4a forged/aftermarket/oem piston identification help...

[oldcorollas]

what the heck are you guys talking about?

early, low comp, stock 4AGZE bigport piston.
looks like a circlip groove in there?

[JP]

They're factory GZE pistons, ART make them for toyota, more pics etc here:
http://www.rollaclub.com/board/index...howtopic=11168

[wombat]

I wasn't sure so I thought I'd ask.

[Sam_Q]

what the? I thought all the bigports had no circlips or groves for it?

[timbosaurus]

ART is common on a lot of factory toyota pistons.

[oldcorollas]

i think it might be this company.. ART Asama
http://asama-piston.co.jp/index.php
edit: from 99

this...
http://www.art-piston.co.jp/
http://www.art-piston.co.jp/products.htm

[Q-Authority]

Those are definitely, absolutely, positively 4agze pistons. They are low comp versions, which use relatively shallow valve cuts. I would suspect similar pistons, with deeper valve cuts, as being hi-comp versions.

I recently bought a new set of 81.5mm os 4agze pistons for my '89 SC, and they are identical to those, except for the icky carbon deposits. Fortunately, you took photos of the undersides, which have the same identical markings as mine. They will all have the ART stamping, plus, what I would assume is a batch number that will vary from batch to batch, etc. Everything else is exactly identical, including the valve cut reliefs, pin hole postion, etc.

And yes, 4agze pistons use fully floating wrist pins that requite circlips, and yes some people have used later 8.9 hi-comp pistons when building both turbo and sc applications, though I'm not sure that many really understand their purpose. To my knowledge they were introduced to help alleviate low rpm power issues, and are usueable for this due to the more advanced fuel, ignition, and engine designs that can compensate for the higher compression at boost.

[DX20VT]

To my knowledge they were introduced to help alleviate low rpm power issues, and are usueable for this due to the more advanced fuel, ignition, and engine designs that can compensate for the higher compression at boost.

Yes, the higher compression gives them more response off boost, which makes them better to drive and also as there is more power down low, makes boost come on earlier.
Higher comp pistons are definatly the go, if you can get the fuel and detonation under control.

Higher compression means the same power at less boost.

[oldcorollas]

Those are definitely, absolutely, positively 4agze pistons. They are low comp versions, which use relatively shallow valve cuts. I would suspect similar pistons, with deeper valve cuts, as being hi-comp versions.

the depth of the cuts is identical (afaik) but the different dish makes them look different.
= they both have same anti-valve-smacking specs...