R33 Rb30 Conversion

[Spoolup]

7500

Brad, so you make peak power at 7400rpm?? What you got the limitter set to?

[VHR32]

i want to clear this up, if I use weisco rb25det pistons, what compression should i order, of the shelf version, suggestions?

Don't use the Wiseco RB30/26 piston, it's 7.0 compression.

Use CP or Arias pistons especially made for the 30/25+26 conversion

[Cubes]

I used the RB25 wiseco piston in mine.

Its not optimal but it works ok. You end up with a highish static comp. Depends if thats what your after.

Either way.. CP's are the best option Im aware of.

Sk uses JE's I believe but I'm unable to find any info on part numbers and what static comp results. SK may have stated one time or another but I'd imagine its been lost in this huge thread.

[SilverECR33]

spoolup thats some nice results , alot better than you previously had... what an animal.

[discopotato03]

87.5mm JE VG30DE with machine work to set CR , deck and crowns . I think between 8.5 and 9.4 is possible .

Cheers .

[@irborne]

thanks guys, i dug through this large thread and found one that has comparisons on different specs and brand of pistons for this setup. looks like CP or Arias will be the better route.

[@irborne]

someone definately need to index all the pages, maybe putting shortcuts on the first thread to crucial information on the sub pages

[shanef]

someone definately need to index all the pages, maybe putting shortcuts on the first thread to crucial information on the sub pages

thanks for offering, let us know when ur done

[r33_racer]

haha...ahh shane and you nearly offered for us to do it in the qld rb30 thread....come in spinner R31Nismoid said hes been cleaning up the rb30 thread for ages and hes only upto page 60.....

[Alf]

Cubes did an index way way back...

Im in the process of adding to it.

Edited March 5, 2007 by Alf

[Stealth-Z]

Don't use the Wiseco RB30/26 piston, it's 7.0 compression.

Use CP or Arias pistons especially made for the 30/25+26 conversion

I can confirm the off the shelf Wiseco's yeild low 7 CR.

They sit .020 inside the bore. The valve relief cuts are a little over 11cc's. I was looking for a 8.3 to 8.5 CR. Alot of decking and shaving needs to be done to acheive that. I do not feel comfortable cutting that much off the block and head.

They would be good for the high boost drag racer I suppose.

[Sydneykid]

I can confirm the off the shelf Wiseco's yeild low 7 CR.

They sit .020 inside the bore. The valve relief cuts are a little over 11cc's. I was looking for a 8.3 to 8.5 CR. Alot of decking and shaving needs to be done to acheive that. I do not feel comfortable cutting that much off the block and head.

As per the PM, decking the block 0.5mm is no big deal, neither is skimming the cylinder head the same amount. We do it ALL the time.

They are SOME valve fly cuts, I can't imagine how much lift you would need on the cams to need that much clearance. Since 9.5 mm needs zero fly cuts.

cheers

[kastin]

anyone comments of my sump?

[@irborne]

thanks for offering, let us know when ur done

lol....we'll see if i have some time on hand.

[@irborne]

does anyone have experience with modifying a chevy 327 small journal rods for the rb30 setup??

[Spoolup]

yes - have done it several times.

[GTRgeoff]

The pig arrived in Brissy alive but didn't run well and only had 160rwkw. I think the cams need dialling in but will do it after Thailand unless Brad can get me the gears sooner.

Felt nice enough but the tuning was only to get it here. on temp internet and no email yet.

[Spoolup]

Hey Geoff,

Good to see you made it , and brought some rain with you

Cam gears arrived today. Give me a call tomorrow and we can sort out how to get them to you.

Cheers

The pig arrived in Brissy alive but didn't run well and only had 160rwkw. I think the cams need dialling in but will do it after Thailand unless Brad can get me the gears sooner.

Felt nice enough but the tuning was only to get it here. on temp internet and no email yet.

[VHR32]

I updated my piston list from P221

Added a new p/n for a flat top piston from Arias and added compression ratios for the Arias pistons. Two are quite high for a turbo engine!

CP

All compression ratios are based on zero deck height, 1.2mm head gasket (7.13cc), RB25 @ 62.5cc, RB26 @ 64.5cc. They assure me they have done alot of work to make sure the facts are correct.

p/n= CP-RB30/26-.20

Flat top with no valve pockets

8.2:1 COMPRESSION RATIO with RB25 head and bit less with RB26 head

21mm pin

1.280" compression height

Only stocked in 0.20 thou oversize but can be custom ordered in any size.

p/n= CP-RB30/26-.20-9.0

6.0cc dome top,

9.0:1 COMPRESSION RATIO with RB25 head and bit less with RB26 head

21mm pin

1.280" compression height

Only stocked in 0.20 thou oversize but can be custom ordered in any size.

*Care must be taken when using on RB26 with more than 11.5mm valve lift*

ARIAS

Suit RB30/26

p/n= AP332103

flat top

21mm pin

1.280" compression height

Only stocked in 0.20 thou oversize (86.5mm).

COMPRESSION RATIO 8.4-8.6

Suit RB30/26

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

Suit RB30/25

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

WISECO

Skyline RB30 w/ DOHC RB25det cylinder head

1.260" compresion height, 66.5cc head chamber, Dish top -11.3cc, 7.0:1 compression ratio, 21mm pin, 1mm gasket thickness, 1mm deck clearance.

K577M865 86.5mm

K577M87 87.00mm

ACL

6MKRY9608 (VL turbo)

87mm, -4.5cc dished top, 1.261" compression height, 21mm pin,

Standard RB30ET pistons are 7.8:1, with RB25 head it is 7.1:1

These are bumped up to 8.5:1 so with the RB25 head it may give about 7.5:1??

Using http://www.csgnetwork.com/compcalc.html I came up with 8.5 for VLT (spot on) and 7.6 with twin cam head with 64cc chamber.

I entered: 2, 87, 85, 87, 1.2, 64cc, -4.5cc = 7.6:1

BUT these have a lower compression height than the CP/Arias and im sure it stuffs up my calculations but its late and im too tired to look at it any more...

Edited March 6, 2007 by VHR32

[@irborne]

yes - have done it several times.

please shed some info as far as bearings and or mods required for the rods?