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Guest Message by DevFuse
 

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Which piston is better for ea81?


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6 replies to this topic

#1 Jerry DeMoss

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Posted 21 July 2005 - 10:49 AM

Someone may have already discussed this but here is my question anyway. I would like to know what would be better for an ea81 build up.The pistons from the ea71 or the newer pistons from the ea82 mpfi.I am aware that they both fit I just thought I would see what one seems to be more durable?Does anyone know what one would have a higher c/r or are the really close anyway?I am planning on shaving off .040 off each head and doing a cam regrind.I would also like to see if it is really true if the ea81 cam that comes in the brat is really better for torque? Has anyone put larger valves in the ea81 head,if so how much bigger?Any answers for me would be great.I am just running some ideas out that I have had in my head for a while.Thanks.:drunk:

#2 Ross

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Posted 21 July 2005 - 08:47 PM

The brat cam is different. however, a cam regrind is also very cheap.

If you're looking for max compression, the ea82 spfi pistons will give the highest, at around 9.5:1 i think.

#3 NoahDL88

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Posted 21 July 2005 - 09:07 PM

IIRC if you take more than about .015 off each head you will have fitment issues iwth the intake manifold, McBrat or Qman should be able to tell you the max amount you can remove

#4 ShawnW

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Posted 21 July 2005 - 10:08 PM

1600 piston is better. The skirt is longer, the rings are tougher, and the compression is 9.5:1 instead of 9:1.

#5 Jerry DeMoss

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Posted 22 July 2005 - 08:48 AM

Thanks,now I just need to hunt the pistons down.I have seen a few ea71 motors in jy but I would rather buy the pistons them selves rather than pulling apart a motor myself,may have to though.I am not worried about the intake fitment,I already have plans to build my own.Anyone know how much larger you can go on the valves and not have troubles?G' day.

#6 NorthWet

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Posted 22 July 2005 - 01:23 PM

...Anyone know how much larger you can go on the valves and not have troubles?G' day.

I don't have specs, but I do have hearsay: I am told that the later "hydro" motors (hydraulic lifters) have larger valves than previous EA81s.

#7 Ross

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Posted 22 July 2005 - 07:14 PM

I don't have specs, but I do have hearsay: I am told that the later "hydro" motors (hydraulic lifters) have larger valves than previous EA81s.


The Hydro engines have a larger exhaust valve, intake is the same.




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