2eighTZ4me Posted June 3, 2010 Share Posted June 3, 2010 I know the block is taller, and the rods are 140mm, not to mention there's like a 1.5cm distance b/t the top of the piston and the first ring land......anyone ever futz around with one of these? Is there any "workable" combination that could be used in a gas type situation? I've harvested the crank for a turbo stroker, but would this block be a candidate somehow for a turbo motor of some sort? The rods are major beefy, and it looks like the wrist pins are the same size. Just tossing ideas out there. Curious to hear what all could be done with it (if anything). Quote Link to comment Share on other sites More sharing options...
e_racer1999 Posted June 3, 2010 Share Posted June 3, 2010 IIRC the rods are cast, not forged like the gas L6. Plus, try weighing them and be prepared to poop your undies. Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted June 3, 2010 Share Posted June 3, 2010 If you want to turn an LD block into a gasser, you should just toss the pistons and rods. They...REALLY aren't ideal for any gas setup Quote Link to comment Share on other sites More sharing options...
mikedc528 Posted June 3, 2010 Share Posted June 3, 2010 (edited) I posted this in another thread...I still believe that it would be amazing high revver. LD28 Block L24 Crank N47 Head Z20E Rods L28 Flat Tops 1mm Head Gasket Rod/Stroke Ratio:2.069 Bore/Stroke Ratio:0.857 Static Compression: 9.471 With a displacement of 2.569L and 0.000 Deck clearance. Might be good for a high revving option. Edited June 3, 2010 by mikedc528 Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 3, 2010 Share Posted June 3, 2010 Exactly what rpms do you propose this will reach, and what real world 'advantage' will you get over say a destroked L28 or L24? With L28's being able to rev to 9000+, and a destroked 2.5L (L20A Crank) being even more revable, along with a larger bore for better valve unshrouding and high rpm breathing.... Why the fascination with the LD block? Of course some 3.5L monster may come of it, but this isn't what's being discussed in this thread, so it makes me wonder. Quote Link to comment Share on other sites More sharing options...
mikedc528 Posted June 3, 2010 Share Posted June 3, 2010 Way better rod/stroke ratio which may or may not lead to less detonation. (Probably not true, but read an incomplete argument on this site about the possibility of it lowering detonation) Not saying that it is the holy grail here, just saying that I wouldn't just think of it as a crap idea. With all of these LD cranks being pried out of these block, using them for their extra deck height might be good. If anything else you can still build another L28 with a better r/s ratio. Like you have said before, it has all been done, I just wanted to know why it isn't more popular. Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted June 3, 2010 Share Posted June 3, 2010 You could sell it to me! Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted June 4, 2010 Author Share Posted June 4, 2010 Sparks - it is for sale. Make me an offer and come down and get the stuff. I'm just a straight shot down I85. I'll let everything go except the crank. Oil pan has been sold, flywheel / clutch and alternator have been sold. The rest I have in boxes. I have way too many items on my honey-do list to start futzing with another project. Come 'n get 'er! Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 4, 2010 Share Posted June 4, 2010 "I just wanted to know why it isn't more popular." Answer the questions I posited from a knowledgable standpoint and your question will be answered. Supposition and incomplete theoretical arguments won't cut it; honest, frank answers to the questions posed will tell you why in a heartbeat. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted June 4, 2010 Share Posted June 4, 2010 LD28 complete is worth far more than the sum of it's parts. Quote Link to comment Share on other sites More sharing options...
