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Hey people,

Got my motor rebuilt about 9months and the Piston that were meant to be put in were Arias Forged Pistons 20tho! I have had problems with compression ratio's so the head has been pulled off and on top of the pistons there is this information

RA9603X 0.50

RIB 0.10R1

Can anyone shed any light on these as to what specs these pistons are? As we are trying to work out the Current compression ratio of the motor!

Any help would be appreciated!

Cheers

Alan

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Well they are 20 thou over....the 0.50 is the oversize measurement. Havent you got a spec sheet with the pistons when you bought them? Or cant you get them from the suppliers website? That will have all the info you need about the piston inorder to work out your CR, more importantly you need your head cc and headgasket thickness. Head cc should be about 64cc i think.

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Hi al_r33

I have 3 sets of arias forged pistons on the desk with me they are rb20det 78.5 rb20det 79mm and a set of rb25det 87mm pistons,none of them have any information on the top's of them they are all marked with a job no on the bottom of the piston and thats it no other marking's .I had to go to the aria's web site to find out what they were just had to search the job no in, so I'd be a bit dubious they were aria's unless someone else has a bit more info than I do

Cheers Peter

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Mine are 40 thou, but were never installed. . No actual spec sheet. This is the meaning of the markings, as explained on the box:

RA9603X = Part Number

0.50 = Oversize (0.5 mm / 20 thou)

RIB = measure bore clearance at RIB (= Bottom / skirt) of piston

0.10 = Piston to bore clearance (mm)

R1 (RI ?) = Batch number

Contact ACL, and ask them the cc of the dome for your C/R calculation.

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