RB26 REbuild Options

[BOOSTD]

1.Go for a 3ltr.... I'm figuring will cost alot more due to the need for a 4WD sump adapter, exhuast mods (3cm higher), etc

or

2. Rebuild the RB26 block.

I am not keen at all on the forged cold piston knock. What pistons are available that would be nice and quite(expand less) and still stronger than the stock pistons? I have heard there are Semi forged and low silicon content forged pistons available. Has anyone had good experiences from certain manufacturers?(CP, etc)

Also what is the maximun width the bore can be honed to. Would it be worth going big for that little bit more capacity?

cheers MAtt

[fatz]

piston slap only exists if your machinist is crap

thats all you need to know

cost about 5K if you do most of the work yourself and go total strength

[Bl4cK32]

Piston slap, as said above by fatz, is only really noticeable if the machinist doesnt know what he/she is doing....

Joel and myself went for twice over std. bore (40 thou) and use Wiseco forgies...they do a great job, and i have trouble hearing any slap, but Joel reckons he can hear it a tiny amount.

Oh yer, one of the guys in the rb30 thread makes a 4wd sump adaptor, and the exhaust doesnt need modding all the time. Joels exhaust bolted straight up.

[BOOSTD]

Fatz: I pulled the motor down yesturday to reveal slight damage to number 6 bore negating the option of standard size pistons. The engine has HKS2530's so will only need to be sfe to 350rwkw(safe side)

Bl4ck32: The sump adapter is quite expensive I think ;( and the Rb30's don't like to rev as much..

I have read that pistons requiring .015-.025 clearance will be noisey... I have found some Arias ($1160 with Rings, pins, etc) and they recommend .030... the salesman at Rocket couldn't assure me they wouldn't be noisey.. Am I able to close they gap alittle without any issues. Has anyone used arias Before?

[Sydneykid]

Agree with the other guys, piston slap is all about machining tolerance and selecting a forged piston with a silicone content the suites your application. Read through the piston manufacturers specs, they have suggested piston to bore clearances for each alloy composition.

The question to RB31 or RB26 is a bit tougher. It usually boils down to how much power you want to make, what you want to use the car for and how much money you want to spend. There is no doubt that you can sell your unused RB26 bottom end for far more than the 4wd sump adaptor will cost. So I wouldn't let that influence the decision.

So ......

1. How much power you want to make?

2. What you want to use the car for?

3. How much money do you want to spend?

Keep in mind if you want say 800 bhp for drags, then an RB26 is going to cost a lot more as it will need much higher rpm to make that power, compared to the RB31. This means including the cost of a close ratio gearbox and lower diff ratios (both of them) whic the RB31 may not need.

[Bl4cK32]

and rb31's can rev...it just needs a set of cams to have a 7500 rpm safe rev limit

[fatz]

yea ill be going to rb31 option next when my engine blows (its done 5k so far) and runs like a dream

i used dominator engineering and he recomended the arias pistons cause out of all the pistons he has mesured and weighed they are the most consistant.. he also didnt recomend venolia's??? which was interesting

if your only looking for 350rwkw i say rods pistons 40thou and ne w big ends (3k)

900 for a full port rub and tug for the head

500 gasket kit

oil water pump 500(nissan horsby)(never had a drama witha nissan headgasket) but hey

put it together

run it in then wind the boost up to 20psi

maybe some cams

or maybe go rb31 for 6-7k rebuild and run some deriouse power (you might need bigger turbos hksgtrs)

[BOOSTD]

Agree with the other guys, piston slap is all about machining tolerance and selecting a forged piston with a silicone content the suites your application.  Read through the piston manufacturers specs, they have suggested piston to bore clearances for each alloy composition.

The question to RB31 or RB26 is a bit tougher.  It usually boils down to how much power you want to make, what you want to use the car for and how much money you want to spend.  There is no doubt that you can sell your unused RB26 bottom end for far more than the 4wd sump adaptor will cost.  So I wouldn't let that influence the decision.

So ......

1. How much power you want to make?

2. What you want to use the car for?

3. How much money do you want to spend?  

Keep in mind if you want say 800 bhp for drags, then an RB26 is going to cost a lot more as it will need much higher rpm to make that power, compared to the RB31. This means including the cost of a close ratio gearbox and lower diff ratios (both of them) whic the RB31 may not need.

hey sk

1. Power wise I won't be upgrading the turbo's from the HKS GT2530's so i guess there max flow will be my max potential.

2. I want the car for mainly street and a few strip runs.

3. I want to spend as little as I can for a reliable quiet engine.

cheers matt

[TTT]

yeh I think that the cost of the 4wd sump for the rb30 bottom end was $450 ish..

that's heaps less than what you will get from the sale of the stock rb26 bottom end don't you think?

as for your points above..

street - what could be better than massive torque for street driving?

stip - again.. torque wins races.

cheap - a touch RB30 bottom end will probably cost similar to an RB26 bottom build but be capable of more power at same boost levels.

since you have a perfectly working head.

I can't see the cost being too much.

rough numbers.

pistons = $1200

rods = $1200 (I think that was a price thrown around in the rb30 thread)

VRS gasket kit was $300 I think.

machining for the block = ??? $500 ???

am I way off?

[BOOSTD]

GtST : looks correct as far as I know... would I need rods tho. I won't be over 500hp

[TTT]

*shrugs*

I was just looking at a tough build.

and assumed you'd want to.

personally, when I do my one, I'll be using rb30 bottom end with stock pistons and rods, stock nissan gaskets, stock RB25de head.

using some decent sized turbo, intercooler, oil cooler, ecu, I am looking at 250rwkw+ and that is my goal.

and I have been told many a times that the above combo will do it.

see mine is all cheap options..

But you already have a RB26dett head with decent turbo's on there.

I assumed you'd spend an extra $1200 odd for peace of mind.

Is it required??? I don't know..

gary would be better off answering that.

[BOOSTD]

Ok so how do I find a good machinist ? Do the crap ones machine the wrong clearances...or do the good ones know they can go tighter without problems??