mikedc528 Posted June 4, 2010 Share Posted June 4, 2010 (edited) "I just wanted to know why it isn't more popular." Answer the questions I posited from a knowledgeable standpoint and your question will be answered. Supposition and incomplete theoretical arguments won't cut it; honest, frank answers to the questions posed will tell you why in a heartbeat. "With L28's being able to rev to 9000+, and a destroked 2.5L (L20A Crank) being even more revable, along with a larger bore for better valve unshrouding and high rpm breathing...." L20A not so easy to get in the states...I personally have never stumbled across one as easily as a L24 crank. Once again, R/S ratio...no answers on that front....incomplete theoretical arguments are what I am trying to have answered... Some info on what I was reading when I first posed the questions. http://forums.nasioc...ad.php?t=424283 http://www.stahlhead...od%20Length.htm Another question is, if you do the math, using the L20A crank in the L28 block gives you almost the same results as using the L24 crank in the LD28 block without spending a fortune or lots of time finding the crank. I know you might have easy access to these cranks as you are a very well traveled man and have many personal connections to Nissan and L6 gurus from your stories, but from what the OP has available to him and from what we mostly have available here in the states, he might be able to pull off a motor that mimics your 9+k shifting Bonneville car at a cheaper price. (If I understood it correctly you built an L20 for class restrictions, might be wrong) Thus my question as to why it isn't more popular.... As for the comment about larger bore, this hasn't been proven, I've read the thread about the 4.0L L6 and there doesn't seem to be a conclusion. Only a statement about sonic testing many blocks with negative results, but same could be said about regular gasser blocks. I am thinking knowlegably, maybe I should pose this question in a thread about internal combustion engine thermodynamic efficiency and how the compression cycle is effected by slower piston speeds (longer rods, shorter stroke). Another point of reference....I am by NO means comparing the flow numbers between L series heads and RB heads. But the idea is very similar L24 Crank 73.7mm LD28 block bored to say about 86mm Looks really familiar. RB25 - 2.5 L (2498 cc, bore: 86.0 mm, stroke: 71.7 mm) RB26 - 2.6 L (2568 cc, bore: 86.0 mm, stroke: 73.7 mm) LD28 Block L24 Crank N47 Head Z20E Rods L28 Flat Tops 1mm Head Gasket Rod/Stroke Ratio:2.069 Bore/Stroke Ratio:0.857 Static Compression: 9.471 With a displacement of 2.569L and 0.000 Deck clearance I am also not arguing the fact that the L28 is bigger, has more stroke so creates more torque motto, this is all a learning expierence, nothing is the best and nothing should be put down ( if this were the case you wouldn't be posting on hybridz now would you ) As part of my learning experience, please explain why this wouldn't be a good candidate, even as a turbo motor. Edited June 4, 2010 by mikedc528 Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 4, 2010 Share Posted June 4, 2010 (edited) "With L28's being able to rev to 9000+, and a destroked 2.5L (L20A Crank) being even more revable, along with a larger bore for better valve unshrouding and high rpm breathing...." L20A not so easy to get in the states...I personally have never stumbled across one as easily as a L24 crank. Once again, R/S ratio...no answers on that front....incomplete theoretical arguments are what I am trying to have answered... The L20A's are out there, and in many cases are freeeee or nearly giveaway as nobody wants them. I paid $100 for the last one I paid for (complete), I have gotten them in baskets for free. The last one I got off e-bay cost more to ship as parts than I paid for it (0.99 cent auction start!) Of course L24's were available here in the USA, so logically they are 'easier' to find. If "Easy" was criteria to the project, then we wouldn't be discussing an LD28 Block Conversion with no practical real-world advantages over existing L28 combinations. I can lay you money that CONVERTING an LD28 to gasoline operation for the same R/S ratio of an LD28/L24 Crank will be FAR more expensive than L28/L20A Crank Combination. The L28/L20A is an existing, proven concept with nothing special to fab, make, convert, etc... Not so for the LD conversion. One is a simple component swap, one takes time, money, and luck. Luck is not required in an L20A L28 crank swap... Some info on what I was reading when I first posed the questions. http://forums.nasioc...ad.php?t=424283 http://www.stahlhead...od%20Length.htm Both of these links talk of theoretical advantages, and some real world advantages. But as you delve into it further 'the point of diminishing returns' comes in. Are the theoretical advantages worth the additional costs involved? Why did Nissan change deck height on the four cylinders---was it for a longer rod? No it was to accomodate more displacement from a longer stroke. Cam selection and combustion chamber design will play a FAR larger role in detonation suppression and cylinder filling than what you will accomplish with the large deck height LD Block and longer rod. Another question is, if you do the math, using the L20A crank in the L28 block gives you almost the same results as using the L24 crank in the LD28 block without spending a fortune or lots of time finding the crank. Stop it! There is no "FORTUNE" spent finding an L20A crank. That's total B.S. And even if it weren't, then the L24 crank STILL gives the same advantages and they ARE arguably dirt cheap and plentiful. What you haven't answered yet was what REAL WORLD payback will you get from this rod combination. I know for a FACT that in an L20A short block, you can fit L20B connecting rods. Do the math on THAT! What R/S ratio do you get? Now if you can ringstack a 'short' conventional L Block to fit an L20B rod in there, what is the argument for an even longer (and flexible) rod? I know you might have