3.0l - Forged Build Vs Standard Build

[The Mafia]

I have a few questions everyone.

I have 2 x 3.0l 250,000km blocks (Both NA) (with cranks, rods, pistons sump etc)

I'm confused. I want to build one with some nice specs (Forged pistons and spool rods) but I've heard a lot lately about how the Standard RB30 internals can handle quite a bit of power. (350rwkw).

I have two options:

Option 1: Standard Rebuild

Deck Block & acid dip

Get Standard pistons cleaned, and new rings

Prep the RB30 standard Rods

Nissan OEM big end and main bearings

clean up the oil feeds and returns

Set the compression to 8.5+:1 (I'd like closer to 9:1)

Give her a hone if the bore is straight

GTR N1 Oil pump

RB25 Harmonic Balancer

Rotating mass balanced

Slap it together properly

Option 2: Forged Build (About $1800 more)

Deck Block & acid dip

Forged Pistons (and whatever rings are needed)

Spool rods

King Bearings

clean up the oil feeds and returns

Set the compression to 8.5+:1 (I'd like closer to 9:1)

Rebore 20thou more

GTR N1 Oil pump

RB25 Harmonic Balancer

Rotating mass balanced

Slap it together properly

Then drop on my prepped RB25 head on:

Ported intake and Exhaust (Exhaust will be polished)

VCT welded and external feed

Cube's mates cams

Greddy Copy Intake

Decked

Extrusion Honed Exhaust Manifold

GT3076 + 0.82IW rear at about 20psi - 22psi.

Here are the main questions:

1. Forged Internals are lighter. I've read that 6 spool rods weigh the same as 5 x standard rods. Same with the forged pistons. How much of a benifit is this? Does this mainly allow quicker revs?

2. Standard Pistons. How much boost would I be able to run safely? Is this a limit? Are they as weak as the RB25 detonation wise?

3. Power Wise I won't need anymore than 320rwkw in the long run. Will the standard engine hold this ok without being on the limit like the RB25?

The RB25 is a tough little engine. I compression tested mine a few weeks ago - copression still in the mid 160s all within 2psi - 3psi of each other. I want to take this engine out and sell it though to cover some of the cost of the build so no point it wringing its neck when its still in mint condition.

Any thoughts or input would be appreciated.

Edited October 17, 2007 by The Mafia

[TTT]

I'd suggest that if you are going to go in to the effort of taking out the stock stuff to prep and clean and so forth, then just do the forged goodies.

also, I don't see how you are planning on using stock pistons to get a 8.5-9.0 comp ratio.

You will get about 8.3:1 unless you shave a bit off the block and possibly head, then you get in to all that quench zone bullshit which I don't understand.

The guy on here (can't remember his name) sells the pistons and rods as a pack for a 9.0:1 comp ratio and they slot right in.

The only time I think the standard stuff should be considered is like a few people here have done.

STOCK bottom end, UN TOUCHED, bolted to head, UNTOUCHED.

Essentially, a BUDGET RB30.

if it pops, you put another $100 jobbie in there.

considering you have a fancy head on yours, I wouldn't risk the chance of a meeting between the CEO of the pistons, team leader of the rods and Managing Director of the valves.

[redevil]

yeah man, by the time you get the stocko components up to scratch you won't be far off forged cost... i have a forged being built at the moment didnt even consider using stock components, especially if u've tricked out the head... Thats like putting a ferrari shell onto a vw body... sure it can be done and will work but wats the point....

[stolen_s15]

I woudl suggest that the small extra cost of forged bits will add up to great peace of mind in the long run. And unless you are can remove/refit an engine yourslef it will probably save you cash long term also.

If the 'cheap' rb30 pops you are looking at around 1k just to get a shop to remove and refit another stock bottom end.

Do it right the first time.

*Would love to know the final cost of it whatever you do, shoot me a pm*

[Adriano]

I just hope either way you dont forget the crank collar.

[wrxhoon]

You want 320 RWKW and you even think of using old pistons ??? Especialy ones that have 250k k's ?? Don't even think about them .. Besides a block that has 250k ks will have some lip and some bore wear so you will beed to bore and hone to the next oversize .

Go the forged and if you are not going to assemble it , make sure you find someone you can trust to do the job right the very first time ..

[SECURITY]

i'd like to know the limits of the standard engine too. rb30's are too cheap for me to care if they blow.

the power level im looking at getting is around the same as The Mafia's. its not alot and ive heard that the 30's can hold that much power on the std bottom ends well, but thats just what ive heard.

a std build will cost around $1500 compared to around $6-7k for a built motor, so if theyre reliable @ 300kw with a std build then why would i fork out the extra $4-4.5k if im not looking to pass the 300-320kw mark?

just thought i'd throw that up for discussion.

[The Mafia]

I'd suggest that if you are going to go in to the effort of taking out the stock stuff to prep and clean and so forth, then just do the forged goodies.

also, I don't see how you are planning on using stock pistons to get a 8.5-9.0 comp ratio.

You will get about 8.3:1 unless you shave a bit off the block and possibly head, then you get in to all that quench zone bullshit which I don't understand.

The guy on here (can't remember his name) sells the pistons and rods as a pack for a 9.0:1 comp ratio and they slot right in.

The only time I think the standard stuff should be considered is like a few people here have done.

STOCK bottom end, UN TOUCHED, bolted to head, UNTOUCHED.

