saxfiend1967 Posted October 5, 2009 Share Posted October 5, 2009 Continuing my train of thought from above, if I was building a 383 stroker and had the option of running 6 inch rods as opposed to 5.7's why shouldn't I? Why does the option even exist if its just "scuttlebutt" as my old buddy Colonel Potter used to say? again run the 5.7 if you want torque which is 1.53333333333333333333333 with a cam on 106 centerline. run the 6 in rod for r/s of 1.6 which will sacrifice torque for hp but will not require larger ports etc with a cam on 110. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted October 5, 2009 Share Posted October 5, 2009 (edited) deleted What????? Wrong post mate!!! Edited October 6, 2009 by johnc Quote Link to comment Share on other sites More sharing options...
Daeron Posted October 5, 2009 Share Posted October 5, 2009 (edited) deleted Sorry, but that went up in the wrong spot ENTIRELY. Go back to the main sub forum branch, and go into Z31 subforum, and post a new thread of your own, there. You might want to search a bit before doing that, though. Edited October 6, 2009 by johnc Quote Link to comment Share on other sites More sharing options...
Raami Posted October 5, 2009 Share Posted October 5, 2009 FWIW, I have my 1.60 r/s LD-crank motor limited at 7200rpm as well and it "revs really nice" up there as well I'd rather have 5% more displacement than a "better" r/s ratio. No doubt about that but still it doesn't rev as good as 1,77r/s. And theres a reason why I don't wan't rev higher than that. Stock cam in my P90. And yes I can take my ld crank too and install it to my engine if I wan't more displacement. Just take 2mm more from pistons. And what I have understand is that it is easier for rods with bigger r/s than smaller r/s. Quote Link to comment Share on other sites More sharing options...
josh817 Posted October 5, 2009 Share Posted October 5, 2009 I would be extremely interested in hearing about that one day. Is megajolt capable of doing that? If its not that complicated, I would really be intrigued enough to try that... The answer is yes I'm pretty sure. Megajolt has one 0-5v input and like 3 or 4 0-1v inputs. I'm persueing mine currently, going to use the 0-5v for a wideband, 0-1v for water temp maybe, and then if a knock sensor is 0-1v I'll definitely do that. Megajolt has a setup that allows for "timing correction" so you can say at like 150º water you want +5º of advance, which is then added onto whatever "block" you're in on the MAP or TPS chart you have. And then you can say when water hits 250º retard the timing by 5º or whatever and 5º is taken away from whatever block you're on. The example on their website: And ironically, the creators of Megajolt are using a 240z to install the system. I guess the big question is whats the knock sensor voltage and how would you calibrate it but thats neither here nor there in this topic. Quote Link to comment Share on other sites More sharing options...
nissan2ner831 Posted October 5, 2009 Share Posted October 5, 2009 ^Wrong thread again?? Quote Link to comment Share on other sites More sharing options...
josh817 Posted October 5, 2009 Share Posted October 5, 2009 No... someone asked about MJ and a knock sensor so you can have maximum advance without detonating, while not having to use EFI. Its on the first page. ;] Quote Link to comment Share on other sites More sharing options...
nissan2ner831 Posted October 6, 2009 Share Posted October 6, 2009 No... someone asked about MJ and a knock sensor so you can have maximum advance without detonating, while not having to use EFI. Its on the first page. ;] ah I looked didn't see it. Now I see where your getting it =P Quote Link to comment Share on other sites More sharing options...
Daeron Posted October 6, 2009 Share Posted October 6, 2009 And what I have understand is that it is easier for rods with bigger r/s than smaller r/s. That is the truth of the matter, but if you could assign a number to "how much easier" and then factor that into the equation, more power will almost always be capable with more displacement. Changing the r/s ratio and making it "easier" is an exercise in tweaking your powerband to be what you want it to be, with the equipment you want to use. Now, to know what you are doing with that, requires about 10-20 different iterations of you L-motor with differing strokes and differing rod/piston combinations, as well as piston crown/head combustion chamber combinations, and induction combinations. I am saying about 10-20 longblock combos, plus the added complications of the induction setups (camming and portwork included with induction) and then make about oh, 50-100 dyno runs comparing your numbersfrom each change. (Finding a good dyno, good operator, who can keep his machine somewhat consistent for this project, etc etc... ugh) It is something that takes DEVELOPMENT. Les Cannaday burst my bubble on this idea by telling me that electromotive did something similar to this at one point, nd did durned good with it.. after they dialed it in to a T. Using resources that pretty much NOBODY here has. Did it kill my interest in the project? Heck no, it made me want to do it to study it. It made me certain that I was wrong in thinking it'd be some whiz-bang junkyard combo that no one had found that screamed in a way that convinced you to chuck the practicality of the stroker out the window. I thanked him generously for bursting my bubble. But if you take a block, bore it out to 89mm, and get some LD28 rods and an L20 crank, youre around 2.6 liters and you are at one end. Get an LD28 crank, and L24 rods, and the KA pistons and you can re stroke your de stroker. I think the de-stroker might require a slight alteration of pin height from the standard KA, but at most two sets of custom pistons, two different cranks, one block, and one head (unless you wanted to have two heads ready to go, so you wouldnt have to change cams.) All it takes is an L28, an L20 crank, L24 rods, and an LD28 reciprocating assembly. Plus the pistons, so maybe 1K for the stock parts and maybe 1K for two set of pistons (could be cheaper.) All that needs to be done is to try it and you start building the experience that you need to REALLY know this stuff. The important part is empirical records tracking improvement. Quote Link to comment Share on other sites More sharing options...
