Rb26dett Pistons In Rb25det

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my is engine knocked and a friend of mine has sn rb26dett in which he recently replance his stock pistons with forged ones, he said i could have the stock ones if i wanted. Has anyone tried the swapping rb26dett pistons into the rb25, what time compression could i expect, are the pistons stronger, any info would be appreciated.

[R31Nismoid]

they are no stronger really

and from memory you need to put the rods/crank in there as well

pistons alone doesnt go

[Adriano]

Cant be done, pin height in the rb26 pistons is 2mm higher

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ok i have put the pistons in the block using rb25det rods and an rb25det crank, the sides of the pistobns however dont reach the top of the engine block, any idea how this affects the compression ratio

++++

[Adriano]

ABout 5:1 with 120 thou of squish

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I DOUBT ITLL BE THAT LOW, DROPPING THE MOTOR IN TOMORROW WILL POST RESULTS AFTER COMPRESSION TEST

[tm_r33]

hey kilo_gulf,

those two engines do have the same bore size but have a slightly different stroke.

rb25 has a bore x stroke of 86 X 71.7

rb26 has a bore x stroke of 86 X 73.7

take notice to the 2 mm difference in stroke.

[Adriano]

Was`there anything wrong with the pistons that came out? As ash said, rb26 pistons are no stronger than rb25 pistons

[Adriano]

Sorry, just did the calcs, and the pistons only sit 1mm down in the block, 8.5:1 rb26 pistons will give a comp ratio of 7.4:1, quite a far cry from the 9:1 an rb25 runs. Hope you are planning on runing 30 psi

[R31Nismoid]

7.4:1

Dear son of rajab... why even bother

[crack]

c'mon ash. some people just can't be told. you know that.

[R31Nismoid]

lol

[mitchy_]

that is going to be awesome off boost...

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THE PISTONS THAT CAME IN THE MOTOR ARE OK , THERE AFTERMARKET, I HAVENT BEEN ABLE TO IDENTIFY THEM, BUT THEY DONT HAVE A DOME ON TOP LIKE THE RB25DET OR RB26DETT PISTONS, THEYRE FLAT TOPS. I DID A COMPRESSION TEST ON THEM ABOUT A MONT BACK AND THEY AVERAGED BETWEEN 115 TO 120 PSI PER CYLINDER. I DONT KNOW WHY THE PERSON WHO BUILT THE ENGINE WOULD USE THEM MY GUESS IS NITROUS, IN ANY EVENT THATS WHERE I STARTED. THUS WHEN THE RB26 PISTONS BECAME AVAILABLE I JUMPED AT THE CHANCE HOPING FOR BETTER COMPRESSION BUT IT SEEMS ILL BE RIGHT WHERE I STARTED.

[gotRICE?]

Would you mind releasing the Caps lock please?

[R31Nismoid]

A comp test doesnt tell you what the overall comp ratio is - you know that right?