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hi guys, i'm building my 26/30 mainly for street use.

is it nessecsary to use a 1.5mm oil restrictor? tomei or other.

the standard one is 2mm. i think?

I'm under the impression that they're only needed for high rpm engines.(race/track use)

thanks simon

depends what pump your using. I would put the 1.5mm in anyway. It wont hurt anything. Plus if on the odd occassion you do do a track day or goto drags or rip a skid somewhere you wont get as much oil getting trapped in the head as you would if you didnt which could become messy.

For about an extra 1K to get the N1 pump, have the crank machined for a pump collar and get some restrictors, its cheap insurance for the big $$$ motor. Thats the way i've gone with my 25/30.

The jun collars were on special on Nengun and might still be. The restrictors you can get from hioctaneracing.com.au and there's some cheap N1 pumps to be had on the forum here.

depends what pump your using. I would put the 1.5mm in anyway. It wont hurt anything. Plus if on the odd occassion you do do a track day or goto drags or rip a skid somewhere you wont get as much oil getting trapped in the head as you would if you didnt which could become messy.

yep, no point having a big $ motor setup if ur oiling isnt up to task

For about an extra 1K to get the N1 pump, have the crank machined for a pump collar and get some restrictors, its cheap insurance for the big $$$ motor. Thats the way i've gone with my 25/30.

The jun collars were on special on Nengun and might still be. The restrictors you can get from hioctaneracing.com.au and there's some cheap N1 pumps to be had on the forum here.

well then saying that, why not spend the extra ~300 and get a JUN pump? or even do the job 'properly' and go for an external pump setup

The JUN are a little more than $300 more... almost double in price arent they?
and to run a jun pump, you will still need a collar

I said the 300 caus he said he was spending $1k on it already, and the juns are about ~$1300.

I dunno about all of this oil pump business. If your building a fresh, forged donk, u should factor into the build price a GOOD quality pump (JUN etc) caus there's been far too many N1's break for my liking. Caus hell, if ur doing a build, of course ur going to be giving it some harsh treatment.

Cheapest N1's Ive found were $420ish. The collar is about $250-270 delivered, and machining the crank for the collar is about $120. Thats what I meant by about $1k.

Yeah the jun pump would be ideal if your building an engine for track, but then you really don't hold back on the spending then too.

N1's seem to be a proven system that works reliably for the street and ocasional track use. What had you heard about N1's breaking? Was it because they were being installed without a collar, or was it something else.

  • 3 months later...

Sorry to revive from the dead but this is relevant to my current build.

I know initially this thread was designed for 26/30 conversions however it seems to be leaning more towards the 25/30 conversion.

I am in the process of buying a RIPPS RB30 bottom and I just want to confirm what I believe I have read in the thread.

The RIPPS RB30 comes with a custom sump extension as well as 4wd adapter, so I wouldnt have any issues with that. It also comes with forged pistons and rods.

So the only modifications I would need to do would be:

Re-Tap for RB26 head studs as they are larger

Redrill the lower bell housing bolts

and possibly extend lower cam cover? (not 100% sure what you mean)

I do have a few questions as I dont know if they pertain just to the 25/30 or also to the 26/30.

Do RB26 Nismo Motor mounts work on the RB30? Or do you need RB30 specific motor mounts?

Do I need to worry about the oil squirters with forged pistons and rods?

Also how about the oil and water pickup lines. Do I have to redrill holes in order to use the RB26 head?

It seems to be a pretty straightforward thing to do the 26/30 conversion in a GTR, however I want to make sure I have all my ducks in a row for when my motor gets here.

Thanks a lot guys.

-Sayajin

If RIPS is doing the bottom end, let him be your guide. He has the experience and also if anything goes wrong you both start from a known point.

He can make all the lines etc for you if you ask him, and will most likely tap the block for the 12mm head studs before he puts the bottom end together. He will also be able to redrill the correct bell housing holes etc for you. In fact, if he is doing the bottom end I'd get him to provide as much 'plug and play'stuff as you can afford. RIPS can pretty much make anything you need as he has jigs/half cuts etc for a whole bunch of combinations, it's not cheap but his fabrication is A1 and he knows what works. Removes the potential for 'head scratching'.

The oil and water lines don't need redrilling but you'll need to account for the 38mm higher deck. Again, RIPS can make the stuff up and knows what you needed.

I don't work for him and haven't met him but have some stuff he made for me and I'm happy.

Cheers

Edited by Scooby
  • 1 month later...

i thought i'd add to this thread that with my carbon fibre bonnet, it fouled on the front of the motor. Cant drop the engine down either caus there's only ~10mm clearance between the cross member and the axles.

Collers are $160 from proengines

He still does them?

Nengun they are around $180 delivered but currently out of stock.

---

i thought i'd add to this thread that with my carbon fibre bonnet, it fouled on the front of the motor. Cant drop the engine down either caus there's only ~10mm clearance between the cross member and the axles.

With the stock bonnet the top cam belt cover fouls the bonnet support beams. Both GTR and GTS4.

Some one did mention that the cefiro rwd cross members mount/position the motor lower. Quite possible its the same for the cefiro 4wd crossmembers. Chances of finding a 4wd cefiro cross member is pretty slim, and even then it may not bolt up.

He still does them?

Nengun they are around $180 delivered but currently out of stock.

---

With the stock bonnet the top cam belt cover fouls the bonnet support beams. Both GTR and GTS4.

Some one did mention that the cefiro rwd cross members mount/position the motor lower. Quite possible its the same for the cefiro 4wd crossmembers. Chances of finding a 4wd cefiro cross member is pretty slim, and even then it may not bolt up.

bummer, hadnt gotten around to trying a std gtr bonnet. now i definately have to give noy a visit at custom carbon :O

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