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styler
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3tgte pistons - how to tell if forged - pic's! 56k warning!! Mon, 18 July 2005 11:03 Go to next message
i have got a 3tgte that has probably been modified when rebuilt. im not too keen on winding up the boost to tell if it has forged pistons lol, so does anyone know how to identify the pistons? id prefer to do it an easy way and not have to take the head off.

[Updated on: Fri, 22 July 2005 23:00]

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jesseT18
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Re: 3tgte pistons - how to tell if forged Mon, 18 July 2005 11:14 Go to previous messageGo to next message
the only way i can think of doing it without pulling the engine apart is do a compression test and see if you get consistantly lower results over factory specs.
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oldcorollas
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Re: 3tgte pistons - how to tell if forged Mon, 18 July 2005 11:14 Go to previous messageGo to next message
take off the sump.. is easiest way.. can at least tell how it was formed and if it is NOT a forged piston.. what you are looking for is a shape that could only be formed with a plug that can be REMOVED.... ie no overhangs.. if it has overangs, it is definitely cast.

other than that, you have to take piston out of the bore to tell...
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kingmick
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Re: 3tgte pistons - how to tell if forged Tue, 19 July 2005 06:11 Go to previous messageGo to next message
as stew said! one will have wipe marks{forged} and the other will have casting dags!take the sump of and have a bo peep.
mick
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styler
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Re: 3tgte pistons - how to tell if forged Fri, 22 July 2005 05:22 Go to previous messageGo to next message
thanks for the input, couldnt do a compression test to easily, the motor is out of the car. i took the sump off though and had a look...

my 2tg pistons have heaps of casting marks compared to what i can see on the 3tgte.

3tgte is smooth and the piston skirt is circular the whole way down to the counterweight. the grudgeon pin housing then also extends from one end to the other of the piston. there are 4 oil holes each end. there is a circular recess for the conrod small end to rotate in.

[img]http://www.imageshack.us][/url]

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[Updated on: Fri, 22 July 2005 05:53]

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styler
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Re: 3tgte pistons - how to tell if forged Fri, 22 July 2005 05:23 Go to previous messageGo to next message
[img]<a href="http://www.imageshack.us" target="_blank">[/url]

[img]<a href="http://www.imageshack.us" target="_blank">[/url]

[img]<a href="http://www.imageshack.us" target="_blank">[/url]

these are the 2tg piston pictures :

[img]<a href="http://www.imageshack.us" target="_blank">[/url]

[img]<a href="http://www.imageshack.us" target="_blank">[/url]
















[Updated on: Fri, 22 July 2005 08:02]

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TE72_Turbo
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Re: 3tgte pistons - how to tell if forged Fri, 22 July 2005 07:19 Go to previous messageGo to next message
Good pictures, but you sure you need so many? Its a bitch to open the thread on a slower connection Very Happy

Look like cast pistons to me. Forged should be fairly obvious with the sliding marks from the die.

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oldcorollas
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Re: 3tgte pistons - how to tell if forged Fri, 22 July 2005 07:33 Go to previous messageGo to next message
styler, what you are looking for is this shape around the gudgeon pin support... ie looks like it was made by puiching a plug into it. if there are undercuts between the gudgeon and the crown, it cannot be forged/squeeze cast.

basically, when ya look at it, think " if i was to pour water into the piston and freeze it, would the ice fall out when i try to tip it over?" (of course with the gudgeon pin holes fille dwith plasticine or whatever)

http://www.materials.unsw.edu.au/~sford/pics/feral-shin1.jpg

[Updated on: Fri, 22 July 2005 07:38]

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styler
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Re: 3tgte pistons - how to tell if forged Fri, 22 July 2005 07:52 Go to previous messageGo to next message
yeah sorry forgot the 56k warning Smile

well they dont seem to be like my 2tg pistons at all, i will fix the pictures of the 2tg pistons asap, the 2tg pics are the ones of the single piston out of the engine.

if you froze water in there it would come out in one piece.

here is a diagram that i was meant to load first :

[img]<a href="http://www.imageshack.us" target="_blank">[/url]

[Updated on: Fri, 22 July 2005 08:05]

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oldcorollas
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Re: 3tgte pistons - how to tell if forged Fri, 22 July 2005 08:08 Go to previous messageGo to next message
k, see the bit between the gudgeon pin housing and the crwon on the RHS pic? how it sorta slopes.. ie the bit near crown is fatter than the bit at the gudgeon pin... thats what you are looking for...