Komdotkom Posted October 6, 2009 Share Posted October 6, 2009 It basically boils down to put the longest rod into the engine that you can afford after you have chosen your engine. If you have an L28, then depending on your budget, put the longest rod you can afford into that. If you were really keen you could use FJ20 rods and custom slugs, but that's going to be a $3k exercise. If you aren't racing then just run L24 rods in an L28, bore it as big as you dare. Cheap and easy. Quote Link to comment Share on other sites More sharing options...
mikedc528 Posted October 6, 2009 Share Posted October 6, 2009 I have another long rod combo that i just plugged into the engine calculator. LD28 Block 86mm bores L24 Crank P90 Head Z20E Rods 152.5mm L28 Flat Top Pistons 86mm = 2.569L 0.00mm Deck Clearance R/S 2.069 B/S .0857 Max Rod Angle 13.893 Deg CR 8.016 Quote Link to comment Share on other sites More sharing options...
nissan2ner831 Posted October 6, 2009 Share Posted October 6, 2009 I have another long rod combo that i just plugged into the engine calculator.LD28 Block 86mm bores L24 Crank P90 Head Z20E Rods 152.5mm L28 Flat Top Pistons 86mm = 2.569L 0.00mm Deck Clearance R/S 2.069 B/S .0857 Max Rod Angle 13.893 Deg CR 8.016 And this is why I hope to eventually build a LD28 converted over to gas and use a nice big stroke =P That extra deck height would let you run much longer rods, but the bore is pretty limited unless you sleeve the block....which of course is part of my pipe dream XD Which includes: Custom crank with an 88mm stroke (be interesting to see if this would fit in the block, and if not what kind of work would have to be done), around 150mm long rods (haven't looked into if any forged OEM rods would work or not) and custom 31mm pin height pistons in a sleeved LD28 bored out to 89mm (leave some room to clean up the bore if needed later) with a dish allowing for a nice big turbo to be placed on it....Yes I would love to have a 3.3L turbo'd LD28....Likely to happen? Well we'll have to see XD (My more realistic goal is a car very much like Garrett76zt's, which while not cheap is much more realistic for most) Quote Link to comment Share on other sites More sharing options...
Pyro Posted October 6, 2009 Share Posted October 6, 2009 I beg to differ. rod to stroke ratio is every thing! a small rod to stroke ratio requires more induction( Bigger carb ,bigger runners) a 1.75 ratio does not.1.75 and up will make more power with small runners and induction. everyone raves about 327 chevy look at the rod to stroke ratio compared to all the other engines a 400 small block chevy has a ratio of 1.6 and makes enormous torque if the rod to stroke is raised it will sacrifice torque for hp nascar is doing this every week a 377 chevy has a low rod to stroke ratio and makes torque out the wazoo ! I have been studying this for a long while. a 273 chrysler engine can use a 750 holley while a 440 with a longer rod uses a 650 the bottom line in lay mens terms if you want a buttload of torque run around 1.5 rod to stroke with a cam ground on 106 centerline or maybe even 104 if you want high end hp run r/s ratio up over 1.75 with a 110 seperation. No offense, but I'll take the side of professional engine builders that publish on such matters. Besides, my old school 350 with a 1.63 r/s ratio revs to 7200 rpm just fine. Would easily go more but 7200 is at valve float for my setup. Yes, the people that rave about 327's are the same people spreading these r/s power myths. A 350 or 400 will easily out power a 327 with todays high flow cylinder heads. The main thing that made 400's into high torque engines was the old small block heads didn't flow enough for 400 cid at high rpms. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted October 7, 2009 Share Posted October 7, 2009 No offense, but I'll take the side of professional engine builders that publish on such matters. Besides, my old school 350 with a 1.63 r/s ratio revs to 7200 rpm just fine. Would easily go more but 7200 is at valve float for my setup. Yes, the people that rave about 327's are the same people spreading these r/s power myths. A 350 or 400 will easily out power a 327 with todays high flow cylinder heads. The main thing that made 400's into high torque engines was the old small block heads didn't flow enough for 400 cid at high rpms. Dunno mate. I think that for this (or any) comparison to be fair with the examples of Chev's you've just given, the engine capacity should be kept the same or very close so that by altering the rod ratio, a direct comparison can be made to the power produced (by altering just ONE engine variable at a time). This idea would be familiar to all those people who develop their engines, or are very involved with fine tuning their machines. Cheers. Quote Link to comment Share on other sites More sharing options...
