Maximum Bore of Sleeved L28 and LD28

[nissan2ner831]

Out of curiosity, what would you guys say is the maximum bore possible in a wet sleeved L28 or LD28? I searched and couldn't find much, but if its been answered before I guess I just didn't look hard enough.

[Xnke]

The answer you will get is this:

 

Cubic Dollars.

 

That's not the answer you want, but for a wet-sleeved engine, it is the answer you'll get.

 

Check out Darton sleeve, or LA sleeve companies. they'll wet-sleeve the block for you, and have a really good reputation.

[MAG58]

Well aside from how deep your pockets are, the real question is what would you want it used for? If money was no object I still wouldn't go above about 91mm. That's what a Mercedes C36 AMG has for a bore. It has the same bore spacing as the L28 and it's cylinder walls are so thin that there is no overbore for the motor, just scrap the block. You also have to consider having a HG made to support such a large bore along with getting pistons to stuff in those giant holes.

 

At this point wouldn't it seem easier to get a stroker crank made with something bigger than a V07 crank? While you're at it you could have it fully counter weighted. As oversquare as a 89mm L series already is, you'd run out of deck height for an even poor conrod to stroke ratio way before you even get close to a square motor. You'll have more cylinder thickness for more compression/boost/whatever mystery power producers you have schemed. If you're looking for a huge bore motor for a still high displacement, short stroke beast, you still have to deal with an L series crankshaft that's 4 counter weights shy of not coming apart at 8500+

[1 fast z]

Remember you cannot just bore out a motor, install sleeves with a press fit and be done. The sleves when doing all cylinders, or even adjacent cylinders for that matter on an L series, you have to V out the top and bottom of the block, and actually WELD the sleeves in. You will also have to mill flats on the sleeves between 1,2 2,3 4,5 5,6 as the bore spacing will be way too close to use .125 sleeves. If you dont weld them in, there is no strength left in the block, from top to bottom.

[nissan2ner831]

haha yeah I know it costs a lot, I'm not expecting it to be cheap I'm not currently saying I have many concrete plans for a Z, mainly because 1) I don't have a Z XD 2) I'm still learning the skills I want to learn to work on my own Z 3) I don't have the money required for any project right now (gotta pay for schooling). Though I do have some general ideas and some ideas I'm considering, like a bigger than 3.1L L series (I'm leaning towards an LD28 right now for the extra deck height), turbo, possibly a front tube frame...nothing concrete right now, and it's all a far ways off. Gotta get my schooling taken care of, and gotta learn the skills I'd need to get this project rolling (mainly starting with welding classes right now) It's just all getting thrown around in my head, pretty much just a dream right now

 

This is really more of a curiosity question, I'm really in the planning stages of what I would like to do with a 240Z.

 

So essentially...with either the LD28 or L28, you can only go about 2mm over the max bore with sleeves compared to a block without sleeves?? I know you can hit 89 with a L28, so 91mm would pretty much be the max if you sleeved the engine?? I'm interested in the LD28 too...mainly because you can fit a longer rod in there for a better rod/stroke ratio. But yeah...an extra 2mm doesn't seem like it's worth it...I know it's expensive, but I was hoping for at least 93mm out of a wet sleeved block XD

[nissan2ner831]

Remember you cannot just bore out a motor, install sleeves with a press fit and be done. The sleves when doing all cylinders, or even adjacent cylinders for that matter on an L series, you have to V out the top and bottom of the block, and actually WELD the sleeves in. You will also have to mill flats on the sleeves between 1,2 2,3 4,5 5,6 as the bore spacing will be way too close to use .125 sleeves. If you dont weld them in, there is no strength left in the block, from top to bottom.

 

Yeah 1 fast z, I've read several threads where you have commented on this. I'm not thinking of this as an idle whim or anything, I'm trying to do all the research I can on it before I even buy a 240Z and get started on it. In fact...I intended in my original post to saying something to the effect that I understand that sleeves in adjacent cylinder cannot just be dropped in, they must be welded in...like I said, I am trying to do all the research I can on this.

[B00STDZ]

http://forums.hybridz.org/showthread.php?t=149379

[PanzerAce]

Be aware that you are going to run into some height issues if you want to use an LD28 block. Also, deck height won't give you any extra displacement.

