View Full Version : 280 ZX F54 versus N42 block???

05-11-2003, 07:50 PM
Hi everybody,

For many, many years I'm driving a 1979 - 280zx T 2+2 as daily car with lots of pleasure and had not too much attention (was always well driving).

But one day it's over, no more SMOG (MOT, CT etc).Even the compression started dropping 135 - 15% (piston side - dry and wet compr.test) and the body had many bad places.

She served me for so many years that I decided to restore her, stripped her completely down,  bought an accidented 1983 one for parts and bodypanels with very low km and  smooth running engine with 176 - 2% compression (what is more than new?).

Now, about a year later the body and paintwork is finished. I never did such a job before but the results are satisfied. So this week I'll start to building her up.

But I stumbled upon a strange problem and I need some advise!!
The 1979 has a N42 block and a N42 head. With one of Carl Beck's articles in mind I thought to put the N42 head on the 1983 engine but...
the 1983 has a F54 block and a P 90 head, when I'm well informed the P 90 is a turbo head with larger chambers and must have a lower compression, but where is than all those pressure  (176) comming from.

I can't find any reference of a F54 block, is it a standard one or not.
The car has no signs of a turbo version.
Can I put the N42 head with its camshaft on a F54 block, or is it better to put the P90 camshaft (if it is so) on the N42 head and do I have to use the 1979 computer or the 1983 one. Wiringharnasses are not the same. Can I expect more problems?

Looking forward,


06-11-2003, 12:57 AM
The P90 is, indeed, the "turbo" head with bigger combustion chambers than the N42 and valves raised 2mm (shorter stems). For normally aspirated Euro cars, this was compensated by the so-called flat top pistons in the later block.

You can build a higher compression engine using the N42 head on the late block, but this will need checking for valve to piston clearance if you use a higher lift camshaft. I would check anyway, even withthe standard cam. Pistons can be flycut for clearance of a thicker head gasket can be used.

The ECU controls the injection system, so use the one that relates to the injection system you choose to use - early and late versions are different.

Overall, the late P90 engine combination (head, block, cam, injection, distributor) generates about 6bhp more than the early N42 combination in standard form.

07-11-2003, 12:24 AM
Bonjour Mike,

Thanks for your explanation.

I really thought when I pulled out the engine that there was something 'wrong'.

Next weekend I'll take off the head to examine the pistons.

When it are indeed flat pistons and I put the N42 head on it, in regarding what you told me, Lifetime of engine will diminish cause higher pression. I'm a normal driver.

I'll keep you in touch.


26-01-2004, 02:52 PM
Hi everybody,

Thanks for so many reactions.

Just fixed the N42 head on the F54 block with an old headgasket.
I've tried the N42 and a P90 camshaft. In both cases (turning by hand) the valves don't touch the pistons.

So I think to go on with the P 90 camshaft (Sorry Shawn, but the camshaft is coming from a non turbo engine), with a 82/83 computer which possibly comply better with the F54 block (more advance?)

When I've build in the engine I'll let you know the results.

280 zx 2+2 T-bar