First Time Engine Build. Rb25/30 Neo Advice

[iruvyouskyrine]

Hi all.

Let me preface this by saying that this is my first time doing anything like this. I have never done any work on an engine before and i am looking to make this a learning experience just as much as i want it to be a decent engine. I a very mechanically minded and am more than willing to give anything a shot. I always do hours and hours of reading making sure that i know pretty much as uch as possible before actually diving in and doing anything. I have spent probably 30 hours reading up on RB30 conversions and now i think that it is time to ask for some input from you guys as i still have some unanswered questions.

For the build i will be using my RB25DET NEO head, 6boost highmount, X-spurt 100cc inj, Hypergear SS2, 44mm ext gate, E85 and the NIStune will be running the show. I will also be using a MLS standard 1.3mm headgasket and ARP head studs on either engine no matter what.

The situation thus far. I have in my possession a known good running RB30 with 180xxx on the clock. I also have an RB30 that had a bottom end knock when it was removed with 170xxx km.

Originally my plan was to tear down the known good block and get it cleaned (i presume this is what acid dipping does) and i would clean the rods/pistons up myself at home. I would then reassemble everything using cleaned stock parts, except for ARP main studs, head studs and rod bolts, and i would use a fresh set of ACL main and big end bearings. I wanted to tear it down to satisfy my information for knowing how things work and wanting to know how to disassemble/reassemble and engine just as much as for engine longevity. I was also going to shim the oil pump as per Simon-S14's RB30.

Now after doing my research and seeing so many other guys running unopened bottom ends i am thinking i should just shim the oil pump, leave the bottom end completely unopened/untouched and put my 25 head on and see how it go, and when money permits tear down the old block and put the bearings and bolts in it and have a spare engine sitting hear waiting for the worst to happen. Any advice will be taken on board and is very much appreciated.

Other questions i have (and yes i have read the RB30 DOHC PDF, and read almost every topic in the RB30 subsection)

• I know it is a bit of a science but can anyone give me a timing belt part number for a Neo head, standard thickness headgasket (1.3mm i believe) and the tensioner tapped as per the PDF?
  
• What size oil restrictors should i use for my Neo head, Superben has recommended blocking one single feed off and leaving the standard 2mm restrictor in place?
  
• Is it worth running the -10AN breather (not drain before i get flamed) line from the head into the sump as an extra precaution, i want to use the standard NEO PCV arrangement and don't really want to run a catch can but i certainly will if i have to.
  

There will more than likely be other questions along the way, but i think those are enough for the moment.

Any advice will be greatly appreciated and taken on board, as i said i like to make sure i am full bottle on things beofre just diving head first into them (if you don't count never having done any work on engine internals and wanting to tear one down and rebuild it haha ) If people like Superben, Simon-S14, Shooter, GTRPSI, r33_racer, Duncan, KiwiRS4T, luke_gtr etc can give feedback that would be excellent.

TL:DR give a noob advice on his first engine build and he will be eternally greatful.

[GOD12A]

Heya SKYRINE

If you're stripping the bottom end, I suggest a hone and some piston rings. No need to bore if they are within spec.

Same as decking the block and head. Unless they're out of spec, just clean them up.

Marking everything as it's removed is also good practice if you're reusing them, so pistons, rods, caps etc etc

Texta won't do. I usually pull bits out one by one and add a little tap with a centre punch or number stamp.

If you're going to get the block chemically cleaned, give the workshop a box of all other bits like stripped oil pump, pistons, rods etc etc Let the chemicals do the hard work for ya

While your sump is off, throw a breather/vent on both sides as high up as possible. I usually vent these to the cam cover breathers on RB26s and block the PCV.

I then fabricate my own oil/air separator which vents clean air just before the compressor on the rear turbo (or between air filter and turbo on single setups). This is also ADR compliant as it's closed loop.

My biggest advice is learn how to measure properly. Having $2k worth of measuring tools is useless if you can't use them properly. And I don't mean hold them right, I mean, repeat results within one increment of measurement consistently. Whether it be 0.01mm for a digital caliper or 0.001mm for a micrometer.

