What To Do Next?

[muchogarcia34]

Hey guys,

Just looking for a bit of advice as I'm not sure what I should do. So here's the story.

I recently picked up my R34 from my tuner after months of work and waiting. Car was running great didn't miss a beat and I was happy with it..... until yesterday afternoon when my idle tensioner thingy failed and slipped the timing belt off to the side, ended up smashing the valves into the pistons and just f*cking everything.

So I have 2 choices. I have 1 spare RB25DET Neo around my place and also a RB30 from a R31 Skyline, I can either just straight up swap out engines or use my other 25 head and go 30.

Now the little things. I am running a R34 specific Vi-Pec, will I be able to run the 30 with this and not have many problems? My second dilemma, how much work and time is involved into getting the 30 bolted up and ready to go. The only reason I ask this is because I need to get the car working again as it's taking up a heap of room at my work and things are gonna start getting lost and damaged and not to mention constricts our work space.

So any thoughts or comments would be appreciated. I'm just looking for a bit of advice as mentioned, the car will be mainly street driven but it will see the track as I want to drift and complete some grip events.

Thanks

Dan

[NYTSKY]

Not as simple as putting a 25 head on the 30 and away you go.

If the other 25 is ok just put that in. Cheaper and easier.

[Duncan]

is the engine builder going to repair it under warranty?

[muchogarcia34]

Well I installed the tensioners and idle. The tuner checked it but I think it's just unlucky that the bearing failed.

[snozzle]

from my understanding and a few unlucky stories, if the timing belt is too tight it causes that stud that holds the idler to flex and eventually snap seems to be the first thing to go

id also stick to a complete neo as its sounds like u need to get her back up and running asap or is it that you werent completely happy with the cars performance when you got it back from its tune?

[GTScotT]

if you keep the Neo head, you will be able to keep all Neo loom etc, so there will be no issue with your vipec.

read the RB30s on this site and see what kind of work is involved in getting it working properly, be it myself I would definitely be going the 30 right now. Bare in mind you are going to want a MUCH bigger turbo once its in.

GL

[StealthX]

There are two types of people in the world, those who have RB30 bottom ends, and those who will.

Do it, sounds like you're pretty handy with mechanicals, and that PDF file on RB30 conversions that's floating around is pretty dam helpful! Pretty sure it's in the rb30 disussion thread.

Good luck dude!

[muchogarcia34]

Hey guys thanks for the input! I've decided to go 30 After reading your input and then discussions with a few people it seems a waste to put the 25 back in when I want to build a 30 anyway. I would just be installing the 25 so I could drive the car again, but I've got another car to get around in anyway. I was happy with the power but you know it never hurts to have a little more And the workshop is my families so as long as I keep the area clean and keep most of the stuff out the way they're cool with it.

Now I've read up on the 30 conversion and there are a few things I'm unsure about. If anyone can help with the following that would be great. First off the pdf says that I must plumb in a new oil line to feed the VCT, what exactly do I have to do to plumb that in? And the other side of it is, can I just run a set Tomei Cam Gears and just not worry about it. I have a set of poncams which were in the 25 that just died so I was gonna re-use those.

The next thing is the guide says that 25 Neo head may be different from the 33 25 head, is this true or is it all good to just block off the VCT oil feed and bolt on, so to speak.

Thanks guys and I'll keep you updated as I go, and any help along the way would be greatly appreciated.

[D_Stirls]

the NEO head has a smaller combustion chamber and you will find you will have a high compression ratio when using off the shelf 30DET or 30E pistons.

Have you read the PDF??

[muchogarcia34]

the NEO head has a smaller combustion chamber and you will find you will have a high compression ratio when using off the shelf 30DET or 30E pistons.

Have you read the PDF??

I read the PDF but it is pretty vague in some areas and left me with a few questions which I'm trying to search now. It doesn't really say anything about Neo heads at all. At first it says that he will check if there are any differences between the Neo head and the 33 head but that's it. He doesn't report back on it or anything. Unless I'm reading the wrong one.

[D_Stirls]

it has covered the head question though;

Three heads can be used for the twin cam conversion.

• RB26DETT Head

• RB25DE (R32) Head

• RB25DE/T (R33) VCT Head

All three heads cc up around the 62-64cc mark.

However, please be sure to double check, there have been cases where people

have bought heads that for some reason are way off. Possibly fiddled with.

As a reference point the RB30’s SOHC head cc’s up around the 55 to 58cc mark.

R34 RB25 heads bolt up fine; The R34 head cc’s up at 50-51cc’s

They utilize solid cams so use a bucket on shim setup. No hydraulic lifters.

So the NEO head has a smaller combustion chamber and therefore a higher compression ratio than a N/A RB30E when using off the shelf 30DET or 30E pistons..

Edited November 21, 2010 by D_Stirls

[muchogarcia34]

Quick question that I wanna just check on. If I use aftermarket cam gears I won't have to drill an oil feed for the VVT right? I can just chuck the cam gears on and voila?

[D_Stirls]

Have a read of this thread; IMHO it's the best of both worlds, no drilling for feeds and you retain your NVCS.

http://www.skylinesaustralia.com/forums/Rb...er-t251669.html

[muchogarcia34]

I have had a look at the neo head and it has a bearing feed running off the head gallery and a seperate feed just for the vvt.

You wont be able to pull the plug out and drill it like the r33 head.

Im appears the vvt solenoid blocks the oil pressure when the vvt is off and when engaged, it pressurises the vvt solenoid. when disengaged the oil pressure bleeds back through the solenoid instead of the constant loss

This is why I ask. I read that thread and you can't do the same thing with the NEO head.

[D_Stirls]

yeah i read that a while ago and had given up on the idea of doing a NEO head due to the compression ratio issues so i must have missed that bit.