L-Series engine specifications and modificatication info

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L-Series engine specifications and modificatication info

Post by torqued » Wed Apr 15, 2009 4:55 pm

L-Series engine internal parts specifications and modifications
Written by: Jason Gray
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 apparently 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 back-issue and are found on other enthusiast websites (datsuns.com for example). 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 useful measurements for height from crank centerline to top of block. With the crank centerline-to-deck measurements in-hand, 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, and 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?
Jason Gray

The Z-Series Motor
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. Although a cross-flow 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 valve train geometry prohibits the use of larger intake valves or high lift/duration camshaft because the valves would contact each other. It is possible to modify in order to adapt an L-series head onto a NAPS-Z bottom end. Building a L/Z hybrid engine is much more evolved than just bolting the necessary parts together. If you have never rebuilt an engine or don’t know what you are doing, just stick with a L20B swap!

Compression Ratio Calculations
For compression ratio calculations, take into account the cylinder head chamber volume, 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)
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. The Nissan 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.

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 (I’ve 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 measurements 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 either 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 Silvolite Catalogs.
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 don’t match other specifications I have seen; SO I would be suspicious of the Silvolite specifications.

Engine Blocks
Block deck height, (crank centerline to top of deck)
L13, L16, L18, L24 and L28 = 207.85mm
L20B, Z20, Z22 and L28 diesel = 227.45mm
Z24 and 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 definitely non-siamesed.

Assembled stock engine deck height
L-16 ('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)

L-18 ('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)

L-20B (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 either flattop or dished pistons.
Z-20S ('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.

Z-22S ('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)

Federal Mogul Z24 piston PN 13013P has pin height of 33.8mm, and unspecified recessed head w/4 valve relief’s

Frankenstein motors:
Collect all the parts at pick-n-pull Junk Yard

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 doesn’t 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? Read below for Ben’s 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.

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
Fit 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 an 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
Long rod 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 long-rod motor. For a more in depth analysis of this motor read below ****
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 other 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 iston 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 an otherwise 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.
*** Ben Pila’s write-up of necessary modifications to create a Medium-block 2.4 Liter
Here's what I've had in my 510 for the past 6 years and in my Coupe
before that and before that a red 510 (My friends.)

Early L20B block
Z24 crank (with .500") cut off each counter weight with no balancing
L20B rods cleaned up and shot peened
stock Z24 89.00 mm pistons cut down slightly on top (can't remember the
L20B (U67 open chamber head, ported, stainless big intake valves, Z
exhaust valves.) Jim Wolf/Schneider cam
dual 44 Mikinis, custom made tri-Y header
Dyno tested at 135HP, 147 Ft Lbs Torque to the wheels (~166 HP, 182 Ft Lbs
torque to the flywheel) This engine makes great power between

The trick to making the crank and rods clear the inside of the block.
You have to grind enough material where the counter weights hit to allow
a .016" feeler gauge to pass.  The crank has to be clearanced first then
each rod (with piston on it,) one at a time until the feeler gauge fits.
Some grinding on the main oil gallery must be done and if done carefully,
shouldn't be a safety issue.  My engine has been fine so far in that
area.  The block must be bored out to 89mm (4mm overbore,), which make the
cylinder walls thin.  The L20B block, which should be an early casting
number, should be ultrasonic tested before boring to check for any
casting shift.  Jim Wolf told me when he told me about this set-up
and sold me the parts, that some oil burning might happen later on in the
engines life sooner than most engines.  I do have a lot of oil burning
now.  I have had a problem trying to keep my coolant temperature down
when I run the engine hard.  Even with my 400HP capacity Griffin
radiator, I still have hit 250 degrees F. at the Thunderhill track at
Shasta (was 103 degrees F. there.)

I would have to say that if I did this set-up again later, I'd not bore
out the block so thin. I would recommend finding a piston with no more
than 2 mm overbore so cylinder wall flex won't be an issue.

