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Rebuilding, What Would You Do?

maka

By maka,
in Western Australia

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maka Enthusiast

maka

Posted
Posted

Hi guys.

My Rb25 melted number 6 piston.. Nasty job, but it did it.. So i was thinking of a few different options for the engine.. I saw a standard rb25det block for sale on the forum, so i grabbed it.. Today i started work on the engine, started stripping the block that I bought, just in case ther was anything that may be wrong with it.. Pulled the crank out, and all the pistons. I didnt intend on doing forged internals and stuff on this engine, I was going to do it as an ongoing project on the other engine with the melted piston. So now that the pistons are out of this spare block, I just checked them, and I can see that number 6 has some marks on it like black crabon build up on the top piston ring. Almost like it has been leaking compression through there.. With the piston out of the block I can see slight markings on the bore as well. Dont get me wrong, its nothing too bad, but not as good as all the other ones. I am going to hone the bore and i think it will be sweet after that. I think i should get some new piston rings too, just in case. So I will get those as well as some new bearings. The rest of the pistons look sweet, and the bearings have hardly been worn, So it looks like a relatively low k bottom end.

I am wondering what anyone in my situation would do? would you go all out and get new pistons and rods as well?? I am kinda limited on funds at the moment, just like anyone else after the holidays, and I am looking at the best way that will get the car on the road as quick as possible. Should i just get the new rings, some new bearings, and put the existing pistons in, put the recon head on it (i am getting that done now) and I bought a TD06 turbo and a new 3" exhaust for it.

Or should I wait a lot longer and get some new pistons etc.. I have access to a RB30 as well if i need it, but didnt want to do that just in case i run into problems, and ned heaps of other stuff like new ecu etc etc..

Any input would be good, and any pricing on parts etc..

Thanks in advance. sorry about long post.

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datsqik Enthusiast

datsqik

Posted
Posted

If your funds are limited and you want to get your car back on the road then get the bores lightly honed, clean and check you pistons especially check for cracks between ring lands and wack some new rings in. You could always re-use the bearings if they are ok or just fit some cheap ndc or acl bearings.

maka Enthusiast

maka

Posted
  • Author
Posted

Yeh, just took the crank in to get machined and check it all for cracks, and ordered new rings. Going to hone the bore tonight, so that should be good. Also getting the pistons cleaned up and check for cracks, and also do the same with the rods. Gonna take your advice and get some NDC bearings.

Looking forward to putting all the bits back together.

Thanks for the input.. Will let you know how it goes.

Just in case you guys were interested, here is a pic of the melted piston in the old block.

post-16376-1200533733_thumb.jpg

bubba Grand Master

bubba

Posted
Posted (edited)

Cheap if you plan on sticking with the stock turbo, a bigger snail you should start looking at other things.. at the very least keep the pistons that came with the 30 and just get the crank machined. Can't help you with things like VCT etc as my head doesn't have that but there is a wealth of information in the Forced Induction section.

Don't get me wrong, I love preaching the RB30 (I have one after all :D) but the guy was after the cheapest option that would get his car back on the road ASAP.

By the sounds of it though he's reasonably cluey with engines and has the capacity to strip them down at least..

Building a twincam 30 isn't a HUGE adventure and if you have access to a workshop/tools then it's even easier. We did my conversion in a weekend, started Saturday morning, went to Manson concert Sat night and got back into it Sunday, drove it home ~2am Monday morning :D

Edited by bubba
maka Enthusiast

maka

Posted
  • Author
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Thanks heaps for the advice guys.

I have stuck with the RB25 bottom end that I bought off the forums, and yeah honed the bore, loooks great now.. and the pistons, rods and crank should be all checked and polished and ready to go in with the new rings and bearings by friday.

Now I am a bit worried though.. I went out and bought a TD06 on Friday, and was gonna put that on, as my turbo has not only up and down shaft play, but forward and backwards (replace your air filter more often)... But then I went out on sat to get my new exhaust, and ended up buying a T04 with top mount manifold and external wastegate. It just looked soooo good, and I couldnt say no for the price. So that is definitely going on the engine. But now I am stuck with the dilema of getting everything running properly. I have some GTR injectors available to me, but I am not sure if they fit on a RB25, has anyone done this, I was told about using some soryt of resistor pack with using GTR injectors on an RB20, buit I am not sure about RB25's does anyone know what is involved, do i need a new rail?? I have a fuel pressure reg, and I can use that to bump up the presure out of the fuel lines. and what else would you guys suggest? I am stuck now, as I know that the turbo can produce a bucket load of power, but I would not wanna go past the 400 mark, as I know GTR injectors are rated to 440.. Ad I still have the stock ECU in the car, so i am not sure if that will be ok to run the engine at least untill the engine is run in.. Anyone have any ideas?

