Here's a list of the 4.2 V8s that I compiled. There are essentially 3 generations here - belt driven, chain driven, and then the fsi.
The belt driven motors are essentially bulletproof and can be had for $500 on ebay. Nearly identical size to our flat 6 and mount to the 986 5 speed and 987 5 /6speed tranny's without modification. Custom mounts will need to be fabbed but it's not overly complicated. Huge aftermarket for mods, especially for forced induction applications.
The chain driven are also great but they have an issue with the chain tensioners - 3 hour job to fix with the motor out of the car but parts are stupid expensive (3k if I remember correctly).
The fsi generation are really fantastic but the ecu gets complicated and aftermarket ecu's aren't an option unless you use motronic (again, big $).
Please don't hold me to any of this, all if this is info that I gathered in piecemeal fashion online. There's only one really well documented build with an ABZ in a 986 to a 5 speed transmission that I have been able to find. He did a fantastic job and at the end of it had a great looking and running vehicle. Truegearhead is building in that platform but he is doing a twin KKK turbo application mated to an 01e transmission and is shooting for a 700hp rocket ship!
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