260pos Posted January 18, 2007 Share Posted January 18, 2007 Okay boyz, how about this; L28 block, bored .040 over Stock Crank LZ22s Pistons L20a Rods E88 Head This should come out at 2818cc’s And 10:1 SCR Has anyone built one yet? Being I keep hearing (reading) about the poor harmonics of the long stroke L's. Wouldn't this fix it? Where do we get the rods? JDM got all the good shi, I mean stuff! -Jim Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted January 18, 2007 Share Posted January 18, 2007 There are a couple guys here that have an extra L20a... I'd get some custom pistons, run a Maxima N47 head with 39-39.5cc chambers an run it at about 11:1 Is this motor for street, strip, road racing, bonnevile flats or what? I would not plan on using an E88 unless it is the one that is the same as the E31 240Z head. The 260Z E88 was pretty much the crappiest head other than having the biggest stock cam. If you want a Maxima N47 head I have one I'd let go of...shoot me a pm about that one. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 19, 2007 Administrators Share Posted January 19, 2007 The E-88 “will” detonate on pump gas at 10:1 compression no matter if the piston is flat top or dished, (i.e. no squish and the L-series is VERY sensitive to detonation). Ideally for any engine, especially the L-series due to its detonation sensitivity, you want a quench style chamber and if a dish is needed in the piston to keep the compression ratio pump gas friendly, then a custom “D” dish “should” be used to retain squish, not the OE circular style dish… Quote Link to comment Share on other sites More sharing options...
260pos Posted January 19, 2007 Author Share Posted January 19, 2007 Okay. So other than the choice of head (Did I mention the wine last night?), would the long stroke / long rod create a freer reving engine. Or were my thoughts last night just way out in left field? Or am I just wasting bandwidth again? Quote Link to comment Share on other sites More sharing options...
260pos Posted January 19, 2007 Author Share Posted January 19, 2007 Search, Search… Okay I didn’t follow up on the discussion that got me thinking about this. So the L20a doesn’t have 135mm rods, 133mm just like the L24. So lets rephrase the question again. To keep people off my head choice lets say I have a L28 F54 block with a P90 head, would converting to the L24 133mm rods and custom pistons with a modified compression height help out with harmonics and rev-ability? http://forums.hybridz.org/showthread.php?t=117949 Quote Link to comment Share on other sites More sharing options...
Zsane Posted January 21, 2007 Share Posted January 21, 2007 Search, Search… would converting to the L24 133mm rods and custom pistons help out with harmonics and rev-ability? http://forums.hybridz.org/showthread.php?t=117949 Read! http://victorylibrary.com/mopar/rod-tech-c.htm Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 22, 2007 Share Posted January 22, 2007 How long do you plan on staying at the critical speed? Harmonics are also referred to as a 'critical speed' and in most rotating machinerly has first, second and third critical speeds. Normally engineering of the machine will have the machine operate below any of the critical speeds. In cases where this is not possible, acceleration through the critical speed as quickly as possible is normally done to minimize the effects of the harmonics. Unless you are running at Bonneville, and severely miscalculate your gearing and tire sizes so you are AT the critical near your terminal speed, you will accelerate through the speed with no ill effects. Quote Link to comment Share on other sites More sharing options...
260pos Posted January 22, 2007 Author Share Posted January 22, 2007 Zsane, that is a very sweet article. Thanks, but it got me thinking more along the lines that a truly “fun†engine needs more tweaking in the short block. TonyD, what are the approximate “critical†speeds on a L6? I understand that it would be based on stroke, component weight and probably the individual grain and temper of each component, is there a way of calculating this? Now the wine has been gone for a while, but the curiosity remains on this question. I came up with these numbers: COMPONENTS / ROD RATIO / ROD ANGLE / SIMILAR TO LD28 block L28 crank w/ custom rods / 1.896 /15.289 degrees / 302 Chev L24 L14 rods w/custom pistons / 1.853 / 15.650 degrees / 340 Mopar L24 / 1.805 / 16.085 degrees / 289 Ford LD28 block & crank w/custom rods / 1.776 / 16.353 degrees / 327 Chev L28 / 1.648 / 17.661 degrees / 350 Chev L28 LD28 crank L24 rods / 1.602 / 18.182 degrees / 396 Chev L28 LD28 crank L28 rods / 1.569 / 18.587 degrees / 454 Chev It seems that the motors that are infamous for revving have the better ratios. Build your own Datsun Z/28 (liter)! This Z Sounds SOOO sweet! Quote Link to comment Share on other sites More sharing options...
Guest d3c0y z3d Posted January 23, 2007 Share Posted January 23, 2007 I just bought an L20ET with the same thing in mind and i was very dissapointed to find that the L20 rods are tiney. They aren't even as wide as my index finger and the big end will not fit on an L28 crank :cry2::cry2::cry2: Quote Link to comment Share on other sites More sharing options...
NZeder Posted January 23, 2007 Share Posted January 23, 2007 I just bought an L20ET with the same thing in mind and i was very dissapointed to find that the L20 rods are tiney. They aren't even as wide as my index finger and the big end will not fit on an L28 crank :cry2::cry2::cry2:Sorry to hear about that - it is a shame that the Lengine.exe has the incorrect figure and has put you on the wrong path. The L20ET and L20aE later than 1979 use these smaller rods they are not as wide, have both smaller big and little ends and as you have found dont work with the L24/26/28 cranks (yes you could machine the crank down so the big end of the L20ET rod will fit but the rod is still too thin at the journal end = still no good) If you want to have a 135mm rod there are two options as I see it (and it has/can be done) then find some early L20a/L20aE or L24/L16 rods that are 133mm then offset bush the little end to give you a 135mm rod or get the now very hard to find L14 rod which have a 136.7mm center to center length and offset bush this in the other direction to give the same 135mm. Re the L14 rods I know that can still be purchased from Nissan new as I had our local Nissan dealer price them up for me however it would be almost the same price as custom rods ($240 NZD each = $165 USD) Quote Link to comment Share on other sites More sharing options...
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