The piston debacle

Sheesh! Finding proper 4A-G(Z)E pistons is a mess!

The following pistons are listed with 20mm pin and 30.68mm (1.208″) compression height

  • Wiseco K506M815
  • CP/Carrillo SC7653
  • Wössner 9035D050
  • Wössner 9191D050 is strange. It has a 30.6mm compression height. WTF?
  • Wössner 9278D050

…and following pistons have 20mm pin and 30.5mm (1.200″) compression height

  • Supertech P4-T4AG16-20-81.5-CR11
  • Toda 13010-4AG-001
  • Toda 13020-4AG-001
  • Toda 13040-4AG-001
  • Arias AP331669
  • Arias 3721070
  • Arias 3731220

If my current pistons can be shaved a bit, I’ll keep them. I’d love to get the compression height from 30.68mm to 30.5mm and shave a bit off the piston crown to get dome volume somewhere around 2-3cc. This would drop the compression rate little bit below 11:1.

Otherwise I’ll get the Supertech pistons. They’re pretty damn near perfect. 🙂

Difference in compression height numbers probably comes from two pin sizes. Early 4A-GE engines had 18mm pin, later models had 20mm. Some of the companies dont seem to care about this.

I promised myself that I wouldnt get any parts from a country, which still uses imperial units. Meh…

  • Supertech = imperial
  • Toda = metric
  • Arias = imperial
  • Wiseco = imperial
  • CP = imperial
  • Wössner = metric

Wössner would do, they’re from Germany, but why do they have that compression height error too?

Matrix Garage has some pistons too, based on their own design.

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