My Rb25/30 Build

[NYTSKY]

Dont attempt it yourself! Having seen the process from another builder you need to know the workings of both heads intimately!

[MRHD66]

Dont attempt it yourself! Having seen the process from another builder you need to know the workings of both heads intimately!

yeh bro I know that !! I'm just goin to use the R33 RB25 head I got as we said your RB25/30 revs to 8500 and I won't need anymore then that !! Edited June 30, 2012 by MRHD66

[NYTSKY]

If you look around you can get your hands on a decent plenum for the 25 for around the same money you want to spend.

[MRHD66]

If you look around you can get your hands on a decent plenum for the 25 for around the same money you want to spend.

yeh but I want RB26 with 6tbs !! I get a RB 25 aftermarket one off but I don't want it

[MRHD66]

The car it's goin into

[MRHD66]

Hmm

Edited October 9, 2012 by MRHD66

[James_03]

yeh but I want RB26 with 6tbs !! I get a RB 25 aftermarket one off but I don't want it

Mate no offence, but you know f**k all. People are trying to give you good advice here. Do you know why VCT was introduced? It was primarily introduced to help lower exhaust emissions and improve fuel economy.

If you don't want your build to end up in a pile of shit, then I would suggest you drop the know it all attitude and starting listening to people. Your hell bent on going individual throttles, yet you don't want to go a 26 head, but you would rather spend what a 26 head costs modding your 25 head so it can run ITB's?

About the only thing it will do is maybe give it marginally better low down throttle response, but that will probably be totally negated by all the negatives of blowing the runner length out.

[MRHD66]

Mate no offence, but you know f**k all. People are trying to give you good advice here. Do you know why VCT was introduced? It was primarily introduced to help lower exhaust emissions and improve fuel economy.

If you don't want your build to end up in a pile of shit, then I would suggest you drop the know it all attitude and starting listening to people. Your hell bent on going individual throttles, yet you don't want to go a 26 head, but you would rather spend what a 26 head costs modding your 25 head so it can run ITB's?

About the only thing it will do is maybe give it marginally better low down throttle response, but that will probably be totally negated by all the negatives of blowing the runner length out.

yeh you all follow the crowed I've already talked to so ppl and shit and I know that's why VCT was inteduced bit it's also good for power as ppl convert there RB26 head to have it and HKS do cams to do same thing as VCT so before you say anything I do a lot of research of thing and an not a sheep for the sake of being the same as everyone so unlike a lot of u I don't do thing cos everyone else said its the best thing to do

[The Dan]

yeh you all follow the crowed I've already talked to so ppl and shit and I know that's why VCT was inteduced bit it's also good for power as ppl convert there RB26 head to have it and HKS do cams to do same thing as VCT so before you say anything I do a lot of research of thing and an not a sheep for the sake of being the same as everyone so unlike a lot of u I don't do thing cos everyone else said its the best thing to do

There's a very good reason people say not to do it. It's been done dozens of times before and it's shit.

Why do you think Blitz stopped making the adaptor plates?

[discopotato03]

They say necessity is the mother of invention but the real question I believe is how much does the OP want to spend . Its all possible and its his money and responsibility to use it usefully .

That aside there was an interesting thread here a few years back where someone welded up the inlet side of a Neo 25 head so it could accept an RB26s inlet manifold complete . IMO if you want an RB to breathe well and have rapid throttle response the 26 inlet and a non hydraulic valve train is the way to go . The complete 26 top end is easiest to bolt on and probably the best from valve/bucket innertia and revs point of view .

As we know variable inlet cam timing is the complication because 26s never got it std .

To me an RB25DET can be a torquey flexible engine and VCT would be a part of this . Going to 3L I'm told just pulls everything down 500 revs compared to the 25 and that must make them a really nice road engine . I'm suggesting a 20% capacity increase probably does more than a bit of inlet cam movement does for low end torque and flexibility so the lack of VCT is possibly no issue for an RB30 .

I look at the RB26 as a complete system from airbox to cat including the front intercooler and ducting via the drivers side .

Possibly the OP needs to consider how he wants to package everything in an old HD Holden and take into account the air/intercooler layout he wants to use .

Something else to work is the overall weight this thing will be because a std HD is probably lighter than say an R33 coupe and less for an angry twin cam 30 to pull around .