This is turning out to cost a fortune, but hopefully at least it will be a bit more fun than the power that the old engine had, and hopefully a bit more reliable...

BTW, the car has cost me that much so far, and I am not willing to get rid of it.. I would rather have something that I know the history of.. I love the look of that car, and the engine looks sweet, but no offence I prefer mine.. Cheers for the offer though..

Cheers

Maka.

bubba Grand Master

bubba

Posted
Posted

GTR injectors won't fit your standard fuel rail.. yours are side feed, GTR/RB20 are top feed with the RB20 items being high impedence. Could be possible to get a custom fuel rail but easier to get direct swap injectors (may work out similar in cost once you get a custom fuel rail made and wire up the injectors) :P

Stock ECU will NOT run different injectors without at the least a remap (don't know of anyone in Perth that can remap 33 ecu's..), you will need a PowerFC or something similar (emange ultimate etc etc).

maka Enthusiast

maka

Posted
  • Author
Posted

Hmm, thanks man...

I will have to look into aftermarket injectors and ecu then..

How about running stock injectors, what horsepower are they rated for?? Would it be ok to run these with the stock ecu, a fuel presure reg, at least till the engine is run in.. but with the T04 turbo??

Chers,

Mark

bubba Grand Master

bubba

Posted
Posted

You could but I wouldn't be running any boost.. the sort of airflow the T04 will push will flip the ecu out and likely hit R&R straight away! if it doesn't, it's likely to lean out and melt a piston again :P

I think stock injectors will be good for high 200s hp maybe more if you bump the rail pressure up, but that is a dodgy fix.

New turbos = tune. Personally if I had just rebuilt an engine and was putting a big turbo on, I would tow it to the tuning shop.

I will be doing exactly that once my GT35R is installed, on the back of a truck to the tuners.

Another thought.. did you find out WHY you melted a piston?

maka Enthusiast

maka

Posted
  • Author
Posted

Hmm yeah the reason for the melted piston...

It was pinging when it was under stress.. so third geat high rpm, and 4th gear high rpm.. The cause for the ping is due to my turbo being towards the end of its life, therefore breathing oil into the engine... The ping would have stressed the piston,til it just decided to let go.. I had known about the ping for a while, and tried a few things, but never got around to getting an oil catch can... After i installed the front mount, it stopped for a while, and i thought it was due to inlet temp being too high, but nah, once the cooler got a good flow of oil through it, it started feeding it into the engine again... I should have replaced the turbo earlier... I also found that my coil packs had those hairline cracks, and saw where they have been earting out to the rail.. But yeah the coils packs are easy fix for now...

Hmm, I will just have to use my mates power FC, and 550cc injectors for now, to get the car running then. Cause I dont think the car will go any other way, and I would die, if the piston melted again.. Hmm, sometimes I wish I didnt have to learn all this stuff and could just give the car to a mechanice, and say.. fix it and make it good.. hehe.. then blame him if it f**ks up.. hehe..

I got my call, and all the pistons crank and rods are good, no cracks, and they are all polished and ready for pick up.. All up that excercise cost $321... Not sure if that is good or bad yet.. I guesss i will kow when it is all together.. Not including the turbo exaust manifold and gate, the whole lot cost me 1300 so far $200 block, 321 machining of pistons etc, 325 for full gasket kit for RB25det, and 500 to recon the head... but looks like it will be about 3 k or maybe $3.5K all up with everything including my stainless 3" exhaust..

Only problem is now i have a TD06 that cost me $850 sitting there doing nothing.. hmm..

I think i will start saving, and start doing some work on the RB30 block that I have as well.. Maybe put some forgies in there, and change the head over one day.. or maybe get a 26 head with twin turbos... All in the far future though.. hehe

Cheers for the quick replies man...

youre a legend...

bubba Grand Master

bubba

Posted
Posted

You have a new fuel pump yes?

The oil in the intake will induce pinging but I don't think a catch can would help if it was leaking out the turbo.. once it's in the intake stream the only place it's going is the combustion chamber..

Build up the 30 in your spare time, if you come across a cheap 26 head grab it as if you're taking your time and building properly that's the way to go. 26 head flows better and there's more options out there as far as bolt on manifolds etc than for a a DE head.

As for the TD06, sell it on - someone will buy it!

Oh and no probs.. was a bit slow at work this morning :D

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