RB25 Rebuild Advice Needed

[Stevo83]

G'day, I have removed the engine from my R33 GTST and stripped it completely. Bores are in good shape and as such I will be able to keep them standard.

What I'm not sure about is the best pathway forward in terms of Forged or not Forged, also which OEM or Brand I should trust. Nitto looks greats but the price will cost me a kidney, CP was my next option however as I look into this more it gets harder to understand.

My question really is this, is there a rebuild kit or item list based on past experience anyone can share?

I want to build the motor with quality, trusted parts and do that at the lowest cost base possible. The motor will be built by myself as a trade qualified mechanic. The intended purpose for the car is to use it as a weekender with Club Registration. No racing or anything like that.

Thanks in advance for any help!


Cheers, Steve

[Duncan]

Any pistons (including standard) will be fine for weekend driving, assuming you are not looking to make substantially more power than standard. Compared to many cars the RB skylines were very well engineered from factory

I'd be using

Standard pistons and rings to suit

ACL rod and main bearings

Reuse Rods and Crank with new standard or ARP rod bolts

New, aftermarket oil pump eg Nitto

VRS kit with metal head gasket

New rear main, cam cover, cam, oil pump and cam half moon seals

New standard head bolts, main girdle bolts, flywheel bolts

Potentially head job, definitely valve stem seals but valve springs are often tired too 

New water pump, timing belt (obviously), timing idler and tension bearings and stud/bolt (as they can fail with time)

 

[r32-25t]

What are your power goals? What fuel are you going to be running? How often will you be giving it a hard time? 

[Kinkstaah]

An important question is:

What actually failed? There's not a lot of logic in upgrading your pistons, if your pistons did not fail. The Engine is only as good as its weakest part, and people OFTEN upgrade things that aren't even close to the weakest link in the chain, and won't be the weakest link in the chain etc.

This, when coupled with what you are going to do with the car (honestly) is where money is to be saved, but not so much saved as spent appropriately.

[joshuaho96]

Another thing to consider when it comes to piston choice is that most of the forged piston options out there are made for like 1000+ whp which means they have fairly short lifespans in street use. They call for fairly large cold clearances which means a lot of blowby and piston slap when cold which means you really have to baby the engine when it's cold with proper warmup. It may even slap when warm if you're just driving on the street. You will also have to compensate in your knock control because the piston slap generates a ton of additional noise on the knock sensors.

So there is definitely a significant downside to overbuilding your engine for the intended application. There's no free lunch and it will really suck to buy the wrong parts for your intended application. IMO if I had the engine apart my biggest goal would be to do things like oil pump gears, appropriate head restrictor, crankcase ventilation, baffle plates, etc. Stuff that isn't necessarily expensive but requires tearing deep into the engine to do.

[robbo_rb180]

Was there anything actually wrong with the engine before removing it? 
If budget is an issue put new rings and bearings in it and call it a day. 

I have used spool rebuild kits on one rb and sr. Good quality for the price and no issues
https://www.spoolimports.com/engine-rebuild-kits/rb25

Edited January 10, 2022 by robbo_rb180