L20S ???

[datzenmike]

Yes.

 

Oct. 1965 - Nissan L20

Nissan's first over head cam, L Type, in-line six cylinder engine was designated the L20 and was introduced in Oct. of 1965 in the 1966 Model Cedric H130 Series (Mark 1), Special Six, which went on sale in early 1966.

In 2004, Mr. Kumano Manabu interviewed the man placed in charge of the design of the L20 and then wrote an article for Nostalgic Hero Magazine. Mr. Manabu reports that in April of 1964, Mr. Hiroshi Iida was assigned to the Second Engine Design Division, of the Design Organization at Nissan. The Second Engine Design Division was responsible for the design of larger displacement engines installed in the Cedric and others, as well as the large displacement engines used in trucks. The First Engine Design Division was responsible for the smaller displacement engines installed in the Bluebird (Datsun 411 and 510) and others.

Mr. Iida reported that the design effort took place on a very rushed schedule, lasting only four months from start to the production of test engines in Oct. of 64. The design cycle was rushed because Nissan wanted to keep abreast of its competition from Toyota.

Mr. Iida tells us this rapid design was accomplished by taking the drawings of the block, from a previously designed L Type 4 Cylinder Engine and adding two cylinders to it. Mr. Iida said that they used the Mercedes Benz OHC design, wherein 12 valves are driven by a single over head cam shaft via adjustable rocker arms. The Cam is driven by a double row, roller chain with power taken off the crankshaft.

During the engine development phase, where pre-production engines are built and tested; problems with the oil pump and distributor drive mechanism were identified and corrected. Problems related to the cam towers cracking were also identified and corrected.

It was later found that the production engines suffered from excessive oil consumption caused by problems with the design of the oil rings and the valve seals. Customers also complained about excessive noise, and poor fuel economy, brought about by the need to maintain the engine at high idle speeds. After the first year of production, several of these problems were at least mitigated in a second production run. The engine originally equipped with twin side draft type carb.'s - was then equipped with a single down-draft carb., and HP reduced from 123 to 112.

Because of its rushed design and development cycle, and the resulting problems that plagued it the L20 would be short lived in the Nissan line-up.

 

 

1970 - L20A

According to Mr. Iida, the design improvements found in the newer and more fully developed design of the L16, were too good to pass up, so L20A OHC, in-line six was designed to take advantage of them. The new 2.0 liter, OHC, in-line six based on the design of the L16 was designated the L20A.

The design cycle of the L20A was completed in Jan. of 1968, followed by the usual production prototypes, testing and then full production starting at the end of 1968. The L20A was introduced in Oct. 1969 for the 1970 Model Year. Introduced in the Nissan Fairlady Z, as well as in the new Cedric.

The L20A was an over-square design with 78mm bore and 69.7mm stroke, producing 125hp at 9.0:1 compression with twin side draft carb.'s.

Notes/Thoughts:

A high performance engine from Prince Motors, the S20 was featured in the Prince Skyline GT-R and the Nissan Fairlady Z 432. The S20 featured four valves per cylinder, three side draft carbs and two overhead cam's. This 1988cc six cylinder was also an over-square design with 82mm bore and 62.8mm stroke. It was rated at 160hp at 9.5:1 compression.

While the S20 provided a 2.0 liter, six cylinder engine with serious performance for the Japanese Domestic Market at a time when engines with more than 2.0 liter displacement were heavily taxed, it was at the same time mechanically complex and expensive to produce. The result was the limited production of the Fairlady Z 432 at a cost of 1.6 to 1.8 Million Yen {about $4500.00 to $5100.00 USD}.

With the L20A completing its design cycle in Jan. of 1968 and entering production by the end of that year, it would offer a less expensive 2.0 liter alternative to the S20 for use in the Fairlady Z. At 976,000 Yen {$2711.00 USD} the Fairlady Z was available to a far greater number of people in terms of both initial purchase price and operational costs in Japan.

Then with the relaxation of the punitive taxes on engines over 2.0 liter displacement at the end of 1971, use of the L24 became an optional performance enhancement resulting in the release of the Fairlady 240Z for the JDM in Oct. of 1971. The L24 producing close to the same HP as the S20 in stock form, with far less mechanical complexity was sold in far greater numbers than the limited production Z 432. Aprox. 4200 Fairlady 240Z's were sold in Japan during the 72 and 73 Model Years. The Fairlady 240Z equipped with triple side draft solex type carb.'s and high performance exhaust system the L24 was rated at 175 HP and replaced the Z432-R as Nissan's domestic competition car.

