Head Cc On Rb20 And Rb25

[PROJECTRB240SX]

DOES ANYONE KNOW THE HEAD CC'S FOR THESE TWO ENGINES? I NEED THEM TO FIGURE OUT THE FINAL C/R ON MY THREE HYBRID MOTORS.

[TommyTheCat]

Found some stuff for the rb25:

http://forums.skylinesdownunde....html

[TommyTheCat]

Something else you might like:

http://home.iprimus.com.au/cobra30/twincam.htm

don't know if you saw it.

[PROJECTRB240SX]

I FIGURED THE HEAD CC OUT ON MY RB25DE ITS 46.2CC AND THE RB20DET IS 44.4CC

[93semax]

I FIGURED THE HEAD CC OUT ON MY RB25DE ITS 46.2CC AND THE RB20DET IS 44.4CC

How did you figure that out?

[PROJECTRB240SX]

HEAD CC = (PI * ((BORE/2) * (BORE/2)) * STROKE) / (C/R - 1)

PI = 3.14C/R = COMPRESSION RATIO

[93semax]

When CR is calculated,head gasket volume, deck volume and dish volume are used to figure combustion chamber CC. If you don't use those your figures wil be off a lot.

[PROJECTRB240SX]

THATS FROM THE STOCK SETUP SO IT IS CORRECT. OUR PISTONS ARE FLAT WITH O DECK. IT EQUALS OUT TO 10 TO 1 (THE ADVERTISED C/R ON THE RB25DE) AND THE RB20 IS 8 TO 1. SO I KNOW MY CALCULATIONS ARE CORRECT.

[93semax]

You sure about the RB25DE? RB25DET/RB26DETT are not flat. I'm surprised the 25DE and 20DET are flat.

[PROJECTRB240SX]

IT HAS A LIP AND CENTER DOME SO THE MOVED AREA EQUATES TO FLAT. ANYWAY THE C/R ENDS UP CORRECT SO I KNOW ITS RIGHT WITH ADDING IN ALL THE OTHER FACTORS ON TO IT IT LOWERS THE COMPRESSION SO I KNOW THAT IS WRONG.

[93semax]

Do you have any pics of the 25DE head?

[PROJECTRB240SX]

I'LL GET SOME WHEN I GET STARTED AGAIN ON THE TEAR DOWN.