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IDI to TDI, a few questions
by
lord_verminaard
on 26 Oct, 2011 13:16
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Say I have an AAZ block, and I acquire a 1z TDI head, would I be able to use ALH TDI pistons in the AAZ block? Or would 1z pistons be my only choice?
Thanks-
Brendan
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#1
by
410
on 26 Oct, 2011 21:47
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You can use the alh pistons but there is one issue. Since the top ring groove on the alh piston is higher than the aaz piston, the ring can catch the ring groove in the cylinder wall. Even the ahu or 1Z pistons have a higher top ring groove than the aaz but not quite as high as the alh pistons. If there is no ring groove in the cylinder wall or you've bored to the next size then your fine. I'm sure you know this but you also need tdi delivery valves, injector lines and valve cover to make it all work.
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#2
by
rallydiesel
on 27 Oct, 2011 13:03
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This is all assuming you are going mtdi. If you want to run an ecu, you will need a tdi block as it has the casting to accept a crank position sensor.
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#3
by
lord_verminaard
on 28 Oct, 2011 11:56
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Awesome. Just the information I was hoping for. Thanks!
So rods. Some use AAZ rods with the TDI pistons, can I use TDI rods on the AAZ block? Since I have a set of those too that I won't need for my Scirocco TDI build.
I do plan on MTDI for the AAZ to-TDI conversion, not aiming for a ton of HP, just double what the car came with in the 1.6.
Thanks folks-
Brendan
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#4
by
MJF
on 29 Oct, 2011 03:31
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130+hp PD rods has larger big end, so those won't fit, but all othes will.
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#5
by
jimfoo
on 23 Nov, 2011 19:22
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And if you don't use TDI delivery valves???
You can use the alh pistons but there is one issue. Since the top ring groove on the alh piston is higher than the aaz piston, the ring can catch the ring groove in the cylinder wall. Even the ahu or 1Z pistons have a higher top ring groove than the aaz but not quite as high as the alh pistons. If there is no ring groove in the cylinder wall or you've bored to the next size then your fine. I'm sure you know this but you also need tdi delivery valves, injector lines and valve cover to make it all work.
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#6
by
410
on 24 Nov, 2011 14:42
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And if you don't use TDI delivery valves???
I don't know what happens if you don't use tdi delivery valves but I do know they are different. The tdi ones have a bleed port and the idi ones are designed to leave a bit of pressure in the injector lines. I remember reading about it in my Bosch manual but I lent it to a friend so I can't reference it right now. The other issue is if they are a different length, so the lines don't fit so nicely!
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#7
by
oldpoopie
on 02 Dec, 2011 20:56
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I think I've got a set of TDI delivery valves lying around.
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#8
by
jimfoo
on 12 Dec, 2011 01:00
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Well, I guess I have been running mine with AAZ delivery valves since '07, although my pump never has become a full M-TDI pump yet. I got a kick out of reading my original IDI to TDI thread, although it made me realize I have forgotten a lot! Well, now that the overheating is finally fixed, maybe I can slowly return to where I left off on my pump mods, where ever that was.....
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#9
by
jimfoo
on 12 Dec, 2011 19:25
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Good to hear. That way I have one less thing to worry about