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shoot me down or guide me


Guest Nic-Rebel450CA

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Guest Nic-Rebel450CA

Hey everyone, I am new to Z's but not new to engines in general. I was looking around for information on the internal specs of Z engines and I found that the rods for the 240 engine are just slightly longer than the rods for the 280. Now, would it be possible to use the rods for the 240 with the piston (tops) from the 280 and have a 280 with the same stock bore and stroke but higher comp? :?:

 

Hopefully I'm not just confusing specs that I read :oops::lol:

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You might run into deck height problems going that route. Read up, do some searches. The L series motors are very easy to build high compression just by bolting on an older head like an N42 to a F54 flat top motor and get close to 10:1 compression. There are other uses for the long 240 rods like stroker buildups.

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Guest Anonymous

Definately download the engine builder program...

 

the problems that you run into are mainly with deck height, I think it's like 1.23mm. Now I think if you start off with dished pistons, the depth of the dish is about 2mm so theoretically you should be able to fly cut the pistons 1.23mm without any problems. But you should probably talk to a realiable mechanic first, you don't want to build up a high compression engine and then have bits and pieces breaking off here and there...

 

I was thinking about doing this, but seeing as I already have the flat tops I'm thinking I'll just get an overbore and shave the head. If you want some more info, go to the discussion boards at http://www.ozdat.com, a guy on there called Steve Lamb has done the swap.

 

Anyway good luck.

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You can use the early type L28 pistons (10.9cc dish) and machine the rim of the dish down until you've created a flat top. Take it down until the factory oversize markings on the top are still just visible. This will create deck clearance for use with the L24 rod which is 2.4mm longer than the L28 rod. Be sure to use '73-on L24 rods (or L16), and NOT the later Maxima L24 rods which have smaller journals.

 

Alternatively, Sterling makes (or made) a piston in L28 sizes (86mm + overbores) that was used on the L24 rod. Let me know if you decide to go this way, I've got one out in the garage that has a part # cast in it and I could dig it up. It's just a cast piston like the stock Nissan but with a shorter compression ht. DAW

 

BTW, either the machined L28 piston or the Sterling piston will yield a c.r. of about 9.8:1; higher if you overbore beyond 86mm.

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Guest Nic-Rebel450CA
or you can use a 240sx piston machined .019" with a 1mm head gasket with 9mm 240Z rods and a LD28 crankshaft and come up with 3.1L ;)

 

What is the bore of the 240sx piston, is that the same as a 280?

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