IMO, engine building is ALL about measuring.

I've always been taught 'bad data is worse than no data' , meaning, if you measure something wrong and rely on that measurement, you're gonna have a bad day; safer to not have an incorrect measurement to incorrectly rely on.

My background is in toolmaking, CNC machining, metrology and quality assurance for the military, mining and high voltage power transfer sectors. I'm also a qualified mechanic and hold a motor vehicle repairers licence.

Sorry for the long email, got on a roll while having a drink

Goodluck!

Mark

[iruvyouskyrine]

Hi Mark, this is exactly the sort of advice that i am after! I have currently taken the head off the RB30 and am having trouble removing the crank sprocket. I am doing exactly like you suggested and keeping everything laid out as i take it off and marking everything and making sure it all goes back together the correct way. After reading about engine builds it seems that there is only 3 key things to keep in mind, clearances, weighting of components and following correct torque specs. I have a digital vernier and a torque wrench, so they should be enough to get me through i think.

The worst part about this all is having never seen any of these components, knowing if something is rooted/good is hard, but i think common sense and the aid of the internet should get me through. What should i look for when i inspect the crank? Not sure how to tell if its in/out of specs.

I was planning on cleaning the pistons/rods myself but just palming them off to a machine shop to do it for me, elbow grease would be no match for the chemicals they would use.

Where do you suggest i get rings for the standard RB30E pistons? Also i measured my bores and they were all 86 +/- .01mm and they look fine so i don't think a hone is really necessary, unless its good insurance?

Thanks for taking the time to respond mate, appreciated

[GOD12A]

Hey SKYRINE

The crank sprocket can be a biatch. Clean the crank nose 100% and make sure they're no burrs on the keyway so you don't damage the sprocket or crank. hit it with WD40 and lever it off square (apply pressure at 0deg then 180 then 90 then 270, repeat process till it pops off. Getting it started is the hard bit.

Balancing the rotating assembly is suggested if you want to make power. I've never built an unbalanced engine. if you're putting the same parts back in the same position they came from, it'll be OK (well it lasted 180k kms already!). If you want to make power, get the whole rotating assembly balanced. OE RB26 spec is +/- 1g per piston and +/- 1g per rod, so each set can be out by up to 2g. When balanced as a rotating assembly, they will get each set within 0.5g easily then they'll dynamically balance the crank with flywheel/pressure plate/balancer so it's dead on neutral.

Do a google image search for crank good/bad pics. It's common sense if you're mechanically competent, so it sounds like you'll be right.

If you're paying to get the block cleaned, give them the extra few bucks to do the whole lot, you'll thank yourself for it

I suggest a hone, even if the bores are on size, you want to bed-in new rings on a fresh bore. They'll seal better after a decent run-in and will have less drag (friction) in the long run. on that note, I prefer to run engines in hard as I'm confident my clearances are dead on. My last engine was assembled fresh then driven 15min to the dyno for 35+ power runs.

Ask the engine workshop to supply rings for you, they usually get them cheaper than you'll find elsewhere. Should be under $150 for a set of moly rings.

They can probably get good prices on bearings too.

If you're not confident stripping the engine, go nuts with a digital camera, taking note of how everything fits and locates as you strip it

One tool I've used for 20yrs and couldn't live without when building an engine is a good oil stone. Basically a sharpening stone with two grits on it for getting things dead flat and removing burrs etc

Not sure if it's just a tool every engine builder uses, but I couldn't build a motor without one.

Mark

[Ben C34]

Hi,

The timing belt is the same wether neo head or not. I can't remember the part number at the moment.

The oil restrictors in the rb30 block are 2mm and 2 of them, in the neo they are 1.5 and 2 of them.

Calculating the surface area of a 2mm diameter is 3.14mm2

a 1.5 diameter is 1.76, and there is 2 so neo has 3.5mm2 of oil feed.

Blocking off one in the rb30 block means approx 10% less flow than on a stock neo to the head.

As my car is a daily, and only going to the drags and sometimes hillclimbs, I didnt see the need to reduce it more than this. (slso just blocking off a gallery is the easy option.)

