Anyone tried AAZ pistons in a Franken engine? (1.6TD with AAZ head)

[R.O.R-2.0]

Correct size for what? 1mm oversize? What brand pistons prothe sells?

correct 1.7TD pistons.. or atleast the same size as what comes in the 1.7

the pistons we get from prothe, come from an ISUZU oem supplier..

[fatmobile]

I had a block that was bored to it's last and was too worn,..
 so I bought 1.7 TD pistons from a guy on here.
 Half money up front and half when they arrived from europe. It was cheaper than buying pistons and finding another block.
 It's taken me years to bring this project to completion,.. and it will take another one before it's a daily driver. Kind of a side project.
 but I did hear it run last week. Cold as hell but it started right up and revved before i quickly shut it off. Winter might be a good/fun time to break it in.
 Bored out to 79.98mm, it just clears the AZZ gasket.

 I didn't know I was getting first oversize, would have rather left that extra .5mm on the walls and got standard pistons.

 The pistons hit the edge of the oil squirter bases it was so wide.

 Got almost all of the wiring and stuff done that will allow me to start it from the driver's seat.
 Waiting for a waterpump pully and battery.

you can bore the cylinders 3mm?!?! how thin does that leave the cyl walls? about as thick as some tough paper?

 That's something I'm not too sure about.
 I have another block but haven't cut it open yet.
77.48 to 79.98 is 2.5mm,.. and standard would be less than that; 2 mm.

 The walls are very thick at the top, where it counts. Hoping there is enough meat left in the rest of the cylinder walls.

 The gassers bore out to 83mm, that's 3mm more and I don't hear of cylinder wall cracks being a problem, even when modded.

 Statements on here showed that people in europe have tried it and bent rods before breaking the walls,
 although there might have been a cracked wall on an engine that was really beat on.

 It's an experiment, a bigger risk than I intended because the original block had a crack and I had to use a hydrolic block that was on it's first bore,..
something that would have worked great with normal/oversized TD pistons so it's not like an block that couldn't be used again.

[Alcaid]

I had a block that was bored to it's last and was too worn,..
 so I bought 1.7 TD pistons from a guy on here.
 Half money up front and half when they arrived from europe. It was cheaper than buying pistons and finding another block.
 It's taken me years to bring this project to completion,.. and it will take another one before it's a daily driver. Kind of a side project.
 but I did hear it run last week. Cold as hell but it started right up and revved before i quickly shut it off. Winter might be a good/fun time to break it in.
 Bored out to 79.98mm, it just clears the AZZ gasket.

 I didn't know I was getting first oversize, would have rather left that extra .5mm on the walls and got standard pistons.

 The pistons hit the edge of the oil squirter bases it was so wide.

 Got almost all of the wiring and stuff done that will allow me to start it from the driver's seat.
 Waiting for a waterpump pully and battery.

Got any pictures of the block with the big bores?

[belchfire]

Back in the old days, I had a ford 300"-6 that I bored .050" and used 390 pistons. Worked great but was sensitive to overheating. I also heard that on some over bored high horsepower engines, that the cylinders would flex and that they would actually loose power. Sounds like you guys will be running #500 of boost,nitrous,&nuclear waste for max power. Hope she don't go boom.

[Syncroincity]

 That's something I'm not too sure about.
 I have another block but haven't cut it open yet.
77.48 to 79.98 is 2.5mm,.. and standard would be less than that; 2 mm.

 The walls are very thick at the top, where it counts. Hoping there is enough meat left in the rest of the cylinder walls.

 The gassers bore out to 83mm, that's 3mm more and I don't hear of cylinder wall cracks being a problem, even when modded.

 Statements on here showed that people in europe have tried it and bent rods before breaking the walls,
 although there might have been a cracked wall on an engine that was really beat on.

 It's an experiment, a bigger risk than I intended because the original block had a crack and I had to use a hydrolic block that was on it's first bore,..
something that would have worked great with normal/oversized TD pistons so it's not like an block that couldn't be used again.

Very interesting. I wonder what those of us with AAZ blocks could get away with, and what pistons we could appropriate to do it with...

[R.O.R-2.0]

AAZ blocks have siamese cylinders, so i wouldnt want to go too big on the bores on those engines. might run into issues with the walls getting too thin in the siamese portion.

[RabbitJockey]

there was someone building a 2.1 i think using ford escort pistons, i think i made a thread for it a while ago, i think the biggest you can go on a vw block tho is 2.2 with alot of clearancing and thats with a gas engine, and no chance at a rebuild if the bore gets screwed

http://www.vwdiesel.net/forum/index.php?topic=19163.0

[RabbitJockey]

i was just thinking of this earlier and figured i would post it, really the best way to build a 1.7 would be to use a 1.6 crank in a decked aaz block with stock aaz pistons and rods.  you would have to figure how much the deck needs cut down, but by using the aaz rods and pistons which are longer you get a better rod length ratio so the revability will be better. plus then you are using an aaz block that is actually made to have the larger bore, and you are using all much more available parts.  but then again, who decreases displacement haha

[R.O.R-2.0]

i think? the 1.9 has bigger rods, at both ends.. as well as longer..

i know the 1.9 is 16mm taller than a 1.6 (deck height)

but im not sure how long the AAZ rods are..

[RabbitJockey]

only the wrist pin end is larger, so with the aaz rod it would work.  i think 1.6 rods are 136mm and 1.9 are 144mm.  the only goofy part would be decking the block

[RadoTD]

Or don't deck it and get crazy low compression ratio and .75" lift cam and boost that sucker like mad!

[RabbitJockey]

i don't think there would actually be 16mm, some where in between i guess.

1.6 stroke
86.4mm

1.6 rod length
136mm

1.6 deck height
220mm

wrist pin center to deck
220-136-86.4/2= 40.8

1.9 stroke
95.5mm

1.9 rod length
144mm

1.9 deck height
236mm

wrist pin center to deck
236-144-95.5/2=44.25mm

so then u add half the 1.6 stroke to the aaz rod length, and aaz pin center to deck, and thats how tall the block should be

86.4/2+144+44.25= 231.45mm

so 236-231.45=4.55mm off the deck and u have a 1.7

someone double check my math but that all makes sense to me... who knows if the 1.7 would actually run better tho

[Runt]

Warning, the stream of conciousness below may contain blasphemy.

So, if I'm reading all of the above correctly, I could assemble an AAZ block with a 1.6 crank, measure piston protrusion (actually recession at this test) and then have the block decked about 4mm to get me to spec for a one hole head gasket.  That does sound very interesting, although I would like to point out that the OP mentioned raising the CR of the frankenmotor to improve cold starts as his motivation, and and this short stroke 1.9 block would still only recover about a third of the lost compression.
So now to run with this thought a little, wouldn't the same details apply to a 1z/ahu, and maybe later TDI as well?  Is this the obvious answer to some people's search for a tdi piston for the 1.6? I'd love to get some deck thickness measurements on both the AAZ and early TDI engines.
I do really like the idea of a 1.6 crank in an AAZ, free breathin, free revving 1.7l.  That said, putting a 1.6 crank in an m-TDI sounds almost perfect to me.

Anyways, I'm just thinking out loud.

[R.O.R-2.0]

if you deck the block that much, how much deck are you going to have left? i think its either going to be paper thin, or an open deck, like a honda engine..

[RabbitJockey]

it would work on a tdi, too but tdis can't rev like an idi because they burn the fuel slower, also don't tdis have a trigger wheel on the crank, so it would need to be a tdi-m, honestly even on an idi it's probably pointless to lose the displacement, it would just be fun to build something different.