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Discussion Starter #1
Hey guys, i'm just wondering is there a differenece between a JDM head and a NA head for the 4age?
There is one for sale, but if there is no difference then i'm not gonna bother.
Thanks
 

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nice guy
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i don't believe there is a diffence..but i am no for sure.
 

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Immortal
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No difference... except for some with 5 valves per cylinder... ;]
 

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Wheels Direct rep
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the 4ag head should be the same in USDM and in JDM. its the blocks that are slightly different. the compression ratio is alittle higher for the jap models. goto www.club4ag.com and goto the refernce sectino and look up the specs.
 

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all bluetop heads are the same. on the redtop, the difference is that there's a MAP version that came out in Japan.
 

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variations

bluetop = largeport
redtop = largeport or smallport

If it's a smallport you need an intake adapter, and smallport fuel rail and fuel pressure regulator to use it.

some say that the smallport NA head has slightly better cams than the largeport.

I'm running a smallport SC head, the cams are pretty mild.


Neil
 

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Re: variations

neil85AE86 said:
bluetop = largeport
redtop = largeport or smallport

If it's a smallport you need an intake adapter, and smallport fuel rail and fuel pressure regulator to use it.

some say that the smallport NA head has slightly better cams than the largeport.

I'm running a smallport SC head, the cams are pretty mild.


Neil
Smallport has same cams as the GZE. Anyway, as far as MAP or AFM goes, I believe only in the US, Canada, and a few other places got AFM AE86s. Everywhere else got MAP AE86s... The head has nothing to do with that. There were two versions of Bigports, one with the 3 rib block (earlier models) and one with the 7 rib block (later models). The later (post 1987) 7 rib models had heavier internals so they did not make as much power as the older ones. These came with both blue and red lettering... and some of the very first 7 ribbed bluetops that were in the last of the 1987 AE86 had the lighter internals. All of the ones in the AE92s and such had the heavier internals, but are essentially the same motor. The bigports had more agressive camshafts than the smallports and supercharged models. Contrary to the popular belief the JDM smallport had high compression and made more power than the US version, that's not true. Both motors are physically the same, both with 10:3:1 compression, smae smallport head, same camshafts. Only difference is one is MAP sensored and one is AFM. The JDM version being rated at 140ps is literally the exact same as the US/Canada models being rated at 130hp. Ps and HP are not the same.

The only 4AGs that had very different heads were the 20V. All of the bigports are the same, and all of the smallports are the same. Blocks have different variations...
 
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