can anyone tell me how to identify an L16-L18-L20

[guzzirik]

I have a 1970 coupe with an A87 head and 720l on the pass side of the block. just bought it and curious. Thanks

[zKars]

A little flat pad on the block will have a stamp, either L16, L18 or L20. Next to it is another flat spot with engine serial number

[datzenmike]

Look behind the dip stick handle, left side...



You may need a wire brush or sand paper and good lighting to see it.

[qwik510]

I have a 1970 coupe with an A87 head and 720l on the pass side of the block. just bought it and curious. Thanks

Is is possible that it says “Z20” not 720?

[datzenmike]

The Z20 is stamped in the middle of the block on the left or driver's side of the block under the two exhaust manifold pipes..



Z22 but Z0 similar.

The Z20 is basically an older L20B block with a Z series head on it. The water jacket holes are differently placed but it uses the same L20B crank but 6 inch rods and flattop pistons. Two different Z series heads were used. One is 57cc which combined with the flattops produces an 8.4 compression for the '80-'81 A10 (HL510) The other is around 46cc and produces a 9 to one compression for the 720's Mileage option truck.


Probably miss reading the L and the B on either side of the L20B

[guzzirik]

That was easy...It's an L18. I don't suppose there is any way to tell which combustion chambers it has short of pulling it. The serial# is 818213 if that helps

[datzenmike]

Look along the bottom edge of the head just behind the #1 spark plug. With an L18, probably A87 open chamber which gives an 8.4 compression. There are closed chamber A87 heads around but I've looked and can find no mention of them being used on any N Am cars even though people swear they have them from new. It very unlikely Nissan used the closed chamber heads and 9 to 1 compression as this would foul up the emissions certification, besides it would have to be an option. Never happened. It's much easier to believe the closed chamber head (used in Japan) came here on an import engine in the 70s/80s and was swapped in or on more cheaply than a valve job or rebuilding it. This is why there are dual SU intakes and carbs floating around too.

Open chamber U67 or even the W58 will also work and keep the stock compression but have larger port diameters and in some cases larger exhaust valves than the A87.

Anything is possible after almost 50 years. An L16 210 head will also fit and produce 9.4 compression but it's severely restricted in valve and port size. I did put a 510 head on my L20B while the U67 was being milled, back in the 70s. It ran just fine. (better gas?)

[Cracker180B]

Look along the bottom edge of the head just behind the #1 spark plug. With an L18, probably A87 open chamber which gives an 8.4 compression. There are closed chamber A87 heads around but I've looked and can find no mention of them being used on any N Am cars even though people swear they have them from new. It very unlikely Nissan used the closed chamber heads and 9 to 1 compression as this would foul up the emissions certification, besides it would have to be an option. Never happened. It's much easier to believe the closed chamber head (used in Japan) came here on an import engine in the 70s/80s and was swapped in or on more cheaply than a valve job or rebuilding it. This is why there are dual SU intakes and carbs floating around too.

Open chamber U67 or even the W58 will also work and keep the stock compression but have larger port diameters and in some cases larger exhaust valves than the A87.

Anything is possible after almost 50 years. An L16 210 head will also fit and produce 9.4 compression but it's severely restricted in valve and port size. I did put a 510 head on my L20B while the U67 was being milled, back in the 70s. It ran just fine. (better gas?)

Enjoy your posts Mike. Over on OzDat too.

I just removed my L18 A87 head & it is closed (peanut). I recently purchased a rebuilt L18 that had a U67 L20B head on it (it was to be boosted) It has had flat tops installed when rebuild was performed. I will be fitting the A87 to it (looks to have been rebuilt a while ago as it's very clean). I don't think it's worth pulling the U67 cam off & using it though...

[datzenmike]

L18 with flattop pistons and open chamber U67 head???

That's going to make a (9.68 wrong) 9.027 compression.

The U67 cam is reputed to be the same as the cam for the L16SSS and L18SSS JDM engines. If it has these square humps between #2 and #3 it's an L20B cam.

[Cracker180B]

L18 with flattop pistons and open chamber U67 head???

That's going to make a 9.68 compression.

The U67 cam is reputed to be the same as the cam for the L16SSS and L18SSS JDM engines. If it has these square humps between #2 and #3 it's an L20B cam.

Both the A87 & U67 cams have the square humps. I've just checked them both now. They both also have U20 stamped on them too.

https://waggottcams.com.au/wp-content/u ... Series.pdf

I don't really want to use the open chamber head with the flat tops. Quelch all wrong & as I understand it. The flat tops were meant to be used with the peanut, closed chamber head.

