Oil pump risk

[DatsunZ31]

I recently bought a RB20 I'm suspicious of. It has a cometic 3 layer metal head gasket and ARP head studs and thats good stuff but it leads me to ask why did they do this? was the motor raced? over heated? or was it boosted up the shanazz?

upon taking the motor apart it looked like it was fiddled with and re-gasketed. I checked the cylinder's and they seem a little worn out, maybe sme racing in japan? anyway my main question was should i pull the crank and get it collared and a new oil pump? I dont know if it's worth it knowing the engine is worn out? It ran EXTREMELY rich, so rich that the bottom end saw the effects of the fuel so it does have a little bit of cylinder wash down.

the engine will see stock rpmsand stock power levels for right now. It however will have a Z31 T3 at 10psi so I dont know it that would be a lot of power through the rb20.

Edit: It also seems to have fairly new pistons, i dont know if that makes sense. not forged pistons just new cast pistons.

[drew6]

You're dealing with 20+ year old engines. The chances of it being 100% stock and never worked on are very slim. Don't stress about it. Just think how many times brand new cars have to get engine work and overhauls.

Regarding the oil pump, that's a big subject with lots of reading material if you look around. The oil system is not something to take a chance on, however, the chances of it becoming an issue are directly related with how you treat it (Or how it's been treated in the past). Personally, if you're doing a complete build then, yes, definitely do not skip it. On the other hand, if you don't have the time or money to do it right now and are planning to keep it near stock then perhaps you should wait for next time (and trust me, there's always a next time). If you go the latter route keep it off the rev limiter.

Best of luck with it.

[speedfreak]

If you haven pulled the pan off yet maybe you will be lucky and it already has good rods!
Have you pulled the front crank seal?
If you do you can look in and see if it has a collar installed already.
Maybe your crank is different and you have a stroker.

[craftz]

My 1993 R32 GTS-T was completely stock when I got it. Stock wheels, airbox, 48K on the odometer. Some may scoff but it even had the original sticker on the CAS bolt. I am now running it at 18psi boost with nistune and fuel upgrades among other things. It is by no means the fastest gts around but dyno at 294.1 hp to the wheels. It is plenty quick for me. Engine sings and is fun to drive. Stock head gasket also. When you pick up a car that has been worked it is like getting the surprise in a Cracker Jack box. Nothing wrong with this, just be prepared to spend some money and time.

[NismoS-tune]

You paid what, $10k for this 20 year old sports car? It's gonna be worn... I wouldn't worry too much. Now if you paid $20k for it, then I'd be worried haha.

[Skym]

Best to refresh engine and fix oilpump drive on front of stock crank.

Stock headgasket can blow, but it depends on boost level you are running and if are thrashing car (racetrack) or just doing short burst's (dyno). Anything above 1bar, thrashing car on racetrack, should change stock headgasket out for a metal headgasket (Tomei 1.2mm, 80.5mm or whatever thickness engine builder recommends after skimming head, block to get close to stock compression). Above 20psi, would change out pistons, as ring lands (said to be too thin, common problem with stock pistons on all RB engines), rings become a weak point (fail) and run a thicker headgasket, port dome area in head to drop compression into high 7's.

I think hybrid stock RB20 turbo is similar in size to Z31 turbo (same Garrett TB03 CHRA), except Z31 turbo has a bigger exhaust A/R. Main problem with this mod is engine running too lean at lower rpm with bigger turbo, breathing mods stock ECU tune. So Nistune for stock ECU to retune for turbo mod and bigger 255lph fuelpump, 550cc injectors, Z32 AFM + Z32 AFM plug are the supporting mods.