Daeron Posted March 14, 2008 Share Posted March 14, 2008 Wow, so basically it's a loophole for a great deal eh?Ring land sizes, is that the depth and thickens of them? I wonder why they have things set up like that though. Its called capitalism; Supply and Demand. They sell FAR fewer "custom pistons" than they do 240SX pistons, and a customer coming to buy parts for such-and-such a car is usually a paying customer of someone Else, so they can get away with charging rather more for a piston for a Generico Blahmobile than they really could get away with charging for whatever specific piston set you wanted. The manufacture of the pistons is all the same, custom orders just take a slight effort to make the machines do "something else." It can be scary how simple it all is sometimes. Quote Link to comment Share on other sites More sharing options...
josh817 Posted March 15, 2008 Share Posted March 15, 2008 Could just get typical 240sx pistons and rings like I did for $130 brand new and dished. Sad thing is that they come in sets of 4, when you need 6 this kind of sucks. Anyways what is your goal for this motor? Just something cool and fun or what? I'm not a master at L-engines or anything but personally I wouldn't let the stroke get to out of hand when compared to the bore unless you are wanting a very torquey motor with lower horsepower numbers. Then again they may even out because didn't the L28 (I'll just use the number I know off the top of my head but I think this for the L24) advertise a 150hp at the crank, and I'm guessing 130ftlb of torque (86mm bore - 79mm stroke). So my thought is that if you inverse these figures and make your stroke bigger but keep the nearly the same bore of 87mm, perhaps it would turn out numbers that have less of a marginal gap like 170hp and 170ftlb or something. I like the high revving high hp motors, big bore - small stroke, but not as crazy as Formula One with like a... 25.4mm stroke and a 97mm bore or something like that. And it shows in their figures off 700hp but only 350ftlb. Then again I'm probably wrong with all that and you probably are building a nice piece. I'm only 17, still scrounging around for money to build a stroker motor; I think both of us know our only saving grace is that we have the equipment to do some of the machine work ourselves... Thats the only way I'm getting away with a $2500 motor. >_> Rod work, head work, building, all by yourself. Shouldn't be too bad if you know what you're doing. Good luck. Quote Link to comment Share on other sites More sharing options...
Xnke Posted March 15, 2008 Author Share Posted March 15, 2008 Josh, you are missing the main point here: Displacement. More displacement == more usable power. You are not gonna rev an L to 10K, not without spending a bucket of cash, no matter how short a stroke. Besides, in a daily driven car, high revs == shitty gas mileage. The stock L28 can rev to 6500 without many problems, slight modifications can easily get this up to 7000, with care, 8500-9500 can be done. Ask Tony D about the Bonneville cars... The goal here is to go for maximum displacement with maximum RPM ability. You cannot bore an L28 to 90mm and expect it to last more than a few thousand miles. You CAN however, offset grind a crank to gain a few mm stroke and not sacrifice structural integrity. As for higher torque and lower horsepower, remember that the Inline 6 is considered to have perfect balance at the first harmonic level, so revs are (relatively) easy to come by. (Torque * RPM) / 5252 = Horsepower. Higher torque will make higher horsepower, assuming revs remain unchanged. In reaility, I'm looking at this because it is feasible for me to do. I cast aluminum and iron all the time, have access to machine tools to do the major machine work. This means that cylinder sleeves are not out of the question, and if push comes to shove, pistons can be made on a temporary basis. Quote Link to comment Share on other sites More sharing options...
josh817 Posted March 16, 2008 Share Posted March 16, 2008 I told you I was going to be wrong, just sharing my current thoughts. >_> I always assumed 5 cylinder was the perfect balance but honestly, I have no idea what the "first harmonic level" is. I'll Google it so I don't get the almighty slap in the face of "use the search option before posting". XD EDIT: And please tell me 89mm bore on the l28 for my stroker won't be only a few thousand miles.... PLEASE x_x I can't do rebuilds that often... Quote Link to comment Share on other sites More sharing options...
Xnke Posted March 16, 2008 Author Share Posted March 16, 2008 Read through this thread again, and you'll see that a .120" wall thickness is considered to be the minimum wall thickness for a decent life. .120" is about 3mm. With the L28, you have a 96mm center distance between cylinders 3 and 4. between 1 and 2, 2 and 3, 4 and 5, 5 and 6, you have a slightly lesser distance, 94mm. Keep this in mind... If you look in your Nissan Factory Service Manual, you'll find the maximum permissible overbore in the L28 blocks is 2mm. Not that that stops anyone... Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted March 17, 2008 Share Posted March 17, 2008 I have seen up to a 91.5mm bore on a Japan-built L28... Probably wet-linered. Liners don't cost THAT much for the amount of CCs gained. OTM Quote Link to comment Share on other sites More sharing options...
josh817 Posted March 17, 2008 Share Posted March 17, 2008 Should be fine with 89mm then I think... Good thing I didn't try for 90mm 3.2L though on my F54 block rather than using the N42 block. Meh, I'll still build it, if it dies early on I can still use the internals and just get another block. >_> Quote Link to comment Share on other sites More sharing options...
