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rb25/30 build questions

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So im about to purchase a 30 for a e36 25/30 build and was wondering a few things so my questions are 

  • will a rb25 wiring loom need much changing apart from the e36 side of things? (ill be ordering a e36 rb25 loom)
  • for a 25 box i just need a 25 slave and starter?
  • is haltec the only real way to go ecu wise or could i nistune a 25 ecu
  • what power can stock studs handle
  • is there a reason i shouldnt use a n/a 25 head and ecu if i dont want to turbo it straight away

above all that i dont want to make big power straight away just want it to be usable 


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RB25 ECU cannot be Nistuned. You can use a Nistuned R32 ECU, with a little fiddling. Going to that effort, you should probably just use a Haltech/Link/whatever the first time. You will not get a 3L to run off a 25 NA ECU.

All RB starters fit.

Don't worry about the studs. But if you are mating a different head to a different block, then you have a prize opportunity to put ARP studs in at the outset. Don't think about it as spending more money than you need to. Think about it simply as being a bloody good idea.

There's nothing wrong with using an NA head. The best choice used to be the (now rather hard to find) R32 RB25 NA head (because no VCT).

The wiring loom, for the most part, attaches to shit on the head. Not the block. But don't go into this thinking that you won't  have to sort out some plugs and shit here and there.

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i think s2  stageas and er34 rbs are supported with nisture and is there a major issue with a n/a ecu?

yeah someone mentioned rb30 starters dying using a 25 gbox is all

and yeah studs and a few other things were on the books just weather or not to do it now or later i dont know as the head will likely come off within six months for better pistons and rods 

as for the loom yeah i already have to modify the loom im getting from wiring specialties as the e36 dash needs a bmw sensor to replace a nissan one on the motor

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Neo ECU is for Neo, not vanilla 25. Has some sensors that the vanilla one doesn't have, leading you to have to dick around to try to make it work. Just skip it. Do the ECU properly.

NA ECU, or any ECU for a 2.5L motor, should not be expected to fuel a 3L motor correctly without tuning. Vanilla RB25 ECUs cannot be tuned (easily - certainly don't take Nistune), ergo, they should not be contemplated for this sort of job.

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ah yeah i guess neo would be a fair bit of extra work fair point there haltec it is i guess 

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