Written by: Ben (in search of HP) Pila
Diehard Datsun Dime Dude
San Diego, California
 Jason's notes: Instead of using a L20B block, start with a Z22S block and bore it only +2mm for thicker cylinder walls or use the Z20S block with thicker siamesed walls. This 2.4L is probably the ultimate street-torque L series engine for a 510 were there is no replacement for displacement. (Except maybe a turbo motor) The very low rod to stroke ratio of 1.52:1 is well below desirable range so will limit high RPM effectiveness but make for great low/midrange torque.

**** Jason Gray’s write-up of necessary modifications to create a Long rod 2.1L motor
Parts: L20B or Z20 crank, Z22E pistons, Z20E rods in a Z22 block or +2mm bored L20B/Z20 block
This would be the best HIGH REVING, increased displacement and high compression, engine you could build from the medium height L20B/Z20/Z22 size block. A "standard" L/Z 2.2 would have 5% more displacement and better midrange torque than this engine but the 2.1 long-rod motor with 86mm fully counter weighted L20B/Z20 crank will suffer less vibration at high RPM than the 1/2 counterbalanced Z22 crank and the hybrid 2.1L will have a slightly over-square bore/stroke ratio, so better revving than the Z22 "truck engine”. The rod to stroke ratio of the 2.1L motor is 1.77:1. Of all the possible L series motors only the L16 has a higher rod/stroke ratio (1.80:1).
The long Z20E rods will reduce stress on pistons and help to make more HP at high RPM. The 1.5mm thick Z22E piston compression rings are thinner than 2.0mm L series piston rings so put less stress on the piston ring lands and are less prone to flutter at high RPM. In short, this motor should be a screamer if you build it well, balanced the rotating assembly, and use a suitable RPM cam, head and induction system.
  The HOW TO MODIFY bible cautions against allowing the piston to come further than 0.30mm above the deck top, when built with 32.1mm pin height late Z22E pistons (1/82 and later), this motor when build would have the piston tops 0.05mm above. The "bad" Honzowetz specifications chart list Z22E pistons as having 32.5mm pin height - so verify that you have the correct pistons!
With a high duration cam and high-octane gas to reduce risk of detonation, you should be able to use a peanut chambered head to get higher CR and better chamber shape. The peanut head will be more detonation resistant for a given CR vs. an open chambered head. If you are re-using old Z22E pistons, they will be 87mm. Engine displacement will be 2044cc.If you are buying new pistons, get Z22E pistons in +1mm oversize, 88mm and bore the L20B or Z20 block +3mm to 88mm or convert a Z22 block and bore only +1mm. Engine displacement with 88mm pistons will be 2092cc for a near true 2.1L motor.  Did I mention that this motor make HP at high RPM!
With 87mm bore, 86mm stroke producing 511cc of swept cylinder area, 9.32cc piston dish, 7.0cc gasket volume and the piston raised up above top of block by .05mm, using an open chambered head (U67 or A87) of 45.2cc volume, I calculate a CR of 9.31:1 or, if you used a 41cc peanut chambered head, CR of 9.92:1. Check and verify the piston dish area and piston deck height!
Since planning this motor, I have realized that it should be possible to use VG30E pistons in this engine instead of the Z22E pistons. I am just not sure if the VG30E piston pins would be compatible with the L series connecting rods, I have seen conflicting specs for the VG30E piston pins that would/would not work depending on who is right. As far as I can tell, the earliest VG30E pistons used wristpins pressed into the rods while the later VG30E pistons use full floating rods retained by circlips. The pressed in pins should work on the L series rods (measure and verify!) of if you use full floating pistons, ensure adequate clearance between wristpin and connecting rod hole and it will be necessary to drill oil supply holes in the connecting rod to splash lubricate the pin bore. The VG30E piston pin height is the same 31.75mm as Z20E pistons so the piston top would not protrude above the block therefore no modifications to the piston would be necessary. Compression ratio would be slightly higher with the VG30E pistons because they do not have the large piston dish of the Z22 pistons.
Written by: Jason Gray

Contact him at jason510@worldnet.att.net
"It's ok, we know what to do...we talked about this a lot on the internet."

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