When is a forged piston not a forged piston?
I have seen heaps of "forged" pistons that have casting marks in them! As far as I'm concerned Forged means getting something hot then hitting it with a big hammer...... This is a true forged piston. I think what some manufacturer's do is cast the piston & then Place it into a die & hit with said Hammer...... So that the critical areas of the piston (gudgeon retainer) have characteristics of forged material.

Hey guys!
I must be missing something!
This thread is the first place i have ever read about the CA18DET not having forged pistons from the factory.... It was my understanding that the CA18DET, RB26DETT and SR20DET (gti-r and S15 only) all had forged pistons, which was one of the main reasons the CA18 had such a short life..... They were alot more expensive to produce than the SR20... But hey I may be wrong.. Is it stated in any nissan manuals? Oh and if you ever need new pistons for your GTI-R you can use S15 .....$99 each from nissan... bargain!

Matt
sales@gofastparts.com.au

left nut... wheel nut? ..which one? I hope that you aren't betting a neutical...FYI (A dogs replacement testicle after neutering)...

if it was knocking as you say, i'm betting its number 2 or 3 or both conrod big end bearings. i'd bet my left nut.

a bearing or loose flywheel bolts

Thanks guys,
I have decided after doing research and reading your posts to simply re-build it to stock and not get forged pistons. Chances are the turbo may need new bearings not to mention a new clutch. Expenses easily get out of hand as you have pointed out.

There was a funny vibration in the engine so I guess it could have been a bearing... I will check. justin

best bet is 2 buy a low km stocko ca18 motor, drop it in 2 get u back on the road and build up your blown motor,
u really only need forged pistons and flowed head if u gona build up a strong reliable motor, stocko rods are very strong due 2 them being short and stumpy, crank is strong!

Quote:
Dont' get me wrong...... A spun big end wont' always drop the compression, but quite often the spinning bearing will create eccentric forces on the rod & piston which, over time will cause the bore to wear, thus reducing compression.
I should have asked if there was a 'knock' that accompanied this drop in compression.... If this is the case it is almost certainly a spun big end bearing.
It was the fact that 3rd or 4th bearings spinning are common on CA18DET's (due to oil supply problems at high rpm) that made me think it was a big end problem.

i guess its always hard to know who to listen to and who not to. but really you have to think about the reason you would need forged pistons. extra resistance against detonation. if you are putiing in forged pistons, what about the rods? H or I beam aftermarket items or shot peened.... then you would need to balance the bottom end. is the head gasket going to be good enough? (i say genuine nissan is a goood thing) copper or metal maybe? then you really should o ring the bock to have it really seal. and when you've done all that you can't just put on a standard head, you'd have to port and polish it and match port the manifolds to the head. throttle body would need to be bigger. aftermarket computer... the list goes on, and how much faster and harder will this setup run than a standard rebuild?

i do get what you mean, but how much is really necessary. basically if you want your car to be really fast (at the drags) you will need to have a big diff and probably something stronger in the gearbox department.

i'm not thinking i'm making any sense, but i am aiming to run an 11.5 with my setup, to go much faster than that would cost me at least double my investment so far and would only gain me one more second max.

im sure ive read that 4AGZE came with stock forged pistons il have to check, but CA do not.
I dont know about you guys but if i was to pop my motor i wouldnt just rebuild it to standard do it once do it right.
LAG i understand your point about how well a internally stock motor can do as you have proven but what happens when you want to run more boost and go faster and faster which i no what will hapenn to me then you say #### i should have added forgies.

Anyway when motor does finally go my plan is to add some aftermarket rods and pistons and to some major head work as CA18DET can make great power with good head work.