 

TBH, you're probably going to get displacement faster by overboring a "normal" amount to 89-90mm, and then getting a crank welded for extra stroke

[josh817]

I still have strong opinions towards what 1 fast z says... unless this is something unique to the L motors (which I having a feeling that it is), I don't follow the whole you can't sleeve all the cylinders because the block will be too weak idea. Triumph TR3 motors (tractor motors) are sleeved on all 4 cylinders. The sleeves are not welded in. In fact, if you take the head off, they will fall out if you turn the block upside down. Usually we put little washers that look like ears on the head studs and then screw a nut down. This way the cylinders don't slide out while jockeying it around without a head.

 

I'd have to go back to the shop and look at a spare motor to see if they're wet or dry sleeves. All I know is that when we go to replace them we actually have to go to a tractor outlet store. Haha

 

Oh and don't forget to mention that their 4 cylinder motors are a 3 main bottom end, so the bottom end isn't even as stout as our Datsun stuff. Dad even did some sort of "monster motor" (their monsters aren't like ours ) and overbored the sleeves by 1/4 inch and that motor still runs just fine. Kicks the ass of the supercharged TR4 we built for someone else too... I know I'm most likely going to be wrong when I say this but block rigidity seems like it would be compromised only at the bottom end if you sleeve because the combustion is now taking place well... in the sleeve, and not the cylinder itself. Even if your machine shop had to weld them in, it shouldn't take much labor if they're good. The place we use welds up combustion chambers in no time, clean resurface and a magnaflux test, ready to go.

[nissan2ner831]

Be aware that you are going to run into some height issues if you want to use an LD28 block. Also, deck height won't give you any extra displacement.

 

TBH, you're probably going to get displacement faster by overboring a "normal" amount to 89-90mm, and then getting a crank welded for extra stroke

 

Yup, I'm well aware that there are height issues if you use an LD28 block in a S30. And I know it doesn't allow extra displacement (well, not in and of itself at least), it just allows you to use a longer rod with whatever stroke is used for a better rod/stroke ratio. Only way you can get "more" displacement out of the LD28 because of the deck height is to use a larger stroke, and the extra deck height allows the use of longer rods to keep a decent rod to stroke ratio.

 

And yeah...if I go with a turbo motor, I've read a lot saying 90mm is too much off the block, but going with sleeves for at most an extra 2mm (from 89 to 91) doesn't really make much sense. I guess if I was finishing the project and was just going to spend a ridiculous amount of money on it I guess, but I can't really see justifying it for a 2mm overbore. I may consider it so I can do a 90mm bore, and have a rebuild still available for the sleeves.

 

I'm kinda agreeing with you PanzerAce, I may have to go with a longer stroke to get the displacement I want. Again, I'm just mulling around different idea's in my head, it's what I do when I am bored XD (like how i decided to sit down and figure out what rod lengths are needed for 4 different strokes (88mm, 87mm, 86mm, 85mm) to have rod ratio's of 1.75, 1.7, 1.65 and 1.6 XD...oh I forgot to mention I did this by hand XD...and I did the same with several combinations of stroke and bore for displacements...again by hand. I get quite bored sometimes lol)

[PanzerAce]

I don't know if I'd pay *too* much attention to R/S ratios. IIRC, someone posted a chart with a bunch of the rev happy honda motor R/S and B/S ratios, and *none* of them were what people considered "good" for revs.

[nissan2ner831]

Yeah I know that...for instance those very rev happy Honda motors like the B16 or B18 are not a "perfect" rod/stroke ratio either. I'm just aiming for around 1.7 (a little higher or a little lower, doesn't matter) just for keeping wear down on the pistons. I personally don't think I'd want the engine to rev over 7500 rpms anyways, I don't need a huge rpm band (and according to what I've read, both the standard L28 and the 83mm stroked L28 can both hit 7000 rpms, so I don't need a big improvement or anything).

 

Anyways, from what I've figured, I may just bore out to 90mm on a LD28 block (not sure if this is "safe" for a boosted project, but I'll keep researching to find out If not...well I can either decide to sleeve the block or just drop my displacement down) with a custom SCAT crankshaft for a 88mm stroke, giving me 3.3589L of displacement...and with the higher deck height of a LD28 block, using custom rods and pistons would allow me to reach a decent rod/stroke ratio. Expensive to be sure, but it should hold up to almost anything you throw at it XD. Who knows, again these are all just ideas I am throwing around in my head right now, we'll see what happens when I can actually get working on a project =P

[1 fast z]

From the V07 Blocks I have sonic tested (4-5), There is no way you could even get an 87mm bore.