 

[metalmonkey47]

Intriguing, DATZENMIKE can't identify a block??

 

 

Subscribed. This is interesting.

[74datsun620]

I think the boat motor was marked L20 but I could be wrong.

[Dat Lurka]

It was a low compression factory Supercharged L engine.

[TFM1066]

It’s just an "L" series 2.0 liter 4 cyl carb motor, just because in the late 1980 Nissan went to the Z20 motor here in the states doesn’t mean they stop making them. We will never know when the last true L20b.e or s motor was last used or where.

 

For example the early in the Z car, L24 6 cyl has no other markings due to the fact there was no other options back then, but when the 810/maximas came out those blocks were stamped L24E because now there were two different L24, one carb'ed and one EFI. So this is same with the very late model L20 and all Z motors.

 

In my inventory I have many Z-20, Z-22, Z24 motors, all have different marks, none,E,S, etc after the motor size. All the late model L20 I have, have the tab casted on the other side of the block for the stamping of the traditional Z motors which you would think Nissan was killing two birds with one stone if it came to the states it was stamped Z20 with the cross flow head, going somewhere besides the states stamped L20 s or e. with the L head

 

Think......The Z22 and the Z24 both have that negative chamfer (cant think of the right word for it at the moment) on the mains and rods the Z20 does not nor does the L20. Z20 and L20 are the same, and made on the same line. The Z22 and Z24 were made in a, or on a completely different production/assembly line.

[Stoffregen Motorsports]

Well, all research aside, I would say it's a later model block, judging purely from the oil filter housing boss and the addition of the non-drilled water outlet boss. I am curious what the cylinder wall thickness is. The L20B blocks are not thich enough to bore .120 over (to 89mm) but the Z20 blocks usually are.

 

On a side note, I have a set of letter dies in my toolbox. Could someone have stamped it themself with an S?

[zed]

 

 

sorry for the crude photos... this is the block from my 1989 Nissan Hardbody. It's engine number is "L18S 254905R" stamped on the block. It's the standard engine in 1800cc South African Hardbodys. It came with V912 head, 4cc dished pistons (85mm), Nikki carb, distributor with points! You could say the ideal L motor setup for a beginner to learn on - with the help of legendary virtual mentors like Hainz and Datsunmike...

[datzenmike]

Excellent info. Our last L18 was '74. Always nice to hear more about them.

[72240z]

Wow a l18 in a hardbody, thats interesting. To think I used to complain about the power of my 5sp vg30 d21 lol.

 

So whats the S mean then? If its single carb why in a hardbody? Is that not correct or? I would say its safe they continued to use the same casting but that doesnt mean they had to stamp it lol.

[datsunaholic]

Notice that it does not say "NISSAN JAPAN" on it. Block was likely cast in SA. It appears to be a slight modification of the early L18 type block- it does not have any of the hallmarks of the later (1979+) Japanese blocks.

[RedBanner]

eoes the whole for the crank case vent point out or up. Didn't see the business side of the block. Measure the piston dish, turbo l4 block maybe.

[q-tip]

i would put my money on it being an non us/jdm market, europe or africa. possibly and early attempt at a z series block. i know that some manufacturers will put parts for the next body style or model change on the last years of a previous body style for proof of function purposes. also seen them use older pieces on newer models jsutbecause they have them laying around

[RedBanner]

O wasn't loading pics there had to refresh, I see the yellow l18s has the c.v. tube sticking straight out. Not only high it means something if I remember correctly. I had a verry long conversation with a dattoist in China, he was an Aussie Turing the big red.

He said that it was a sighn of a higher performance stock setup. Probably bullshit but who really knows.... Any one?

[ggzilla]

How is the block different from a Z block?

 

And what is the 3-digit casting number?

[datsunaholic]

Redbanner, the PCV tube sticking straight out doesn't mean anything special. That was normal for all L16 and L18 engines in the US. All L20B engines had the upward-facing port. The reason was the position of the PCV valve itself changed due to the addition of the EGR on the L20B (on the '74 L18 it wasn't "in the way" so to speak). So the PCV pointed rearward, the tube had to be rerouted.To clear the exhaust manifold the tube was routed back with a bend, then a curved hose connected that with the PCV.

