Anyone Know How Easy Rb30 To Rb25Det Conversion Is For Vl Commodore

[saltdragon]

Hi,

I have a VL Commodore with a naturally aspirated RB30, done near 300,000KM and it's screwed. How tricky is it to go to an RB25DET and what mods will have I have to do to the engine bay? Is it worth doing this or would it be cheaper to rebuild the RB30 to take a 35-40 Garrett turbo which will set me back roughly $12-15K?

Also where do I get a good RB25DET from? I live 3 hours from Brisbane.

Thanks heaps

[GTSBoy]

RB25 should fall into the engine bay. You will need to sort out the most suitable mounts for engine and (bigger) gearbox. You will need VLT tailshaft. The wiring looms are very different. There is a reasonable amount of work to sort the wiring out. Need a big fuel pump. Need bigger brakes. Being QLD there is a need for mod plate engineer approval stuff (best wait for a QLD member to comment there). Need an LSD otherwise you will peel one tyre.

The best place to buy one would be, well, I dunno....how about the for sale section on here? I recall seeing several for sale lately.

I also recall seeing a built RB30 turbo for sale somewhere recently. That's probably the smart thing to do. Can't remember if I saw it on here somewhere, or perhaps on PF. Possibly PF.

[MillsyR33]

not too hard , pretty much swap mounts over and bolt in, run all vl anciallaries. get a 33 box as well, will neeed vlt manual tail shaft of get a shaft made through hardy spicer or driveline sevices, get a cable type speedo drive to run the old vl, as mentoned previously a mod plate too. would probably suggest front brake upgrade and vlt diff too, run disc rear, which in turn will need double diapram booster and 1 inch master.. not meaning to be rude as i am an ex vl person i would consider ditching the vl all together and just getting a 33 or 34. chalk and cheese really.... i made the change 5 years ago and havent looked back.

[saltdragon]

Hi GTSBoy, thank you for your reply.

I have done the brakes with PBR and got rid of the drums on the back and now have disc brakes, it's lowered as well. I have heard that the RB25 is better than the RB30 but (more reliable and stronger) but by the sounds of it I might just rebuild the RB30. I will check for the RB30 that you mention though.

Now the question is, is there anyone around Sunshine Coast or Brisbane that will do a really good job, this car will be a show car eventually.

[GTSBoy]

RB25 is not intrinsically better than the RB30 except that a twin cam head is a better thing. There is no difficulty with making huge power out of a single cam RB30 though. The VL racers have been doing it for years and years. If you were to go with a 30, you'd probably be going with a freshly built one. If you go with an RB25, it's a fair bet you'd be dropping in a secondhandy with 80+ thousand kays on it, probably more.

Admittedly, if it were me, I'd be putting an RB25 Neo in there. That's what I did with my R32. But in that case I was moving up from 2 litres, not down from 3. So mine was double smart. It's only half smart in a VL.

The absolute best thing would be to build a 25 head onto RB30 bottom end. There is bulk info on these forums on that topic. Look at the sticky thread.

Engine transplant alone is many thousands. Engine + box + wiring + fresh consumables + labour is well >$5k.

Building an RB30 for turbo duties would possibly run to about the same $$ as long as you're not building it to handle silly power levels. Maybe you'd expect to part with $10k+ for that sort of thing. But you could also easily spend $30k if you set your mind to it.

I must echo Millsy's thoughts. I wouldn't be wasting money building a dirty old VL into a show car. I can understand making it a better drive by giving it more power and handling and brakes and so on, but I can't see sinking many many thousands of $$ into one as being sensible. Show car paint is a $20k proposition. The era of VL show cars was 20 years ago. We've seen it move from poor taste to bad taste. It's time to build something else. How about a Honda Odyssey with NSX motor? Or a Volkswagon Caravelle with Toureg motor?

[GTR_JOEY]

If it was me,

Id keep the 30 and freshen it up with forgies

Run a twin cam head

Slap a big single turbo on there.. Id go a Borg Warner again.. awesome power for money

Beef up the auto if its not a manual

What power you chasing? my mate has a VL with 230rwkw.. and its still a handful with that much power..

Like GTSboy said, the days of the VL show car are over and no ones really impressed anymore

But if making it a show car is what will make you genuinly happy then go for it... its alot of money though

[saltdragon]

lol yes I know, everyone keeps telling me that I am wasting my time with the VL but I am very partial to them and I have had it since I was 16 which has been 13 years so I can't part with it, thanks Millsy for your input as well, very helpful and good to know more of what I need to do to get it up and running with a new engine.