You could look at what restrictors guys run on rb26 or other neos and decide if you want to go smaller.

I had the vct gallery welde up, some people plug it with a screw, but I wanted to ensure no chance of leaks. At the same time I got a section welded onto where I drilled and tapped for the external vct feed to provide more material to tap into.

Tee piece oil feed to vct from the pressure sensor, which is 1/8 bsp. Some pople have meentioned npt in the past which I garantee is wrong, they are very similar and screw together partially, but 1/8 BSP is what is used.

The spot specified to tap the block for the tensioner n the PDF is not correct and means the belt would be super tight (might be why guys use two tensioners). I put the belt on, and held the tensioner in place at its loosest setting and spotted that onto the block, and then drilled and tapped it. Using two tensioners is odd to me, but does give you some ability to dial in the cams, but i would rather just get a vernier cam gear for the exhaust and the neo inlet vct gear is adjustable anyway, you will notice this when you have it off.

[Ben C34]

WTF,

formating got screwed... thats annoying

[KiwiRS4T]

Rings, bearings, rod bolts don't worry about studs should be ok. How much power do you want? 300kw is easy more you really want forged high comp pistons (crank and rods normally ok) and a balance and a new harmonic balancer. Oil control as per Mark's post.

[Ben C34]

With a neo head you dont need high comp pistons due to the smaller combustion chamber. If you used the high comp pistons for a non neo 2530 (which most are) you would end up with way too much comp.

Stock rb30 e pistons end up over 9:1 with the neo head as it has a smaller chamber than the rb30 (55 vs 50-53cc)

[iruvyouskyrine]

Hi, The timing belt is the same wether neo head or not. I can't remember the part number at the moment.

The oil restrictors in the rb30 block are 2mm and 2 of them, in the neo they are 1.5 and 2 of them. Calculating the surface area of a 2mm diameter is 3.14mm2 a 1.5 diameter is 1.76, and there is 2 so neo has 3.5mm2 of oil feed. Blocking off one in the rb30 block means approx 10% less flow than on a stock neo to the head. As my car is a daily, and only going to the drags and sometimes hillclimbs, I didnt see the need to reduce it more than this. (also just blocking off a gallery is the easy option.) You could look at what restrictors guys run on rb26 or other neos and decide if you want to go smaller.

I had the vct gallery welde up, some people plug it with a screw, but I wanted to ensure no chance of leaks. At the same time I got a section welded onto where I drilled and tapped for the external vct feed to provide more material to tap into. Tee piece oil feed to vct from the pressure sensor, which is 1/8 bsp. Some pople have meentioned npt in the past which I garantee is wrong, they are very similar and screw together partially, but 1/8 BSP is what is used.

The spot specified to tap the block for the tensioner in the PDF is not correct and means the belt would be super tight (might be why guys use two tensioners). I put the belt on, and held the tensioner in place at its loosest setting and spotted that onto the block, and then drilled and tapped it. Using two tensioners is odd to me, but does give you some ability to dial in the cams, but i would rather just get a vernier cam gear for the exhaust and the neo inlet vct gear is adjustable anyway, you will notice this when you have it off.

Reposting for readability haha.

[iruvyouskyrine]

Just getting around to starting on the block now. Is it beneficial to be cleaning the carbon build up on the top of the piston. I am using steel wool/scotchbrite and very light pressure on a small flat blade to try and scrape it off. Is it worth trying to clean it off as it just wants to fall down in the gap between the piston and the cylinder.

I am using a vacuum cleaner and sucking it up regularly trying to stop if from getting in the gap but there is always some getting in there. Will this have any detrimental effects or just get burnt up and sent through the exhaust?

[Ben C34]

I cleaned mine, on an engine stand, and spun it upside down so the shit just falls on the floor.

[Ben C34]

Another little bit of advice,

I know the pdf says you need to grind away the block to clear the exhaust manifold, but cos im lazy I decided to cut 5mm or so off the exhaust manifold flange.

That way you don't need to cover the engine bores to protect from grinding, and if I need to use another block later on, my head and manifold will just go straight on.

