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luke_mcmahon85

Maxima N47

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over at zcar.com there's been alot of talk about the n47 head that came on early 80's maxima's....these are designed like the p90 with the quench design and heart shaped combustion chambers, but have much smaller combustion chamers, giving higher compression.

 

so....i went to the junkyard the other day to poke around, couldn't find any maxima's but noticed that some early 80's skylines with the L24(E) have an N47 head...i think this is the same as the maxima one

 

is anyone running a MN47 setup?

i have an F54 block, i think with dished pistons, so i don't think that the compression would be too high

i'm running a p90 head at the moment, and the car is NA so compression is quite low....

 

just wondering what you guys think?

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I am pretty sure the ports on that head are really small so you would have to do lots of porting and put bigger valves. I think you would be better of taking a bit off the bottom of the p90 (or putting flat top pistons if you havent already) to get the compression up.

 

 

Ash

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Yeah I saw this post the other day but wanted to take the time to post a proper response.

 

Like Ashley said I'd keep the P90.

 

However best results would be from changing the pistons over. The P90 flows well it's just not as easy to get a high compression ratio from as say the early E31/E88's.

 

I would highly recommend reading the "How to modify your Nissan & Datsun OHC Engine" By Frank Honsowetz he goes over all the heads and advantages/disadvantages of each.

 

I don't recall alot of info on the N47 myself. However with regard to the l24E I believe they use a different bearing set up on the crankshaft which isn't that great for higher power applications.

 

IMHO the best non cross flow heads for the Z are as follows in order of preference.

 

P90(A) (A requires change over to standard lifters).

N42

E88 (Early 240z 70-73ish).

E31

 

Of course that's the heads in standard form each can be modified and changed to be almost as good as the other it will just cost you more money.

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My compromise given the choices of the Skyline heads E31, the P90 ex series 2 dattos and the N42 is to use an N42 ex 1978 Fairlady 280z and its associated inlet system, with a dual throat throttle body and a start injector and in the exhaust system an O2 sensor (yes O2 sensor) the appropriate Fairlady 280z showa protocol ecu, coupled to the rear exhaust gas temp gauge and a rebuilt F54 bottom end running 1 mm o/s pistons dished, Crane 53846 cam. I also threw out the power steering and air-conditoner pumps and the 25 kg hamrmonic balancer in favour of one from a 180B, and then fitted the non-powered rack from the 1978 Fairlady 280z result 8.8:1 200 hp no power draining accessories from 2850cc. I also run on LPG and with a 3.7:1 rear and a 5 speed manual gearbox, turn in 300 kM for $15 worth of LPG which I can afford unlike the current $100+ to fill the gas guzzling fuel tank with premium unleaded.

The final drive turns in 2600 rpm at 100 kph.

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