@ GTSBoy - Good point about the RB25 heads on the RB30 bottom end, that will def be a consideration now that you mention it, didn't even think of that.

[VLSteve]

Its very easy to do. All wiring info can be found on the R31 forum/wiki, but you will have to play around with the alterator/starter/battery loom.

Use the RB25 alternator

You can either use the Rb25 power steering pump and have custom lines made, or use a VL S1 pump and lines. It bolts up, but you need a small spacer made up for the top bolt that goes into the head. Also the VCT oil return line needs to be slighty bent around it.

VLT manual tail shaft (or VL NA manual shaft with R33 yoke)

VL engine mounts and manual gearbox crossmember- Skyline rubber mount is the same as a VL one.

VLT exhaust nearly fits, engine pipe just needs to be cut and rotated slightly.

Use VL radiator, RB25 top hose, VL bottom hose, VL heater hoses.

For the speedo, go to nissan and find one for a Navara (look on www.calaisturbo.com.au for part number) speedo will be correct for 3.45 diff gears.

Standard VL fuel pumps are fine if using stock injectors/turbo/ecu setup, even when running 10psi. (no matter what anyone says, VL NA/Turbo external pumps all flow the same, even though some part numbers are different)

Then you just need and intercooler and piping.

That might be about it...

Edited January 14, 2013 by DasBlitz

[AngryRB]

Hi,

I have a VL Commodore with a naturally aspirated RB30, done near 300,000KM and it's screwed. How tricky is it to go to an RB25DET and what mods will have I have to do to the engine bay? Is it worth doing this or would it be cheaper to rebuild the RB30 to take a 35-40 Garrett turbo which will set me back roughly $12-15K?

Also where do I get a good RB25DET from? I live 3 hours from Brisbane.

Thanks heaps

I wouldnt bother with transplants, id do a simple rebuild on the stock rb30 and add a gt 3076 with 0.82, with that combination you'd have an awesome street 250-300kw easy..

i remember when my brother had a vlturbo manual, was mind blowing torque, even in mild state it was a traffic light weapon, 2000rpm and its all on

a vl turbo with a gt30/35 will do 13's and under, a rb25 will be a backward step in my opinion, torque will drop and not be as much fun.

Edited January 14, 2013 by AngryRBGTX

[GTR260]

I have a brand new genuine factory built crate rb30 last one in the contry, will sell it for the right price. pm me if ur interested

[discopotato03]

I think if you are VL centric the best would be an original turbo car mainly because the important bits are already there and you are not replacing the whole driveline . I feel like I've spent a lifetime taking local content parts out of locally built "Japanese" cars and it only ends when you buy Japanese built cars .

With VLs I think the best part was the Japanese engine and gearbox and they almost look a bit lost in an Australian built car . As a platform VLs were alright and the best I can say about them is that they are reasonably light and compact for a three litre car .

The things that arguably let them down are the five link live rear end and the Macpherson front struts . Skylines from R32 on have mulitilink independant rear ends and an interesting double link upright front suspension style . They get fiour piston front and opposing piston rear brakes and the raditor height and support panel format are higher than a VL which reduces cooling issues .

Anyway mechanicals aside a VL possibly has a little less of the kid ratbag image than an imported Skyline and that may appeal to some , not sure what the cops think but I guess that depends on how you car looks in the height/tint/ doof doof stakes .

A few years ago an associate of mine had a VL turbo with a 26/high mount GT35 in it and thought it was a blast , until his missus out dragged him in some Hi po AWD Audi wagon . The VL found a new home quick smart .

If it was me doing a VL it would have an RB30 because the bore stroke rod and block height is a better formula than an RB25 - and its the native engine meaning a lot less legal hassles . All the 25 has going for it is piston oil squirters and the better top end . To run less capacity probably means using shorter gearing so I can't see a gain anywhere . As mentioned you can make quite reasonable power with the single cam head though that may require warmer cams and a bit less refinement than a twin cam one .

Only you can know how much you like your car and what you're prepared to spend on it , BTW have a look at what hotted up VLTs sell for before throwing bulk money at it . You may be able to pick up someones expensive project and save on the devaluation at the same time . Also an original should hold its value a bit better than a clone because its " a real one " .

You call , cheers A .