datfreak Posted July 8, 2004 Share Posted July 8, 2004 hi all, I was planning on doing the ld28 crank and 89mm piston thing BUT i think i'll go the lamer standard stroke way. I am hoping on keeping the std l28 crank and fitting some 89mm (120 thou over) pistons that should give 3.0l. Does anyone know if any standard 89mm pistons will fit, with correct piston height etc(even with diff rods)? The L series engine calc program is good but i still want more details before I go ahead.(like sussing out oversize head gaskets etc) Has anyone done this? Quote Link to comment Share on other sites More sharing options...
Guest Aguyandaredhead Posted July 8, 2004 Share Posted July 8, 2004 If memory serves me right (which might be a long shot) In the stroker I built 7 years ago I used 240 rods and KA24 pistons from a 240sx.. 89mm bore and right pin height with the 240 rod.. Hope that helps Jeff Quote Link to comment Share on other sites More sharing options...
DAW Posted July 8, 2004 Share Posted July 8, 2004 That's twice now. I don't know if it's my computer, the ISP, or the site, but there's an interruption and deletion of my response each time. The first time I'd invested a huge amount of time into a detailed technical response..oh well. To simplify, LD28 and FJ20 rods are 140mm. The LD rods use large floating wrist pins, while the FJ20 are 21 or 22mm. Both would requie 28.5mm compression ht. (c.ht.) 89mm pistons. Chevy S-10 are close but the pins are tiny. Forged would have to be ordered, but the rod/stroke is nice. So, L24 (133mm, 9mm bolt) rods are more practical and give a ho-hum rod/stroke of 1.68; better than a stock L28, worse than a stock L24, much better than an an 89mm/83mm hybrid with L24 rods. KA24 and Z24 pistons leave you with negative deck ht., and dished-piston compression ratios, BMW 3.0L 89mm and Toyota 20R 89mm pistons leave you with far too positive deck ht., requiring shorted rod lengths or shorter stroke (L24 crank) in order to use them, and both have pin-fit problems. I'm in the same situation as as you, as I set out to build an 89mm/83mm stroke L28 with L24 rods. But the abysmally low rod/stroke dissuaded me and I'm building instead a LD28 block/crank (1.5mm-over to 86mm), L28ET piston, L20B rod, adapted P90 head, L28ET turbo system engine with a 1.76 rod/stroke; and not a L28 block/LD28 crank hybrid with its 1.60 rod/stroke. Huge difference. Stock L24 was 1.8. Anyway, looking at 87-88.5mm pistons with the appropriate pin size and c.ht., ordered in the appropriate oversize, seems like the reasonable way to go to keep it on a sane budget. I'm going to check out some options and I'll post when I have some candidates. DAW Quote Link to comment Share on other sites More sharing options...
Drax240z Posted July 9, 2004 Share Posted July 9, 2004 DAW, I don't have my calculations handy here, but I'm pretty certiain that the LD28/L24/KA24 stroker combo ends up at 1.68:1 rod/stroke, which is better than the stock L28 of 1.60:1... (if I am recalling this correctly, I do remember that the stroker setup has a more favorable rod/stroke than a stock L28 however) Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 9, 2004 Share Posted July 9, 2004 L28 = 79mm stroke and 130.2mm rod = 1.648 LD28 = 83mm stroke and (L24) 133mm rod = 1.602 So the L28 has the better rod ratio. Personally I'd rather have a stroker than the L28 I have, but the L28 does have the marginally better ratio. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted July 9, 2004 Share Posted July 9, 2004 Ah yes, I must be on glue, my calcs agree here with what you guys just said. Quote Link to comment Share on other sites More sharing options...
datfreak Posted July 13, 2004 Author Share Posted July 13, 2004 hi all, some one said that some toyota 89mm pistons can fit, but i could be mislead. Has any one heard of this?(any details) Quote Link to comment Share on other sites More sharing options...
DAW Posted July 13, 2004 Share Posted July 13, 2004 20R pistons in +0.5mm oversize are 89mm but the pin is 22mm (L24 rods are 21mm) and the c.ht. is high, 38mm at the outer edge with the center even higher at 41mm c.ht. You have to study listings by Weisco, TopLine, Sterling, and Silvolite to come up with potential possibilities. You may have more luck finding a piston that is just smaller than 89mm, but otherwise meets the c.ht. & pin criteria, and order oversize (+0.5, 1.0, 1.5mm etc.) to get the 89mm piston that meets all the parameters. DAW Quote Link to comment Share on other sites More sharing options...
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