Unfortunately my ca18 shat itself - compression in cylinders was 160, 160, 155, 120. drove worse than the a12!

I am forced now to take the engine out (probably cracked piston ring) and was wondering if there was anything i should tell the engine rebuilders to do when it's out.

What are the advantages and costs of these things for example:
chrome/moly rings, balance crankshaft, forged pistons, o-ringed head. Obviously i will fit a new clutch, any ideas here? Will forged pistons extend the life of the engine?
are the standard pistons ok for slightly increased boost to 10psi?
Any other ideas will help!!!
thanks, justin

i would put my money on head gasket, passenger side rear of the motor. firstly tear down your motor and see what has happened, if the pistons rods and crank are all fine, i'd just re-use them.

if all of these things are fine...
chrome/moly rings are just a different type of metal, and a lot harder. they take a lot longer to bed in than the standard cast rings (up to 3000km's) and you do run a small risk that they wont bed in. having said that they are a good thing and cost less than a set of genuine rings from nissan roughly $100 - $120.

no need to balance your crankshaft if you are using all of the same bottom end components as it is done from the nissan factory.

i believe forged pistons are only needed if you are going for some really big power and want to tune your car really close to its detonating threshold. if your engine is pinging it will last 10 seconds longer if the pistons are aftermarket forged items. the factory CA turbo pistons are a good thing.

don't o-ring the head.

there are a few fairly priced clutches on the market. adelaide extreme, daikin exedy, just have a look around and speak to them.

i rebuilt my CA18t with fresh bearings and molly rings. the rest is standard. at the drags i was running 16psi (T28bb) and revving to 7500-8000. my pistons are fine so slight boost increase will be more than ok.

Just get it rebuilt to standard. USE A GENUINE NISSAN HEAD GASKET. $90, can't be beaten! buy a complete gasket kit for the rest and throw the head gasket on ebay or the bin.

or you could buy that other fella's CA18 package for a 1200, its very fairly priced for the motor alone!

good luck

if you like i have a complete ca18 engine with brand new gasket kit, sump to cam covers, reco'd head and heavy duty valve springs for around $1000 which is a lot cheaper than a rebuild if you need the option.

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You say that your engine is a CA18, then you refer to boost pressures, so i'm guessing that it's actually a CA18DE that you have fitted a turbo to, or it's a CA18DET.

If it's a CA18DET, then i believe it will have forged pistons anyway.
Can anyone verify?

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I hope (for your sake) that it is just a cracked ring, or a head-gasket as lagwagon suggested, but I'd be willing to bet $$$ that you've spun the 3rd & or 4th big end bearing..... This is a common problem for CA18's.
I'm pretty sure the stock CA18DET has cast pistons, but unless you are looking for a 10 second car you should be o.k to stick with the cast ones.

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Educate me here coops, a buggered big end is bad news by all accounts, but why would it drop the compression

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No, CA18's don't have forged pistons..very few factory engines do. With the exception of some of the early turbo cars (they didn't know any better), and the factory racing specials eg. Ford Sierra.

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.

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.

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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.