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i am gonna have to rebuild my bottom end wen i got the gts-4 it was all good now i have blow by and loosing oil preasure some one put a new head on the old block and the standard old ring couldnt handle the new spec and its ratshit now. so if i have to rebuild the block i think i am gonna go rb30 with my standard head as they should all match up i am told if i am gonna spend money i think i am gonna go all the way do it once and do it proply!!!!!!!!!!

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I was under the impression you cant use the RB20 DET head on an RB30???

Considering my bottom end looks like its stuffed but the head and manifolds have so much work done it would be handy to just swap the head over onto the RB30 with the adapter awd plate.

Though that would increase the height of the motor which currently hits the hood air duct anyway ;-(

Ita a dilema as I have RB20 and RB30 NA Blocks in the shed.

The RB20's bore is considerably smaller than the RB25 / 26 / 30. Therefore the combustion chamber is considerably smaller (in both capacity and diameter). So the risk is that the pistons will be smashing into the rim of the combustion chamber every time they come up to TDC. And the compression ratio will probably become way to much for a turbo system.

Added to that, there are some alignment problems between oil galleries in the RB20 head and the RB30 block.

Just about every RB30DET uses a RB25DE(T) head - I am aware of only 1 successful RB20DET head transplant onto a RB30 block.

agreed... most RB30 builds these days are done using the Series 1 N/A RB25DE head, it also helps that this is a cheap and common part.

Good to see the number of GTS4's on the rise :P

The RB20's bore is considerably smaller than the RB25 / 26 / 30. Therefore the combustion chamber is considerably smaller (in both capacity and diameter). So the risk is that the pistons will be smashing into the rim of the combustion chamber every time they come up to TDC. And the compression ratio will probably become way to much for a turbo system.

Added to that, there are some alignment problems between oil galleries in the RB20 head and the RB30 block.

Just about every RB30DET uses a RB25DE(T) head - I am aware of only 1 successful RB20DET head transplant onto a RB30 block.

Have a search for the DIY RB26/30 link for some good advice on this subject.

gts-4me - I would seriously sit down and put numbers to this plan of yours.

You haven't said what mods you have so I am going to assume you have the standard mods of, exhaust, filter, boost controller and fmic...

I'll give you some rough numbers on doing it on the cheap and doing it yourself.

my plan was to do a budget rb30det build for my gts4 and get about 280-300rwkw.

here is a small but crucial list.

$100 = rb30 bottom end

$750 = rb25de head from r32

$300 = valve springs from rb25det (used)

$250 = VRS Gasket kit

$300 = New bearings and new rings

$200 = New timing belt and pulley

$150 = New water pump

$300 = AFM (Z32 or Q45)

$300 = Fuel Pump

$600 = Decent clutch to handle the new torque

$300 = GTR injectors (6 x 444cc should be enough for the 280-300rwkw)

$1900 = GT30 (500hp internally gated turbo)

$450 = 4wd sump adapter

$500 = mods to the above sump adapter (not something you can really do yourself)

$1300 = R32 power fc

$500 = Tune

Now this is assuming you can do it all/most yourself.

as in, you have an engine stand, you have all the right tools and space to do it all.

if you don't and need someone to put all these things together, modify the engine mounts so the motor sits lower, bolt it all together, put it in car ... add another $1000 at least.

now, if you go easy on your stock GTS4 gearbox, it'll last for a while.

you break it??? buy a gtr one for about $1000, plus who knows what dollars for mods to fit it to standard diffs and shafts.

so lets see, what this new rb30det gts4 on the cheap costs.

$8200 = parts.

$1000 = someone putting it together and putting it in car

$1000 = gtr box

your other options..

build rb23 or 24 - probably a little cheaper than above as you use your bottom end and therefore don't need the 4wd adapter stuff. still... over $5K on parts and machining.

rb25 from stagea (4wd block) = engine alone is worth about $3500

putting it in, making it work, blah blah = $5K

rb26dett = $5K on average for the engine and you don't even know it's condition..

expensive cars to modify these things.. well at least to get good power out of..

i wouldnt suggest bolting a rb20 head straight onto a rb30 bottom end

i know a guy that did it.. using a old r31 skyline with its stock rb30 and auto.. simply bolted the rb20 head on ran all the rb20 stuff.. comp ratio worked out to be somewat around 11:1 which is well way to bloody high for a turbo motor and well.. it did pull a good skid.. full boost very very very early(stock rb20 turbo) and a couple months later it went bang not sure wat broke but yer it was sold to some young bloke before it died and died abou 2 months after the bloke bought it

you would be better off sourcing a rb25de head and doin everything gtst has said in above post

where do i get another rb20 for 600 bucks i just bought the rb30 and was gonna do the goods but i dont want to spend that dosh as my engine is lossing oil presure and has a wine at 1200 rpm and sounds like its coming from the 1st cam bearing (help)

where do i get another rb20 for 600 bucks i just bought the rb30 and was gonna do the goods but i dont want to spend that dosh as my engine is lossing oil presure and has a wine at 1200 rpm and sounds like its coming from the 1st cam bearing (help)

It looks as if the GTR head in the gts4 is the way to go.

No issues with clearance and having to work out how to lower the motor.

If you can pick up a gtr head, inlet manifold, exh manifold with a set of stock turbo's it could be an easy and quick way to 250rwkw.

It also leaves open the option of picking up a set of well priced s/h 2530's and bolting them on, a little more fuel pressure and push those injectors. :cool:

The piston oil squirters.. ignore that, there are no issues. VLT's have been around for years and do not have problems, mine and many other rb30det's don't have problems either.

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