I thought the combustion chamber volume (Compression ratio too I suppose) was the same for both the A87 open chamber & U67 heads?

[Byron510]

Here is a page of L series engine combinations initially published by Jason Grey in the 90’s, copied from a post by Richard N here on the realm in the 2000’s. It may give you more questions than answers, and doesn’t include the cc volume of the various cyl heads. But there is still a plethora of L series information in this one post that is very useful.

https://www.the510realm.com/viewtopic.php?t=2887


++++++++++++++++++++++

L series engine internal parts specifications and modifications

While searching for measurements of L and Z motor internal specs, I have found numerous errors in available published data sources. Many of these incorrect measurements originate from the Honzowetz book HOW TO MODIFY NISSAN OHC ENGINE. Honzowetz worked at Nissan Motorsports and appearantly knew Z cars but he really neglected the quality of the 4 cylinder info in the book. Even Nissan Motorsports catalog specifications are not always correct, they are sometimes guilty of truncating important decimals. The incorrect specs from the Honzowetz book were re-published in a 510 again backissue and are found on other enthusiast websites (datsuns.com, ugly datsun page). Do not trust everything you see! I have not completely verified all this data myself, it is just my best attempt to straighten out the prevailing confusion. Verify specifications yourself before buying parts!

The block heights listed in the Honzowetz book for the different L and NAPS-Z motors are the height from the oil pan surface to top deck. This is not a particularly useful number if you are trying to compute piston deck height at TDC. I researched a bit and came up with the more usefull measurements for height from crank centerline to top of block. With the crank centerline-to-deck measurements inhand, it was easy to see that there were some mistakes in the rod lengths in the Honzowetz data, especially among the NAPS-Z motors. I was able to double check some of the suspicious measurements in other sources. Knowing the crank stoke, deck height and piston pin height, I was able to make some reasonable guesses as to what rods Nissan actually used in different motor to achieve near zero deck height of the piston at TDC. (most of the L, Z series have the piston slightly below the block deck at TDC). With the corrected information, I experimented with a spreadsheet to design some hybrid crank, rod, piston, block combination. HOW TO MODIFY recommends not letting the top of the piston protrude further than 0.3mm above the block at TDC. The following is what I have come up with. Please comment if you have verifiable corrections to any of my measurements. Did I miss any other useful combinations?

A NAPS-Z20, Z22 or Z24 block can be modified to use a L-series cylinder head for better performance potential. A stock NAPS-Z head probably has performance equal to a stock L series head but modification potential for the NAPS-Z is limited. Altho a crossflow head may seem like a better design, the NAPS name is an acronym for Nissan Anti Pollution System and this head was not designed with serious performance or modification potential in mind. The Z20E head I examined had 37mm intake ports and 42mm intake/ 38mm exhaust valves and 45cc (dual plug) open chambers. The ports are set too low so there is a sharp bend in the port "shielding" much of the valve and little porting can be done due to close proximity of water jacket. The valvetrain geometry prohibits the use of larger intake valves or high lift/duration camshaft because the valves would contact eachother. It is possible to modify in order to adapt a L series head onto a NAPS-Z bottom end. Building a L/Z hybrid engine is much more envolved than just bolting the necessary parts together. If you have never rebuilt an engine or dont know what you are doing, just stick with a L20B swap! Further advice for converting NAPS-Z block to use L series head is HERE.

For compression ratio calculations, take into account the cylinder head chamber volume (see http://www.pl510.com/cyl_head.htm ), dish volume in piston top, volume contained within head gasket (crushed thickness is 1.2mm), chamber volume created by or occupied by the piston due to non zero deck height at TDC cylinder and the swept cylinder displacement (Pi*r^2 * stroke),.

Compression ratio =(total chamber volume at TDC+swept cylinder displacement)/(total chamber volume at TDC)

Example, stock L20B = (45.2cc + 11.36cc + 7.0cc +2.6cc + 488.0cc) / (45.2cc + 11.36cc + 7.0cc +2.6cc)= 8.4:1


Connecting rods
Center to center length, all use the same 21mm diameter piston wristpin.
L18, L28, L26--------------130.2mm
L16, L24---------------------133.0mm
L13----------------------------139.9mm
L20B, Z22S, early Z22E-145.9mm*
Z20S,- ------------------------??**
Late Z22E-------------------149.5m*
Z20E--------------------------152.5mm
Z24, KA24-------------------165.0mm


*Through 12/81, the Z22E used exactly the same rods, pistons as the Z22S. After 12/81 production date, longer but weaker looking rods were used in the Z22E. Motorsport catalog list the Z22E as having 148.6mm rods but if you order these (12100-D8110) you will get the 149.5mm rods. I am not sure if the 148.6mm rods exist or were ever used in stock applications. Part # 12100-A7660 is a 148.6mm rod but uses 23.5mm wristpin diameter, might work well with bronze bushing to reduce to 21mm pin size.

