rb26dett pistons

[always_me]

does anyone have any information about standard or forged pistons, I never knew if i had forgies or not so I was told to take the spark plug out and have a look to see what was on top of the piston.

there are only 2 possible things you could see and that wil tell you either if you have forgies or stock pistons,

outcome 1: you have a little blister on top of the piston which indicates that the piston was frm an injection mould which means they are stock,

outcome 2: piston has a little indentation which means the piston was spon on a lathe making it forged.

from what i can see by taking out the spark and shining a light down the hole, is a little ring the size of a 5cent piece and some writing which looks to say 05U

i have no idea what this means and havnt come to any conlusions cause of this, if anyone has any pictures of some stocky or forged pictures from top would be much appreciated....

[Beer Baron]

pretty sure they are stockys. 05U would be nissan code possibly indicating size and type of the piston.

[always_me]

anywebsites where i could find out some info

[Beer Baron]

no idea. the only reason i said that is that standard GTI-R pistons have '54C' written on them as this is nissans code for that variant of SR20, makes sense the other nissan pistons would have a similar code.

forged ones will generally not have any writing on the top of the piston.

[DoughBoy]

They be schtock.

[always_me]

is there any other way to find out, im not sure how they can be stock where they make very loud piston slap when cold, and ive been boosting 20psi for the last 2 years and still holding up. even with nos

[BigMicky]

they are stock!!!

If I have to I'll post a pic of the stock piston. it looks exactly as you described.

let me find the camera....

[DoughBoy]

20psi is within the limits of premium unleaded, and considering you've always run good fuel at the drags detonation would not have been present.

[Sydneykid]

And the knocking when cold would be worn piston skirts.:headspin:

[GTRgeoff]

and the 05U would be 0.5mm OS perhaps??

[SteveL]

and the 05U would be 0.5mm OS perhaps??

No....05U is part of the Nissan part number for the piston. It will be something like xxxxx-05Uxx. I believe it identifies it as an R32 GTR part.....certainly an R32 GTR flywheel has 05U cast into it, as does the standard RB26 block (N1 block has a different number). Usually the last 2 numbers after the '05U' will be different for o/size pistons.

[Sydneykid]

From the Nissan R32 workshop manual;

[GTRgeoff]

[Ronin 09]

No....05U is part of the Nissan part number for the piston.  It will be something like xxxxx-05Uxx.   I believe it identifies it as an R32 GTR part.....certainly an R32 GTR flywheel has 05U cast into it, as does the standard RB26 block (N1 block has a different number).   Usually the last 2 numbers after the '05U' will be different for o/size pistons.

yup "05U" appears on alot of R32 GTR part numbers

[always_me]

so i guess i got stockies in there, doesnt mater they still doing good job.