Essentially, a BUDGET RB30.

if it pops, you put another $100 jobbie in there.

considering you have a fancy head on yours, I wouldn't risk the chance of a meeting between the CEO of the pistons, team leader of the rods and Managing Director of the valves.

I'm starting to agree with you. Its not much more to go forged and piece of mind.

yeah man, by the time you get the stocko components up to scratch you won't be far off forged cost... i have a forged being built at the moment didnt even consider using stock components, especially if u've tricked out the head... Thats like putting a ferrari shell onto a vw body... sure it can be done and will work but wats the point....

Agree;

I woudl suggest that the small extra cost of forged bits will add up to great peace of mind in the long run. And unless you are can remove/refit an engine yourslef it will probably save you cash long term also.

If the 'cheap' rb30 pops you are looking at around 1k just to get a shop to remove and refit another stock bottom end.

Do it right the first time.

*Would love to know the final cost of it whatever you do, shoot me a pm*

Will do. I'm not looking to spend a massive amount of dollars, so I am planning on doing the engine swap myself. I have access to lots of equipment that will make things easier. (Truck pits, crane, top of the rage tools etc) So I guess I'm lucky. Got some long weekends ahead of me though, lol.

I just hope either way you dont forget the crank collar.

Hey, thanks for this little bit of valuable advice. I forgot to ask this question. So I definately need one? I'm pretty sure this pump is a N1 oil pump. Maybe its just a standard GTR one? Either way, its better than the RB25 pump.

You want 320 RWKW and you even think of using old pistons ??? Especialy ones that have 250k k's ?? Don't even think about them .. Besides a block that has 250k ks will have some lip and some bore wear so you will beed to bore and hone to the next oversize .

Go the forged and if you are not going to assemble it , make sure you find someone you can trust to do the job right the very first time ..

There are plently of people here (including family) that I can get to help me set everything up properly. I know what you mean by finding people that you trust - they are hard to find these days. We have a engine builder in mackay here that is known for building some of the best engines in the district, and he's family so thats going to make things so much easier.

[Cubes]

Go forged and as Adriano said don't forget that crank collar.

You will soon be dropping a GT35 on it in chase of that 400rwkw. Especially as you already have a WMI setup it would be almost too easy.

Rods are cheap as these days; when I built mine up a ~3yrs and 70,000km's ago forged rods were up around $1800. The Spool rods didn't exist and aftermarket pistons weren't really available for the combo.

FYI I comp tested mine recently and its still got the same compression as it did after it was run in. Still the same cyl 3 is 1psi down; the rest all exactly the same. Bores still looked like new with no scuffing. I was expecting to see a little scuff up top as its running forged pistons and does slap ever so slightly when cold.

I had the head off to block off the rear oil restrictor and drop a 1.5mm restrictor up front. So make sure you do this also.

For 2k rods/bolts and pistons you really can't go wrong.

You'll most likely be looking at in total 4.5-5k for the motor build with forged rods/pistons. There's really no reason why it should be anymore; when pricing around for my build some were charging stupid amounts and were unable to tell me what they were doing 'extra' to justify the cost of the build.

Also why the N1 pump? They are not that crash hot, apparently brittle due to the hardened metal and cause an increased amount of oil floating around in the head which we really don't need. Std GTR pump is fine.

I and a mate who had our motors built at the same time; we got lucky we stumbled upon a true enthusiast that got it right the first time.

[discopotato03]

Mafia only you can know what sort of money your prepared to spend , the RB30 short being 20% larger will show up in the overall torque output for that reason . The thing is how much of this can you get to the tarmac before the rears go up in smoke ?

Your call but I'd be looking at an RB26 head and inlet system to plonk on the RB30 block with possibly std rods and good std pistons if possible . You wouldn't need to fix the 25 VCT issue and the solid bucket valve train has lots of advantages if your chasing real power . Exhaust stud pattern different though not too difficult to change .

Fair std RB30's can be freshened up reasonably cheaply so if you used up a few who cares ? Could even have a spare standying by .

Food for thought , cheers A .

[Guilt-Toy]

I have said it before and i will say it again.

DO NOT attempt a rb30det build in your r33 skyline UNLESS you have broken your rb25.

If you want more power then change the turbo and push the 25 then replace it when a 30 when it blows.

Its just not worth the hassle unless you have big bucks and want the big power.

& Using the "i will sell my rb25 to cover the costs" excuse is BS because they are only worth $300 - $400 second hand anyway.

I got 260rwkw outta my stock rb30 with stock rings bearings etc and all the rings were broken and it spun a bearing and all other bearings were nearly spinning as well.

Keep the 25, thrash it till it dies.

[r33_racer]

what if its what you want? regardless of anything else.

[Jmaac]

shot peen the stock rb30 rods should be ok

[Cubes]

Shotpeening the rods is a complete waste of time.

Factor in the cost of shotpeening + a set of rod bolts and you may as well buy the spool rods.

----

The rb30det in my own car as a daily driver has made toodling around so so much more enjoyable. Its not just all about the increased mid range but more so the low end when just cruising. The accelerator pedal feels hard and responds to throttle input much more than the rb25det.

I've even pulled tree stumps out with the R32 rb30. Did it easy as without having to rev and ride the clutch, also towed a a VN commodore for 50km's up big arsed hills etc. The motor loved it and towed it really really easy.

I've since driven rb26's etc and the torque comparison and enjoyability of cruising around keeping up with trafic just isn't there.

I know the GT35's on the rb30's don't feel as such but the GT30 makes the motor feel like a big arsed n/a that pulls strong from idle to 7000rpm.