Careless Posted March 17, 2008 Share Posted March 17, 2008 Meh, I'll still build it, if it dies early on I can still use the internals and just get another block. >_> thinking that way will cost you money when your piston breaks through a water/oil passage and turns sideways in the bore, damaging more than just your block. Quote Link to comment Share on other sites More sharing options...
josh817 Posted March 18, 2008 Share Posted March 18, 2008 A lot of people do the 89mm bore. Haven't heard any disasters yet... :/ I just don't know if I should do it on my F54 block or go out and get a N42 block. Besides, I bought 8 pistons (2 sets of 4). >_> Enough thread stealing, lets respect Xnke's thread and keep on topic. Didn't mean for it to get around to this... Quote Link to comment Share on other sites More sharing options...
Careless Posted March 18, 2008 Share Posted March 18, 2008 that wasn't my point. it was your reasoning behind re-use after a catastrophic mechanical failure that i was trying to get at. Breaking is breaking. You'd be lucky if you find the low calorie version called "Break Light", especially when pistons move at the speed they do. LOL. Just sayin. On with the show. Quote Link to comment Share on other sites More sharing options...
Xnke Posted March 18, 2008 Author Share Posted March 18, 2008 Until midsummer at least, my stroker won't be taking much shape. I'll be able to purchase the Block soon enough, but with the modifications needed and sourcing other parts, I'll be a while. Anyway....What do liners (the physical part, not the machine work) actually cost, on average? It may not be worth my time to cast and machine my own... Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted March 18, 2008 Share Posted March 18, 2008 Until midsummer at least, my stroker won't be taking much shape. I'll be able to purchase the Block soon enough, but with the modifications needed and sourcing other parts, I'll be a while. Anyway....What do liners (the physical part, not the machine work) actually cost, on average? It may not be worth my time to cast and machine my own... I have seen plain dry liners for $12 each... Whereas wet liners are a whole different story. Maybe $100+/cylinder? Check out Darton for wet sleeves. They can install them for you too if you ship them your block. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted March 19, 2008 Share Posted March 19, 2008 This is the every reason I will build my LD6 SC using the stock bore punched to 85mm. The cost of wet sleeving (the only option with this block for major bore increases) adds up quickly. At every turn, it makes a V8 conversion look more economical from a hp/tq standpoint IMHO. Quote Link to comment Share on other sites More sharing options...
josh817 Posted March 20, 2008 Share Posted March 20, 2008 Any aspect there is probably a cheaper route for more power. Really though, this is like a fight between buying a Vette or a Ferrari. The Vette may perform just as well maybe even better than the Ferrari, but honestly, who has a Ferrari on your block? Here in Keller, if you have a Vette you are simply part of the crowd, same goes with the V8 or the turbo conversion. This here though... it isn't joining any group... Not the V8, not the turbo, not the stroker. Genuinely unique and original which is what I like best. Maybe you're a different story. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted March 20, 2008 Share Posted March 20, 2008 My project is for the heck of it. It isn't the best $ for $ value. I like the challenge and the sound of a straight 6 winding up. Like the Vette vs Ferrari, it is the uniqueness of a SC'd L6 I seek over the more traveled road of turbos and V8's. Quote Link to comment Share on other sites More sharing options...
Xnke Posted March 20, 2008 Author Share Posted March 20, 2008 Hear, hear! Exactly why I want to do the LD block conversion. Quote Link to comment Share on other sites More sharing options...
josh817 Posted March 21, 2008 Share Posted March 21, 2008 Speaking of costs... Doing such a project these days may suck with the American dollar getting weak, and gas prices for your everyday activities. I was talking with my dad about how much it will cost us to race the BMW, thinking fuel would be a big part of it but apparently you can run the whole weekend on about 7 gallons at... >_> $9 a gallon. I was like "well thats not that bad" and he just stared and then reminded me how he use to get twice as much truck time for that price... because 110 octane was $3. XDDDDDDD We can get 87 octane for that now. Lovely. What compression will your LD motor be? Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted March 22, 2008 Share Posted March 22, 2008 I'm looking at 8.5 and running 6-8 psi boost (no intercooler). That may not be much by most standards here but it should provide for spirited driving and reliability too. Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted March 22, 2008 Share Posted March 22, 2008 You get 87 for 3 bucks? Do tell. Out here I'm feeling pinched with 91 at about 3.89 Quote Link to comment Share on other sites More sharing options...
Careless Posted March 22, 2008 Share Posted March 22, 2008 My project is for the heck of it. It isn't the best $ for $ value. I like the challenge and the sound of a straight 6 winding up. Like the Vette vs Ferrari, it is the uniqueness of a SC'd L6 I seek over the more traveled road of turbos and V8's. ... hoo yoo been talkin 'choo Quote Link to comment Share on other sites More sharing options...
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