Daeron Posted October 7, 2009 Share Posted October 7, 2009 Which includes: Custom crank with an 88mm stroke (be interesting to see if this would fit in the block, and if not what kind of work would have to be done), around 150mm long rods (haven't looked into if any forged OEM rods would work or not) and custom 31mm pin height pistons in a sleeved LD28 bored out to 89mm (leave some room to clean up the bore if needed later) with a dish allowing for a nice big turbo to be placed on it....Yes I would love to have a 3.3L turbo'd LD28....Likely to happen? Well we'll have to see XD (My more realistic goal is a car very much like Garrett76zt's, which while not cheap is much more realistic for most) I do not think the LD28 block can even come close to an 89mm bore. I haven't got a moment to look for posts to show, because I am speaking from what I have read (and not first hand knowledge) but I am still pretty sure your ceiling on an LD block is significantly less (in terms of potential bore diameters) than the gas L6 blocks. Sorry I can't recall specifics, but I know I have seen multiple threads where brian (1_fast_z, the guy who built his own DOHc head for the Z engine out of 240SX heads) repeatedly stated over and over that the block he sonic tested couldn;'t be bored out to over 83mm? Again, I am fuzzy on the details, but I know I have seen pipe dreams of 3.4 liter engines based on that super tall block with an 89mm bore, but it just aint going to happen. Quote Link to comment Share on other sites More sharing options...
Pyro Posted October 7, 2009 Share Posted October 7, 2009 Dunno mate. I think that for this (or any) comparison to be fair with the examples of Chev's you've just given, the engine capacity should be kept the same or very close so that by altering the rod ratio, a direct comparison can be made to the power produced (by altering just ONE engine variable at a time). This idea would be familiar to all those people who develop their engines, or are very involved with fine tuning their machines. Cheers. just in case you didn't see this link I posted a few pages back. Drag engine builders trying to make more power by only changing the s/r ratio. didn't change anything. http://www.hardcore50.com/Articles/georgeklass/greatmyths.htm Quote Link to comment Share on other sites More sharing options...
Raami Posted October 7, 2009 Share Posted October 7, 2009 Who has said that you wouldn't get more power if you would have so much more displacement?? Everybody knows that. This topic is about better r/s with the same displacement and the effects of that. And that 7200rpm is just the revlimiter what I use know. Quote Link to comment Share on other sites More sharing options...
Pyro Posted October 7, 2009 Share Posted October 7, 2009 Who has said that you wouldn't get more power if you would have so much more displacement?? Everybody knows that.This topic is about better r/s with the same displacement and the effects of that. And that 7200rpm is just the revlimiter what I use know. don't you guys read before posting? here it is again. http://www.hardcore50.com/Articles/georgeklass/greatmyths.htm they ONLY changed the r/s ratio. no power difference. they used 500 cid drag racing engines. Quote Link to comment Share on other sites More sharing options...
nissan2ner831 Posted October 7, 2009 Share Posted October 7, 2009 I do not think the LD28 block can even come close to an 89mm bore. I haven't got a moment to look for posts to show, because I am speaking from what I have read (and not first hand knowledge) but I am still pretty sure your ceiling on an LD block is significantly less (in terms of potential bore diameters) than the gas L6 blocks. Sorry I can't recall specifics, but I know I have seen multiple threads where brian (1_fast_z, the guy who built his own DOHc head for the Z engine out of 240SX heads) repeatedly stated over and over that the block he sonic tested couldn;'t be bored out to over 83mm? Again, I am fuzzy on the details, but I know I have seen pipe dreams of 3.4 liter engines based on that super tall block with an 89mm bore, but it just aint going to happen. hehe it's a pipe dream I know. I think from what I've read from 1 fast z was that the maximum bore before you hit water jackets is 86mm (if I'm not mistaken, I'd have to go back and look). If that's the case, then a wet sleeve theoretically could be used to get a larger bore, but I'm no professional so I'd have to leave it to someone who actually has looked and worked on those blocks to either confirm or destroy my pipe dream XD. I don't see why you couldn't bore them out that far if you wet sleeved the block, unless the LD28 has more material and the same sized water jacket around the cylinders as the L28 (if that makes any sense). I think there have been some large displacement LD28's that were sleeved to more than the limit other wise, so I'm basing the idea off those XD Quote Link to comment Share on other sites More sharing options...
Raami Posted October 7, 2009 Share Posted October 7, 2009 don't you guys read before posting? here it is again. http://www.hardcore50.com/Articles/georgeklass/greatmyths.htm they ONLY changed the r/s ratio. no power difference. they used 500 cid drag racing engines. So you think that it isn't easier for rods and cylinder walls with the bigger r/s? Or it isn't better with high revs? I have never said that it would make much more power with better r/s, only that it is easier for those parts. Quote Link to comment Share on other sites More sharing options...
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