blue72 Posted July 13, 2010 Share Posted July 13, 2010 (edited) I happen to have pistons and rods from an L24, L28, L28ET and LD28 as well as a 2000 gram digital scale which I calibrated just before measuring began. Left to right: L28, L24, L28ET, LD28 It has taken me some time to acquire this selection of stock pieces. My only real interest in gathering them was to satiate my own curiosity and share my findings here with the HybridZ community. Part 1: Weight results as well as some general observations Note #1 All rod weights were calculated with the rod bolts and nuts in place. Bearing shells were removed prior to weighing. Note #2 These weights were taken from individual pieces, not from the average of all six. Note #3 Your results may vary. Do not taunt Happy Fun Ball© L24E – This engine was in my Z when I purchased it. As it turns out, the early L24E engines from 810 cars have the desirable 133mm rods w/ 9mm rod bolts which are exactly the same as what came in the late L24 engines in the Z cars. Rod Length = 133.0mm Rod Stamp # = N01-1 Rod Weight = 711.1 g Wristpin Diameter = 21mm Wristpin Weight = 120.2 g press fit design Piston Diameter = 83mm Piston Weight w/ Rings = 402.0 g L28 – This was a JDM replacement 2bbl carb engine from an emissions era sedan (think Cedric / Laurel / Leopard / Gloria). It wound up in a junkyarded 280Z where I culled its internals. Rod Length = 130.35mm Rod Stamp # = A87-2 Rod Weight = 727.0 g Wristpin Diameter = 21mm Wristpin Weight = 120.2 g press fit design Piston Diameter = 86mm Piston Weight w/ Rings = 451.9 g L28ET – Pistons w/ rods purchased from board member Rod Length = 130.35mm Rod Stamp # = A87-1 Rod Weight = 711.2 g Wristpin Diameter = 21mm Wristpin Weight = 120.2 g press fit design Piston Diameter = 86mm Piston Weight w/ Rings = 455.3 g LD28 – Pistons w/ rods purchased from board member Rod Length = 140.0mm Rod Stamp # = V07-1 Rod Weight = 789.9 g Wristpin Diameter = 25mm full float design Wristpin Weight = 165.4g + 1.3 g each for snap rings Piston Diameter = 84.5mm Piston Weight w/o Rings = 523 g In case you've never seen the combustion chamber of the LD28: The bottom of the cast iron cylinder head is flat. All of the fuel and air is compressed into the top of the piston. Interesting note: LD28 rod bolts have a slightly different shoulder than the other 9mm L series bolts. Left to right: L28, L24, L28ET, LD28: To summarize: The LD28 rods are not some mystical and outrageously heavy pieces with lots of extra mass. They look almost exactly the same as any other L series rods with the exception of their added length and full floating wristpins. There is almost no difference between L28 and L28ET rods. The discrepancy with weight may be because my L28 rods came from a JDM car. Part 2: L28ET ringlands, where they differ from the regular L28 L28: Piston Stamp Mark = none Piston Dish = 10.9cc Top Ringland: 7.2mm Second Ringland: 3.4mm Third Ringland: 2.4mm Top Ring Thickness: 2mm Second Ring Thickness: 2mm Oil Rings Cumulative Thickness: 4mm L28ET: Piston Stamp Mark = P90 Piston Dish = 10.9cc Top Ringland: 7.2mm Second Ringland: 4.4mm Third Ringland: 2.4mm Top Ring Thickness: 1.5mm Second Ring Thickness: 2mm Oil Rings Cumulative Thickness: 4mm Interesting Note: The wristpin oiling is done differently on the L28ET piston which has two grooves at the top of the pin instead of the single top hole like on the L28 piston. To Summarize: The two pistons weight almost exactly the same, have the same dish and are both made of cast aluminum. The one major difference is that the second ringland on the L28ET piston is 1mm thicker than its N/A brethren and the top rings were .5mm thinner after 1980. Ringland thickness is a fact that gets thrown around here every once in a while in conjunction with detonation resistance but the real numbers are occasionally misquoted. Just trying to clear up any confusion because as is common knowledge, a picture is worth..... well, you know the rest. If anyone else out there has weighed their own rods and has the measurement along with the number stamped in the rod we might be able to get some averages going. If your stock parts look different than what I've shown I'd love to see them as well as know what they came out of. Edited July 14, 2010 by blue72 Link to comment Share on other sites More sharing options...
jc052685 Posted July 13, 2010 Share Posted July 13, 2010 Brilliant!!! Link to comment Share on other sites More sharing options...
