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Unless the poncams 260 will be restrictive at 500rwkw ( head with port job, valve springs etc ), I need something bigger. Whats avaliable if any? Nengun seem not to have anything? Also been told anything bigger is hard to install on the Neo head becasue of it's design???

RB25/30 with t04z 1.x a/r

cheers

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I would assume there wouldnt be many choices since the Neo has twin VVT. Lots of people delete the VVT and run the 26 cam's which come with many choices and much cheaper. Just an option.

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due to them having similar soild lifters to rb26, yes it is possible to use gtr cams. Although max lift that can be used is around 9.5mm ive been told. Apparently due to their lifter desgin, bigger lift pushes down and exposes oil feed galleries.

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drag and dyno applications..Im just concerned that 260's will restrict power from the t04z using 1.x a/r and rb30 bottom. Although i have seen 256's pull 487rwkw from a rb25 with the same turbo...Concerned the extra cc's may need more breathing

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  • 2 weeks later...

IMO the only way to get the best from an RB30 is with an RB26 head . Std and aftermarket GTR cams are set up to work with the RB26's six throttle inlet manifold system and thats why they can cope with the increased overlap . When you use a single throttle per cylinder system the plates block the positive pressure reversion pulse you get from reflecting back into the plenum chamber when using greater overlap and longer period cams . So the multi throttle system gives the least throttling losses and copes far better with reversion which is the mark of a competition engine .

Broken record I know , do something with the head stud holes and the 26 head falls on . Almost always the best manifolds for super duty engines are for the hottest one out of the box - RB26 in the RB family . Heaps of cam/valve/spring options .

For the best from a T04Z your going to need a divided T4 flanged manifold (and housing) because you won't get the gas flow through a T3 flange no matter what sized housing it has - particularly with 3L in front of it .

If it were me I'd sell the Neo head and that won't be hard to do because they are not like grass seeds , and buy an RB26 head .

RB25 heads in a way are a big PITA , people want to fit GTR spec cams / adapt the GTR inlet manifold / exhaust manifold/s and end up spending more money than the right head costs . The 25's VCT is a pain to work around and has no place in a high RPM engine .

Your call , I know what I'd do .

Cheers A .

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IMO the only way to get the best from an RB30 is with an RB26 head . Std and aftermarket GTR cams are set up to work with the RB26's six throttle inlet manifold system and thats why they can cope with the increased overlap . When you use a single throttle per cylinder system the plates block the positive pressure reversion pulse you get from reflecting back into the plenum chamber when using greater overlap and longer period cams . So the multi throttle system gives the least throttling losses and copes far better with reversion which is the mark of a competition engine .

Broken record I know , do something with the head stud holes and the 26 head falls on . Almost always the best manifolds for super duty engines are for the hottest one out of the box - RB26 in the RB family . Heaps of cam/valve/spring options .

For the best from a T04Z your going to need a divided T4 flanged manifold (and housing) because you won't get the gas flow through a T3 flange no matter what sized housing it has - particularly with 3L in front of it .

If it were me I'd sell the Neo head and that won't be hard to do because they are not like grass seeds , and buy an RB26 head .

RB25 heads in a way are a big PITA , people want to fit GTR spec cams / adapt the GTR inlet manifold / exhaust manifold/s and end up spending more money than the right head costs . The 25's VCT is a pain to work around and has no place in a high RPM engine .

Your call , I know what I'd do .

Cheers A .

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  • 2 weeks later...

Im a bit confused with this thread... so u have a rb25det neo head on a rb30 bottom end is this rite...?

Now the biggest u could go with the neo head is the hks cams drop in's they are bigger than the tomei poncams

cheers

high octane should know beta!!!

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yes ita a neo head going on a rb30 bottom end. What specs are the hks cams and where do i get them from? I have searched on greenline and nengun. Also been told from numerous people including hi octane themselves that tomei are the biggest???

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