2.5t head onto rb30 NA block WHAT TO DO?

[25t]

Hi ,can you guys help me out ,PLEASE

I want to put the head off my 25t on a N/A RB30 block ,can anyone tell me the correct combo for rods, pistons etc

this isnt a race motor but rather a good solid road motor .

SYDNEYKID ,I reckon you can answer this

GRATITUDE in advance

[meggala]

your best to start here if your doing it

http://www.meggala.com/RB30head.htm

meggala

[25t]

thanks,meg

but i need more specific info, regarding pistons and rods ,comp ratio etc

thanks

[blind_elk]

The RB25 head simply bolts on top of the RB30 block. No need to change anything inside the block.

You need to change some stuff in the timing cover area - new pullies, relocate pullies. And you need to change the computer to one that can run coilpacks.

Zoom ([email protected]) did an article a while ago, but I believe that issue is now out of print. Ask them, let me know the issue number, and I'll see if can dig it out. I can only fax it to you.

[25t]

Ok i did a search and got some more great info,

can anyone turn the light on the variable INLET cam (94 R33)

OIL THING??

THANKS AGAIN

[Steve]

From my previous investigation, the VVT is driven by oil. If you want to retain the VVT, you will have to drill the BR30 block where the oil gallery for the VVT is and presto - VVT RB30.

Also from my investigation, if you go to aftermarket cam on the inlet side - no more VVT, so you may not wish to do this?

If you can find a VVT RB25DE, and steal the inlet cam, you will have (I believe) a 250 duration ??? lift inlet cam with VVT - IF you can find a cam.

[25t]

thanks Steve ,excellent exactly what i needed to know thanks

above mentions that it is as simple as bolting the 25t head onto the rb30 bottom ,no piston/rod change required?

will the factory 25t turbo supply enough flow to the engine ,will the 370cc injectors be ok?

i know lots of questions for a newbie

thanks again

[Steve]

Injectors will be too small (only good for about 250rwkw with adj fuel pressure reg and fuel pump), turbo will be way too small.

Exactly what do you have for this conversion? You would probably be better off getting everything else sorted before you go swapping to a 3L.

[Steve]

Pistons and rods, depends on what sort of power you are chasing

[25t]

hi Steve

I have a sick 25t ,broken rings,to much boost ,194000ks,bore still has hone marks

i have a rb30 block with low kays

im trying to work out weather

i should put rings, bearings into the 25t block or bolt up the rb30 block.

the 25t motor/turbo are standard

thanks

[Steve]

Well, I wouldnt hurt to do a 3L in that case, but it will be a little more expensive than the 2.5 due to needing to relocate the timing belt tensioner, new timing belt. But it wouldnt be a significant increase in cost.

The stock turbo will be a bit small, but it wont hurt.

I am a bit confused how you got 'too much boost' out of a stock turbo though.

After you have done that, start asking questions. You are still being a bit vague, ie what sort of mods you have and what you are after when the job has been complete.

If it were me, I would be doing the 3L, (but you are not me) dollar for dollar more bang for your buck - just remeber it will cost you alot more than the rebuild to get the most out of it - but that would be the case with the 2.5 bottom end too:)

[25t]

hi steve

well ,when i say too much boost ,bleed valve = detonation

other mods are full 4inch exhaust from dump pipe with rear muffler only

k&n pod and above mentioned bleed valve

what im after is a strong reliable road motor that is capable of running 14psi boost

[25t]

oops

thanks for you replys Steve much appreciated

[Steve]

Do you have aftermarket ECU? or fuel cut defender? stock gtst has fuel cut at about 12psi????

Even at 14psi with stock ecu, seems a bit strange that you are leaning out enough to cause detonation. Perhaps your injectors aren't flowing too well? or fuel pump? AFM playing up? Might be worth investigating....

Boost isnt too relevant to making power, airflow is. Different turbos flow differently at the same boost pressure.

Unlikely the stock one will last at 14psi - esp without a decent cooler. It would be worth investing in a decent high flow or bb turbo. Some more things to think about.

[Cubes]

I'm sure you've looked here..

http://www.skylinesaustralia.com/forums/sh...&threadid=15420

[Sydneykid]

Hi steve, I keep reading about going LEAN out at 14 psi. Our experience has been, exactly the opposite, in that they go way RICH at anything more than 10 psi. The only cars we see that go LEAN have fuel pump, pressure regulator or filter problems.

Which becomes more obvious at over 10 psi, but is not really boost related, the problem is still there at 7 psi.

Hope that helps

[lowlux]

yup most ecu's when theres too much boost will give it a tanker load of fuel and rip the timing out of it,

[25t]

Thanks Joel

I did a search but didnt find that post ,thanks man

out of interest i pulled my 25t dowm today and found no1,4,6 pistons had broken ring lands and on the r/hand(east?) side if the piston ,no bore damge at all.

is this the result of to much boost?

thanks

[Steve]

Detonation, which can be caused by many different things. There is a thread on here called boost and piston damage, may be worth a read, can explain it better than I can in one post.

[25t]

Hi Guys

just went to bolt up my 25t head and what happens?

the VVt oil feed hole in the head, lines up with the water Jacket in the block.

Steve said

From my previous investigation, the VVT is driven by oil. If you want to retain the VVT, you will have to drill the BR30 block where the oil gallery for the VVT is and presto - VVT RB30

is there another point to feed the VVT from???

thanks