Tyler Posted July 13, 2010 Share Posted July 13, 2010 Invaluable information! Thank you for the time and effort. Link to comment Share on other sites More sharing options...
ozconnection Posted July 13, 2010 Share Posted July 13, 2010 Mate, gotta love your work here! Well done and thank you for the factual and visual information. Link to comment Share on other sites More sharing options...
rjstcroix Posted July 13, 2010 Share Posted July 13, 2010 Hey, Great work. I vote for sticky. RSC Link to comment Share on other sites More sharing options...
Tony D Posted July 13, 2010 Share Posted July 13, 2010 sticky vote #2 Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted July 13, 2010 Administrators Share Posted July 13, 2010 Stick it is. Link to comment Share on other sites More sharing options...
blue72 Posted July 14, 2010 Author Share Posted July 14, 2010 I'm glad everyone liked it. Hopefully this will save frustration for someone down the road. Link to comment Share on other sites More sharing options...
junglist Posted July 14, 2010 Share Posted July 14, 2010 This is good info. Took me forever to cull all the correct info I needed when ordering new L28ET pistons & rings last year. Link to comment Share on other sites More sharing options...
tyler031734 Posted August 1, 2010 Share Posted August 1, 2010 (edited) I think you my have some info switched around regarding the l28 and l28et ring thickness, I always thought the turbo rings where the thicker ones... Am I wrong? Bravo on the work though. Currently Im trying to find a way to make my l28et into a ~2.9 with a better rod stroke ratio just for the sake of being different! plus a little machining on some flat tops to add some new age knowledge of spark events. this should be fun! Anyone have any info on what a shorter piston will act? Like will it fight my gains from a better rod/crank ratio? trying to find a good combo of longer rod and a shorter 87mm piston Edited August 1, 2010 by tyler031734 Link to comment Share on other sites More sharing options...
blue72 Posted August 2, 2010 Author Share Posted August 2, 2010 (edited) Nope, this information is correct. This is what I was trying to prevent, the "I think..." or the "I heard that..." sort of comments that get thrown around. I made sure to keep everything orderly and I measured the L28 and L28ET rings and ring lands twice on separate occasions with the same results. It can barely be seen in the pictures if one peers close enough. Truth is that in the U.S., beginning in 1981 (around August of 1980 if you want to be technical) all L28 (both N/A and Turbo) pistons had a 1.5mm top ring (the Laurel wasn't sold in the U.S., so its 1.2mm thick top ring isn't applicable here), 2mm second ring and the customary 4mm oil ring groove. Edited August 2, 2010 by blue72 Link to comment Share on other sites More sharing options...
Tony D Posted August 2, 2010 Share Posted August 2, 2010 Nope, this information is correct. This is what I was trying to prevent, the "I think..." or the "I heard that..." sort of comments that get thrown around. I made sure to keep everything orderly and I measured the L28 and L28ET rings and ring lands twice on separate occasions with the same results. AMEN BROTHER! Link to comment Share on other sites More sharing options...
roger280zx Posted August 26, 2010 Share Posted August 26, 2010 Did you check the crank journals? I have an L24E with 133mm rods; however, the rod journals are smaller than the z stuff (read will not fit the 240, 260, 280 crank). Nevertheless very good information and thank you for starting the topic. And could you please weight a flat top piston? It would be nice to have it done on the same scale for reference. Link to comment Share on other sites More sharing options...
blue72 Posted August 26, 2010 Author Share Posted August 26, 2010 They might not be 133mm rods then. There were two versions of L24E, early and late in the U.S. The early style, like what I posted above, are the same as a late L24 from a Z car. Same 133mm length, same 21mm wristpin, same 9mm rod bolts and the same rod bearing big end diameter of 53mm, etc... The late style came with 135mm length rods which have 20mm wristpins (or possibly 19mm), 8mm rod bolts and a rod bearing big end diameter of 50mm. The same, or very similar rod was used on late L20E and L20ET engines as well. I don't happen to have a set of either to tell you for certain, but if you've got the measurements of the piston pin diameter I sure wouldn't mind adding it to my collection of definitive figures. I'd love to weigh a flat-top piston (I assume you mean L28) and / or rods. Does someone have a loaner or a very cheap used set for sale? Link to comment Share on other sites More sharing options...
kiwi303 Posted August 30, 2010 Share Posted August 30, 2010 Since this is a "the TRUTH about these motors" thread, will you be expanding the info to include the L20 (A, B, E) and L16/L18 motors? I've seen talk about using L16 rods in strokers. and if you want L20b data I have a 2 litre L20B 4 cyl in the shed I need to get around to stripping. I could send you the rod and piston data off that. Link to comment Share on other sites More sharing options...