easy access to these cranks as you are a very well traveled man and have many personal connections to Nissan and L6 gurus from your stories, but from what the OP has available to him and from what we mostly have available here in the states, he might be able to pull off a motor that mimics your 9+k shifting Bonneville car at a cheaper price. Big news here, the sourcing of the L20A for that car was done TOTALLY within the USA and was done really cheaply. Anybody in SoCal is able to reproduce this motor with minor effort at searching. The block was from a guy who advertised a Fairlady Z on e-bay and responded to an e-mail asking him what he had done with the 'original engine'---there are PLENTY of guys with Fairlady Z's out there continually asking about changing the engine from the L20A they have...you find one, you buy one. This has nothing to do with my being well travelled or having connections. If you will recall Nissan Corporate moved to Nashville years ago. There's nothing here from corporate any more! (If I understood it correctly you built an L20 for class restrictions, might be wrong) Thus my question as to why it isn't more popular.... How many Z's race at Bonneville? Most of them have (gasp) V-8's. How many Z's at Bonneville have taken ALL the available records in their respective displacement class (17 at last count in F/Engine Class)? One. When you have all the records at 3.0 Liter Class Break, you have a choice: Go up to 4.5L class (no engine made legal for the car) or go down to 2.0L class (existing production engine legal for the class). This isn't rocket science, what does that have to do with anything, it's a matter of logic and available parts. There are no engine combinations LEGAL to put into a 1976 280Z 2+2 which will allow us to rin in 4.5L Engine Class. So we went down in capacity. Most of the guys are struggling to make their FIRST record, they haven't come to the point of 'we broke them all, now what do we do with this thing?' I mean, we COULD have put a stroker crank in and gotten closer to 3.0 and MAYBE picked up some speed, but we're breaking our own records....what fun is that when all those juicy fat 2.0 liter records exist? Does that answer the question sufficiently? I still fail to see what that has to do with the subject at hand... As for the comment about larger bore, this hasn't been proven, I've read the thread about the 4.0L L6 and there doesn't seem to be a conclusion. WHAT hasn't been proven? That a larger bore unshrouds the valve better? This is basic engine building. This is not subject to debate, it IS proven. You need to clarify what you're saying there, as if your contention that moving the block away from the edge of the valve does NOT aid in unshrouding the valve, you need to do some serious research. I can tell you conclusively from flow bench data that the L28 Bore flows GOBS more air down the cylinder with the EXACT SAME CAM, HEAD, AND VALVES than the L20A bore. Again, this is not rocket science, nor hard to check with basic metrology and some plexiglass cylinders...That statement about sonic testing many blocks with negative results, but same could be said about regular gasser blocks. I am thinking knowlegably, maybe I should pose this question in a thread about internal combustion engine thermodynamic efficiency and how the compression cycle is effected by slower piston speeds (longer rods, shorter stroke). Another point of reference....I am by NO means comparing the flow numbers between L series heads and RB heads. Then Don't! I am also not arguing the fact that the L28 is bigger, has more stroke so creates more torque motto, this is all a learning expierence, nothing is the best and nothing should be put down ( if this were the case you wouldn't be posting on hybridz now would you ) Understand that asking 'what's the point' is not 'putting something down'---if you want to do something, at least be intellectually honest with yourself to answer the hard questions. Questions like 'what is the practical payback?' You have totally missed my point on the L28 as the basis for the build for a high revving DEstroked long-rod motor. The BORE is larger, and this helps with valve unshrouding. You say it doesn't and that's just plain wrong. If you were talking about making a gas motor out of an LD28 using the LD28 CRANK and not just the block we could discuss torque and it's advantages (and it would still come down to valve unshrouding with a smaller bore of the LD compared to the L28. You were discussing DE STROKED motors, and my contention was there is a point of diminishing returns and what is the point of using an LD when for all practical purposes the larger bore of the L28 will be far more important in breathing at higher rpms than a smaller bore of the LD. As part of my learning experience, please explain why this wouldn't be a good candidate, even as a turbo motor. I'd suggest the basics get covered before you move to turbo. Edited June 4, 2010 by Tony D Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted June 4, 2010 Share Posted June 4, 2010 If I had a LD28, I would bolt up the stock 280zx turbo manifolding, swap to a 280zx turbo rear sump pan and pickup, and use the stock 5 to 6 pounds of boost to net what would be a pretty peppy yet very frugal engine in a Z car. Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 4, 2010 Share Posted June 4, 2010 Just try to get the L20ET turbo, same internals as the L28ET, but with a .48 A/R housing, meaning full boost is available at well under 1700 rpms on a diesel. Yes, I have a penchant for JDM stuff that wasn't available here. But that appears to be the correct A/R for the LD28 (at least I'm betting on it, I got three of them in a milk crate two months ago for my LD28T conversion of a 77 280Z Coupe in my back yard!) My quandary is wether to keep that tasty diesel four speed autobox on there for my daily commuter duties, or go with the spare ZX Box I have laying around... Decisions, decisions... Quote Link to comment Share on other sites More sharing options...