the 2TG one looks cast.. in fact it looks like you can see some steel that has been cast into it, above the gudgeon pin..



this pic... looks like it is similar to the 4AGZE piston.. in which case it is either semi-solid formed or forged, ie a decent piston.
http://img307.imageshack.us/img307/1729/dscn09268iy.gif
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styler
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Re: 3tgte pistons - how to tell if forged, 56k warning!! Fri, 22 July 2005 22:59 Go to previous messageGo to next message
i see what you mean, if it was forged the die would be pushed in and out, so it would not have any space bigger at the far end of the piston because that is not possible, ie the frozen water thereoy, the ice has to slide out like the die does.

heres the same pic but the original jpeg, i converted them previously to gif's to save loading time but the quality isnt too good in gif format.

i know the area you mean, the section around the grudgeon pin,
if it curves back in then it cant be forged, it has to go straight down. well its hard to see but i will look again at the motor.

i managed to measure the piston and its 86mm which i think is stock.

[img][/url]
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September_Squall
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Re: 3tgte pistons - how to tell if forged, 56k warning!! Sat, 23 July 2005 02:12 Go to previous messageGo to next message
86mm is 1mm over, so it's had pistons replaced at some point in its life.
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GefGef
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Re: 3tgte pistons - how to tell if forged - pic's! 56k warning!! Sun, 24 July 2005 05:55 Go to previous messageGo to next message
Sorry didn't bother to read all posts but all the pistons I saw were cast not forged. A forgy won't have casting marks or the steal inserts in the side of the piston. For what it's worth a compression test won't tell you a thing about the type of piston in the engine cause they could be higher, lower or the same compression as standard. Also taking the head off won't definately tell you either. The forgies in my T look just the same as standard after the engine has been run for a period of time.

[Updated on: Sun, 24 July 2005 06:03]

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oldcorollas
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Re: 3tgte pistons - how to tell if forged - pic's! 56k warning!! Sun, 24 July 2005 20:36 Go to previous messageGo to next message
if you'd read the posts you would see we are discussing the bottom og the piston now Wink the ones with steel inserts are the 2TG ones and are definitely cast.. that had ben established.. it's the ones in the block that are in question...
from the pics they look similar to 4AG pistons.... so you nevr know... maybe get a bit of bent wire and have a poke in the bottom of the pistons below (as you are looking at them int he pics) the gudgeon pin.... go the ice theory Very Happy
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GefGef
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icon12.gif  Re: 3tgte pistons - how to tell if forged - pic's! 56k warning!! Mon, 25 July 2005 12:10 Go to previous messageGo to next message
Like I said. All the pistons I saw are cast, including the ones in the block Wink
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oldcorollas
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Re: 3tgte pistons - how to tell if forged - pic's! 56k warning!! Mon, 25 July 2005 12:35 Go to previous messageGo to next message
GefGef wrote on Mon, 25 July 2005 22:10

Like I said. All the pistons I saw are cast, including the ones in the block Wink


would you like to elaborate as to how you can tell the ones in the block are cast, and not semi-solid formed?
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GefGef
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Re: 3tgte pistons - how to tell if forged - pic's! 56k warning!! Tue, 26 July 2005 07:27 Go to previous messageGo to next message
Have a close look at the casting marks!
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styler
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Re: 3tgte pistons - how to tell if forged - pic's! 56k warning!! Wed, 03 August 2005 08:24 Go to previous messageGo to next message
so it seems they may be stock then, at least they are decent.

someone on here must have played with 3tgte pistons before!
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Mr Revhead
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Re: 3tgte pistons - how to tell if forged - pic's! 56k warning!! Wed, 03 August 2005 09:59 Go to previous messageGo to next message
definitly cast
they dont really look like 4agze ones.
forged have a smooth finish, and you can see a "poured" grain

cast are rough surfaced. on the lower one above, you can clearly see the casting marks.
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TerryOBeirne
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Re: 3tgte pistons - how to tell if forged - pic's! 56k warning!! Fri, 05 August 2005 08:05 Go to previous message
these are almost certainly cast pistons. the give-away is the distinct steps in the underside of the crown (pic #2) . you dont get those with forged pistons. I regularly repair these engines with both cast & forged pistons. hope this helps. terry
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