I know of plenty of CA20s and e engines still going strong and taken to their redline daily without issues. The secret is making sure its always running well with good servicing and thats it most in wreckers in all Nissans have over 300,000kms, the ones that are revved beyond their redline or abused do throw rods which are known to be high carbon powder cast grey iron units, yet there is an S12 member I chat with, that had an S12 with hybrid ca20det using stock but shot peened rods 20psi and has been reliable for several years of racing set some good times which has not been able to better with his new race setup sr20det s12, he kept the ca20det at 6200rpm redline but later built another that revved higher using common mitsubishi 4g63 rods. The rods just need a smidgen taken off the sides of the big ends then are perfect fit. ca20s engines are lighter than L18 engines due to having no bottom skirt.

A good lightweight combo would be an L16 (lightest block) done by Bas from Masport using L18 crank (bolt on) and 90mm C sleeves (he uses his own special casted head plate made from L series heads to bore and hone under the correct head bolt compression required so bores stay true and rings have excellent sealing) machined from crank centre lines and then fitting a ka24de head using toyota 22r bottom chain sprocket to suit shortened ka24de chain and a slight mod to the timing case as shown on Ozdat.com. This will give you a 1985cc L series with 155hp stock head and cams but with higher compression using milled 90mm ka24de +1mm oversize replacement pistons that with good exhaust and inlet (eg. r1 carbs or 48mm webers) should crack 160-180hp.
The L16 block weighs 37kg bare with mains while L18 weighs 10kgs more due to siamesed bores and thicker casting around the bores. The ca18de block weights 37kg and the ca20s block weighs 35kg or as heavy as an a14 block. The ka24de heads are everywhere atm cheap as chips.

If you are thinking NA another possibility is the same L16 sleeved bottom end with Ka24e sohc 12 valve head. Timing gear is straight forward and just needs one oil drain at back of head tapped or welded and z20 head bolts. Pistons choice is important as ka24e head has large chamber so will benefit with flat top piston or slightly domed from 2 valve hemi of some sort with machine valve recesses to suit. valve springs, solid lifters, billet and ground cams of all sorts are available as it was the only Ka allowed in SCCA racing in the USA and 2.4 litre race setups made somewhere from 340-360hp at 7600rpm. The L18 crank could be taken to 8000rpm with more safety.

i would choose for the ka24de head as its already an awesome bit of gear with cam over bucket and already 155hp from factory with average cast headers etc.

sohc 16v L series and Z
http://forums.mightycarmods.com/showt ... 11909-Single-cam-builders