[MAG58]

1 fast Z is very wise about this, he's done a lot of research and first hand experience at trying to build big motors. I believe the point he's trying to make, about the welded in sleeves is that Nissan designed from the factory for the L series to have cast in cylinders, and since it makes logical engineering sense, I'm going to bet that these sleeves also serve a substantial amount of bracing for vibrations running down the length of the block. Josh, you're correct in saying that there were a lot of alloy motors, Fiats, Alpha's and many others that had wet sleeves in an alloy block that were held in solely by cylinder head tension, semi's even use this system. However, these blocks were all designed with this application in mind and as such the outer crankcase is strong enough to withstand the lateral forces within the engine. Unless the L's block has the sleeves welded in, there would be a big compromise of the lateral stiffness of the block since this block design was designed for cylinders to be cast in. Before you say it, I know there are dry sleeves in the L28 and variants, but there is still a cast in cylinder in the block.

[josh817]

Perhaps it will just take one of us to figure out the hard way. :] Probably me because I still want to do it.

[nissan2ner831]

Yeah 1 fast z again I was reading that somewhere else earlier today XD If I go to a 90mm bore I'd sleeve it, and hopefully have room for at least 1 rebuild if needed later. I'm liking the idea though, using a custom crankshaft, rod and pistons would leave around a 1.7 rod/stroke ratio and a displacement of 3.3589L (what would you guys say, should that be rounded up to 3.4L or no?? =P). Things may change, I'm still a far way off from building anything =P

[josh817]

Kameari makes an 85mm stroke crank for $4000 or something like that. Give or take a couple of thousand. Having one custom made or having an old crank welded up, may be cheaper when those sorts of numbers are floating around.

[MAG58]

Then again you have to look at it like this... You'll have a big dollar 3.4L bottom end... with a old non-crossflow head. Doesn't seem too cost effective here...

[josh817]

Oh jesus lets not get into cost now. These threads where "money isn't an issue" made by someone with less than 50 posts are annoying. You want to be cost effective, get a V8. Simple as that. There are dudes in Japan building 280whp NA motors (who knows what displacement and at what cost). What seems illogical to one person might not be the same for others.

 

Example: I sold all my turbo stuff, msII, eveything to go to a carb'd stroker. If I were to go back and try something else new, I'd try the turbo L engine again but I would never throw in a V8 or an RB into my Z. But why, its more cost effective?! Yah well to me its a '72 240z and so at the least it WILL keep an L engine. If I want to rape something I'll get a 280z/zx or a z31. I won't ever put giant fenders or huge wheels etc on my 240. A 280, yes. :]

 

To say the least, if all these stupid no budget threads are true, they're doing it for the passion of the Z car rather than to tear the asphalt off the road.

 

Sure you may not see it as being worth the amount of labor and money you put in but someone else did:

[Daeron]

Now, my understanding of all the issues involved is not secure enough to try to school anyone, or even try to explain to anyone, alot of this kind of stuff.. but one thing I have gathered about considering rod and stroke ratios, and RPM ranges, and detonation resistance of this or that design.... is that there is no "right" or "wrong" way, each engine must be built with all factors considered, as individual cases.

 

To the OP: the bore center spacing on most of the gaps in an L-series block is 96mm; the gap between #3 and #4 is 98mm. No matter what you do, bore it, weld in sleeves, melt out all the metal and install paper-mache jugs, if it uses an L-series crankshaft, there will be a maximum circle of 96 mm before your imaginary pistons wont fit on the crankshaft outside of a block or in it.. they simply wont line up if they are any larger than 96. Obviously 96mm itself won't work. SO.. work backwards. How much of a wall thickness is tolerable? if you go with, say, 91mm bores, you only have a total of five millimeters of metal in between each of your paired pistons. That is just a little more than 3/16s of an inch. That, to me, seems pretty much impossible in the real world, unless you are prepared to go through a new engine block with every tank of gas (or oil change, or some other ridiculously shortened lifespan)