Which engine for a 77’ 280z

[Av8ferg]

Gents, 

I’m considering getting a replacement engine for my 1977 280z.  First the back story.  The car has an engine that runs but has a myriad of issues that make it ripe for removal and likely rebuild and or replacement.  Odometer currently reads 28k.  It was locked up when I bought the car, and broke t free with som mystery oil. So I’m assuming it’s 128k.  1. Some of the freeze plugs are leaking due to rust from the inside.  I’ve temp fixed those with JB weld. 2.  I’m getting what I think it timing chain slap.  I hear a what sounds like the chain is hitting the cover as the RPM retards from a rev.  So I’m might have a tensioner problem.  3. I may have a head gasket leak because my exhaust seems to have an unusual amount of white smoke.  4. Cold compression check had 2 cylinders in the mid to high 140’s while the others were in the 160-170’s.  Bottom line , I want a reliable motor that I can enjoy with peace of mind.  So this is why I’m asking the question.  I can’t bring my car to my house for a least 6 more months because I don’t have room for it, and currently building a new house with an 1,100sq ft garage.  I do have room to rebuild an engine while I wait for the car to come home,, plus I need a project...I always need one.  My thought is a good motor can be ready for install when the car gets here,  I’ll keep the old motor as a backup or sell it.  

So a yard near me has three complete L28 engines available.  All are sitting in cars.  

1976 L28 with N42 head 

1982 L28et with P90 head (turbo)

1982 L28 with P90 hean (non-turbo)

He wants $400 for any of the engines with all the parts and pieces.   If I want the turbo with the L28et he wants an extra $100.  

I’m considering going with the L28et.  It might be nice to have the extra power if I’m spending the money to rebuild an engine anyway.  

My goal to to have a fun, reliable car that will mostly be a weekend driver.  I’m not after a show car or track car.  

Finally, what do you think will be a cost estimate for an average rebuild if I do most of the work myself?

So which engine?  I want to grab one before they disappear.  He said he sold his other L28et last month. 

Thanks.

 

[240260280]

Turbo is  lot more work and effort. I'd say the 82 P90 is best.  Shave it to boost the compression and you are good to go.

[Reptoid Overlords]

Also, the N/A `82 F54 already comes with flat top pistons.

 

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[Av8ferg]

What do you mean by a lot more work with regards to the turbo version? Is the power increase of the turbo not worth the effort and cost?


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[siteunseen]

I've read the turbo has more wiring than the stock wiring harness plus you need the turbo ECU.  The turbo may need rebuilding plus there is more piping on a turbo.  Things I've read in the past only, never owned a turbo car but they were fun back in the 80s.

@Zed Head is more familiar with zcar.com, that's were most of the turbo guys hang out.  He may shed some light on this?

I'd go the N/A P90 route also because I like to keep things as simple as I can.  You won't out run these newer cars with a turbo Z.  Save your money for a 240.

I rebuilt my '77 L28 myself for $500 or so, new everything except the basic engine parts.  Reused the block, crank and pistons and head.

gaskets, oil pump water pump fuel pump and injectors, new timing components

[Av8ferg]

Thanks Cliff. I drove a turbo once in like 1989. It was a peppy little car and fun to drive. I know there was like 1 turbo for every non-turbo built so they’re harder to find for sure. I forgot about a new ECU and probably AFM and wire harness. Maybe the guy would throw those in....probably not?
I’ll wait for ZedHead to chime in. He always has good comments.
Starting to think a 240 not rusted out is becoming like a unicorn these days.


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[Av8ferg]

That’s 3 votes for the 82’ non-turbo so far!


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[240260280]

L28, high compression, cam, some triples and you are set.

 

Turbo items:

HG worries

Coking on bearing

Cooling on shut down

Getting fuel and timing right,

Intercooling pipes

Heat and exhaust

EFI system

 

A lot more to rebuild, set-up and maintain with a turbo.... and how many times will you use the full power of either motor? Put the extra effort and $$$ into the suspension that you save with the NA, you will always be turning ?

