R33 Rb30 Conversion

[Skyrine-Dave]

Just saw the engine dyno sheet for one of our RB30DET's (RB30 + RB26) with GT35R at 1.3 bar made a nice 632 bhp.:headspin:

What did the motor have done to it? Anything special or standout-ish?

How much would that translate to @ the wheels?

I'm very anxious to see what my RB30DET (rb25 + rb30 tho) with GT35R

[WooD]

not sure if this has been posted on here before, i've read the first 40odd pages and dont think i've come across it.

pretty good guide to a twin cam conversion.

http://users.tpg.com.au/cobra30/twincam.htm

[masTers]

Does anyone have any dyno charts they can email me of their RB30-DET's with the GT35/40?

[OFENSV]

when using the cometic metal head gasket did you torque it down to the factory nissan specs or is it diffent being a 3 layer metal gasket?

[Cubes]

I ended up paying my engine builder $200 to bolt the head on, locate and drill the tensioner, fit the cam belt etc.

I figured for $200 it wasn't worth the hassle to do it my self.

[Sydneykid]

What did the motor have done to it? Anything special or standout-ish?

How much would that translate to @ the wheels?

I'm very anxious to see what my RB30DET (rb25 + rb30 tho) with GT35R

There were very few "brand" name parts used;

Standard RB30 block, crank, water pump, oil pump and balancer

Balanced up & down and round & round bits

O'ringed block and double annealed copper head gasket

ACL Race Series pistons, rings and bearings

Pistons were ceramic coated on the crowns and oil retention coated on the skirts

Argo I beam rods with ARP rod bolts

Std VL RB30 Commondoor gaskets and seals

Fabricated sump with wings and baffles

ARP studs for cylinder head and main bearings

Std RB26 Camshafts, valves, retainers and followers

Performance brand valve springs

Adj camshaft pulleys (no name brand, early Jun style)

Gates cambelt

Ported head with polished and matched combustion chambers

GT35R on a no name high mount manifold with a no name (HKS copy) wastegate

850 cc Cosmo injectors

Bosch 044 fuel pump

Nismo regulator on the standard fuel rail

Power FC

PWR intercooler

Q45 AFM

Run in on the dyno for around 1 hour all up, change oil and filter and get into it.

Calcs..........

632 bhp = 472 kw less ~60 kw (2wd) = 412 rwkw

The average power from 4,000 rpm to 7,000 rpm is massive and it's not straining at all. A/F ratios are not over 12 to 1 anywhere and the knock is less than 20. Cams and a bit more airflow (no more boost required) it would make 500 rwkw easily.

It's a customer engine so I have no permission to post up the graphs. My new RB31DET is similar (+ cams though) and I will post its graphs up when it is done.

[WooD]

hey guys just 1 quick question,

do you HAVE to move the tensioner?

cheers.

[Cubes]

Depends if you can find a belt to suit.

[WooD]

is there one avaliable to suit that you know of?

[masTers]

I think if there was, we would all be using that instead.

Steve

[CruizinCairns]

hey you seem to have a bit of knowledge on this site and i'm wandering if i can put it to use. I know you guys are all skyline lovers but my girlfreind and i have just invested in a vl calais with a stock rb30e. as it is to be her new car she wants to put on a dohc head and probly turbo. we've been offered an rb20det out of a mates old r31. will this head be sufficiant? or should we continue to look elsewere? we got onto a site called rb30 dohc. but i got a little confused. the info would just jump from one engine to another. i would have confidence in some of the info but could still use a simple yes no answer. would it work? we've also lined up a rb30 short motor block with forged pistons for fifty bucks. would anyone have the pros and cons for me? any info would really help. cheers.

[StockyMcStock]

2 problems:

1) RB20 head uses very small valves, and the bore size is different to the RB30. it will not work.

2) if you can score an RB30 short motor with forgies then they are 90% likely to be turbo pistons (low compression) and i would throw a custom cam in it and turbo the RB30. changing pistons and using the 25 head will take a lot of money and may not be worth the hassle.

[Sydneykid]

hey guys just 1 quick question,

do you HAVE to move the tensioner?

cheers.

That places the teeth on the belt too close to the other teeth going in the opposite direction. Even the slightest whip in the belt will mean they touch. At high rpm it wouldn't take much touching to rip the teeth off the belt, very ugly.

My suggestion, stick with what has worked on hundreds of of RB30 DOHC conversions.

[Benster]

Hi everyone,

I'm new to the forum and I'm currently researching some options for my fathers VL RB30... He has requested that it not be turbo'ed but the possabilty of a supercharger may come into play at some stage in the future.

After reading through as much as I can on this HUGE topic I haven't found much information on using the hybrid RB's for NA purposes... from what I can tell the biggest issue will be the compression ratio.

At the moment all he wants to do are some basic modifications on top of the head change... such as exhaust, larger injecters and the like...

