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L28 is out - decision to be made


trwebb26

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I've taken the 78K mile L28 engine from my 78' 280z to finish up my subframe connectors. I know this engine runs fine. I've already added megasquirt and will be adding a turbo (I've already got the manifold and turbo). I have a 83' Turbo motor in my garage. All I know about it currently is that it has 250K+ miles. So I need to decide what to do next:

 

Option 1) Put the known good L28 motor back in the car and run low (less than 7psi) boost.

Option 2) Run a compression check on the 83' Turbo motor and if it turns out good - use it and boost away.

Option 3) Do a very basic engine freshening to include new bearings, head gasket, fasteners, rings, timing set, and a check of the tolerances (probably will include a freshening of the head). I'd guess this would cost me ~$600-$1000 in parts/machining. I'd rather not build the block up because I want to eventually swap out for another engine. I'd consider building it up.. maybe. Anybody done a L28ET motor build up that can tell me what a build up would cost? I'm guessing just north of $2K?

Option 4) Find a more "known" junkyard turbo motor.

 

Right now I'm leaning toward just using the L28 motor that I've got, but I'd appreciate other people's thoughts.

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If you know you're going to be swapping out motors eventually, put the known good one back in the car. 250k is a lot of miles... I'd almost be willing to bet that one's been rebuilt at least once in its life, but either way if you're not familiar with the history of that motor, you really have no way of knowing how long it will last in its current state. Even more so since the mileage is so high.

 

So yeah... I'd go back to the known good one for now, tear apart the junkyard motor and potentially use that for a buildup down the road.

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I would say compression test the turbo motor with 250k and see what it looks like. Install it and play around until:

a) it blows up

B) you're happy

 

You could also so with slown280z's suggestion too. The stock n/a motors are pretty robust and will handle ~7psi all day long. I don't even think it would be necessary to swap the head. Just swap on the manifold, and some injectors. Tune around 7psi and then move it up. 17psi has been had on a stock n/a block with an intercooler and meth injection.

In the mean time you can build the turbo block (3.1 stroker? :D) and all of your intake and exhaust stuff will be able to be put on the built longblock, bringing you to your end result.

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Freshen up the head on the turbo motor and put in on the NA block. Build the turbo block up with forged internals/bearings etc.

 

When your addiction to boost destroys your NA block/pistons, swap the built up bottom end in.

 

I vote for this!

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If you have a lot of time to play and swap motors etc.... then I would go with the turbo motor. You mentioned you wanted to swap for another engine down the road? If it's an L series motor build then go with slown280z recommendation. If its another type of engine just save your money and use what you have for now.

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