**Z20S rod length given as same as Z20E on the incorrect charts, Impossible considering 35.56mm piston pin height! Please contact me if you have a verified length for Z20S rod.

Pistons
Piston pin heights (center of pin to top of piston) / piston dish volume/ stock bore
L13, L24-------------38.1mm / 0.0cc dish / 83mm bore
L16, L26------------ 38.1mm / 7.01cc dish / 83mm bore
L18------------------- 38.1mm / 4.36cc dish / 85mm bore
L20B------------------38.1mm / 11.36cc dish / 85mm bore
L28 (early)---------- 38.1mm /10.90cc dish in 280Z, early ZX.('75-'80)/ 86mm bore
L28 (late)------------ 38.1mm /0.0cc Flatop in '81-'83 ZX / 86mm bore
Z20S------------------ 35.56mm / ? dish / 85mm bore
Z22S, early Z22E-- 35.5mm* / 9.32cc dish / 87mm bore
Z22E, late------------32.1mm **/ ? / 87mm bore
Z20E------------------ 31.75 / approx 13cc dish / 85mm bore (Ive also seen flattop Z20E pistons).
Z24-------------------- 34.0mm, / 15.0mm dish / 89mm bore
KA24----------------- 34.0mm / 2.8cc dish / 89mm bore
VG30E--------------- 31.75mm/ approx. 1cc dish/ 87mm bore


* Actual measurements of Z22S pistons yield 35.5mm. Honzowetz chart shows Z22S pin height at 35.0mm. There may also be 35.0mm pistons available?

** Actual measurement of late Z22E pistons have pin height of 32.1mm. Honzowetz chart shows Z22E pin height at 32.5mm. There may also be 32.5mm pistons available?

Note- there are two types of VG30E pistons, using eithor pressed in piston pins or full floating wristpins. The later full floating pinVG30E pistons have been verified to interchange with LZ series rods (with oil hold modification to rod). VG30ET (turbo) engines use larger non-interchangeable wristpins.

Piston information is published in the Federal-Mogul Pistons and SilvoliteCatalogs. Pin diameter height, ring pack type & position, piston crown configuration. Check out the silvolite online catalog for possibilities of non-nissan piston swaps. Most engines use wristpins larger than the datsun 21mm size, it might be possible to enlarge the connecting rod small end hole for the piston pin for non-nissan pistons with larger pin. (Or stay with nissan 21mm pin and use bushings between pin and piston?) BTW- some of the specs in the silvolite catalog for nissan pistons dont match other specifications I have seen, I would be suspicious of the silvolite specifications.


Engine Blocks
Block deck height, (crank centerline to top of deck)
L13, L16, L18, L24, L28: 207.85mm
L20B, Z20, Z22, L28diesel: 227.45mm
Z24, KA24: 247.45mm
Among the "medium" height 227.45mm blocks, it is rumored that the Z20S blocks have the thickest cylinder walls and can tolerate the largest diameter overbore because the Z20S blocks have the cylinders castings "siamesed" together without coolant passages between cylinders (like the L20B, Z20E and Z22 blocks). I have heard that some Z20E might also have siamesed cylinders but the Z20E block I checked was definitly non-siamesed.


Assembled stock engine deck height
L16 ('68-'73 510 and later years 521pickup)
bore 83mm, stroke 73.7mm
(stroke/2)+connecting rod+ piston pin height = 207.95mm
piston deck height: 0.10mm (above block)

L18 ('73-'74 610, and 620 pickup truck)
bore 85mm, stroke 78.0mm
(stroke/2)+connecting rod+ piston pin height = 207.3mm
piston deck height: -0.55mm (below block)

L20B (various '75-'80 610, 710, 200sx, HL510, pickup truck)
bore 85mm, stroke 86.0mm
(stroke/2)+connecting rod+ piston pin height = 227.0mm
piston deck height: -0.45mm (below block)

Z20E ('80-'81 200sx)
bore 85mm, stroke 86.0mm
(stroke/2)+connecting rod+ piston pin height = 227.15
piston deck height: -0.30 mm (below block)
These motors can come with eithor flattop or dished pistons.

