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Poncams Or Larger For Rb25/30

stomper

By stomper,
in Engines & Forced Induction

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stomper Community Regular

stomper

Posted
Posted

Hi all,

Just a little advice in terms of what cams would be worth running in the 25/30 build i have just started.

The head is a R33 RB25, and the intention is to disable the VCT and run adjustable cam gears. What cams would be a good option, or are the stock RB25 cams okay.

The current RB25 motor gives a little over 235kW ATW, and have saved my new SARD 850cc injectors to go in the new hybrid block.

Other parts will include:

CP forged pistons 9.0:1

1.4mm Head gasket

Forged pistons - make undecided

Adjustable cam gears

T04z or GT 3540 undecided

SARD 850cc injec

Thanks

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stomper Community Regular

stomper

Posted
  • Author
Posted
Hi all,

Just a little advice in terms of what cams would be worth running in the 25/30 build i have just started.

The head is a R33 RB25, and the intention is to disable the VCT and run adjustable cam gears. What cams would be a good option, or are the stock RB25 cams okay.

The current RB25 motor gives a little over 235kW ATW, and have saved my new SARD 850cc injectors to go in the new hybrid block.

Other parts will include:

CP forged pistons 9.0:1

1.4mm Head gasket

Forged pistons - make undecided

Adjustable cam gears

T04z or GT 3540 undecided

SARD 850cc injec

Thanks

anyone got an opinion?

Cubes Grand Master

Cubes

Posted
Posted

I'd match the cams to the turbo.

GT35r/T04z you really want to start looking at cams with decent lift (9mm+) with a mid 260 duration to make full use of the turbo on pump fuel.

Ideally for street gt35r/t04z a mid 260duration and 10-11mm lift but thats not easily achievable with the hydraulic head. :cheers:

Dale FZ1 Veteran

Dale FZ1

Posted
Posted

Go beyond 9mm lift and there are issues with getting valve springs that can physically fit and do the job without coil bind problems.

A good bet is to get the stock head and springs measured up so you have a known base to work from. There are good, useable cams and springs available to suit RB25 heads, but you'd likely need a 26 head if you want to be able to use some serious cams easily.

Cubes Grand Master

Cubes

Posted
Posted

Neo = solid followers.

Grab some suitable springs from performance springs and shove in a set of cams with decent lift. Decent lift and they make power so much easier on less boost with pump fuel and you don't need to ring its neck by running long duration cams to try and make the power. 8000rpm is really all you need with peak power sitting just over 7000rpm and holding nicely to 8k.

drgnball34 Rising Star

drgnball34

Posted
Posted
on the subject of higher lift with a neo head

has anyone worked around the issue that Spool found with any lift over 9.xx mm lift, and exposed oil galleries (if my memory serves me correctly)?

intererest to know this aswell because if my cams are choking then will need to upgrade to something bigger. And 8k rpm is plenty for me.

R32 Driver Mentor

R32 Driver

Posted
Posted (edited)

as far as i know

the crank bent on the dyno while increasing its rev limit

and it runs a ross balancer

most of the workshops here dun wanna know about the 26/30 (yay wa)

they either suggest a stroker or stick to the 2.6 and rev it a bit more

Im planning on

CP pistons

Spool rods

Cometic headgasket

Acl shells

crank collar

arp headstuds undecided 11mm or 12mm

arp main studs

N1 oil pump

4wd adaptor plate

ati balancer

will/wont this rev safely?

either that or i might just buy an engine from proengines/lewis engines

Edited by R32 Driver
Cubes Grand Master

Cubes

Posted
Posted

The workshops don't want to know of the 26/30 because they have no experience with them.. :P

The cranks simply do not bend they break oil pumps so possibly a build issue due to lack of experience with the rb30's.

Speak to Rajab racing and a few of the other workshops (inc. proengines) that build serious RB's they know how to get them to hold together at high rpm. i.e grub screw the crank.

There are a few tricks to be performed its not just a matter of giving the rb30 a refresh and a good balancer then hope for the best.

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