 

The late L20B engines shared the exact same casting as the Z20 block. It is in fact a Z20 casting. The only difference was in the finish machining- the dipstick tube was installed on the opposite side, and the proper serial number plate was machined smooth and the numbers stamped in. In fact the dipstick could be in SEVERAL positions since cars vs trucks used different locations. Until that happened, the blocks could go either way.

 

Likewise, late L16 and L18 blocks came from similar Z16 and Z18 castings. All of those also had the upward-facing PCV. This wasn't normally seen on a L16 or L18 in the US, since the change to the PCV was concurrent with the introduction of the L20B in 1974, and the US didn't use the smaller engines after 1974. But they do surface as either JDM-market "Used" engines, or "Crate" engines (which are identifiable by having 2 dipsticks). This is more common with late L16 engines, since used JDM L18 engines were plentiful and typically had the side-facing PCV since they were pre-1979 manufacture.

 

 

All the above only applies to engines made in Japan. South Africa made L-series engines LONG after production stopped in Japan. In some cases, the tooling was shipped there after production ceased in Japan. The yellow block pictured above shows signs of improvements, but generally looks to be based on the mid to late Japanese L18 casting. It does not, however, say "JAPAN" on it, as far as I can tell. Generally a good indication of an African-produced engine. If ANY of those made their way to the States I'd be very surprised.

[RedBanner]

My l20b crank vent tube is straight out.,

[datsunaholic]

I'd heard that possibly the '74 610 one was, but having never had one I haven't seen one. Pictures required, I think.

[RedBanner]

Copy and paste from my 2 door thread. Excuse the rest of the quote... I tried to erase it. :( messed up like 6 times and it wouldn't work.

Damn, well I found some differences in the motors I had, the 610 l20b I had gotten from micro , disnt have the pcv tube. Found out not only was it a different angle, but it should be a larger diameter tube.

For now I have a "fix"

Windchime finely doing some good.

Left it plenty long, wish I hadnt. But its in, it runs,

It has machine shop stamps from 2/17/97 on the head (dry intake u67) and the block.

Big thanks,to micro machinery for the good deal on the l20b, to freaky510 for a coolent outlet and l16 mani,

Hanks to crackerjack for the split exaust manifold, and to phil for keeping a mental inventory of who has what :lol:

And greasemonkey for the storage space!

Also trimmed up the b210 facia piece for my cheapy airdamn. Wish I remebered who posted that idea.

I get an hour maybe 2 a night but atleast I get that.

 

As you read it is a 610 motor. Not that I thought it was a "higher hp stock motor" just hadn't seen another l20b block with tube coming straight out. Have on l16s and 18s tho. But the tube is a different diameter such is why I run the ol ' sharp wind chime lol

[datsunaholic]

That's right, I did see that thread now that I think about it. Anyhow I have one of the L16s with the later type. Wonder what the casting number is on that L20B- probably U60. Mine are U67 or later.

[Burabuda]

L20s is an engine code and

 

david is correct. s = single carb

 

these engines came in '80 720 trucks i believe

[datsunfreak]

Also trimmed up the b210 facia piece for my cheapy airdamn. Wish I remebered who posted that idea.

 

That would be me. B)

 

Firsties!

[RedBanner]

Lol, you diserve it. Tried to find that post several times. Gave me a great idea that didn't cost me anything. And post right at 710... And I have no likes... I never have any likes.

[merlin]

my 80 720 2wd engine is stamped l20b...

[datzenmike]

L20s is an engine code and

 

david is correct. s = single carb

 

these engines came in '80 720 trucks i believe

 

 

I can see it being on the engine tag under the hood. I can't see how/why the block would be stamped with what's supposed to be attached to the manifold on the head above it. It would make much more sense to stamp the head U67S. Don't you think?

 

I know that Nissan uses 'S' for single carb and 'i' for throttle body injection, 'R' for supercharger etc. etc. Stamping the block seems ridiculous for designating what carb was on it. I think the S must mean something else.

[72240z]

Especially since it seems to have been used on multiple cars not running a single carb.