Guest DaneL24 Posted April 24, 2003 Share Posted April 24, 2003 I just have an idea for an N/A L6 set-up, and want to get some opinions on what you guys think it would run in the quarter...just out of curiosity. Predicted 0-60 times would be interesting too. So here goes: -1971 240Z -P79 L28 bored to 3.0 liters (3mm over with 240SX Pistons, L24 Rods, L28 Crank) -10.0-10.5:1 CR -262/272 Cam -SU carbs running rich with SM Needles (not sure if bolt-on to P79 is possible?) -Exhaust Headers -280ZX Dizzy (Electronic Ignition) -Early 4-Speed with 3.9 Diff -Standard width tires, just a little wider Assuming it was well driven, I think the car could hit 13's. Just looking for more opinions here. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted April 24, 2003 Share Posted April 24, 2003 how are you going to use KA24 pistons with L24 rods and L28 crank? you would need the diesel crank to bring the pistons back up to the deck. -1.37mm deck height with your setup. compression is 7.88 with LD28 crank deck height .63 and compression 9.75 according to L enigne calulator I would say I'll go with more cam. 270/280 range. with 10:1 to 11:1 compression Quote Link to comment Share on other sites More sharing options...
Guest DaneL24 Posted April 24, 2003 Share Posted April 24, 2003 I know, this combination will result in a negative deck height. There are ways to increase the compression though. I found this at http://www.zhome.com/rnt/L28conversion/3031FAQ.html: "The top of the block can be milled to increase the compression ratio, but several concerns must be addressed: the timing chain slack will increase, the heads bolts might bottom out, the oil passage restrictor plugs would have to be pressed further down into the block, and the keyholes used to position the head in the block would have to be re-machined, etc, etc. Needless to say, this is not a popular approach, but it has been done." Timing chain slack is solved with cam shims and thicker lashpads, head bolts bottoming out shouldn't be a problem (since there are no problems with head shavings, bolts could be trimmed if necessary). I'm not certain about the oil passage restrictors and remachining the key-holes. Like I said, this was just an idea, and not something I'm about to go do this second. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted April 24, 2003 Share Posted April 24, 2003 I would mill the head if I were you, it works better. Your cam is ok, but you really need some compression to make a big cam run right. What head are you planning on using, the P79? If so that is a pretty good choice if you mill it some, like at least 85 thous. You can probably get down into the low 14's, high 13's if you get really good traction and leave hard. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted April 24, 2003 Share Posted April 24, 2003 Oil restrictors should be ok with .010" shaved. but I don't know about .050"-.060" shaved. If you run a shaved head on top of that, you'll need alot of shims Quote Link to comment Share on other sites More sharing options...
Guest DaneL24 Posted April 24, 2003 Share Posted April 24, 2003 I should have mentioned a head shaving to go along with it. So yeah, a block shaving to bring piston deck height near zero, as well as a head shaving for more compression. -.080" Shaved P79 Head -Cam Tower Shims (a lot for both head and block shaving) -Thicker Lashpads Thats how the extra compression would be attained, and all the other bits to maintain timing chain tension and valve-train geometry. And yeah I understand why you need a lot of compression for a bigger cam, you have to compensate for the intake valve staying open longer ABDC. I'm not familiar with the oil restrictor plugs and keyholes for head positioning though. What are they and what do they do? Quote Link to comment Share on other sites More sharing options...
yo2001 Posted April 24, 2003 Share Posted April 24, 2003 The oil restrictors restrist oil to the head so the bottomend won't starve for oil. The key holes hold the dowl so the head will line up right during installation. Quote Link to comment Share on other sites More sharing options...
TimZ Posted April 26, 2003 Share Posted April 26, 2003 Ummm - voice of sanity here... With all the trouble you are going to go through trying to get the 240sx pistons to work, you could probably come really close to paying for a set of forged pistons, made to the proper deck height. Then you could avoid all the silliness of compensating for chain slack, cam timing, re-boring holes for oil restrictors, etc. AND you'd have a much nicer set of nearly indestructable pistons. Also, with -1.37mm deck height, you might be able to get the compression back up by milling the head, but all of the supposed advantages of the closed chamber P-series head design will be negated, essentially making it an open chamber head with a bunch of exposed sharp edges. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 26, 2003 Share Posted April 26, 2003 Ummm... Thank you Tim. Mike. Quote Link to comment Share on other sites More sharing options...
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