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Guest Message by DevFuse
 

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carb pistons in ea82t for performance build


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8 replies to this topic

#1 Jeepman775

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Posted 05 January 2005 - 03:56 AM

I got my spfi engine lying around and I am thinking of building it as an ea82T performance oriented engine + teach myself how to rebuild engines. so what performance stuff should I do to it. and would 8.7:1 pistons out of carbed engine be too much still? if not how much boost would be safe on a moderatly built engine? I still want daily driver type of thing and reliability. as well as it to last awhile. right on

#2 calebz

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Posted 05 January 2005 - 04:41 AM

Hopefully I will have some answers for you by this weekend. My Ea82T is utilizing a carb shortblock. Am hoping to have it in the car tonight. Would have the info for you then, but I still have to finish puzzling a few things out with the new turbo.

#3 Caboobaroo

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Posted 05 January 2005 - 10:35 AM

caleb, why did you go with the whole shortblock and not just the pistons? I know about the knock sensor on top of the block and the oil passage I believe it is for the turbo? Don't you need those cause from what I've seen on a carbed motor, is that they're not there!

#4 calebz

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Posted 05 January 2005 - 12:24 PM

When I did my visual comparison, The only differences I found were:
1- the pistons (obvious)
2 - knock sensor
3 - pcv hole in the top of the block

- The pistons (higher compression) are what I was after

-The knock sensor spot is there on the carb block, its even threaded already, so no problem there

-the pcv will be set up differently..

I didn't pull the pistons and put them in the Turbo block for a couple of reasons.. Main one is that I'm lazy

#5 ballitch

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Posted 05 January 2005 - 01:41 PM

are the carbed pistons up to taking boost pressure, I thought that they were cast, not forged.

#6 garner

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Posted 05 January 2005 - 01:54 PM

are the carbed pistons up to taking boost pressure, I thought that they were cast, not forged.


All OEM subaru pistons are cast, you have to big big bucks for forged pistons for these motors...

On a related note, has anyone used NA heads on a turbo block/pistons? Obviously, work would need to be done to plumb the turbo but I wonder what the compression ratio would jump to? It would be an easy(er) way to raise compression without spliting blocks/swapping pistons etc...

just a thought...

garner

#7 calebz

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Posted 05 January 2005 - 01:58 PM

N/A heads on Turbo block / pistons?

C/R would stay at the 7.7:1 that the turbo comes with .

C/R on these motors is determined completely by piston shape.

#8 Jeepman775

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Posted 05 January 2005 - 09:50 PM

Hopefully I will have some answers for you by this weekend. My Ea82T is utilizing a carb shortblock. Am hoping to have it in the car tonight. Would have the info for you then, but I still have to finish puzzling a few things out with the new turbo.

Hey tell me how it goes. is most of the plumbing on spfi same as mpfi once everything is switched over?

#9 calebz

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Posted 05 January 2005 - 10:41 PM

is most of the plumbing on spfi same as mpfi once everything is switched over?

All I'm using is the carbed shortblock. theres not much in the way of plumbing on the block itself. I am using turbo heads and all that jazz.. Thats where all the wiring and plumbing is (except the water pump itself, while not necessarily the same, are interchangeable)

The differences in the actual block between each type of fuel delivery is minimal.

I'm told that the turbo crank has bigger bearings.
SPFI and carb do not have the PCV bung behind where the knock sensor goes.
Turbo - dished pistons = 7.7:1
SPFI - Domed pistons = 9.5:1
Carb - Flat top pistons = 8.5-9.0:1 (I hear differering information, and none of my service manuals are old enough to have carb info in them)

PS - I am moving this to the retrofitting forum. Seems like it would be more at home there.:)




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