With the r32 ecu and loom and a basic setup, what and how can the compression be changed, ie. is shaving the head enough to bring the compression up? How much more performance can we expect to get Naturally Aspirated? We've been told it would be anywhere between 15% - 30% added performance, is this about right? And can we bring the compression down again if he wishes to go with a Supercharger in the future? Maybe a spacer?

I'd ask the question on some of the VL forums but IMO it's a bit of a booner cult and information is sketchy at best... I find too many contradictions.... I'm a Nissan owner and have found Nissan owners to be a bit more intelligent and methodical in the ways of mechanicals.

Congrats on a brilliant and FACTUAL topic... you all made my day and I've had most of my questions answered.

All opinions welcome... and thanks in advance

Benster.

[Sydneykid]

Hi everyone,

I'm new to the forum and I'm currently researching some options for my fathers VL RB30...  He has requested that it not be turbo'ed but the possabilty of a supercharger may come into play at some stage in the future.

After reading through as much as I can on this HUGE topic I haven't found much information on using the hybrid RB's for NA purposes...  from what I can tell the biggest issue will be the compression ratio.

At the moment all he wants to do are some basic modifications on top of the head change...  such as exhaust, larger injecters and the like...

With the r32 ecu and loom and a basic setup, what and how can the compression be changed, ie. is shaving the head enough to bring the compression up? How much more performance can we expect to get Naturally Aspirated?  We've been told it would be anywhere between 15% - 30% added performance, is this about right? And can we bring the compression down again if he wishes to go with a Supercharger in the future?  Maybe a spacer?

I'd ask the question on some of the VL forums but IMO it's a bit of a booner cult and information is sketchy at best...  I find too many contradictions....  I'm a Nissan owner and have found Nissan owners to be a bit more intelligent and methodical in the ways of mechanicals.

Congrats on a brilliant and FACTUAL topic...  you all made my day and I've had most of my questions answered.

All opinions welcome...  and thanks in advance

Benster.

Hi Benster, an RB30DE is an interesting project, around 250 bhp is quite possible for a mild road engine and close to 400 bhp for a race engine. The VVT from an RB25DET cylinder head would be an advantage, but the multiple throttle bodies from an RB26DETT would be a bigger one, in my opinion anyway. There are plenty of camshafts available that would do the N/A job quite nicely, the RB26DETT would be the pick again due ot its higher lift and solid followers. The standard RB25DET injectors (370cc for 370 bhp) or RB26DETT injectors (444cc's for 444 bhp) would be fine for the task. So there is very little that would stop the project from succeeding using standard parts, hence easy and fairly cheap. Well compared to a mega power turbo build up anyway.

You have correctly indentified compression ratio as the main problem, for a good road N/A engine you need at least 10 to 1 and for a good race engine 13.5 to1 is the current target. An RB30E bottom end will get you around 8.3 to 1 using any of the DOHC clinder heads as their combustion chamber volume is much larger than the old SOHC. You could sneak that up to 9 to 1 with a bit of judicious cylinder head machining, maybe a light block skim and a thin head gasket.

ACL make RB30 pistons locally so you should be able to pick up a set that will boost the compression ratio, or you could use JE's 87.5 mm VG30DE (non turbo) pistons. They will give a bit over 10 to 1 compression ratio and at the same time be suitable for mild boost later on.

As usual it all depends on your budget which way you choose to go.

Hope that was of some help:cheers:

[Benster]

SydneyKid,

Is it possible to lengthen the stroke instead? Maybe slightly longer rods or a different Crank that will bolt on, short of having one custom made and ground?

Also, are there any known issues with thinner head gaskets? Do they last, etc?

[Benster]

Another thing. I just read on the VL Calai forum that changing the pistons from the rb25de into the rb30e will provide a 10.5:1 compression (approx).

But most of the research I've done says that it will lower to something like 7.5:1 (from memory). It did state that there was a difference between the pistons from the rb25de and the rb25det. Is any of this true? In my slow brain it makes some sense to up the compression this way in a non turbo engine for economical reasons at manufacturing... but I'm not educated enough on these matters to guess with any confidence.

I'm getting more confused now?

I'm assuming that if I could change the pistons over, that the rods from the rb30 will go on them?

But somehow this doesn't seem right to me and it seems to easy... So I thought it best to seek advise... I am probably going to order the non VVT half cut from a 32 within the next couple of weeks and sell off what I don't use. I might just rebuild it and buy another head, I dunno. Is there much of a demand for 32 bums with internals and also gearbox's?

Thanks

Ben

[Benster]

Anyone Need to confirm as opportunities for an RB25DE engine/s have come up... It may soon be bought... I want to limit any mistakes... don't mind a good learning curve but I do mind a thin back pocket.

[Looney_Head]

Sydneykid

what compression ratio would vg30dett pistons give in a rb30det?, if they can be used.

thanks

[Sydneykid]

Sydneykid  

what compression ratio would vg30dett pistons give in a rb30det?, if they can be used.

thanks

Very low, as the VG30 has smaller combustion chambers than RB's, because of the flatter valve angles. Low 8's if I remember rightly.