Z20S ('80-'81 HL510)
bore 85mm, stroke 86.0mm
(stroke/2)+connecting rod+ piston pin height = 227.16
piston deck height: -0.29 mm (below block)
Rod length given as same as Z20E on the incorrect charts, Impossible
considering piston pin height! Using 148.6 rod length, the calculations
seem much more reasonable but this is entirely unverified.

Z22S ('81-'82 720 pickup) , early Z22E 7/81-12/81 200sx)
bore 87mm, stroke 92.0mm
(stroke/2)+connecting rod+ piston pin height = 227.4
piston deck height: -0.05 mm (below block)

Late Z22E (1/82-2/83 200sx)
bore 87mm, stroke 92.0mm
(stroke/2)+connecting rod+ piston pin height = 227.6 mm
piston deck height: +0.15 mm (above block)

Z24 ('83-'86? 720 pickup)
bore 89mm, stroke 96.0mm
(stroke/2)+connecting rod+ piston pin height = 247.0mm
piston deck height: -0.45 below deck (using 34.0mm pin height pistons)

Fedral Mogul Z24 piston pn 13013P has pin height of 33.8mm, and unspecified "recessed
head w/4 valve reliefs

------------------------------------------------------------------
Frankenstein motors:
collect all the parts at pick-n-pull JY and buy it as a rebuildable $50 short block


Medium block 2.4 Liter.
Stuff a Z24 crank and pistons into NAPS-Z or L20B block bored to 89mm by cutting down crank counterweights and clearance grinding block as per Ben Pila. This gives you a 2389cc L-series motor that doesnt require using defective (crack prone) Z24 block, fabricating timing cover, lengthening timing chain or modification to close hood. Z24 piston tops will need to be milled down slightly. Fedral-Mogul 33.8mm pin height pistons might not need milling? Click HERE for Bens write-up of necessary modifications.
Compression ratio with Z24 pistons and open chambered head is 10.25:1 before pistons milled.
parts: : modified Z22 block, modified Z24 crank, modified Z24 pistons, Z22S/ L20B rods
s/2+r+p: 227.7
piston deck height: 0.45 (above deck)


Stroker 2.3 Liter
Stuff a Z24 crank into a modified Z20/Z22/L20B block by cutting down counterweights as above.
No piston modification or block boring needed for 2283cc L series.
see http://hobbslaw.nissanpower.com/custom2.html for an example
Russ noted that his deck height measured -1.77mm with the Z22E pistons that he first tried using, he eventually used milled Z22S pistons to achieve a higher compression ratio.
Parts: Z24 crank, Z22E pistons, Z22S/ L20B rods in a Z22 block or +2mm bored Z20/L20B block.
s/2+r+p= 96/2+145.9+32.1= 226.0 mm
piston deck height: -1.45mm below deck


Big Bore 2.3L
KA24 pistons into a bored Z20/Z22/L20B block. The small 2.8cc dish area of the KA24 pistons helps to preserve compression ratio even with the low piston deck height. Compression ratio with a open chambered U67 head is 9.9:1 or use dished Z24 pistons and peanut chambered head for 8.9:1 compression ratio.
Parts: Z22 crank, KA24 pistons, Z22S/ L20B rods in a +2mm bored Z22 block or +4mm Z20/L20B block.
s/2+r+p= 92/2+145.9+34.0= 225.9 mm
piston deck height: -1.55mm below deck


Longrod 2.19L/2.24L
Start with VG30E pistons and have the tops milled by 2.7mm to produce 29mm pin height. Custom pistons of similar specifications would also be recommended. Using the long Z20E connecting rods gives this engine a better rod/stroke ratio of 1.66:1. (stock Z22 rod/stroke ratio is 1.59:1). Start with +1mm VG30E pistons and bore the block +1mm to 88mm to gain a bit more displacement (2238cc). This engine with custom 89mm pistons is rumored to be the basis for the "rebello 2.3L".
parts: Z22 crankshaft, Z22 block, Z20E rods, milled VG30E pistons.
s/2+r+p: 227.5mm
piston deck height: +0.05mm (above block)



