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czy18e

By czy18e,
in Engines & Forced Induction

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czy18e Community Regular

czy18e

Posted
Posted

Hey all,

Long time reader but i don't post much...

I have been racing a built rb25det at willowbank for a couple of years now and have cracked the 9 second barrier finally but on my last oil change i found small pieces of metal in the filter.

Fearing the worst i am preparing myself for the inevitable upgrade that has been long overdue to a built rb30.

I am not chasing 1000hp or anything i just want another reliable strong engine capable of around 150mph.(pb with the 25 is 135mph)

To keep prices down i was just going to get a workshop to take my mildly worked 25head and manifolds and throw it on a built rb30 bottom end with a gt42r thrown on in place of the t04z.

My question is, roughly what is the ballpark price range from a reputable engine builder to do this job and / or do you have another option for me that may be better bang for the buck like how limiting is the 25 head vs 26 head or anything else???

Im not real knowledgable with engines i just like to go fast.

Cheers

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GTScotT Grand Master

GTScotT

Posted
Posted

What was done to the current motor for starters? I am assuming it was stock, yet a lot can be done and a lot can be spent.

Knowing where your at now and what has failed you will be a good bit of knowledge to have before giving you advice moving forward.

In terms of heads limiting the things, IMHO the RB25 does not limit the motor in a built and ported trim. If anything I would rather a NEO head ontop of the 30 bottom end than any other. The VCT puts the pants on the ants as far as results are showing.

R32Abuser Mentor

R32Abuser

Posted
Posted (edited)

For starters, use a RB25 Neo head...do the VCT mod

How much a built RB30 bottom end will cost is asking a very open ended question. Forged bottom end? High end components (CP, Carillo, Nitto, Weisco etc.)? All of this depends on how much you want to spend and what you need from the car. The RB30 thread has a wealth of knowledge in there. You just have to read it!

In saying all of the above, ensure that you address oiling issues that all stock RB's have.

Upgrade oil pumps (Jun, Nitto, Tomei etc.), install winged wet sump with trap doors etc, head oil drain modifications and appropriate oil restrictors. Have a detailed read of the following thread:

http://www.skylinesa...ntrol%20in%20rb

Edited by R32Abuser
czy18e Community Regular

czy18e

Posted
  • Author
Posted (edited)

Ok a little more info...

The 25 is a built r33 25 with mildly ported head and his step2 cams, upgraded springs ect

So by having a read of the threads you mentioned as long as i use a quality workshop i can expect around 10k too far over that and I'm getting taken for a ride?

As i said built 30 with my 25 head and a gt42r, e85 should net my 150mph reliably for many years?

The 25 may only need new rings and bearings but i will probably just go the 3025 rather than muck around.

Thoughts??

Also my car runs a c4, do you reckon the 2530 with gt4202r will get on the trans brake no dramas without nos?

Would a gtx4294r do the job?

A friend is selling a gt45r but i thought it might be a stretch?? thoughts??

Edited by czy18e
Greekos Proficient

Greekos

Posted
Posted

budget for 10k on a decent bottom end with the top end being freshend up, you'll get cheaper prices but by them time its finished it will be usual be around that figure, the most important part is finding someone who will stand by their engines and warrent them if anything goes wrong, i knew a forged rb25 that lasted 7 years saw lost of limter, was taken to the strip almost evey weekend, hundereds of dyno runs, in the end it only lost a bit of oil pressure running an n1 oil pump and making between 350 to 400rwkw, on the other side i have built motors last less than 1500km's

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

So you are just worried about drag and not much else?

If so then really no point going all out with big oil pumps, epic winged sumps etc. That's more for circuit. You are only running hard for 9 sec runs, it's a different ball game. Do the usual oil control modifications, ensure you don't sit on limiters and use a RB30 pump. (seems a typically good forumla)

Ensure the block is well grout filled - probably the most important part.

Put some good rods/pistons in there (and of course bolts). Port it to the heavens, put big cams & plenum on it - as at the end of the day loaded up on a transbrake, it's not going to matter all that much with a GT42 on it.

10k you should get away with it, but really for 150mph I think you'll be spending a tad more as it wi largely depend on how much you spend on the head more than the bottom end.

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