GZE forged pistons v aftermarket forged pistons

[stidnam]

Hi am debating as to which pistons to use for my 4AGTE and and trying to decide between factory GZE pistons and aftermarket forged pistons.

I've tried to sum up to pros and cons as below. Do I have my assumptions right and is there any other factors that I haven't considered?

GZE advantages
- Ceramic coated where as aftermarket forged pistons are not (ceramic coating is good for reducing heat???)
- Stronger due to more metal used to make the piston (Not necessarily true as pointed out below)
- Cheaper than aftermarket pistons by a few hundred dollars

GZE disadvantages
- weigh more than aftermarket forged pistons - more reciprocating mass meaning slower acceleration and more engine wear in the long run (debatable and any extra wear may not be able to be proven)
- Less wank factor. You wont be able to say I run brand x forgies and they are fully sik.

Aftermarket advantages
Lighter - less reciprocating mass meaning faster acceleration & less engine wear in the long run (again debatable and any reduced wear may not be able to be proven)

Aftermarket disadvantages
- Cost more than GZE pistons by a few hundred dollars
- A bit weaker than GZE pistons as less metal used to make piston (Not necessarily true as pointed out below)
- Not ceramic coated

[twentyEight]

I think you'll find that the GZE pistons (4A-GZE as opposed to 1G-GZE) are only semi-forged...

I would also say that the GZE pistons wouldn't be as strong as aftermarket forged pistons as the GZE pistons would still have more imperfections than aftermarket forged pistons...

[Talasas]

Semi-forged? I thought that the massif thread about looking into that came up with the consensus that they are forged.

Anyway that aside, they are proven pistons and work well, and the cost alone is a good start, you can get them for around $400 versus $800+ for aftermarket ones.

[twentyEight]

There has been a couple of threads around the subject, this one being the most recent: http://www.toymods.net/forums/showthread.php?t=19003

They are certainly stronger than cast pistons, but the most notible comment on whether they are forged or semi-forged is the one below...

The word that Stuart is looking for is hyperuetere ...... something, I can never spell the damn thing!
The photo of the piston above show a cast piston, that's for sure because you can see the casting flashes where the mold sections join.
A forged piston has no suchs marks, as they have are forged under the hammering of a powerful hammer that forces the metal into the piston blank mold.
The hyperwhatsit pistons are made in a process pretty similar to forging, but are squeezed under pressure rather than hammered. Thus the metal grain structure is similar to that of forging.
And .... I have some news from a reliable friend in Malaysia that got some 4AGZE pistons tested by a metalurgist, they may well be the hyperwhatsit type, not forged as we've thought for years.

[The Witzl]

4agze pistons may as well be considered forged. They display a grain structure like a forged piston.... so should be just as strong.

Plus.... several people have run huge numbers with them. That in itself should be enough proof.

Who do you know who's killed a 4agze piston?

[YLD-16L]

Who do you know who's killed a 4agze piston?

This rules out "I read on teh interwebz", "my bro's mates cousins friend with a VL knows a guy who gets his car tuned at a dyno shop that reckons"...... etc.

I think 30psi_4agte on these forums has put some punishment through these pistons, we'll see what he has to say on the subject when he gets a chance.

I'm more interested to know what rings people are running when they are doing a ZE/TE rebuild than what pistons?

[abently]

Ok this post is going to be end to end all questions !

Fisrtly, Hypereutectic Pistons contain a reasonable amount of Silicon ( http://en.wikipedia.org/wiki/Hypereutectic_piston ), so the term 'Semi-Forged' shouldn't be used as it suggests that they are made from almost pure 4032 or 2618 Aluminum. Even then, most are still CAST rather then pressed in a 2-Piece die.

A lot of users of Hypereutectic have found them to be weaker then Factory Cast pistons purely due to quality control issues. When produced under OEM control, they are certainly stronger.

Here is two pictures of what a real 'Semi-Forged' Piston looks like.





You can clearly see the difference on the underside.

Note: The Piston weight (ie amount of material used) is not an indicator of Piston strength. Design and where the weight is located along with exact material used, IS a real indicator of strength.

