Pistons For Your Rb30

[TiTAN]

Give the person doing the machining the block and ask them to find out if the block will need to be bored out then get your pistons based on that. Not every brand of piston/ring combo is made for the same tolerances, too big and you get blow by and lots of piston slap issues too small and the pistons may not even move when its up to temp.

[[200]]

Give the person doing the machining the block and ask them to find out if the block will need to be bored out then get your pistons based on that. Not every brand of piston/ring combo is made for the same tolerances, too big and you get blow by and lots of piston slap issues too small and the pistons may not even move when its up to temp.

Whats why you bore the block to suit the pistons...

[TiTAN]

i thought i had that in there must have removed it before i hit submit.

[daisu]

So basically, the engine builder might say "the block needs boring out 20thou (0.5mm)" so then I'd go buy some 20thou oversize pistons and the pistons would come with a spec sheet detailing the required bore clearances, which the mechanic would use to bore the block to the correct size?

[TiTAN]

correct.

[T04GTR]

yeah, we dont want to re-invent the wheel here.... if only they would make a piston with a small dome.. problem solved

[TiTAN]

yeah, we dont want to re-invent the wheel here.... if only they would make a piston with a small dome.. problem solved

Dave, there are dome top pistons for the twin cam 30. Arias make them 9.2:1 CR, they also make another slightly higher CR piston also but cant remember what it was.

Edit. Found the info.

p/n= AP332104

10.6cc dome top

21mm pin

1.280" compression height

Only stocked in 0.20 thou oversize (86.5mm).

COMPRESSION RATIO 9.2-9.4

p/n= AP332105

13cc dome top

21mm pin

1.280" compression height

Only stocked in 0.20 thou oversize (86.5mm).

COMPRESSION RATIO 9.5-9.8

Edited September 23, 2008 by TiTAN

[bubbabooga]

hey im just after a quick hand..

i have found some dirt cheap forged arias pistons with 8.5-1 comp ratio with the single cam head..

what would the comp ratio be with my rb25de head??

thinking around 7.8-1??

is their any down sides to decking the block to get higher comp ratio??

id like comp ratio of around 8.6-1..

cheers tom

[R32 Driver]

i believe there was a problem with deckin the rb30 block to much

eitehr something to do with oil/water galleries or strength problems

[bubbabooga]

ah thats cool never mind... iv binned that idea...

haha

[works 510]

Guys, bumping a old thread.

Ive noted all the part numbers and what CR's they give

But,

Where abouts did you purchase the pistons and what were they worth?

Cheers,

[hendraaaaa]

Using either the RB25 or RB26 head on the RB30 block you need to use RB30E pistons the RB30ET pistons will result in a far too low compression ratio to be much use as a street car.

Hey guys sorry to revive an old thread. Im also building a 25/30, R33 S1 turbo head and RB30 turbo block and as TITAN said it will give me way to low compression ratio (to my liking anyway). I was looking more between 8.5-9.3 compression ratio. I dont want to spend a fortune on forged pistons (Im only looking no more than 350hp atw), so i was thinking more towards getting stock pistons. Do you guys recommend getting a RB30 NA pistons or should I go more towards RB25 NA/Turbo pistons?

Sorry for the n00b questions any help would be greatly appreciated

Thanks in advance.

http://cgi.ebay.com/...8#ht_1055wt_907

HEHEHEHE

[JonnoHR31]

use 30e pistons, 25 wont work

[hendraaaaa]

use 30e pistons, 25 wont work

thanks

[Bl4cK32]

use 30e pistons, 25 wont work

using forged 25 pistons in cubes and my motor since '04

[JonnoHR31]

yer some forgies will work but standard 25de pistons will sit way too high in the 30 block

[r33_racer]

Ive used some Ross 25 pistons in a 30. It actually sat low in the bore by abit and we had to skim the block to get the CR up.

[tazzy]

i got some pistons made by JE with a CR 8:7.......

[Speeddm]

How much were they?

[Glynn82]

Sorry to dig up such an old thread but I searched long and hard and I can't seem to find the answer. With stock rb30e pistons and a r33 s1 rb25det head (obviously rb30 block) does anyone know how much I can deck the block before valve piston clearance etc becomes an issue? The block is stock as a rock no previous decking as far as I know