Edited February 14, 2019 by 240260280

[Zed Head]

Wow, that's some pressure.  I'm not really the turbo guy though, I just read a lot.  I always recommend picking the project that has what you like to do in it.  To do a turbo engine right you really need to enjoy working on engine management, the wring, computer, AFM, associated turbo parts like the blow-off valve, etc.  You need to be very techy.

If you're not going to get the extra 1982 parts, like the computer, wiring harness and AFM from the ZX, then you'll need to choose an engine management system.  1982 engine management is pretty primitive though.  Most guys end up with Megasquirt, for example.  If you go that route then you'll need to tune it, using a computer and adjusting various tuning values.  Very computery. @cgsheen1 has some definite views on turbo engine swaps, he's done a few.  His view, as I recall, is that you'll learn a lot trying to use the 82 ZX engine management but in the end you'll want Megasquirt or a later model Nissan system.

If you want to add power to an NA engine you'll probably need Megasquirt, again.  The stock EFI system isn't tunable.  Hard to get them running well after power mods, like a cam, apparently.

The opposite is carbs of course.  Then all of the old school stuff applies.  If you're going to have the engine rebuilt anyway, the choice kind of boils down to carbs or computers.  Which makes you feel best?

By the way, the P90 head engine non-turbo might be a low compression dished piston engine.  A turbo engine with no turbo.  So it might need new pistons if you want to get some pep out of it.  If you can tell by examination which engine seems least abused, that might be the way to go.  Less money to make it right.

Alright, the coffee has worn off...

[Zed Head]

p.s. if you get the turbo manifold you can make any NA engine a turbo engine, using Megasquirt.

When examining the engines don't forget the little stuff like injectors, broken bolts/studs, water pump quality.  The nickel and dime stuff.

[Av8ferg]

ZedHead....here’s my takeaways from your post.
Turbo mean lots of tuning work and extra stuff to do.
Are you saying the NA engine isn’t flat top pistons? I thought hey were and dished on the Turbo.
I don’t think I want all that extra work but it sounds like megasquirt is the way to go either way. So It’s not a good idea to use my current EFI stuff on the 82’ engine?
Are you voting for the 82’ non-turbo.
After reading all this I’m seeing that the turbo might be the wrong direction.
My Goal...reliable, strong engine that is low maint and fun to drive. A little power is just fun to have


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[Zed Head]

The P90 head was usually, but not always, used on the turbo engines.  If you see a P90 head you expect dished pistons in the block.  The P79 head was the 280ZX NA head.  Somebody might have swapped a turbo engine in to an NA car.  All they'd have to do is remove the turbo parts.  So it would end up as a low compression ratio NA engine.

Your EFI stuff will work.  It will work best if you keep everything factory stock.  You said it would be nice to have more power.

One other consideration is the "lifter", actually the rocker arm pivots.  Most P90 heads used hydraulic rocker arm pivots.  You can swap them to mechanical using Timesert thread inserts.  Just one more mechanical thing to do of the hydraulics don't work right.  They do wear out eventually.

I'm not going to vote.  No idea what you enjoy.  My method is to go stare at the engines and poke around.  You might find some show stoppers that just leave one.  Look through the spark plug holes, and the oil filler cap.  Take the valve cover off if he lets you.  If they all have dished pistons then only the 76 engine will give the CR that you probably want for an NA engine.  And, from what I've been reading over the last year or two, pistons are getting harder to find.  The old days of getting cylinders bored and a set of oversize pistons might be gone.

This guy posted a lot of interesting stuff.  People don't always agree with everything he says but it's still informative. 

http://datsunzgarage.us/p90/

Don't overlook that your 77 engine's head can be used on any of those engines.  You could pick the best short block of the P90 head engines to be sure that the pistons are reusable.