,000rpm and only cost me $10k, and used a Datsun n42 head. 
 

neat to see, but let's hope those "10 kits" don't go the way of the old OS Giken dohc head

californiamilleghia
californiamilleghia SuperDork
8/4/21 1:44 p.m.

was there ever a factory  Nissan straight 6 Motor with DOHC  

its a neat idea  just spendy !

MadScientistMatt
MadScientistMatt UltimaDork
8/4/21 1:51 p.m.
californiamilleghia said:

was there ever a factory  Nissan straight 6 Motor with DOHC 

Most of the RB series motors.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
8/4/21 2:01 p.m.
MadScientistMatt said:
californiamilleghia said:

was there ever a factory  Nissan straight 6 Motor with DOHC 

Most of the RB series motors.

Which are, apparently, an evolution of the L series sixes.

 

Also, the S20, used in the Skyline GT-R and the Fairlady Z432.  I used to think this was just a DOHC version of the L20, but it turns out, the Nissan L20 had problems, so when Nissan acquired Prince, they redesigned the engine using the Prince G-engine as a starting point - the L-series (starting with L20A) and the S20 are both based on that Prince engine, but the Prince engine came first.

 

Apparently there'd been a lot of cross-company rivalry between the former Prince company (which made the Skyline) and the old Nissan company (which made the Fairlady), which is why they often got completely different engines.

GB
GB New Reader
8/4/21 7:03 p.m.

Sounds nice ....

frenchyd
frenchyd UltimaDork
8/4/21 7:31 p.m.

In reply to Colin Wood :

Is the bottom end strong enough stock to take 9,000 rpm?   Am I to assume it will go over 9,000 because people do miss shifts etc. 

mikeatrpi
mikeatrpi HalfDork
8/4/21 7:39 p.m.

Wow that's cool.  

j_tso
j_tso GRM+ Memberand Reader
8/4/21 10:42 p.m.

In reply to frenchyd :

Z Car Garage link says this head is on a 3.2L Rebello engine, so it'll take 9000.

Peter Brock recounts the L24's vibration issues above 7000 in this Classic Motorsports article

malibuguy
malibuguy GRM+ Memberand HalfDork
8/5/21 7:12 a.m.

I love how they kept it classic looking.  This is badass

people will buy it, but it obviously not going to be sold in the 1000s

If it were me, Id rock an NA RB fwiw

wspohn
wspohn SuperDork
8/5/21 11:02 a.m.

One issue I wonder about is why modern engines that can run for 200.000 miles with fuel injection (old days = more like 100,000 with cars with carbs that washed down the cylinder walls under choke) have pretty much completely switched to single width one row timing chains.

Yes, it saves some money and a small bit of weight, but a simplex chain wears more quickly than a duplex, so in an engine that will get higher miles put on it you choose the lesser chain that will be a maintenance pint for sure before the rest of the engine wears out.  Bean counters again?

Oh well, we have come a long way from a 1954 Healey I used to own which had the simplest tensioner (bar none at all) - a rubber ring that you installed under the chain on the large sprocket. You can guess how long those lasted.

frenchyd
frenchyd UltimaDork
8/5/21 11:25 a.m.

In reply to wspohn :

Manufactures don't want cars to last a lifetime. They want to motivate you to replace the car often.  10-15 new cars in your lifetime is their goal.  

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
8/5/21 11:32 a.m.
j_tso said:

In reply to frenchyd :

Z Car Garage link says this head is on a 3.2L Rebello engine, so it'll take 9000.

Peter Brock recounts the L24's vibration issues above 7000 in this Classic Motorsports article

IIRC, that issue was only in the very first 240Zs - as in, the first shipload in 1969.  Later cranks had revised counterweighting.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
8/5/21 11:34 a.m.
wspohn said:

One issue I wonder about is why modern engines that can run for 200.000 miles with fuel injection (old days = more like 100,000 with cars with carbs that washed down the cylinder walls under choke) have pretty much completely switched to single width one row timing chains.

Yes, it saves some money and a small bit of weight, but a simplex chain wears more quickly than a duplex, so in an engine that will get higher miles put on it you choose the lesser chain that will be a maintenance pint for sure before the rest of the engine wears out.  Bean counters again?

Oh well, we have come a long way from a 1954 Healey I used to own which had the simplest tensioner (bar none at all) - a rubber ring that you installed under the chain on the large sprocket. You can guess how long those lasted.

Friction, size, weight.  Double row chains are also really, REALLY overkill for a DOHC engine with its light valves, light springs, and low lifts.

Toyota still uses large pitch chains, most everyone else has gone to 1/4" pitch give or take.  Those chains are the ones that have stretch issues, lots more pins and holes in plates to wear.

ShawnG
ShawnG UltimaDork
8/6/21 2:15 p.m.

Being that there are already DOHC Nissan I6 engines available, the only reason I could imagine someone spending money on this is if there were some rulebook restriction that mandated a stock block but any head you wanted.

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