N47 or P90 Swap? - Nissan : Datsun ZCar forum :Nissan Z Forum: 240Z to 370Z
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post #1 of 3 (permalink) Old 07-08-2019, 05:21 PM Thread Starter
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N47 or P90 Swap?

Right now I'm running N47 head in my L28E 280zx. Since I have to take apart the engine to resurface the head and block, I'm thinking of swapping the head and everything else to the P90 in order to get lower CR so I can run turbo. In order to run 300 HP without blowing the engine, would it be smarter to keep the N47 and raising the CR or just buying the new head and turbo send it? I keep looking around throughout the forums but it doesn't seem that anyone has asked this question.
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post #2 of 3 (permalink) Old 07-09-2019, 01:07 AM
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what year is your Z? does it have its original engine?
they say the P79 is the best flowing head. personally, i favor the F54/N42 block/head setup. flat tops and higher compression. pair this with a 3.90 rear end and you've got a nice NA setup. if you're only going turbo, get a complete turbo engine out of a turbo car. there are many options, depending on what your vision is.

here is a website with invaluable information regarding every L-series engine that came in the USDM cars:



All the Gods, all the Heavens, all the Hells, are within you. - Joseph Campbell -

Pooja II ~ 1984 300ZXT 50th AE ~ 2018 - 2019
Pooja ~ 1987 300ZX 2+2 NA2T ~ 2012 - 2018
Suzanna ~ 1983 280ZX Coupe ~ 2010 - 2019
Alana ~ 1976 280z Coupe NA2T ~ 2008 - 2019
Dianna ~ 1980 280ZX Slick Top ~ 2001 - 2007
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post #3 of 3 (permalink) Old 07-10-2019, 07:31 PM
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You don't need to lower compression with modern ECU technology, you just need to control heat and spark very well. The N47 has exhaust liners which will disintegrate and eat your turbo so you're better off with a square port exhaust for a turbo. The P90 will lower your compression if you have dished pistons (well it'll be lower versus the N47/N42 regardless of piston choice). 8.3:1 is a good compression for an L28ET which is what the N42 with dished pistons will give you. I think the P90 is around 7.5-7.8:1...but you can make a ton of power with the P90...just won't be as peppy out of boost.

Try to get an N42 if you can...but the P90 will work. You need to get a good intercooler and I would definitely consider running methanol injection. I'd personally swap to a wasted spark crank trigger like EDIS or GM coil on Plug (and you can run the GM plugs with the EDIS box so you don't have to make custom ignition wires.)

If your power goals are for less than 300 HP it's not that bad of a build....just factor in a high flow fuel pump, turbo oil pump, oil cooler, intercooler, spark system, injectors and your ECU. You can run it with a megasquirt I which is pretty affordable, but you'll need to make mods to control spark. Megasquirt II is a bit easier to work with. If you want launch control/antilag/two step then I would go megasquirt III it's kind of overkill for most builds but it's got 4 switched inputs so you can have two tunes, datalog over Bluetooth and a bunch of other shite.

if you just want 275ish HP... slap on the P90 and start buying the other parts.

FYI the hardest turbo part to source is the exhaust manifold...once you have that it's pretty easy to find the rest.

1977 280Z, 3.1L Stroker , Ported N-42, Lonewolf performance Intake, 3 into 2 headers, Megasquirt I-V.3, Kumho Ecsta XS's (supa sticky),

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