Honestly the mods you are talking about are big money. I just finished putting together my aaz today. I went stock everything except for arp main and head studs. I dont believe there is a listing for rod studs and from the research I've done they aren't really necessary. It's the main caps that typically let go. Your money would be better spent on a holset he200wg turbo, a decent intercooler, a good exhaust and a Giles pump. That should give you more power then you would need and be plenty reliable. Porting is cheap if you do it yourself and will help make some power. While I want decent power from my build I'm worried about the rest of the drivetrain so I didn't go above what I suggested. I'm hoping for 150hp and 200ft-lbs and a long service life from it. I can't give you an exact cost of what my rebuild cost but ive got $1050 (all Canadian dollars) in machining, about $300 in my holset (used from eBay) then probably another grand in pistons and other parts. That's not including a new head that I had bought years ago for $600. Stuff really adds up quick. Don't be in such a huge rush to drop thousands on getting every ounce of power possible. Figure out what you need and will make you happy and go from there.
I have to ask about your decision to stick with the AAZ rather than turn it into an mTDI. With performance as your goal, there are a few reasons to really consider an mTDI. The AAZ has the pre-combustion chamber and insert in the head. The insert has a very small opening. All of your combustion air gets pushed through that small opening when being compressed and pushes back through that opening during combustion. That small opening and the resistance of the air flowing through it causes additional pumping losses over the TDI system that has the combustion chamber in the piston. The added surface area in the head also causes additional combustion heat to be lost to the cooling system rather than turned into useful work. The result is a drop in fuel economy of approx. 10-15% for similar power. That additional heat lost to the cooling system also means a much larger heat load on the cooling system meaning that the cooling system needs to dissipate approx. 2X the heat to keep the engine from overheating. IMO the biggest deal, though, is the fact that with high power and high heat, the pre-combustion chamber inserts can crack or loosen in the head. If they crack into two pieces, a piece falls into the cylinder destroying the engine. If they loosen, the insert can start wiggling up and down with each compression/combustion causing the opening to wallow out and the head gasket to fail. In that case the head is ruined and if it goes on long enough can damage the head gasket surface of the block. Considering the fact that you are talking about getting performance rods, pistons, valves, etc... the additional parts required to convert the AAZ to mTDI are minuscule in comparison. You could very likely break even with the sale of the AAZ head/injectors/pump bracket/timing covers for the purchase of the AHU components. A Land Rover 300TDI mechanical injection pump would be very similar in cost to a Giles pump. Everything else would be the same.The TDI will give more torque lower in the rpm range, the AAZ will rev higher. The result is that the TDI prefers lower gearing than the AAZ. The additional torque of the TDI at lower rpms is harder on the transmission.The AAZ is a fine engine, but considering your project and goals, if it were mine the very clear choice would be an mTDI.
A) - You can use the 020 transmission with the AHU/1Z/AAZ block. You'll probably want some spare transmissions or get one built since it sounds like you'll be thrashing on it a bit but you can deal with that later. B) Get a mTDI pump built that fits the stock AHU/1Z pump bracket. I don't know what the rover pumps are worth currently so this may add quite a bit of cost. I'm sure someone else will chime in. C) A built AAZ will benefit just as much from a newer/better transmission To convert your current engine setup to mTDI:Buy TDI pistons (and rods I think)Buy AHU or 1Z head (with valve cover and injector hold dows clampsBuy mTDI or Rover pumpBuy AHU/1Z timing belt covers (inner and outer)Buy TDI injectorsRegardless of what engine you decide, if you are running a serpentine belt, you MUST use a clutched alternator pulley and have the crank nose machined for the TDI gear if you want this to last. I also would go mTDI over AAZ. Parts are much easier to find, they are more reliable and efficient.
The AAZ rods have the same length and big end/small end diameters. They are a little bit different in design but can work. If you are planning on getting custom rods, then it's irrelevant. The AAZ injection pump bracket and the AHU/1Z injection pump bracket are very similar except that the AHU/1Z except that the AHU/1Z have an additional timing belt idler added between injection pump and cam. The idler bolts to an added boss that is part of the pump bracket. The timing belt cover and backing plate are different in order to accommodate that extra roller. I know of a couple different people who have turned AAZ into mTDI and used the AAZ bracket and timing covers and just done without the extra idler roller. I personally prefer having the added roller as it increases the wrap of the belt around both the pump and the cam. Obviously the factory thought it was a good idea also. Along with the parts that Tyler mentioned, you will also need a set of TDI injectors and AHU/1Z injection lines. If you use the Land Rover injection pump, the mounting bracket would need to be machined to accept the larger snout. FWIW, I happen to have an AAZ engine here that I will be converting to mTDI before very long. I got the AHU head complete with valve cover and injectors from one person. I got the pump bracket and timing covers from another. I got a set of ALH rods (because the AAZ had two bent rods) and pistons from a third person. I have a 4BTA pump that I built a while back and held onto that I will use and it will work without modifying the bracket. Making the necessary changes to a 4BTA pump is more challenging than machining the bracket for someone who is not totally familiar with the inside of an injection pump. You could get 150-200hp with either engine. The Mk1 is so light I can't imagine being disappointed with the performance of either.
An AHU or 1Z head will work - 1996 to 1999 is the year range. ALH and later are a no-go. An aftermarket performance cam is not a bad thing, though you need to have the fueling to actually use the air it provides. There's no power gains from the cam itself, just a reduction in EGTs which does allow you to crank up the fuel which in turn yields more power. It's a "supporting mod" rather than a direct power adding device. Valve springs really aren't all that much of a concern. Max RPMs are still low by gasser standards, the overall valve lift isn't all that huge, etc. A modified diesel ends up with factory gasser requirements on the springs. The only exception to that is if you are running really high boost levels with a restrictive turbo, where exhaust pressure might cause valve float. That's not a common scenario though. Sent from my XT1097 using Tapatalk
