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Smith666

Help/advice Rb30 rebuilt head power figures

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Smith666    0

Hey guys just joined, been using the page for awhile very helpful thanks. As title states unsure if power figures are low or normal/expected.

I've had my head rebuilt (will post Pic of cam specs) camtech cam, 1mm oversized stainless steel valves, Port & polished, new lifters, cracked tested, match ported manifold etc. Stock bottom end 

Bolted everything together took it in for a nistune and dyno tune, had a few minor issues. He finished the tune ended up with 108kW and around 240nm.

Just thought it would produce more kW with the head work.

Mods: rebuilt head, match ported manifold, 6-3-1 extractors 2.25inch straight though, believe hifow cat, nistune, k&n podfilter

Thank you

DSC_0842.JPG

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KiwiRS4T    495

What's your compression ratio... what head is it?

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Dale FZ1    120

RB30E with a cam and extractors.  If it made a genuine 120rwkW you'd have to be satisfied.  Not far short at 108.  Guessing it's all done at 5000rpm?

It's a lot harder to make NA hp, and it's going to involve compression, proper fuel eg E85, lots of revs and light components that rotate and reciprocate.  Toss out the 2 valve head and get a 4 valve.  Multiple throttles inlet, and then find someone who understands inlet tract length, header design, and cam spec/timing.

Presuming you're in love with NA RB engines.

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Smith666    0
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  • 17 minutes ago, Dale FZ1 said:

    RB30E with a cam and extractors.  If it made a genuine 120rwkW you'd have to be satisfied.  Not far short at 108.  Guessing it's all done at 5000rpm?

    It's a lot harder to make NA hp, and it's going to involve compression, proper fuel eg E85, lots of revs and light components that rotate and reciprocate.  Toss out the 2 valve head and get a 4 valve.  Multiple throttles inlet, and then find someone who understands inlet tract length, header design, and cam spec/timing.

    Presuming you're in love with NA RB engines.

    Differently not disappointed with the power, just wanted abit more torque and kW's as I'm hoping to get into hill climb/time attack, I was thinking around 120rwkw but like you said not to far off. Yeah on the dyno sheet all done by 5000rpm.

    Yeah nearly everyone I've spoke to has said go DOHC or turbo but I wanted to keep the SOHC and remain NA, ahaha yeah don't know why just not a fan of turbos in my cars, driven a hand full and their fun to drive just rather NA.

    Just got into RB's so pretty much a learning experience, pretty much just been into rotarys for the last 10 years. (I'm only 23)

     

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    Dale FZ1    120

    I started motorsport in rally, navigating in a R31.  There's nothing wrong with a good NA.  It's just that a 2 valve RB head is nothing at all special. 

    The whole thing can be made better ie able to breathe and make the torque at higher rpm with a 4 valve head. Depends how much you want to go down that path, and what the budget is to make things less wrong.

    Big heavy NA RB won't go through twisty hillclimb stuff that easy, and you'll need a sun dial to time it for Time Attack.  But you could certainly have fun.  Fatz evidently had a whale of a time in 24 hour Lemons event with his R31. 

    • Haha 1

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    Get a RB25DET NEO head on it, bring up the comp to about 11:1, put massive cams into it and rev it to the moon... could even adapt ITBs to it.

    A high comp, 3.0L, NA with ITBs and VCT would be pretty fun.

    And as Bill said, nitrous.. I would spray nitrous into it.

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