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R33 Rb30 Conversion

JNR24

By JNR24,
in Engines & Forced Induction

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Duncan
Duncan

Just thought I would bump this 20 year old thread because the Skid Factory have just posted up a video summarising a lot of the content, format might be more familiar for newer members

JNR24
JNR24

fyi guys, Well yesturday i picked up a RB30 for my conversion into my R33. I will be using my RB25DET head on the RB30 block. So i started stripping the motor down, pulled the crank, pistons, girdle

Cubes
Cubes

Here is all I have at the moment: http://www.geocities.com/r32_jjc/ Unless you are on broad band make sure you right click then save as. The file is around 120kb. If there is anything I have got w

Posted Images

SirRacer Experienced

SirRacer

Posted
Posted (edited)

ive just come up with a wee dilemma unfortunately right down at the stage when my engine was going to go off to the shop to be machined

on placing order of my pistons the chick at the shop couldnt find the code on her computer. id previously been told by a rebuilder here that acl make a good cheap forged piston for the rb30/25 engine transplant. i rung the distributor who gave me the part number 6mkry9608.

when speaking to the distibutor he informed me this was a new piston and would end up with a compression ratio of 8.5 on the rb25de head. he seemed very knowledgable and spent ages talking to me on the phone about the pistons. i never thought to question it.

i liked the idea of acl as the girl i know whos at repco gives me her staff discount which obviously saves a lot of money when building a forged engine. i went home now and checked them to find they are the rb30et pistons and would give me a horrible 7.1 comp ratio

http://www.aclperformance.com.au/tech_p_cast.htm

they make a standard pistons for the na rb30 also part no 6mkry9301 (Not listed on their site) however this isnt forged.

what i was wanting to know is part numbers for other piston manufacturers that make forged pistons for this conversion.

i know cp do and cubes has mentioned wiseco do (one place i rung previously said they were also 7.1 ratio) but was wanting to know all the others and specific part numbers for these.

cheers

Edited by SirRacer
StockyMcStock Proficient

StockyMcStock

Posted
Posted

or save yourself a grand and use high silicon content cast pistons (RB30E) from ACL. i won't wade into the forged vs cast piston debate here but i would actually never ever use forged pistons for a road car that was planning on running more than 50,000km between pull-downs.

SirRacer Experienced

SirRacer

Posted
Posted

the reason i have always wanted to go forged pistons is im planning on running a gt3540 or t66 at around 25psi and going for 350+kws. the more rugged the piston the better as im also going to be entering it in a number of burnout competitions.

ive also got acl race bearings for the build, aftermarket valve springs, gtr headgasket, and will be running (most probably) a r33 gtr pump with oil restrictor(one blocked and a 1.5mm restrictor). 700cc gtr sard injectors with gtr resistor pack

what are the pro's and con's of decking the block etc. in laymans term is this like shaving it? with the CP pistons ive also been told that they dont come with rings which would be extra?

conan7772 Mentor

conan7772

Posted
Posted
or save yourself a grand and use high silicon content cast pistons (RB30E) from ACL. i won't wade into the forged vs cast piston debate here but i would actually never ever use forged pistons for a road car that was planning on running more than 50,000km between pull-downs.

That's interesting to hear as I've been told quite the opposite.

When I cracked a crown and threw a rod last year, I spent some time over my options on the re-build.

After stressing that I want a car that I can thrash from time to time, do it again tommorrow, and come home the next with no problems, I was told having a forged bottom end should last me a long time, with care and maintenance.

Already I've read three incidents of cracked stock rods, pistons with an RB30 conversion right here in this forum!

I'm not one for annual pull-downs nor could I ever afford it.

My Grandmother used to say"We are not so rich to buy so poor", meaning one can spend more money in life replacing low quality things as opposed to acquiring quality to start with.

I don't see why some people think that selecting forged components = race engine.

I see it as eliminating possiblities for fatigue and failure for those components in an every day road engine.

conan7772 Mentor

conan7772

Posted
Posted
Why not do the job right and use the RB30DET piston from CP?Other RB pistons have the wrong pin height making them a very dodgy option.

Spot on !

CP RB30 are 8.3:1, exactly the same ratio as the stock RB25DET engine, after 20 thou deck off the block.

Same as Wiseco.

Cubes Grand Master

Cubes

Posted
Posted

Conan, For a high km motor you still best off without a forged piston. Its well known forged pistons cause greater bore wear.

I consider the greatest benifit of a forged piston being its lighter weight, not so much its slightly greater strength that still breaks under detonation.

