Jump to content
SAU Community

Recommended Posts

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 by The Mafia
Link to comment
https://www.sau.com.au/forums/topic/189608-30l-forged-build-vs-standard-build/
Share on other sites

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.

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....

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*

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 ..

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.

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.

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. :worship:

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.

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 .

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.

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.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Surely somebody has one in VIC. Have you asked at any shops?  Is this the yearly inspection or did you get a canary?
    • This is where I share pain with you, @Duncan. The move to change so many cooling system pieces to plastic is a killer! Plastic end tanks and a few plastic hose flanges on my car's fail after so little time.  Curious about the need for a bigger rad, is that just for long sessions in the summer or because the car generally needs more cooling?
    • So, that is it! It is a pretty expensive process with the ATF costing 50-100 per 5 litres, and a mechanic will probably charge plenty because they don't want to do it. Still, considering how dirty my fluid was at 120,000klm I think it would be worth doing more like every 80,000 to keep the trans happy, they are very expensive to replace. The job is not that hard if you have the specialist tools so you can save a bit of money and do it yourself!
    • OK, onto filling. So I don't really have any pics, but will describe the process as best I can. The USDM workshop manual also covers it from TM-285 onwards. First, make sure the drain plug (17mm) is snug. Not too tight yet because it is coming off again. Note it does have a copper washer that you could replace or anneal (heat up with a blow torch) to seal nicely. Remove the fill plug, which has an inhex (I think it was 6mm but didn't check). Then, screw in the fill fitting, making sure it has a suitable o-ring (mine came without but I think it is meant to be supplied). It is important that you only screw it in hand tight. I didn't get a good pic of it, but the fill plug leads to a tube about 70mm long inside the transmission. This sets the factory level for fluid in the trans (above the join line for the pan!) and will take about 3l to fill. You then need to connect your fluid pump to the fitting via a hose, and pump in whatever amount of fluid you removed (maybe 3 litres, in my case 7 litres). If you put in more than 3l, it will spill out when you remove the fitting, so do quickly and with a drain pan underneath. Once you have pumped in the required amount of clean ATF, you start the engine and run it for 3 minutes to let the fluid circulate. Don't run it longer and if possible check the fluid temp is under 40oC (Ecutek shows Auto Trans Fluid temp now, or you could use an infrared temp gun on the bottom of the pan). The manual stresses the bit about fluid temperature because it expands when hot an might result in an underfil. So from here, the factory manual says to do the "spill and fill" again, and I did. That is, put an oil pan under the drain plug and undo it with a 17mm spanner, then watch your expensive fluid fall back out again, you should get about 3 litres.  Then, put the drain plug back in, pump 3 litres back in through the fill plug with the fitting and pump, disconnect the fill fitting and replace the fill plug, start the car and run for another 3 minutes (making sure the temp is still under 40oC). The manual then asks for a 3rd "spill and fill" just like above. I also did that and so had put 13l in by now.  This time they want you to keep the engine running and run the transmission through R and D (I hope the wheels are still off the ground!) for a while, and allow the trans temp to get to 40oC, then engine off. Finally, back under the car and undo the fill plug to let the overfill drain out; it will stop running when fluid is at the top of the levelling tube. According to the factory, that is job done! Post that, I reconnected the fill fitting and pumped in an extra 0.5l. AMS says 1.5l overfill is safe, but I started with less to see how it goes, I will add another 1.0 litres later if I'm still not happy with the hot shifts.
    • OK, so regardless of whether you did Step 1 - Spill Step 2 - Trans pan removal Step 3 - TCM removal we are on to the clean and refill. First, have a good look at the oil pan. While you might see dirty oil and some carbony build up (I did), what you don't want to see is any metal particles on the magnets, or sparkles in the oil (thankfully not). Give it all a good clean, particularly the magnets, and put the new gasket on if you have one (or, just cross your fingers) Replacement of the Valve body (if you removed it) is the "reverse of assembly". Thread the electrical socket back up through the trans case, hold the valve body up and put in the bolts you removed, with the correct lengths in the correct locations Torque for the bolts in 8Nm only so I hope you have that torque wrench handy (it feels really loose). Plug the output speed sensor back in and clip the wiring into the 2 clips, replace the spring clip on the TCM socket and plug it back into the car loom. For the pan, the workshop manual states the following order: Again, the torque is 8Nm only.
×
×
  • Create New...