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N42/N42 with .50 trim, stock injectors and 25psi, bad idea?


Mycarispurty

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There is a guy somewhat close to me with a pretty clean looking 280ZX I'm interested in going to check out.  He doesn't seem too familiar with the motor other than what the guy he got it from has told him.  

 

Anyways, here's what I've gathered from what he's told me.  It's an N42 motor, with an N42 head.  He said the p/o told him it needed a new head because it was burned up, so likely valves.  Here is what I've kinda figured is the problem:

 

Way too big of a turbo, stock injectors, stock motor, and 25 psi without any sort of fuel management or boost controller or fancy electronics...he forced way too much hot air into it without an intercooler on it, and melted the valves, and probably even damaged the pistons/walls, then once he figured out what he did, he passed the savings on to this kid that has it now.  

 

He says it'll run but won't stay running unless you spray some fuel into the intake.  I'm thinking the previous owner pretty much melted the internals.  Care to give your .02?

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The stock system is designed to run at 7 psi with the stock injectors.  What do you think happens with the stock injectors and stock fuel management when you run it at 25 psi and no intercooling?  Its not so much the scalding air - its the extreme lean conditions and detonation that would be the problem.  Surprised the thing runs at all....

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the turbo is not a problem but if he ran over 10-12 psi without a intercooler not good but he could NOT have ran at that boost level with out lean missing and spark blow out! hell it may not be hurt at all or could be toast have to pull head to see. i would rent a bore a scope at auto zone pull the plugs and have a look. im running 20-22 psi but big injectors/megasquirt but thats a no go with the stock efi and squirters. good luck hope it works out for you!!!

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What do you mean there is no way to control boost?  Is there no wastegate?  I would check compression first, before I did anything else.  From what I've seen the head gasket is the weak link, but with the right (read wrong) combination any number of things could have been hurt.  Rings, valves, pistons, bearings, rods or a combination of these could be problematic.  It can be tempting when you find a poor old sap you think you can get a "He doesn't know what he's got" deal from.  Just imagine the "He doesn't know what he's getting.." deal that proceeded it may have been like.  Now if he's giving or paying you to take it away that is a different story entirely!

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