[GTRPSI]

I just tape over the deck, then grind away.

Either way is fine though, id rather the grinding done to the block so any manifold changes dont require the new manifold to be worked on again.

[Simon-S14]

im a bit late to the party but my advice would be to leave the known good condition bottom end alone and just do the following.

-block rear feed, fit 1.5 mm to the front, plumb up external VCT feed

-increase the oil pressure using 2xm6 washers on the pressure relief spring, reseal the sump

- clean the deck and get the head skimmed, dont weld the vct fitting, just grub screw and loktite it.

-ARP studs and mls gasket

-bolt it all together, do the two timing tensioner method.

[iruvyouskyrine]

Thanks for the input guys. I finished cleaning the piston crowns before and i went over the block multiple times with a razor blade to try and get a good seal for the MLS head gasket.

Simon you just summed up everything i was going to do in a single post. The only difference is i was going to use a 1.2mm oil restrictor, is this too much? Am i better running the 1.5mm?

Today i will be ordering the following items, unless anyone suggests otherwise.

- Cometic RB25DET MLS head gasket

- ARP RB25 head studs

- Gates RB30DET timing belt

- Standard NEO water pump

The only thing i am slightly unsure about is if the gates belt has the timing marks on it, will this be an issue if it doesn't? To assemble the engine i was just going to set the block to TDC and then do the same with the cams (which is just done by aligning them with the marks on the cam gear backing plate yes?) and sit the head on top and bolt it all together.

Edited March 23, 2014 by iruvyouskyrine

[Simon-S14]

do you didn't strip down the block then? if so good factory nissan FTW, so many people pull perfectly good motors for a freshen up only to have it fail within 10K kms

a single 1.2mm will be a bit too small. the 1.5 single feed is find for solid lifters. works well in mine with 26 head and sees limiter and no oil issues.

dont need timing marks on belt. you will need two tensioners to time it properly tho. just line up TDC on crank, and line the cams up with their marks and then tension it up correctly ensuring the marks stay the same.

[Simon-S14]

oh and when putting head on block it doesnt hurt to put the block at TDC and then go back 20-30 degrees so that all cylns are below deck height, that way zero risk of contact with valves, then dial the cams to their spots then move crank back to TDC then time up

[iruvyouskyrine]

oh and when putting head on block it doesnt hurt to put the block at TDC and then go back 20-30 degrees so that all cylns are below deck height, that way zero risk of contact with valves, then dial the cams to their spots then move crank back to TDC then time up

So as long as the cams line up with the TDC marking on the cover and the crank sprocket lines up with the marking on the oil pump then it should be all sweet. And yeah taking the pistons back to below deck height is a good idea, cheers.

The grub screw that you block the head with, is it the same blank that you use for blocking the internal VCT oil feed? They look to be about the same size as seen in pictures here

http://www.skylinesaustralia.com/forums/topic/389937-so-i-pulled-my-rb25-neo-down-over-the-weekend/

EDIT: Just realised that the restrictors are just plugs and not actual screws, so the head just needs to be tapped and a 6mm grub screw put in. PS i really am just winging it haha, having never taken an engine apart its hard to try and visualise what everything looks like and how it all works when you have never seen it!

Edited March 23, 2014 by iruvyouskyrine

[Simon-S14]

yeah restrictors are plug inserts, you knock the stock ones down with a punch.

head needs to be tapped and screwed. easy to do. do this then clean the head and get it skimmed and then clean again.

[iruvyouskyrine]

What are people's thoughts on my running a GT30 with a .82 rear on the 30 block. Have only really seen cubes (i think that was his name) results with a GT30 frame turbo and not many others. Most people tend to go GT35 or larger, and the VL turbo boys go even more massive.

Some food for thought, will be on a 6BOOST mani with 45mm Turbosmart gate to atmo, 3" straight through exhaust runing on E85 and want to limit RPM to about 7000

I should be getting some pretty decent area under the curve, but just worried about the possibility of the turbo choking the engine at higher RPM.

Edited April 27, 2014 by iruvyouskyrine