I'm beginning to plan for a future engine replacement for my Z16XE/YNG (factory converted LPG). It's done me proud for 146k now and is losing minimal oil between the 20k changes, dropping only a mark or two on the dipstick which is nothing really, but at some point it is going to be in need of a rebuild or replacement.
I know I could just change the car, bigger engine etc, but I doubt finances are going to allow for that for a good few years, so unless I change jobs to work closer to home, I'm still going to have a good 20k+ per annum worth of driving to do - that and I've put a fair bit of effort (and money given I bought the car new) into the car as it stands, and it'd be good to get some more use from it.
I'm aware of plenty of mods for this engine (and most other NA engines), but I still have a few doubts on how well the engine can handle these mods long term. I think I'm fairly right in saying that sticking to 'external' engine mods should keep things safe - inlet/exhaust manifold mods being the main ones I know of. Match these with a suitable remap and I reckon 140bhp is more than feasible given where I am now.
Personally I'd rather look to improve mid-range bhp/torque over top end bhp - inlet/exhaust mods should be of benefit here, I already have ~130ftlbs torque with only catback and the usual airbox mods so sorting the exhaust manifold and cat might well help things further, possibly gaining some from inlet manifold improvements too (assuming a remap is done)?
The last thing I'm curious on is camshafts - SBDev suggest that simply sticking in a fast road cam is going to do nothing but increase tappet/lifter wear to the point of failure, and due to OEM piston design you can't go too hairy without changing the pistons. If I was to stick to some uprated cams with a marginal lift change and purely look to increase the valve opening duration to improve flow (more exhaust gas getting out, more new air getting in), is this likely to increase wear to a point where I'd be better off also uprating the tappets/lifters too for long term reliability? Many companies (Piper/Kent for example) offer a full cam kit which has all of these bits and more so I assume these would be a good option?