Spacer Plate On 25 With 30 Crank ?

[discopotato03]

I've been contemplating RB30s again but I don't want all the BS dramas with engine numbers etc .

So I'm curious to know if its practical to bolt a spacer plate on top of an RB25 block and bore both for thin walled liners .

It may look obvious to an informed eye but at least it has an RB25 number on it .

Curious , cheers A .

[Dobz]

The machining and fitting of something like that would cost a lot of money. If you can find out what's involved with building an os giken 3 litre for the rb26 then that would give you a good starting point for the rb25.

[KiwiRS4T]

You still need to change the crank to get a longer stroke. Is there a major problem with changing the block? After all a lot of recond engines are done on an exchange basis.

[discopotato03]

I was just wondering if this was a way around the legal minefield to get a 30 twin cam into an R33 coupe - in NSW .

I think the OS method uses very thick removable liners where I was asking about thin walled ones .

I did ask one blue slip place about 30s in 33s and they said no prob based on the cars weight , not sure if thats legal in NSW these days .

A .

[wolverine]

Last I checked with a NSW engineer he was happy enough providing stock intake, emissions test and "too too big a dyno number".

[discopotato03]

Sounds like a deck spacer 25 "tall block" is the only sneaky wayto fly under the radar with a legit engine number .

[Adriano]

But with all the stuffing around and cost its probably easier and not much more to fit a 2.8kit to an rb25

[Gerg_R31]

http://www.skylinesaustralia.com/forums/topic/314402-project-rb31dett-the-development-of-my-open-deck-rb-engine-and-the-quest-for-more-torque/

take a read GTRNUR has done something similar to what your thinking

[StevenCJR31]

i THINK the os giken setup uses a 26 block with the spacer plate and bullet proof bottom end - with no manifolds or head. . . but as stated above it comes with a BIG $$$ pricetag

[KiwiRS4T]

None of the options can compete pricewise with an RB30 block - are you sure you can't do that legally?

[discopotato03]

I'd say the story is if you have to ask and it isn't a factory option you go through the mill .

I suppose its not easy to make a 30 block "look" like a 25 one .

My guess is that many just do it knowing that a number check is not part of the yearly safety inspection in new south cactus . Provided you didn't make a target out of yourself by driving like a lunatick it could go unnoticed forever . Insurance is probably the issue .

Anyone know the current pricing of liners and spacer plate for 25 block , Harris thinks it maybe 5G and can't use an OE 30 crank .

A .

[Adriano]

Why cant yoou use the crank?

[JonnoHR31]

Better off spending the money on making a 30 block look like a 25. Machine the engine number off and get your 25 number stamped on, make a custom bottom timing cover and re drill the engine mounts 20mm lower (and patch the old holes if you want extra stealth).

[discopotato03]

Don't know about the crank didn't ask . The person I know that had a bit to do with race use RB30s said better with a 25 block to do a 2.7L conversion .

Otherwise as mentioned .

I'm sure RD28 cranks were not found to be usable and if I search I'll probably find out why .

A .

[discopotato03]

http://www.skylinesaustralia.com/forums/topic/58134-rd28-diesel/

I read this some time ago but couldn't remember where .

A .

Edited June 13, 2012 by discopotato03

[TiTAN]

why even bother making the 30 block look like a 25?

mine has been engineered and passed the NSW emissions testing which is all you need to have it legally registered. end of the day that all up is cheaper than the 5k you want to spend on a spacer plate and liners etc.

[Gerg_R31]

Rd blocks - unless your going full drag and intend to completely fill it, waste of time

head bolt holes line up, rb cranks fit fine

you will have to make sure 100% there is no diesel oil hidden anywhere

drain back holes don't line up

rear drain back on exhaust side of head won't have anything connected to it

water jackets don't line up

there is not enough material to relocate the tensioner in the right spot

casting is f**k all thicker

does have oil squirters

water pump, oil pump rear main seal housing fits any other rb parts

a spacer plate and sleeve job would be cheaper then an rd block

[discopotato03]

Thye only RD part I was checking out was the crank but its not really suitable for a 25/26 block . The stroke is really a bit long and the crank pins I believe a bit small possibly needing custom con rods .

Its much easier using an LD28 crank in an L6 block because dimensionally everything is much closer to an L28 crank - except the stroke .

Not that anyone cares but LD28s use FJ20 turbo rods too .

Possibly easiest if the numbers are what eyes are expecting to see . Don't they all come like that ?

Of course if you don't drive like a fool or venture out in packs to the known hotspots the probability of the Sky falling in would be lower .

Edited June 13, 2012 by discopotato03