Ceramic coating is only beneficial on the top of the Piston. The coating on the skirts doesn't last longer then 5000K's on a mild HP Engine.

Reciprocating Mass does not alter HP, it only alters acceleration. The friction losses are negligible and can not be conclusively sighted on an Engine/ or Wheel Dyno.

Less Engine wear due to less Piston Mass, is also negligible. The crankshaft counterweights are designed with the Piston mass factored in.

Late model Mitsubishi Evo's run real 'Semi-Forged' pistons and have proven to withstand 500+ WHp (DynoJets) - At least 30-40 documented cases. No one has yet tested the limits as they generally swap to real Forged Pistons afterwards for peace of mind and extra safety margin when Tuning.

If the GZE Factory Pistons are real 'Semi-Forged' Pistons and your not pushing more then 150Hp (Engine) per Cylinder, then it should be relatively safe. Unless the Factory Ring / Ring Land combination are known to be weak ?

[abently]

I think 30psi on these forums has put some punishment through these pistons, we'll see what he has to say on the subject when he gets a chance.
?

30 Psi means nothing.

If you know the exact Turbo which was run at 30psi on these Pistons, then please state it, so that we can quantify the HP limit of the Pistons.

HP (Peak Cylinder pressures) will break Pistons, Psi does not.

[mr2gze]

30 Psi means nothing.

If you know the exact Turbo which was run at 30psi on these Pistons, then please state it, so that we can quantify the HP limit of the Pistons.

HP (Peak Cylinder pressures) will break Pistons, Psi does not.

He's talking about the user 30psi 4agte. Not 30psi per se

[ed]

Ok this post is going to be end to end all questions !

o'rly ?

and its loose, open, hand-wavy statements like this that make it so

A lot of users of Hypereutectic have found them to be weaker then Factory Cast pistons

as for *actual* analysis of these piston, please refer to stewarts old threads

parts 1,2 and 3:

http://forums.toymods.org.au/index.p...t=0#msg_184686

http://forums.toymods.org.au/index.p...t=0#msg_198924

http://forums.toymods.org.au/index.p...t=0#msg_200356

[twentyEight]

Well, all that points to them being Forged (or at least close enough to class them as Forged) so I retract my above posts...

[YLD-16L]

He's talking about the user 30psi 4agte. Not 30psi per se

Yep, that's who I was talking about, not an amount of boost I just couldn't remember the rest of his user name but I knew most people would know who I was talking about.

His engine is pushing big numbers and he has done a lot of time on the spanners with his car so he's worth listening to if you're a 4AG fan in my opinion.

[stidnam]

Thanks for the replies guys. I'm leaning towards the GZE pistons due to the $ saving and the fact that I'm not aiming for insane power figures.

I'm more interested to know what rings people are running when they are doing a ZE/TE rebuild than what pistons?

Assuming that there is not a huge difference in the strength of the different rings isn't the ring land position on the piston the thing that matters most?

[abently]

as for *actual* analysis of these piston, please refer to stewarts old threads

parts 1,2 and 3:

http://forums.toymods.org.au/index.p...t=0#msg_184686

http://forums.toymods.org.au/index.p...t=0#msg_198924

http://forums.toymods.org.au/index.p...t=0#msg_200356

The only difference between them and most new Pistons now days is that the Top ring is generally thinner, with a thicker ring land instead of being the same thickness as the 2nd Ring.



Oh and sorry, I shouldn't have speed read that post....... 'cause there's no way I would have misread it as 30psi instead of a Username if I wasn't so busy with other things....

[abently]

Assuming that there is not a huge difference in the strength of the different rings isn't the ring land position on the piston the thing that matters most?

Yes, but that can't be changed on the Factory Pistons.

I think if people are breaking the Ring lands on these Pistons, its probably more to do so with having TOO MUCH Piston-Wall clearance which places more of the load on the very edge of the Ring land.

That's what comes to mind, when I saw the above pics. Because the 2nd Ring Land has broken and then probably contributed to breaking the Top Ring land possibly assisted by any crankcase pressure.