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sorealsosurreal

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Posts posted by sorealsosurreal

    need help choosing a piston 3.1L

    in Nissan L6 Forum

    Posted

    ok so to use a press fit, did you just use the pin from the 240 rod and press it into the ka24 piston and there yeah go or what? im going to order from a company called EPWI (my school has a deal with them) and the pistons i will be getting from them are the ITM pistons or another brand that i cant think of at the moment

    3.1L blueprints

    in Nissan L6 Forum

    Posted

    haha thanks its still very good info i havnt oredered pistons yet so i also havnt ordered a head gasket. i was wondering about taking layers out of the metal gasket but figure it wouldnt give a seal but thats very good to know. much appreciated

    need help choosing a piston 3.1L

    in Nissan L6 Forum

    Posted

    Ok so I think I'm going to go with a ka24de piston and then before I buy me head gasket make sure that there will be no clearance issues between piston and valves +1mm for the preferred head gasket and if so ill just go and buy a 2mm. Now if only some one made stock compression forged ka24de pistons (9.5cr). I searched the web and it seems even the 240sx guys couldn’t find them for their car!

    need help choosing a piston 3.1L

    in Nissan L6 Forum

    Posted

    so im building a stroker motor and am not sure what piston to use. im looking for a forged piston and plan on running a N/A high compression engine (10.5-11.5:1) not sure if all nissan ka24 pistons are forged but some of the pictures ive seen it looks that way. also before i buy a piston i need to know what headgasket to use. i was told that in doing a 3.1L stroker that the piston will rise above the deck surface .6mm so he encouraged me to use a 2mm head gasket. id perfer a 1mm if possible because its less likely to cause me trouble. anyways, advice on piston whether its oem or aftermarket (dont have money for custom) would be very helpful oh and the head i plan on using is an N42 if that helps at all. thanks everyone!

    Matt

    3.1L blueprints

    in Nissan L6 Forum

    Posted

    A few assumptions.... if you're building a 3.1L, that must mean you're using a Maxima diesel crank and 240Z (hopefully 9mm) rods. This setup by default gives you .6mm negative deck height (meaning the piston sticks out of the bore .6mm). If you're using a 1mm head gasket, compression is going to be pretty high, and you'd have to almost go with a custom dished piston to get below the 9:1 mark - meaning a really deep dish. (Also dependent on which head/chamber you use) You're also going to lose quench with a deeper dished piston, which will rob some performance.

     

    Most (if not all) 3.1L builds I have read about are using a 2mm head gasket to compensate for the deck height and to preserve quench. Stroker turbo can be done, but with carbs, you're pressing your luck, as you don't have near the control over fuel/timing as you do with an EFI MsNs.

     

    BTW - I have an SK blow-through surge box for triple Mikuni/Weber's that I probably am not going to use.....

     

     

    Ok thanks for the heads up, I've worked on cars a lot (mechanic) but never built an engine before. Didn’t know that the KA pistons would surface out of the block. I was thinking of using an aftermarket KA low CR turbo piston for the build. I’ve skimmed through this write up on building a 3.1L stroker many times

    http://www.geocities.com/row4navy/engine.html and I didn’t see the writer never mentioned his head gasket choice or what he did to the pistons whether they were shaved or not. So here's my question to you. If I used a 2mm head gasket and a deep-dish piston (no clue which one, pointers are welcome) would the CR be turbo applicable? as far as the carb vs FI I like the idea of a carb and it involves a lot less to worry about although I know that I would lose about all tuning capabilities

    3.1L blueprints

    in Nissan L6 Forum

    Posted

    ok changed my mind again, thinking of a blow through setup on my 3.1L. what i need to know is what compression KA pistons would give me an 8.5:1 cr in a 3.1L with a 1mm headgasket and no deck of block or head. all the z calculators give you a choice of pistons but i dont understand how to put in an aftermarket pistons and convert the info they give you on the aftermarket pistons to the dishvolume it asks for on the calculator.

    http://www.atlanticz.ca/zclub/techtips/calcs/engine%20builder/index.html

     

    i plan to if i do this set up run the car on low compression till i have the money for the turbo parts. should i throw this into the turbo thread? i really hope this post makes sense. thanks everyone

     

    Matt

    3.1L blueprints

    in Nissan L6 Forum

    Posted

    :cry2:nevermind going to part out the 280z. but on another note the engine from it turned out to have nice beautiful thick walls. and i got all my ARP hardware yesterday. now in search of some pistons!

     

    and with the other f54 block i think ive decided when the time is right to make a blow through turbo setup. i have the block, crank, rods, and a spare n47 head so why not????

    3.1L blueprints

    in Nissan L6 Forum

    Posted

    it might be easier if you look for the car they came in rather than the block itself. you could buy a run down N42/N42 block/head carrying 1976 280z parts car from someone and then sell off the shell and associated parts.

     

    College projects usually eat up money if you look at things like this. If you can't find it, then simply don't overbore your engine and look to other means for generating power. Higher compression maybe?

     

     

    ACTUALLY I DID JUST THAT! im the proud new owner of a 1975 280z. It had the n42 block but not the head. an N47 if anyone wants it. my dad and i are now think of what to swap into it. the previous owner had taken it aprt to restore it and had money troubles and its been sitting in storage for who knows how long. came with brand new nissan sheet metal for the hood and fenders. everythings there just not together all for $500

    3.1L blueprints

    in Nissan L6 Forum

    Posted

    ok thanks for the info im going n/a but still the f54 block i have is just to thin. im hunting down an N42 as we speak. just sorta pissed considering this is a college project im getting graded on and if waisted the time i have preping this block. oh well what can yeah do

    3.1L blueprints

    in Nissan L6 Forum

    Posted

    so im building a 3.1L for my 240z starting with an F54 block out of a 280zx turbo. i used a sonic tester to measure the clinder walls and got a couple readings that are concerning me. the samllest being .075 which turns out to be almost 2mm and if i have to bore from an 86mmbore to an 89 that will leave me about .5mm of wall thicknes. being that these smaller measurments are towards the bottom of the cylinders will this really matter. can any one whos actually machined a 3.1L themselves give me any advice on this. thanks Matt

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