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Parts Wanted: Looking for a standard 280zx flat top piston


Ttiger

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7 hours ago, dutchzcarguy said:

I think we had those F54's to.. but i never opened one up to see if it had flattops in it.. is it that why the later ones had a bit more horsepower?

Yes sir it is. The ZXs weighed a good bit more with all the added creature comforts for the female market they hadn't broken into yet, or so I've read.

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The P79 head had a bigger combustion chamber.  The flat tops kept the CR up.  8.8 versus 8.3.

People say the HP numbers are higher because the numbers were calculated differently.  They are not actual measurements.

 

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The 280Z had the N42 block all with dished pistons

The 280ZX had a couple of block/head combinations

79-80 had the N42 block with dished pistons and the N47 head. 8.3:1 compression ratio.

81-83 had the F54 block with flat top pistons and the P79 head. 8.8:1 compression ratio.

ZX turbo had the F54 block with dished pistons and the P90 or in 83 the P90A head.

You need a piston out of the F54/P79 combination.

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8 hours ago, dutchzcarguy said:

I have a addition..  A 1979 280zx (euro!)  has a N42 block with dished pistons and a N42 head !!  I know for sure because it's a original Dutch version.

True. I didn't mention any combinations outside the states. Europe didn't get the N47 head. They stayed with the N42 until  the P79 came.

The N47 was a legacy of the emmision rules in California. Basically a N42 with round emmision exhaust ports and steal valve seats for lead free fuel. Both the N42 and N47 had 44.6 cc chambers.

The P79 and P90 both have 53.6cc chambers. The P79 was fitted to a NA engine with flat top pistons. The P90 and the P90A (version with hydraulic lifters) were used in combination with dished pistons in the turbo engines.

The dished pistons are 10.9cc

The P79 with flat top pistons has a CR 8.5:1

The P90(A) with dished pistons has a CR 7.35:1

An interesting combination was to change the P79 head to a N47. Everything else unchanged would give you a CR 9.75:1.

 

None of this is helping the OP. He still needs a flat top piston out of an engine that used the P79 head. BTW "Stamped P79 on top." Is refering to the head. The block will be a N42 or F54 in combination with the P79 head. Everything else has dished pistons.

 

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