Monster R31 Conversion

[-scooter-]

Hello peoples...

I own an R31 2 door skyline and the red top nics motor is getting old and worn. So i am thinking of doing an rb25det transplant.

I have many questions that i want to ask but for now i would just like to know if the rb25 gearbox will fit without modifaction or not, as i dont think the rb20 box will last long at all. I have benn told the 25 box is longer then the 20 box and a new tail shaft is needed..... what truth is in this???????

Any help will be great

thanks guys

:D

[R31Nismoid]

dunno about that.

I'm 99% i got a RB25 box behind my RB25 (in an R31)

Post this in the R31 forums.

www.r31skylineclub.com

one of the boys is doing the conversion, and a few have already done it too.

[sky^rkt]

hey mate, im doing the conevrsion myself to my r31, and im using the rb20det box for now til i can afford a 25 box, as for ur question, yes u wil need a new tailshaft due to the different length of the 25 box, if you have anymore question do not hesitate to pm me or email me on [email protected]

[Skyrine-Dave]

run the rb20 box, as long as you treat it nice it should hold up for a while.

i know a car that has 340rwkw and run a 10.10@142mph and runs a stock RB20DET 5pd

[-scooter-]

I'm at the stage of shopping for the engine at the mo. i rang a place called ALL JAP at virginia and the can do an rb25det with uncut loom,computer and gearbox all complete for $2750. That is good rite????

Also wat is the the cost of a tailshaft made to specifaction these days, im sure it is expencive though.

Cheers

Dan

:headspin: :headspin:

[sky^rkt]

a 1 peice tailshaft set me bak 250 dollars, if u pay more than 300 its a rip off

[-scooter-]

Well thats good news, i was expecting to pay 600 to 1000 dollars.

so is that the only prob with the 25 box into R31 convert????

Sorry bout asking again but i just wanna make sure that everything is peachey before i go converting and find probs that i dont wanna find, if u know wat i mean.

i also heard that the speedo on a 25 box is electronic and 31 box is cable. Is this true???????

Cheers

Dan

:Bang: :Bang:

[Skyrine-Dave]

i also heard that the speedo on a 25 box is electronic and 31 box is cable. Is this true???????

true... You will need to source yourself an R32 GTR Speedo drive as they are mechanical. And then i think you use the RB25 sender on the end of this to fit the gearbox. This should get it all linked up to the R31

you also have a PM

[-scooter-]

alrite then sounds like the gearbox is sorted.

so wat bout the engine and computer, is it pretty much a direct swap for the motor thats in there now

EG: ecu for ecu

motor for motor

any major problems with this????????

i think i might sit down and think hard and write a list of things that might need to be changed and post that, and c wat people think.

[R31Nismoid]

you need the RB25 loom preferrably

the RB25 ECU wont plug'n'play with your loom without modification.

[-scooter-]

well i made a list of questions to ask this forum, so here goes.....

1. Can i use the rb20 radiator i have now or use an rb25 one in its place?

2. Will my power steering and aircon pumps bolt straight on the the 25 block?

3. Can i still use my stock inter cooler (as i wont be able to aford a FMIC rite away)

4. Any engine mount modifaction required for fitment.

5. Any braking or suspension mods required.

6. Will i need an rb25 dump pipe or will rb20 be alrite.

7. Will the diff be ok for the power increase.

thanks in advance for any help.

cheers

Dan

:slap: :wassup: :Bang: :flamed:

[Skyrine-Dave]

1. Rb20 radiator should be fine

2. yes they should mount to the same place on teh rb25 engine

3. dont run more than 12psi and ya should be ok, factory cooler sucks

4. no will fit original RB mounts

5. it would be wise to upgrade the brakes, even to R32 calipers/discs/ and hubs (5 stud)

6. yes

7. if its LSD... yesm

[-scooter-]

cool cool.

Which would be cheaper in the long run??

to buy the motor and get some one to put it in for me (as im not experienced enough to put it in my self)

OR

find a place in bris that will do drive in with rb20 and a week later drive away with rb25 kinda package??????

Is there any places in brisbane that do this conversion at all?????

Cheers

Dan

[sky^rkt]

1. i wouldnt advise using the rb20 radiator as it is pretty small, i would advise going to a wreckers and geting a 3 litre radiator as i have done.

2. the power steering pump wil go on yes, but u will need to put a biger belt most likely. i had to put a new belt on mine due to my car having hicas. the aircon will bolt straight on.

3.you can use your intercooler, but i would sugest trying top source a stock rb25 cooler.

4. the engine wil be a straight bolt in.

5. if you got the stock suspension in your r31 coupe i would sugest upgrading, because the stock setup is utter crap, shop around for a good deal. as for brakes they import brakes r a decent size, i would put on better brake pads. and if you can afford later on try get r32 calipers onto it. or even put slotted/cross drilled discs.

6. yes

7. the diff should habdle the power ok, u would have the r200 diff and they r a bloody good diff!, just hope u got lsd =]

hope this all helps

[-scooter-]

Hmmmmm

i agree with u about the sus it is bloody crap.

It all gets me thinking, it would be so much cheaper to just buy an R31 with an b25 in it already. That way i can spend all my money on mods!!!!

they are in the trading post every now and then.

OR

could do the sus first, then brakes and so on, and leave the engine till last. Will take longer to do (because i will have to save money for a little while). But the convert will be mine and the way i want it done....

Decisions, decisions......

Any advice on which way to go????? PROS & CONS

cheers

Dan

:Bang: :Bang:

[sky^rkt]

i would sugest u change ur suspension first. then upgrade your brakes. then off u go to get a new engine. yes it might end up costing abit more doing the conversion rather than buyin a car with one already in it, but it all comes down to personal choice. i personaly feel better that i got a rb25det instaled in my car rather than go out and find a aussi model with an rb25det, but anyways good luck with it, just research the prices etc and decide what your going to do

[BIGBLOCKR31COUPE]

The power steering will all bolt straight on. Same belts as you already have because the mounting points are all in the same places on both blocks.

[-scooter-]

Another question

alittle while ago i went hunting for some wheels for my car but came up with only 3 or so different types of wheels that will fit due to the super large 4 stud pattern.

So im thinking maybe it is possible to fit r32 brakes (5 stud) to the front end and either a whole 32 diff in the rear or just the brake set up to my diff???????

is this all possible, as there is a much much larger range of wheels for 5 stud r32 wheels.

Dan

:Oops: :wassup: :bs!: :flamed:

[Skyrine-Dave]

do the r32 conversion on the front... and back if u want.

i got R32 front and 300zx rears... muchly worthwhile upgrade

[-scooter-]

Did u do a complete 300zx conver (diff brakes etc) or just the brakes????

wat is involved in r32 front end convert????

Dan