If it were me and money was in any way a question a good runner RB25DET with a bit of bolt on help would be a good start .

Your call lets hope the HD shell can take three to four times the stress of a turbo RB compared to an Olden grey , or was it a red ?

Cheers A .

[TTT]

lol.

Man build twin cam RB30.... to be different.

Well done genious

[MRHD66]

They say necessity is the mother of invention but the real question I believe is how much does the OP want to spend . Its all possible and its his money and responsibility to use it usefully .

That aside there was an interesting thread here a few years back where someone welded up the inlet side of a Neo 25 head so it could accept an RB26s inlet manifold complete . IMO if you want an RB to breathe well and have rapid throttle response the 26 inlet and a non hydraulic valve train is the way to go . The complete 26 top end is easiest to bolt on and probably the best from valve/bucket innertia and revs point of view .

As we know variable inlet cam timing is the complication because 26s never got it std .

To me an RB25DET can be a torquey flexible engine and VCT would be a part of this . Going to 3L I'm told just pulls everything down 500 revs compared to the 25 and that must make them a really nice road engine . I'm suggesting a 20% capacity increase probably does more than a bit of inlet cam movement does for low end torque and flexibility so the lack of VCT is possibly no issue for an RB30 .

I look at the RB26 as a complete system from airbox to cat including the front intercooler and ducting via the drivers side .

Possibly the OP needs to consider how he wants to package everything in an old HD Holden and take into account the air/intercooler layout he wants to use .

Something else to work is the overall weight this thing will be because a std HD is probably lighter than say an R33 coupe and less for an angry twin cam 30 to pull around .

If it were me and money was in any way a question a good runner RB25DET with a bit of bolt on help would be a good start .

Your call lets hope the HD shell can take three to four times the stress of a turbo RB compared to an Olden grey , or was it a red ?

Cheers A .

RED and its full rebuild of the HD not just waking a RB in a Regod car HD full optioned up weigh 1200kgs or there abouts

[James_03]

yeh you all follow the crowed I've already talked to so ppl and shit and I know that's why VCT was inteduced bit it's also good for power as ppl convert there RB26 head to have it and HKS do cams to do same thing as VCT so before you say anything I do a lot of research of thing and an not a sheep for the sake of being the same as everyone so unlike a lot of u I don't do thing cos everyone else said its the best thing to do

I actually felt less intelligent after reading that response.

There are so many things wrong with that paragraph I don't even know where to begin, and because your an idiot, seeing you spend all your cash being "different" might actually be a good learning exercise for you.

Edited October 10, 2012 by James_03

[TTT]

you're

[jet_r31]

Some people are being a bit rough on you, but they have a point..looking at your posts, your are overcomplicating you engine

part of the build IMO...just throw the thing together, put some drop in poncams in it and it will make enough power to turn the old HD inside out with that turbo (i had 2 HD's when i was younger) wilst saving you a lot of time and effort that you could use on the rest of your buildup of the old girl. You woudn't get me in a HD no matter what you did to make the torsional ridigity better with that motor in it ...lol

cheers

darren

Edited October 10, 2012 by jet_r31

[Akshunhiro]

Fact;

VCT is not required when you have the torque of a 3L

ITB's are only there for response and have no performance gains when used in a forced induction application

LS2 or LS7 will be a cheaper, better & easier option

[MRHD66]

Fact;

VCT is not required when you have the torque of a 3L

ITB's are only there for response and have no performance gains when used in a forced induction application

LS2 or LS7 will be a cheaper, better & easier option

cheers mate I know LS will be cheaper but I'm not a V8 guy that's why I'm goin RB

[MRHD66]

Some people are being a bit rough on you, but they have a point..looking at your posts, your are overcomplicating you engine

part of the build IMO...just throw the thing together, put some drop in poncams in it and it will make enough power to turn the old HD inside out with that turbo (i had 2 HD's when i was younger) wilst saving you a lot of time and effort that you could use on the rest of your buildup of the old girl. You woudn't get me in a HD no matter what you did to make the torsional ridigity better with that motor in it ...lol

cheers

darren

cheers mate

[MRHD66]

dont think I'll have room for the RB26 inlet and adaptor in the engine bay of the HD anyways

Edited October 10, 2012 by MRHD66

[MRHD66]

got this HKS oil cooler block

just hope the rear RB25dipstick clears it as the RB30 one dosent