Author Topic: Question about 1.9 AAZ pistons in AHU engine... (Read 3841 times)

Sierra94 · « **on:** April 12, 2007, 02:08:09 pm »

Can I use AAZ pistons in a AHU/1Z engine block? I got hold of a shortblock AHU engine for almost nothing

I want to re-ring my existing AAZ pistons, hone the AHU block and put my AAZ head on it and hopefully have a engine that works for a while.

Is it possible? Are the connection rods and crank the same in the engines? All the other accessories such as the IP bracket etc looks to be in the same place on the engines. All the castings looks the same.

The AHU should be the strongest block of the 2, right? It looks like it has some reinforcements cast into it.

Thanks in advance....

jtanguay · « **Reply #1 on:** April 12, 2007, 03:57:41 pm »

nope won't work. TDI pistons have a special chamber right inside the piston itself. it's amost like a 'post combustion' chamber. :wink:

due to the lower compression ratio of the TDI, the rods & maybe crank will be different.

depending on how cheap you got the block, bore it out, install oversized pistons & rings, and bottom end if its bad. you will have an awesome motor after that!!! I payed $1200 for my 1Z, and everything looks great! just going to put new rings, do a very light honing, and use it as is.

new pistons run at around $800 or so.

rabbit GTI/GTD · « **Reply #2 on:** April 12, 2007, 05:40:12 pm »

but hes putting a aaz head with aaz pistons, so the tdi "dished" pistons dont matter, IMO if the bore is the same, then it should work.

mdonau · « **Reply #3 on:** April 13, 2007, 03:02:17 pm »

hi,

it works, connection Rods are 144mm in both 1Z/AHU & AAZ,
so changing Pistons & Head to AAZ will do fine.

greets, Michael (doing the same)

Sierra94 · « **Reply #4 on:** April 13, 2007, 04:19:14 pm »

Sound great

jtanguay · « **Reply #5 on:** April 13, 2007, 08:41:16 pm »

oh i didn't read it properly... i was quite tired! I did not know that the crank is the same... i thought it would be a bit stronger on the TDI as per their over-engineering.

houseofdiesel · « **Reply #6 on:** April 19, 2007, 12:17:50 pm »

It works alright, the Mexican sourced AAZ engines from Overland or on ebay all have TDI blocks with AAZ internals. (block is stamped 1.9 tdi) only mk3 engines of course (external waterpump)