Rb25/30det Engine Build, Need More Info? - what machining is needed on the 25 head & the 30 block???  

E-Z

please search the internet.

iamhappy46

Stock RB30 N/A pistons, rods and crank are good for around 400rwHp since the 35 head drops compression to a much more boost friendly 8.3:1

Skylines Australia website has a complete walk though on the conversion, it is not hard with tapping the block for the extra timing belt pulleys about as hard as it gets

blown7

ok sweet what about VCT do i block that off on the head or block? then run an external line from somewhere?
you wouldn't know the link on SAU would you? as i dont have an account there....
cheers

pipster11

sign up

if you own an rb its the best resource out there

i think you can weld and retap and drill the gallery but i can't remember

make sure you keep it tho, helps bring boost on earlier

09ONE

Fuck the VCT it's not important, and with the 3L bottom end you DON'T notice the difference (been there and done that)

blown7

ok so i've sourced an already built rb30 block that has previously been used for the rb25/30det set up before so all the work has been done to the 30 block, nothing i need to get machined on that.
I currently have s2 R33 rb25det head so the question is what machining need to be done to that to make it fit onto the rb30 block?
whats the best way to go with the VCT? i've been told it may have to be welded, where does it have to be welded on the block or head?
& do i have to still run en external oil line for that???

cheers

TwinCam16

Do yourself a favor, and start a new thread.

blown7

ok i'll just do that.... fuckkk

TwinCam16

Sorry, my bad.

I thought this was another thread.

Having one of those days

blown7

yeah i was kinda like WTF :S all good

iamhappy46

If your not using the VCT, then nothing needs to be welded up. Just converted to adjustable cams gears to get rid of the VCT solenoid cam gear

If you want to use VCT, then it is a little more involved

blown7

yeah not gonna keep VCT .
just to make sure i just have to cap the oil feed on the head? as shown in the pic right? nothing more nothing less?

stephen16

As far as I have researched there is no machining to be done, you grab a rb30 block, and slap the head on, tap the hole for the timing belt adjuster, and turbo oil lines if you don't have a s2 block

I think it's only the 26 head you have to tap bigger holes in the block for the rb26 sized head bolts

iamhappy46

You could cap it, although most of the time I have just left the VCT solenoid unplugged, since the headgasket design means nothing is going to get in at that end anyway as the RB30 block has not have an oil feed at that point and since the VCT is blocked off, there will be no oil pressure control problems anyway.

blown7

ok sweet would there be anything else i'd need to know or look out for when putting it all together? also i did source an already built rb30 block thats had a rb25 head bolted on. just need to know if i'm missing any info on the head side of things now. if not i''m pretty much set...

stephen16

No mate that's it, do you know what compression ratio the pistons are to suit

blown7

also whats the best head studs to use? & do i use rb25 or rb30?

pipster11

25 i would say

blown7

also will the rb25det sump & oil pump fit straight onto the rb30???

pipster11

why not keep the 30 sump?

not sure about the oil pump tho, google to see what ppl do there

some have different crank collars and things

09ONE

Depends on what head gasket he uses. If using an RB30 one then no its fine as this will cover the hole but a RB25 head gasket will have the hole cut into it. Either way I would be welding the oil feed for the VCT up in the head.

For oil pumps you should be using a NEW RB26 pump at a mimimum with a properly machined crank collar as the RB30 Crank doesnt not extent into the pump drive far enough. Dont use a N1 pump they are fragile as fuck. Make sure you also enlarge the oil drain backs from the head and definately use oil restrictors 1.2mm in the feed to the head. Ceramic coating the piston crowns is a good idea because fitting oil squirters to the RB30 block is near on impossible due to casting irregularities.

blown7

yeah using an rb30 head gasket i guess. but i'm still going to block or weld the oil feed...
the crank already has a collar on it, new one unsure what sort tho kinda looks like a stock one so i'm guessing my rb25 oil pump will be fine to use on it?

09ONE

Yeah the RB25 oil pump will work fine, but RB26 pumps flow more oil at same PSI. The gear is like 4mm or so thicker (from memory) on an RB26 pump.

blown7

i'm guessing the rb30 stock head gasket will be fine to use right? or should i use something stronger/metal? (COMETIC 3layer metal one)

iamhappy46

http://www.nzgaskets.co.nz/pages/Performance.aspx

blown7

i've just noticed on the rb25det there are an extra line from the head running to the block. what could these be used for? & what do i do with it as the rb30 block doesn't have a tapped hole on the block to fit it...

here's a pic of the rb25det block with the line>>




& here's the rb30 block that doesn't have a tapped hole to fit the line>>

blown7

also i'm not keeping the VCT, i'm guessing all i have to do is block the oil feed off in the head & thats it? anything else i have to do?
it wont stuff the head or anything blocking the VCT off will it???

09ONE

Thats pretty much it, Its a mechanical setup so with no oil feed there is no retarding of the inlet cam.

The oil feed for the VCT is purely to activate the VCT as its a hydraulic setup. There is no lubrication etc provided by the oil initating the VCT.