ozconnection Posted June 5, 2010 Share Posted June 5, 2010 Just try to get the L20ET turbo, same internals as the L28ET, but with a .48 A/R housing, meaning full boost is available at well under 1700 rpms on a diesel. Yes, I have a penchant for JDM stuff that wasn't available here. But that appears to be the correct A/R for the LD28 (at least I'm betting on it, I got three of them in a milk crate two months ago for my LD28T conversion of a 77 280Z Coupe in my back yard!) My quandary is wether to keep that tasty diesel four speed autobox on there for my daily commuter duties, or go with the spare ZX Box I have laying around... Decisions, decisions... Turbo diesel and an O/D auto tranny.....aaaahhhhhh a match made in heaven..... Quote Link to comment Share on other sites More sharing options...
woldson Posted June 5, 2010 Share Posted June 5, 2010 Ahhhh, nothing like a smoldering heap of data in the morning to make a brain feel MIGHTY,,,,,,,,,,,,,small. Calibration hurts sometimes. This comment is directly purely at myself. When I do my build, whatever it will be, will be for the experience. The more I know the less I understand. My cars are an indulgence, hence, the lack of work done. Quote Link to comment Share on other sites More sharing options...
DAW Posted June 8, 2010 Share Posted June 8, 2010 (edited) I have 2 2.8L 10:1 L6's configured differently. One is an F54 flat-top shortblock with an N42 head with headers and triple carbs, and the other is an LD28 shortblock with an N42 head with headers and fuel injection. Both have stock cams. The F54 based engine is prone to spark knock, while the LD based engine is not. I attribute this to the longer r/s of the LD (140/83 = 1.69) vs that of the F54 (130.4/79 = 1.65) and possibly the effect of the pre-combustion indent in the head of the LD piston (the clover-leaf thing, it is named after someone...). The LD based engine has an abundance of low end torque vs the F54. The LD is in a Maxima and I'm using the original 3spd A/T with lock-up torque convertor. The diesel torque convertor has a lower stall speed than even a gas Maxima but the response off idle is impressive. The F54 is a M/T so it's a little hard to compare, but it doesn't seem to have the low-end torque that the LD produces. I'm reluctant to turbocharge the LD based engine because I think the N42 head will be prone to detonation, but I'm thinking a low pressue intercooled turbo (even at 10:1 c.r.) may be the next step. I'm not looking for high rpm power, but for maximum torque from this engine. If I ever get around to it, I'll put together an LD shortblock with longer rods, flat top pistons, overbore, and a high quench head (P90) to extend the rpm capability some and preserve the off-turbo high torque characteristics. I hear so many anecdotes and myths about the LD bottom end but very few personal empirical accounts from anyone re hybribization for gas use. I put together my LD28/N42 combination 12 years ago and it's been a daily driver and a ski car over the years. Last year an Expedition made a U-turn into me and totaled the passenger side. It still drives fine but is an eyesore. Ultimately, I was going to put together various LD-based gas engines with various configurations using the Maxima as a test mule before pulling them to convert to rear sump and transplant to a Z car...but I don't have the time these days. Some info I could use though is some RELIABLE, accurate data re sonic testing of cylinder wall thickness of the LD28 block; not heresay. DAW Edited June 8, 2010 by DAW Quote Link to comment Share on other sites More sharing options...
Raami Posted June 8, 2010 Share Posted June 8, 2010 IIRC the rods are cast, not forged like the gas L6. Plus, try weighing them and be prepared to poop your undies. How do you know that those ld-rods are cast and not forged like the gas-rods? Those ld-rods have to handle great forces in a low rpm and the piston is also much more heavier than the ones in a gas engine. I would say that those ld-rods are stronger than gas-rods. But that is just my opinion and I have those ld-rods in my N42 L28 with custom forged pistons. The R/S ratio is now 1,77. Quote Link to comment Share on other sites More sharing options...
e_racer1999 Posted June 8, 2010 Share Posted June 8, 2010 How do you know that those ld-rods are cast and not forged like the gas-rods? Those ld-rods have to handle great forces in a low rpm and the piston is also much more heavier than the ones in a gas engine. I would say that those ld-rods are stronger than gas-rods. But that is just my opinion and I have those ld-rods in my N42 L28 with custom forged pistons. The R/S ratio is now 1,77. For one I don't KNOW that the rods are cast, I just thought I read that they were cast, hence the If I Recall Correctly. Also IIRC, Nissan forged the rods because it was more expensive at the time to cast for some reason. I could be way off base, but that's how it goes when I think I think I read something somewhere Quote Link to comment Share on other sites More sharing options...
blue72 Posted June 8, 2010 Share Posted June 8, 2010 Plus, try weighing them and be prepared to poop your undies. Really? From what I've read the difference isn't quite enough to make you go pants-crappingly mad. I've seen others weigh the LD28 rods at 784 grams while an L24 rod is 710 grams. Quote Link to comment Share on other sites More sharing options...
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