Rb26/30 build

[lilley's gtr]

I've been building a 26/30 for a few years now. I've had the head built with all the good stuff. I had a 32 gtr but blew it up and yes its all going into a vl but im looking for some advice from some RB nuts on pros and cons on putting a 26 head on a 30 bottom end is it worth it

Works are as follows

Head

-Extensive porting

1mm oversized supertech valves

Supertech double springs

Supertech valve guides

Supertech titanium retainers

Tomei solid lifters

Tomei 270 x 10.25 cams

Head drain

Bottom end series 2 rb30 block

Cp ceramic coated pistons

Eagle rods

Romac balancer

Oil restrictions 

O ringed blah blah spent a fortune

And will get a girdle because the 30s arent used to handling that much rpm

Nitto billet oil pump

Hypertune plenum

6boost mani

Refurbed astra pump thats the cover for it in the boot

I did have a precision 6262 but sold it because drag car life.

Currently building the ass end full 4 link floater rear end with a 2 speed 

But the dilemma i have is my mate rekens I should just stick with the 30 head for reliability. Has any one had any issues with mounting the 26 head ie compression blowing gaskets etc. Just looking for some advice from people who have gone down this route.

Here's some photos. Blew the oil pump in the gtr and decided to rip the motor out at the time and do a full build only to find it had been a repairable write off so went down this path. 

 

 

[GTSBoy]

2630s work perfectly well.

There is something to be said for just using the 30 head, as it saves all the pain of the conversion, still makes tons of power, still sounds cool, etc etc. 2630 will obviously make more power again, but the differences are not stupidly big.

It really depends on whether you're racing for sheep stations or not. If it's dead serious, then it's a 26 head. If it's just for fun, it could go either way. But the 26 head and the effort to get it set up, etc etc, is part of the fun.

[Butters]

Both heads will be equally reliable or unreliable depending on what you do to them. 

Stock the RB26 head will flow more. You have access to the stock intake ITB manifold on the RB26 cheaply which flows really well(1000hp+).   Arguably more aftermarket support for RB26, though in Aus we love our RB30 SOHC heads too. 

 

The only downsides to the RB26 head is if you have a VL commodore and want to keep the SOHC look. 

Where you may have an issue is drilling out the rb30 block for the bigger head studs but if you are building a big power motor you'd probably put bigger studs on the SOHC head too.  This is just about finding a good machine shop, sometimes easier said than done. 

RB30 head worked can make big power just like a Rb26 head, so really it actually more comes down to what your preference is for your car.  People now even making billet versions of both.

Edited May 3 by Butters

[MBS206]

And if you want more power, more reliably, and cheaper, go get the Aussie RB... The 4L Barra and put that in instead.

[r32-25t]

You’ll want to have the block drilled and tapped to suit 1/2in head studs and the head for the same.

How much power do you intend to make?

[lilley's gtr]

13 hours ago, MBS206 said:

And if you want more power, more reliably, and cheaper, go get the Aussie RB... The 4L Barra and put that in instead.

No doubt barra is a great cheap way to make power but... so many around now I just call them cabs lol. And low revving compared to the rb doesnt sound anywhere near as cool haha. And talk about sacrilege, i love the rbs jist something about them 

[lilley's gtr]

7 hours ago, r32-25t said:

You’ll want to have the block drilled and tapped to suit 1/2in head studs and the head for the same.

How much power do you intend to make?

Years ago I wanted allllll the power but realistically 700hp would be more than enough for what I want. I started the build with the intention of dragging it. But times change family etc I just want a mad streeter than I can take to powercruise.

[lilley's gtr]

14 hours ago, GTSBoy said:

2630s work perfectly well.

There is something to be said for just using the 30 head, as it saves all the pain of the conversion, still makes tons of power, still sounds cool, etc etc. 2630 will obviously make more power again, but the differences are not stupidly big.

It really depends on whether you're racing for sheep stations or not. If it's dead serious, then it's a 26 head. If it's just for fun, it could go either way. But the 26 head and the effort to get it set up, etc etc, is part of the fun.

Been looking at PRP and how much work and development they've put into making it easier to put the 26 head on. They even make this bracket to tap the idler pulley on, its so awesome how far that stuff has come in the last 10 years.

[lilley's gtr]

Just have to perfect the oil flow with the 26 head but I think they've got it down to a T now. Which oil restrictions and sizes to put where as the 26 head flows differently. 

[lilley's gtr]

If anyone has done a similar build I'd love to see what they did and why 

[GTSBoy]

There's a whole subforum right here. 3rd sticky down.

[lilley's gtr]

[lilley's gtr]

1 hour ago, GTSBoy said:

There's a whole subforum right here. 3rd sticky down.

Sorry what's a sticky 

[MBS206]

29 minutes ago, lilley's gtr said:

Sorry what's a sticky 

A sticky, is a post in part of the forum that is "Stuck" and doesn't disappear. Sticky threads will be always the first topics to appear in the forum areas.

[MBS206]

2 hours ago, lilley's gtr said:

If anyone has done a similar build I'd love to see what they did and why 

To help you out... If you head for the "Forced Induction" section of the forum, you'll find these two threads.

RB30 Hybrid Dyno Results.

RB30 Conversion Thread

[lilley's gtr]

On 04/05/2025 at 4:50 PM, MBS206 said:

To help you out... If you head for the "Forced Induction" section of the forum, you'll find these two threads.

RB30 Hybrid Dyno Results.

RB30 Conversion Thread

Thanks man