ozconnection Posted August 30, 2010 Share Posted August 30, 2010 Hey, I have an L20A ET piston and rod out of one of my spare engines. Its an M spec. block and the internals are the light duty versions often described in the books as the L24E Maxima spec.(or at least similar to). The engine came out of a JDM R30 Skyline, the year is unknown. Top ring is 1.5 mm's Second ring is 2.0 mm's Oil ring is 4 mm's. Rod bolt is 8 mm's Small end is 20 mm's Big end is 48 mm's As for the weights of the rod, piston and rod length, I can't accurately give those figures ATM, sorry. Hey Kiwi303, I just read your post as I was writing mine..... Link to comment Share on other sites More sharing options...
blue72 Posted September 2, 2010 Author Share Posted September 2, 2010 Will you be expanding the info to include the L20 (A, B, E) and L16/L18 motors? Yes, I would like to get my hands on some of each eventually. I've currently got a line on some cheap used L18 pistons. L20a will be a little more difficult for me here in the states, but I'll keep an eye out for a set. I'd like to have one of each if I could. L20 (1965-1969), L20a, L20aE, L20ET (early and late), L23, L24, L24E (early and late), L26, L28E (flat and dished), L28ET, LD28. Then the fours: L13, L14, L16, L18, L20b, LD20, LD23, Z16, Z18, Z20 (E and S), Z22 (E and S, early and late), Z24, ZD30, etc, etc... There are still plenty of gaps missing in the info I've gathered for the above engines. Thanks for the measurements on that L20ET setup ozconnection. If anyone else has info they'd like to share about weights and measures then feel free to help dispel the rumors and myths. Link to comment Share on other sites More sharing options...
ozconnection Posted September 3, 2010 Share Posted September 3, 2010 I should have mentioned that the L20AET specs above are for the "light duty" engine. I have another L20AET which has the "normal" or standard sized rods with 21mm small ends and 53mm big ends and 9mm rod bolts. Below is some information I found out about the nnormal duty L20A rods from Brian who emailed Japan for confirmation "Info I came up with: L20 rods are 133.0 mm from center to center... This is the same as the early 240z 9mm rods!!! Best RegardZ, Brian Z Car Custom's-JDM Your Source for KAMEARI & O.E.R.-JDM Products! www.zccjdm.com P.O. Box #213 Terrebonne, OR. 97760 541-913-6530" Some engine builder programs list the L20A rods as 135 mm's centre to centre and I've even read in a Datsun book they're 128 mm's. Go figure! Link to comment Share on other sites More sharing options...
blue72 Posted September 13, 2010 Author Share Posted September 13, 2010 (edited) Okay, finally got my hands on a cheap, used set of L18 pistons and rods. I cleaned up two of them in my solvent tank before weighing. Note: I measured two separate rods because they had different casting numbers. Just like before, these are individual rod weights and not an average taken from multiple pieces. L18 - Pistons w/ rods purchased from ratsun board member Rod Length = 130.35mm Rod Stamp # Both A87-1 (rods 3 and 4) and A87-2 (rods 1 and 2) Rod Weight A87-1 = 690.4 g Rod Weight A87-2 = 688.4 g Wristpin Diameter = 21mm Wristpin Weight = 120.2 g press fit design Rod Big End Diameter = 53mm Piston Diameter = 85mm Piston Dish = 4.36 cc Piston Weight w/ Rings = 442.6 g* Top Piston Ring Groove = 2mm 2nd Piston Ring Groove = 2mm Oil Ring Groove = 4mm *I only had half of a top compression ring to work with, so I doubled its weight and added it to the total. This photo may help explain why I was able to acquire these at such a reasonable price: Holy flying chunks of piston Batman! No, I didn't use that piston for the weight above, but rather an intact slug instead. Edited September 13, 2010 by blue72 Link to comment Share on other sites More sharing options...
rayaapp2 Posted December 6, 2010 Share Posted December 6, 2010 I have a heavy duty L20e. Rods are 133mm with 9mm rod bolt shanks The piston is the odd ball. Pin Height is 39.9mm not 38.1mm! Piston is slightly domed. I have no way to accurately measure the CC's of dome. 8mm top ring land 2mm top ring 3.2mm 2nd ring land 2mm 2nd ring 2.9 third ring land 4mm oil ring I have no way to accurately weigh anything either. Saw some difference and thought I would post them up... Link to comment Share on other sites More sharing options...
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