Long rod 2.1 L
I really like the possibilities for this 2.1L longrod motor. For a more in depth analysis of this motor click HERE.
Parts: L20B crank, Z22E pistons, Z20E rods in a Z22block or Z20/L20B block bored +2mm
s/2+r+p: 227.9mm
piston deck height: +0.05mm (above block)



Long rod L18
flattop Z20S pistons and peanut chamber head for 9.7:1 CR, better rod/stroke ratio for higher RPM.
Parts: L18 crank, L18 block, L16 rods, Z20S pistons
s/2+r+p: 207.66mm
piston deck height: -0.29 (below deck)


Low compression combinations for use with turbochargers

Turbo 2.2L
7.87:1 Compression ratio with 45.2cc open chambered head.
Parts: Z22 crank, 2.2E pistons, Z22S/L20B rods in Z22block or Z20/L20B block bored +2mm,
s/2+r+p: 224.4
piston deck height: -3.45 (below block)



Medium-Long Rod Turbo 2.05L
Use 32.1mm piston, 149.5mm rod from late Z22E. These rods are not as sturdy as onther L series rods.
Parts: L20B crank, Z2.2e pistons, Z22e rods, Z22 bock or Z20/L20B block bored +2mm over
s/2+r+p: 224.1
piston deck height: -2.85 (below block)


Short Rod L16
This is my current low compression L16 for turbo use.
7.8:1 CR using 37cc cylinder head. Lowering compression of a L16 would be easier by just installing a open chambered L20B head and using stock bottom end. I just wanted to utilize a good 37cc head I already had.
parts: L16 crank, L18 rods, L24 (flattop) pistons, L16 block.
s/2+r+p: 205.2mm
piston deck height: -2.70mm (below deck)



Turbo L18
Use deep dished L20B pistons in a otherwize stock L18 for 7.63:1 compression ratio (using open chambered head) or bore +1mm and use dished 280Z pistons for 7.85:1 compression ratio.

[Cracker180B]

"Here is a page of L series engine combinations initially published by Jason Grey in the 90’s, copied from a post by Richard N here on the realm in the 2000’s. It may give you more questions than answers, and doesn’t include the cc volume of the various cyl heads. But there is still a plethora of L series information in this one post that is very useful."

Thanks Byron, I have read this info over @ OzDat, as I'm in Aus. But, not all on the same page as you've put it. Brilliant! This explained things in length. Thank you

Pretty sure I read that the combustion volumes for the L18 & L20B open chamber heads are the same. Around 45cc. But, that can't be right in these next 2 scenarios that have been covered plenty of times:

a) L18 Block with flat tops & A87 closed chamber (same as SSS) = 9.5:1 comp
b) L18 Block with flat tops & U67 open chamber = 9.68:1 comp. This is what confused me badly...

From this info you've posted. I can see both the piston dish volume & deck height would make the difference when it comes to the static compression ratio. That would explain why an L20B block used, in place of the L18 would automatically give significantly higher compression ratio. But if so, proves the stock open chamber L18 & U67 heads can't have the same combustion size. The U67 gives higher end compression ratio, apparently.

"Turbo L18
Use deep dished L20B pistons in a otherwize stock L18 for 7.63:1 compression ratio (using open chambered head) or bore +1mm and use dished 280Z pistons for 7.85:1 compression ratio."

Had to laugh to myself @ the absurd thinking way back concerning turboing an engine. Those extra low comp ratios stated above would give horrendous turbo lag lol. The set up on this rebuilt engine was 9.68:1 apparently, as datzenmike had informed me Most stock boosted models today with clout run around 9:1 - 10:1 comp. Of course, that's due to EFI & tuning tech advancement etc

[datzenmike]

L18 with flattops and any closed chamber head.... 9.68 compression
L18 with flattops and any open chamber head...... 9.02 compression

[Cracker180B]

L18 with flattops and any closed chamber head.... 9.68 compression

In a few posts above, you said "L18 with flattops and U67 head will give 9.68 compression" Thought you must've meant closed chamber, as the L20B U67 head is only open chamber. That's why I was confused. I've read your info elsewhere (very much appreciated) & you know your stuff

I have read that the L20B with flat tops & closed chamber head (A87 peanut) will give around 10.2:1 so, I gather it's due to both the piston dish & deck height of the L20B that makes the higher compression, when comparing with the L18 block with flat tops & closed chamber head?

[datzenmike]

Yup I did post that. I have since corrected it to 9.027.

All my calculations use Jason Gray specs including the crushed gasket thickness of 1.2mm.