The S130 280ZX was offered with four different cylinder heads. The chart below will explain what heads were available on what year cars.

Discription of Heads

• The N47 came on the 1979-1980 280ZX. It has diamond-shaped exhaust ports with emission liners. They have steel valve seats for use with unleaded gas. If you install this head on the later (F54) blocks, the compression will be in the mid 10:1 range.
  
  
  
• The P79 came on 81-83 flattop piston L28 (F54) blocks. It has a 53cc chamber and must be used with flattop pistons or compression drops to 7.8:1 (with dished pistons). The exhaust ports/liners are identical to the N47, and used an internally oiled cam.
• The P90 is the turbo head from the '81-82 ZX. It has the same combustion chambers as the P79, but has square exhaust ports. The P90 and P90a are said to be the best flowing heads due to their turbo origins. They both use an internally oiled cam.
  
  
  
• The P90a is an interesting turbo head which was available in 1983 only. It has hydraulic valve lifters instead of standard rocker arms, which make the engine almost silent. It has identical chambers and ports to the P90 and uses an internally oiled cam.

Head Swapping

Ever wonder what comression engine you will get by swapping different heads on your motor?

While these specs are reasonably accurate, remember that just having a higher compression ratio doesn't guarantee better performance. Conventional engine wisdom is not to match dished pistons with chambers designed for flat pistons. The clearances and quench shape will allow the flame kernel to spread away from the spark, instead of being quenched into it. As a result it's easier for the motor to get 'pingy'. Aluminium heads can run higher compression before pinging than iron The highest compression you can use on the street with 93 octane gas is about 10-10.25:1. A quality ignition will help you run higher compression without pinging, as will richening the mixture.

But rather than partake in the "which is best" game, keep in mind that compression aside, using the stock large valves, and ported to hot specs, they all work pretty much the same. Also keep in mind, these heads are approaching 35 years of age and may have been shaved/rebuilt before you got it.

Sources used on this page:

• 1979-1983 Datsun Factory Service Manuals
• Datsunzgarage.com
• N47 and P90 images by: 1 fast z of hybridz.org