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R33 Rb30 Conversion

JNR24

By JNR24,
in Engines & Forced Induction

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Duncan
Duncan

Just thought I would bump this 20 year old thread because the Skid Factory have just posted up a video summarising a lot of the content, format might be more familiar for newer members

JNR24
JNR24

fyi guys, Well yesturday i picked up a RB30 for my conversion into my R33. I will be using my RB25DET head on the RB30 block. So i started stripping the motor down, pulled the crank, pistons, girdle

Cubes
Cubes

Here is all I have at the moment: http://www.geocities.com/r32_jjc/ Unless you are on broad band make sure you right click then save as. The file is around 120kb. If there is anything I have got w

Posted Images

VHR32 Community Regular

VHR32

Posted
Posted
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 :happy:

Cubes Grand Master

Cubes

Posted
Posted

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.

Stealth-Z Rookie

Stealth-Z

Posted
Posted
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 :happy:

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.

block.jpg

Sydneykid Grand Master

Sydneykid

Posted
Posted
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.

:happy: cheers :D

GTRgeoff Grand Master

GTRgeoff

Posted
Posted

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 Mentor

Spoolup

Posted
Posted

Hey Geoff,

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

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 Community Regular

VHR32

Posted
Posted (edited)

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 by VHR32

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