Forged or Not, how to tell? 4a-gze Vs 1g-gze

[stradlater]

So I'm into engine rebuild mode now and I need to see what pistons I'm going to use, and which are the best in my case.

I've been suggested a few things, my man 6boost clearly has the most well trodden believeable and sturdy option, but I want to understand the differences..

SO.

The questions are:

A) How to tell if a piston is forged or cast?

B) Is a 1g-gte piston cast or forged?

C) Is a 1g-gze piston cast or forged?

D) Is a 4a-gze piston cast or forged?

E) Are 1g-gte and 1g-gze pistons interchangeble (irrespective of being cast or otherwise)?

[4agte]

there was a big writeup from oldcorollas about the 4agze piston with some sort of metterlurgic (spelling?) or whatever its called analysis of 2 4agze pistons i think they are forged cant remember exactly they are ceramic coated aswell i believe

[Karma Supra]

D'oh! If I was at home I could fire up the EPC and match up the part numbers to see if they are the same.... my rev 3 1G-GTE pistons looked as if they had casting marks in them.... but I could be wrong!

I think work would get slightly upset if I installed EPC on my work PC

As far as I know the blocks are all laregely the same, (bar oil ways etc) so I would imagine all the pistons are interchangable, the GZE and GTE certainly look the same in the service manual pics! But they are hardly detailed!

[crowncustom]

D'oh! If I was at home I could fire up the EPC and match up the part numbers to see if they are the same.... my rev 3 1G-GTE pistons looked as if they had casting marks in them.... but I could be wrong!

I think work would get slightly upset if I installed EPC on my work PC

As far as I know the blocks are all laregely the same, (bar oil ways etc) so I would imagine all the pistons are interchangable, the GZE and GTE certainly look the same in the service manual pics! But they are hardly detailed!

Different compression ratio GZE-8.0,GTE-8.5.So the pistons should be different.
Unless the compression is changed in the combustion chamber of the head but you are correct that the pics in the manual do look the same.
Cheers Brett.

[30psi 4agte]

4agze pistons: If i remember correctly we came to the conclusion that they are forged.

[Dimmy]

4agze pistons: If i remember correctly we came to the conclusion that they are forged.

yep that's correct

[The Witzl]

4agze pistons: If i remember correctly we came to the conclusion that they are forged.

Correct - both the bigport and smallport (8:1 and 8.9:1) types are forged.

And now, for the spoon.....

Click me!! CLICK MEEE!@!!!!!111onewon

[stradlater]

So long as it's a silver spoon, and it's in my mouth, I don't care..

Is the 4a-gze big port or small port or both as per that post..

[kingmick]

both!

ten char

[takai]

So long as it's a silver spoon, and it's in my mouth, I don't care..

Is the 4a-gze big port or small port or both as per that post..

Correct - both the bigport and smallport (8:1 and 8.9:1) types are forged.

It came in both, the 8.0:1 was mostly bigport (although ive seen one or two smallport versions, but 3rib blocks i.e. attributable to change over of head/block) and the 8.9:1 was exclusively smallport.

[The Witzl]

if you click the link like it says to do - you can see all the pics of BOTH pistons....

[stradlater]

Is the 4a-gze big port or small port or both as per that post..

I did, clearly, I was just verifying.

[oldcorollas]

just to clarify,

while the shape of the GZE piston and the grain structure indicate that they are forged, they may not be actually forged.
a die was used to form them, and the grain structure appears to have forging flow lines, so they appear to have the desirable properties of a forged piston.

the coating is non-metallic, but i couldn't get XRD (low angle), or RAMAN spectroscopy information from it that made sense (for ceramic or polymer) so i don't know what it is coated with.. but it is definitely something....

[The Witzl]

mmmm, something

(sorry, couldnt help it)

[stradlater]

Don't suppose there is some way I can cast (excuse the pun) that methodology on the 1g-gze piston to determine if it's forged too?

[oldcorollas]

the way to do it would be to slice it in half, and then give it a macroetch..
usually this involves HF acid, but since i didn't want to use that before (restricted at my old uni), i used some different grinding/finishing techniques to bring out the grain structure.

next, you would check the microstructure, look for silicon particles and the like, and check the bulk composition, to see if it is closer to a casting or forging alloy.

then again, not all forging alloys are same composition, and same for casting.... so that is not 100% way to tell....

[The Witzl]

... in short, talk to the bloke who made the fecking things!!

[love ke70]

... in short, talk to the bloke who made the fecking things!!

i dont think god and stradlater are on talking terms right at the moment

[kingmick]

Don't suppose there is some way I can cast (excuse the pun) that methodology on the 1g-gze piston to determine if it's forged too?

Turn them upside down and take a picture and ill tell you what i think! The 4agze have wipe marks so the 1g should have the same if made alike!

[oldcorollas]

that just tells you that a die has been used and withdrawn. the smearing at the bottom of the pistons could have been made if it was forged or pressed when semi-solid...

much easier to ask the guy that made them

without that, it is a best guess from available evidence.....

they "look" to be forged or possibly pressed when semi-solid... not possible to differentiate by eye.

however, you can say they are cast and not forged when looking by eye