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RB25 Neo NA head

DieselTime

By DieselTime,
in Engines & Forced Induction

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DieselTime Contributor

DieselTime

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RB25 Neo NA head

Hey all,

I am having a surprisingly difficult time finding an answer to this question, essentially I have an R34 GT which I'd like to get a bit more power out of and I'm wondering whether its NA Neo head is of any use in building an RB30DET? I wouldn't be chasing mad figures, just something with a bit of high comp for that early boost sitting around the 300hp kinda range, something that runs fine on the streets but can have a bit of fun. Unfortunately that PDF everybody loves to link to every time an RB30 build is brought up has next to no info on the Neo heads, and I'm assuming there's a good reason for this, and that's that the intake ports are too small for them to be useful. But I thought I'd check in before I scrap the idea and buy a GTT or, if money allows, start looking into an LS1.

Cheers fellas

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KiwiRS4T Grand Master

KiwiRS4T

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Its do-able. Depending on the pistons etc you are using you need to check that the CR will not be TOO high. Cam duration is the same as DET and inlet lift is the same but exhaust lift is smaller. Should be OK with the right turbo.

DieselTime Contributor

DieselTime

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Spool sells a piston kit they're saying will net an 8.7 comp ratio with a Neo head. I shot them an email and they seem to think the ratio'll be about the same regardless of whether it's a DE or DET head which I'm not so sure about, but they'd hopefully know a f**k ton more than I do on the subject.

When you say the right turbo, could I get some more elaboration on what you mean by that?

DieselTime Contributor

DieselTime

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For anyone still interested, I've been told the NA Neo combustion chamber is around 51.5cc in comparison to the DET's 55-56, meaning the comp ratio with Spool's pistons'll be closer to 9.2. Not sure on the accuracy of the chamber numbers though as Spool thinks the DE and DET share the same size, just with smaller valves and ports on the NA head. How will these smaller sizes impact on the feasability of a small turbo 30DET?

DieselTime Contributor

DieselTime

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Haven't done too much research into the turbo side of things, wanted to make sure it could even be done before getting too invested. Would be aiming for a nice 275-300rwhp if possible, anything more'd be a bonus. Was thinking smallish turbo to avoid the mad lag of a big unit, just want something nippier than the DE. In my mind quick spool small turbo > max power big turbo

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