Do remember .... When it comes to forged pistons use the piston your engine builder is familiar with. If not, you are only asking for trouble. :(

conan7772 Mentor

conan7772

Posted
Posted (edited)
I agree with StockyMcStock.

NIB, there's nothing wrong using the rb25det pistons. 0.020" is bugger all.

Come on guys,

These engines are pushing between 400 - 500 fwhp mildly, never mind worked.

Everyone says they're happy with their power, but next thing you know you're back in the Nengun homepage before you've even payed off your last tune !

Just a little more...

Then, you're slowly creeping up to the 300 kw mark, and you wished you had that perfect bulletproof bottom end.

Anyway Cubes, you got Wisecos, I bet you want a hell of a lot more than 50,000 k's.

Edited by conan7772
Cubes Grand Master

Cubes

Posted
Posted

I do want a hell of a lot more than 50,000km's and I have no doubt the condition the motor is in after 40,000km's it will easily do another 40,000km's.

With regards to being happy with their power.....

300rwkw through rwd + rb30. It doesn't work to good.

One reason why Sk30 now is dropping the rb30 in to a GTS4, rwd with so much torque and power doesn't work on the street.

Mine is a daily driver, rwd, I'd be happy with up to 300rwkw and then tune the mid range down in order for it to get some traction.

Realistically for the amount of power that can be used on the street we don't need forged pistons, traction is a big problem. :(

conan7772 Mentor

conan7772

Posted
Posted (edited)
I do want a hell of a lot more than 50,000km's and I have no doubt the condition the motor is in after 40,000km's it will easily do another 40,000km's.

With regards to being happy with their power.....

300rwkw through rwd + rb30. It doesn't work to good.

One reason why Sk30 now is dropping the rb30 in to a GTS4, rwd with so much torque and power doesn't work on the street.

Mine is a daily driver, rwd, I'd be happy with up to 300rwkw and then tune the mid range down in order for it to get some traction.

Realistically for the amount of power that can be used on the street we don't need forged pistons, traction is a big problem. :(

Couldn't agree with you more on that.

Every time I lose it, my lady calls me immature.

Imagine that...

Anyway, I think one of my next consideration is some bloody good tyres.

Right now I'm still on some hard compound Falkens.

Had them for 3.5 years and still less than half worn !

All I really want is 0-100 in 4 secs but my mates reckon I need 4WD for that.

I guess maybe without slicks they're right.

Edited by conan7772
conan7772 Mentor

conan7772

Posted
Posted

Cubes,

Bore wear, is something I haven't really considered as a problem, given use of quality oil and maintenance.

After how many kms roughly would you expect wear ?

Don't the rings take most of the contact ?

Cubes Grand Master

Cubes

Posted
Posted

Due to the metallurgy of forged pistons they are smaller when cold.

During this time they 'slap' around in the bore essentially wearing it slightly, once warm there's no real problem with bore wear.

A typical street driven motor see's many heat cycles of which accelerate bore wear.

I really have no idea how many km's to expect from a forged piston motor as it depends on how its setup initially.

Wiseco pistons have a recommended bore clearance for usual street use that see's absolutely zero audible piston slap when cold.

I went with a clearance of what they call '24+psi or race use', i do hear slight piston slap when cold but I do have to have the bonnet up, its so quiet some one who doesn't know what they are listening for will not hear it.

Google piston slap, bore wear amongst other things. You will see lots of GM LS1's mentioned. :(

conan7772 Mentor

conan7772

Posted
Posted (edited)
Due to the metallurgy of forged pistons they are smaller when cold.

During this time they 'slap' around in the bore essentially wearing it slightly, once warm there's no real problem with bore wear.

A typical street driven motor see's many heat cycles of which accelerate bore wear.

I really have no idea how many km's to expect from a forged piston motor as it depends on how its setup initially.

Wiseco pistons have a recommended bore clearance for usual street use that see's absolutely zero audible piston slap when cold.

I went with a clearance of what they call '24+psi or race use', i do hear slight piston slap when cold but I do have to have the bonnet up, its so quiet some one who doesn't know what they are listening for will not hear it.

Google piston slap, bore wear amongst other things. You will see lots of GM LS1's mentioned. :)

My slap with the CP's is heard clearly behind the wheel never mind outside for a good five minutes.

Using Titan Fuchs oil.

But I have to say man, I wouldn't trade this engine for anything.

Gets up and goes like a 15 yr old boy on his first root. :(

Edited by conan7772

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